Published: June 18, 2014

Categories: Hot Water

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A question asked on the Wall, "Who, in your opinion, makes the best modulating-condensing boiler?"

Andrew Hagen replies:
My favorites in order:
1. Viessmann Vitodens
2. Triangle Tube Prestige
3. Lochinvar Knight
I am torn between the simplicity of the Prestige versus the complexity of the Vitodens. The Knight would be my choice for larger sizes. Also the built-in ability to control multiple boilers is a nice feature of the Knight.

Steve Ebels replies:
My three weapons of choice in the same sequence.

David Goldman replies:
Curious andrew and steve why buderus GB series NOT on list? features, reliability, price, ease of maintenance?

Steve Ebels replies:
For me, and maybe I'm paranoid here but..........Aluminum in a heat exchanger just doesn't seem right to me. I've heard all the stuff about extra thick HX walls. Oxidation forming a corrosion barrier etc etc but I'm going to wait and see what happens. Customers are too few and far between to have something I installed turn to junk in just a few years.Not saying they are going to, just that I've seen a lot of products hyped with "new and improved" that turned out poorly. For that reason I will wait and see on the Ultra along with the Buderus, Dunkirk and other aluminum HX models. I sincerely hope that my doubts are totally without merit.

As an example, I'm seeing failed secondary HX's in LP fired Carrier and Bryant condensing furnaces almost weekly.Secondaries are galvinized steel lined with high temp PE plastic. Those were supposed to be better than the
competitions stainless steel versions. Guess how many SS heat exchangers I've had fail in the Goodman and ThermoPride furnaces I've sold.............ZIP, NADA, NONE Neither have I had a single HX fail in a Viessmann, TT,
Knight or a Munchkin. They are all stainless. I'm not saying that stainless is nuclear proof, just that it has a little more proven track record from what I can see.

Call me "previously burned".

Brad White replies:
Agree with Steve and forgive me if I sound like a broken record here. Most manufacturers of aluminum heat exchanger ModCons require that you maintain the water-side chemistry at a pH of 8.5 to 10 depending on whom you ask (note: Alkaline side of the scale).

Why is it then that the hotter and far more acidic combustion side, with a pH of 3.5 to 5.0 is said not to be a problem?

Yes, you can engineer around depleting aluminum with thicker walls, but the slurry that results not to
mention the degradation, concerns me.

My $0.02

Steve Ebels replies:
Brad,those thoughts, backing up my concerns, coming from a person with your knowledge, intellect and experience.......... well....... it just makes me feel all warm and fuzzy inside. I am truly humbilified! ;o)
Have a nice evening!!

Drew replies:
Brad,could you be more specific with what manufacturers have given this information about the pH levels you've given? I'd like to speak with them on this issue.

boilerpro replies:
FAVS....I am using the Tube with excellent success. Solid welded heat exchanger with 15 years of use in the field, small low wattage pumps are all that's necesssary, no need for P/s pumping on most systems,common sense design and good support. I haven't used any Vitodens yet as they are hard to get pricing on in my area and aren't supported well yet (most wholesalers haven't even heard of them around here.....just sad), even though that may be changing. I really dont like the Giovani (sp?) heat exhanger used in so many modcons, it does not seem to be a well thoughtout design with condensate and debris being able to drop onto the flame.

Also the high pressure drop on most modcon heat exchangers really is wasteful when you look at electrical use.

NRT.Rob replies:
the prestige solo is a really well thought out, simple, elegant machine isn't it? We're really impressed. 6 replacement parts and you're fully stocked for service too... pretty cool. Still not selling boilers, but we're recommending the solo as the standard recommendation these days.A true one pump system sure is nice.

Robert O'Brien replies:
The quality of the Vitodens 200 is incomparable. Prestige would be my second choice.

Derheatmeister replies:
My choice: Viessmann, Triangles Prestige, and baxi luna..will look at the Lochinvar soon.. never installed a Munchkin ,Had to service one 2 weeks ago and it was not pretty.

sam weene replies:
The vetro 3m23tu is excellent

sven replies:
While it's still very new, so far I LOVE my Weil Mclain Ultra 3.

spicoli replies:
Doesn't matter..
The installation is ten times more important than the brand. What does your local radiant contractor recommend?

Mike replies:
Munchkin, BAXI, and Triangle seem to be the most popular choices locally. (Colorado)

Shaun Anderson replies:
In my area of Colorado...
Prestige, Prestige and more Prestige with a little Viessmmann thrown in. Not seeing much of Munchkin , Baxi in my neck of the woods of Colorado.

My top choices based on proper installation: Viessmann Vitodens 200 Triangle Tube Prestige

Don replies:
I am a former Munchkin dealer and have switched to the Lochinvar Knight. Munchkin boilers USED to be the one of choice for residential.....then they got too big too fast. We had an install go south....WAYYYYYYYYY south on our last Munchkin install (Oct 06) and are still paying for it. The Knight is the greatest thing since sliced bread in my opinion. Easy set up, constant update, flashable firmware. I've got 11 out there in both commercial nad residential, and they are going strong and trouble free. Built in cascading sequencer and priority zone DHW. Everything you could ever use and more. They've even got 2-10v DDC input for setpoint shift and BMS use. My .02 worth.

Mad Dog replies:
We have had outstanding success with the Buderus GB series. Have had no problems at all with them - very affordable and high quality. Aesthetically, I find them superior-looking in comparison to many out there.

Glen replies:
Yes to all mentioned - and I would add the IBC boiler out of Vancouver BC. But the best condensing boiler is the one with which the installer has intimate knowledge and experience with. Even the best or most expensive can be emasculated by poor installation.

carragebolt replies:
Have installed Baxi was not impressed.Viessmann vidodens 200 is graet but very complicated-230v 50 htz circ pump. My favorite by far is buderus GB142.Simple and installs very Quickly and is half the price of the Viessman

Justin replies:
I'm in New Hampshire and a Baxi dealer. On the whoelsale level we have sold hundreds of baxi boilers. THe are one of the best mod con boiler with out door reset. The Work extremely well during harsh conditions when properly set up!!! After selling all the others... vitodens munching and triangle tube BAXI is #1 in my neck of the woods.. I even have an HT-330 in my own home!!!

Rod K replies:
I really like the Knights, a dream come true so far. Very simple to set up. You don't have to be from the planet "Smart 5" to make these things sing a nice quiet tune. Best of all, made in the USA.

J. Mac replies:
TT Prestige Knight Viessmann. Based on my personal experience. We've installed a truck load of the TT's with virtually no issues. Many on LP which seems to be problematic with some of the mod/cons. I only rank Viessmann at the bottom of the three because of the price, I think they are better made (by a small margin) but not by 100%, but they seem to cost 100% more than the TT. The TT's low pressure drop and very simple and user-friendly interface are key in my book.

Recently had a customer for whom we did a change out from CI boiler to a Knight compare his therm usage from Jan 07 to Jan 08 after the change out. He reported a 45% reduction in therms. According to DD records the two January's were very similar. This was on a hot water baseboard retrofit and is operating on ODR. He is one happy customer.

Best of luck to all.

Mad Dog replies:
I guess only time will tell BUT i AM CONFIDENT IN THE PRODUCT. Even though we work in some of the
wealthiest areas of the USA, most of the folks are not willing to go for the extra bucks of the Viessmann.

Darin Cook replies:
There are some great mod-cons on the market. I personally am a big Buderus fan. Excellent product for the money. I have many beautiful installations out there purring along, saving folks money on their fuel bills. Another great side feature is that I can seamlessly integrate all of Buderus's solar product right into the boiler controls

I have been to the Locinvar Knight boiler presentation and it appears to be a well engineered product. I have a couple of jobs where building a wall to hang a GB 142 may not be an option and the floor mount Knight would fit the bill nicely.

I have personally installed five of the TT prestige. It is a great product also. I think it also is a nice boiler for the money also.

All of these boilers are great equipment and the challenge for the homeowner is to find a qualified installer for any of these appliances.

Bob Bona replies:
I like the Prestige. You get a LOT of boiler for the money.

Mad Dog replies:
When 3 of the Greatest hydronicians (Jimmy The Gent Burke of Comfort Zone on The East End of LI, Mark Hunt and Darin Cook) I know have installed TONS of the product (Buderus)I had No hesitation installing the GB. If these guys don't know their S%^%$&*^%^[email protected]#$#2!!! I don't know who does and I need to go work at the hardware store. As I've said before, Viessmann is an excellent product and we do offer it, but is a hard sell because of the extra cost.

realolman replies:
Am I missing something? Is the smallest condensing Oil boiler 70,000 btu?

Tim "The tool man" Taylor replies:
The Binford 2000. It's a manly mod/con. (grunt, grunt)

Tim Smith replies:
I like the Prestige not one problem in 3 yrs of installing. That's enough to keep me going. Well thought out boiler, ease of installation. All that's needed to say.

Bob Gagnon replies:
The Buderus and Utica/Dunkirk Reps both told me they have used aluminum heat exchangers for over 20 years, without any problems, they say it has to be vertical so the condensate doesn't sit in the exchanger. You can't ignore the heat transfer capability of aluminum. What is the rate compared to stainless steel? I use the Utica UB95M-200, it is a great boiler. It has a 15 year warranty on the heat exchanger, and I would rather have a one piece cast exchanger than a gasketed, multi-piece heat exchanger bolted together. Parts and service are easy to come by at Utica.

Steve Ebels replies:
Heat transfer rate - From what I can see, that's a smoke a mirrors type thing. It is a true statement, aluminum does transfer heat better than stainless. What you never hear though is the complete statement regarding that capability. It would read something like this in layman's terms.

While it is true that aluminum heat exchangers transfer heat at a faster rate than stainless steel, the increased thickness required for strength in an aluminum product largely eliminates any heat transfer advantage it would have over stainless steel.

At least that's the way I understand the physics of the two metals.

jp replies:
Little tricky steve, while Al is about 15 time more conductive than stainless, it needs to be thicker. You also need to look at the specific heat of both, btu's needed to raise 1lb 1F, Al takes almost 2x more Btu's per lb. but then you get a lot more Al per lb than stainless. Hard to say without knowing weight of similar heat exchangers? Though I'd agree with you that stainless is preferred.

scott markle replies:
Seems like condensing oil is still in it's infancy. As far as I know Budarus has an offering as does Peerless and that's it in N.A I Had a look a the inside of a Vitodens oil wall hung, wow did it look sophisticated, Apparently it requires ultra low sulfur fuel so it won't work here. Not sure what the firing rates on this unit were but it's a true modulating boiler so I would imagine they go below 70k.

Maybe this is misinformation but I have heard that firing rates below .7 gal. gph are prone nozzle clogging issues.

JimmyK replies:
Just finished a nice install on the Crown Bimini. Once the wiring got tightened up this unit really sings.

Dave replies:
Bombarded with many choices, but has anyone given you anything to really see? I'm partial to the TT Prestige myself as many have endorsed,, here`s a PDF for your perusing, I`m sure you`ll find it supreme quality, fantastic tech support, a great "bang for the buck" and very flexible system adaptation. Enjoy!

Rick replies:
What Darin says - Having witnessed many many installs by Darin & Mark, I will have to say "Whatever they say works for me" Absolute masters...

Jeff replies:
I am very satisfied with the ease of installation with the Buderus GB. The Performance in phenomenal with the outdoor reset. The controls are simple. The pre-piped manifold makes life easy and installation cleaner and faster. I will attach a recent boiler change out.

Dave Stroman replies:
No thing mentioned in this thread about Trinity. I have had great success with them. I have heard so many good things about the TT that I am adding that one to my favorites also.

BadgerBoiler replies:
Mod/Con zealot - I too have installed both aluminum (Ultra/GB) AND stainless steel (Munchkin/Knight/Prestige etc.) without incident. I never met a Mod/Con I didn't like.

Dobber replies:
GB for me - I to couldn't be happier with the GB's. I've have around 35 of them out there and had only 1 problem and that was the condensate trap. As for PH, I don't care what boiler you use you should make sure your PH is set properly. If not for your boiler, then for the rest of your components.

mike replies:
Dobber, nice work. What type of pipe supports are you using to hold the 3/4 to the wall??

Dobber replies:
Thanks. There called ring stays or stand offs. Quite popular up here in Ontario.

cfh replies:
SS Mod Cons - How many of those boilers use the same Giannoni France heat exchangers? Munchkin,Knight, Trinity, Alpine ect. Has any one found out who is making the heat exchangers for the Ultra and other products that are similar. The Ultra and the Alpine use the same controller

joel boucher replies:
We have installed several vitodens 200 and 100 models and some Prestige,just did a TT 60 and that is a sweet low output unit I don't like how they do not give you all the programming info with the boiler. Went to set it up yesterday and couldn't find my special book grrrrrrr now I've got to get it from TT they should put it with every boiler like Viessmann does. People think programming the TT is simple compared to a V200 but that's only because with the basic instructions TT isn't letting you do anything!!!!!

Scott MIlne replies:
I find it hard to believe that one of the largest boiler manufactures in the world would stake its reputation on a boiler who's heat exchanger has not been field verified ??? I am a huge fan of the Buderus GB boilers.

Dan Holohan replies:
If you've picked a favorite, would you please tell us why you like that one the best? Is it the technology, the
company, the service, the reputation? What makes you like that one best? Thanks.

Robert O'Brien replies:
I prefer Viessmann.You have to see the HX to understand the difference between Viessmann and all the Giannone's. Pictures are useless,hold a piece of a Vitodens and Giannone HX in your hands and you won't have to think twice.The 200 control is incomparable to anyone else's as it should be at the price point.The 100 is the
same HX without all the extras.Add a Tekmar and you're all set at a very reasonable investment, if the 200 is not in the budget. The Triangle Tube Prestige,although I don't believe the quality is Viessmann level, is very nicely made and quite a bargain at the price.The downfired design has a lot going for it and the low pressure drop will allow non P/S piping in some cases making it easier and cheaper to install. I have no install experience with the aluminum HX boilers although I install a tremendous amount of Buderus products and have never been disappointed. I service quite a few aluminum HX boilers and would use them in the right application,I just don't see the right one very often.

Scott replies:
I prefer the Buderus GB142. It's a well-made, simple design from a company that backs all its products. It is affordable and allows outdoor reset in a simple design that is easy for my men to set up. It has shown itself to be reliable.

bill clinton replies:
My favorite is the Prestige. Very well made, very reliable, well supported. I do not like the aluminum heat exchanger brands because I have bad experience. I have had two heat exchanger disasters with Buderus GB.

One disaster was caused by a leaking relief valve. By the time we found out about it, chunks of oxidized aluminum had clogged two zone valves. Amazingly, we got it cleaned up, leak fixed, and it is still operating. Cost a lot of time, though.

The second disaster was caused by a very small leak in the tube embedded in the floor. Yes; we DID pressure test the installation and it was tight at that time. Something got to it after the test. Slow but constant flow of makeup water flushed out the corrosion inhibitor we had installed and constant source of new oxygen corroded HX. We came out because the customer reported no heat. GB heat exchanger totally plugged up and no
way to clean it. Replaced with a Prestige and ate the entire cost. Buderus, understandably, would pay nada. Ouch!
You can argue til the cows come home that this was not the fault of the boiler: It wasn't meant to operate
under those conditions and you would have a point.

My point is that my system was not meant to operate that way either, but due to circumstances out of my control; it did. The natural result was severe corrosion.

I conclude: Why risk it when stainless is available?

scott markle replies:
I say the Vitodens 200- for having a user adjustable parallel shift to the heating curve. True constant circulation ODR requires a well-calibrated reset curve. Some here have commented on the complexity of the Vitodens, true but in some ways it is also very simple. Simple enough that the user is invited to make adjustments to the reset curve. Room temperature on the Vitodens is expressed as a relationship between an analog 1-10 dial and the programed curve. I like that the curve is expressed a single parameter (reset ratio) as opposed to design temperature parameters. If the selected curve is off it's easier to understand the effect of this one setting than it is to tweak one or both of the axis.

As far as ease of use- the four button pad + jog wheel, menu interface is miles ahead of the interface used on The MCBA. The really cool thing about the comfortrol interface is how it presents it self to the user. The sun and moon dials. When turned these analog dials (digitally) display the desired temperature. If the reset curve is set incorrectly this displayed temperature will be incorrect. The beauty is that these dials are parallel shift adjustments to the heating curve. If the user I discovers that 68 on the display is really only 65 in the room, they know that the curve needs to be raised. Giving the user simple direct shift adjustment is a unique and efficient mode of control.

Less "complicated" systems generally use a curve that supplies temperatures a bit hotter than what the average heating load requires. The user has comfort adjustment by means of on/off indoor thermostats. This means that we are operating at higher temperatures than we truly require most of the time. User access to shift gives a combination of responsiveness and lowest possible heating temps. Tekmar tn4 also accomplishes this by different means. One reason not to like the vito 200- it's not particularly friendly to third-party controllers, I wish they had a paired down control option that was 1-10v ready.

Mike T. replies:
I have to agree with you regarding the controls Scott. I especially like that FULL reset curve adjustment (shift and slope) is contained in the USER manual. I find it a bit of a shame that most mod-con manufacturers consider the curve "off limits" to homeowners. It's not particularly difficult to make the adjustment, but it does take considerable time as you really need to wait a few days between adjustments--even a week or two once you've gotten really close. I found it FAR easier to start with too low of a curve and work my way up. The starting suggestions in the user manual are pretty good, but my curve (I have massively oversized standing iron rads) is down in the "radiant floor" area. My 200 has been running with an ideal reset curve for three seasons now. Even though I have TRVs on
all radiators, the sun dial setting is right at the maximum temp I can maintain in any room. An important thing to remember about the sun/moon dial parallel shift is that it does NOT flush the boiler's memory. Coded changes to the curve (shift or slope) clear the memory and it must re-educate itself.

Once fully-educated and operating under an ideal curve, I've found that should I want to raise temp fairly fast in a room whose temp is normally kept low, I have to press the "Party" button. Even a radical change in the sun dial setting won't greatly increase output and it can take many hours--even a full day--to get the temp up to the desired level.

My only beef with the control system is really a suggestion for improvement. I greatly appreciate the "German efficiency", but it seems to assume that every structure is solid masonry (likely with exterior insulation) and thus SLOW to respond to outside temperature changes. An old (1903) house like mine with reasonable but meticulously installed insulation and LOTS of big windows and glass doors in ALL directions responds FAR more rapidly to outside temperature fluctuation. I really wish the thing had a three-position switch: one showing a stone castle; one showing a row house; one showing a detached "stick" house. I've FINALLY installed my outside temp diversity system. One outside sensor (the original) is properly installed on the North wall. The second is on the South. I'm going to switch between the two (using a good relay with gold plated contacts) going to the South-facing sensor from early-to-mid morning to mid- to-late afternoon.

Mike Bernasconi replies:
We have installed both Vito Dens 100 and 200. Buderus GB142 and alot of Lochinvar Knights. The Vito Dens 200 is the best product but it's price point makes it a difficult sell to the average home owner. The 100 with the added Tekmar control kind of made things a little more difficult and definitely not as clean looking. The Buderus GB 142 is a great looking unit and installs pretty easily. Their control options are somewhat limited but will improve greatly with the RC35 which will be coming. We have concentrated mostly on the Knight's for several reasons. First of all you can cover a huge cross section of the residential and commercial market with this product all using the same built in control. This makes training service techs very easy. With the addition of the wall hung units it is now even better.The units look good and the foot print is great. Local and national tech support has been great with all three manufacturers. That's my 2 cents.

Rely Mech replies:
I have installed a number of different boilers in the past 5 years and all where great the day they first where started up. The true test is when you have a failure at night or the weekend and you know tech support is not there. I have had this happen to me being the Guru of condensing boilers in my area and I know that most who post here are in the same boat, we'll get a call from Mrs Smith that her boiler that was installed by ABC company is not working and ABC is not answering the phone and could you please come out and fix my boiler. I have seen a lot and 9 times out of 10 its is a bad install but there are those times that it is a problem with the boiler.I have called tech support on weekends and in the middle of the night of many companies but all yet only one has called me back NTI and it was the engineer at his home I could hear his wife and children in the background I was impressed.I have been to many training functions in the past 5 years for new condensing boilers only 2 have had combustion analyzer there and showed how to use it Buderus and Triangle Tube again I was impressed.I know that many of us are in different parts of the country and your experience will be different but the bottom line is all of these boiler will fail sooner or later! Do we have the backup and training to install and repair these boilers and then when all training and wisdom have failed to repair the boiler is there tech support? I think Trinity was a great boiler that got a condensing boiler in the homes of middle America. Now that it has been time test we know the flaws of this heat exchanger still my hat is off to NTI they got the ball rolling.Now we see 4 or 5 borthers to Trinity and we are worried. Triangle Tube looks like a good design and we have installed 17 so far but again time will tell how good a design it is and then we will put tech support to the test.So all the Companies out there beware you need to have no just tech support but the greatest tech support to get my vote. Still on the fence. Thanks.

Dave Yates replies:
Check out the current Consumers' Digest "Best Buys for Boilers, Furnaces & Heat Pumps"

Steve Gronski replies:
I only will install the Viessmann Vitodens or the Triangle tube Prestige. I am fortunate enough to have Viessmann right here 5 minutes from my shop when I need support advice or just being able to send the customers into there showroom to see the product and actually hear it in operation. I also have been fortunate to have the opportunities to actually go to Viessmanns plants in Germany in the past, and triangle Tube (ACV Industries) in Belgium this year to see how the plants are run and how these boilers are manufactured. Both are the only boilers with there own patented design on there stainless steel heat exchangers. I use both boilers depending on the applications, situations and circumstances of the job. Here In RI I do alot of homes with these boilers by the ocean, and stainless holds up better to salt air than aluminum all day long. Call Weil McClain, Lochinvar, or Buderus and see if you can get a straight answer on heat exchanger warranty with there product if it is going to be installed around salt water. Vitodens are a bit pricey compared to the Triangletube Prestige,and they do offer more features for shifting heat curves controlling mixing valves, and even solar. If you take TriangleTubes training class in Blackwood NewJersey, you can learn to shift curves as well with there control and clever ways to use there boiler with mixing valves. When I do an atmospheric gas boiler swap out, I can usually pump right thru the Triangle tube 90% of the time without any need for a low loss header (like the vitodens require) or primary secondary piping.Both companies offer great technical support, service and training classes.I will usually use the Vitodens on most of my radiant heat systems because you can set it up with there mixing valve that works right with the boiler.If I people cant get the to accept the cost of the Vitodens, the Triangle Tube is a great option as well with a Taco I Series 3 way mixing valve, and 9 out of 10 times it will get you the job and save the customers significant money. I have a VitoDen Heating my house, I have the curve so dialed in after a year, that my house only needed 153 degree water on a 1 degree day last year to maintain 68 degrees and it is set up on constant circulation. I have a Triangle Tube Prestige Solo 175 snow melting my driveway, no low loss header, Just a Taco 0014 pumping thru the boiler, the manifold and loops.I have a nice 30-degree delta on my snow melt when she is up and fully running to temperature.

Jeffrey Eichenwald replies:
All of the previously mentioned boilers are fine. For those of us who work with tall multifamily buildings, the list is much shorter. Most of these boilers are only rated at 30- 40 psi which is not enough for a building four stories or more. The Lochinvar Knight boiler is rated at 80 psi and the Heat Transfer Products "MOD CON" is rated at 160 psi. The Laars "Neotherm" which uses the same Giannoni heat exchanger as the "MOD CON" is also rated at 160 psi.

Brant Wininger replies:
All the Knight Boilers are now rated at 160 PSI.

Glenn E Sossin replies:
Press rating significance?? - I don't think the pressure rating of an exchanger is relevant for most residential installations. I'd be more concerned about maintenance issues, longevity, and what it was made of. I spoke with a plumber who installed an Ultra, which he had to pull out after just 2 years. He said in the course of removing it, his fingers penetrated the casting- it was that corroded internally. I am waiting for some photographs.

My favorite is the Prestige. The heat exchanger is vertical, multiple baffles/flue/water paths so it has a very low head loss. You can usually pipe straight through it, primary/secondary not required, although I'm a big proponent of using hydraulic separators.

If you've ever looked inside the cabinet - it is simple. So simple, that if you didn't understand the concepts of condensing, you'd look at it and wonder how it could possibly work.

The multiple sensors are the same so it's easy to trouble shoot and confirm a bad sensor by swapping them and or leads.

It uses the MCBA reset/relay board, same as WeilMcClain Ultra, Burnham, Dunkirk.

It has an internal relay providing fused contacts for the primary(central heating) and DHW pumps. A service kit (attache case) is available with all the major components, gas valve, fan motor, transformer, MCBA board, sensors, - virtually every part that might fail.

I believe it has the highest water content of comparable wall-hungs - helps to prevent flashing, and having the controls shut the boiler down because the temperature rose too quickly.

439 S/S Heat exchanger. Even with high soluble iron content water, I don't see this ever plugging up. It's a vertical design essentially makes it self cleaning.

Although sometimes difficult to reach - they have a great tech department - especially Greg Mana. When I have a question, or need a 2nd opinion on a design - he's there.

Multiple venting options - PVC exhaust, easy to do combustion testing/adjustments, relatively easy to convert from LP to Nat - or back.

Dan, I thought it also be interesting to see/hear the other side - so I will volunteer - WHAT I DON'T LIKE about the Prestige.

The terminal strip / wiring board requires this little plastic key. I think its difficult to work with - lose it and your in trouble. I carry a few extras around with me in my car and attache case.

Programing the control is not very intuitive - no real user interface options to speak of. We just took on Viessman so I will start to get some 1st hand exposure to that product. By some of the comments made, they obviously have a usable user interface. With fuel costs as they are, I think this is important. I think the quality of the finished product could be better with respect to the boiler connections. I have had several boilers with loose internal union connections. Not a real big deal - you notice it when your connecting up to the boiler or start to fill it and water spurts out in the cabinet.

I'm concerned when it's sold to a gorilla plumber, you know the type, - the guy who splits open IPS ball valves and brass couplings because he tightens them so much.

What I like most of all, the value. The price is reasonable and competitive with all the other brands. When you look at what you get for the money - I think they above everyone else.

WHAT I'D LIKE TO SEE - A version of the Prestige without the MCBA board. We have used these
boilers on multiple boiler installations and snowmelts, and essentially give the boilers a lobotomy when we use Tekmar controls. Now the customer is paying for something they are not going to use.

My $.02

Joannie replies:
Pressure Rating Clarification - The pressure rating of the heat exchanger does make a difference, because it dictates the maximum pressure setting allowable for the pressure relief valve on the boiler.

The pressure relief valve cannot be any higher than the pressure rating of the boiler. In high-rise applications, the pressure inside the boiler can be high enough to exceed the relief valve setting of units that are rated for the typical "residential" 30-50 psi.

Some of our units are 30 psi maximum, because they are intended for residential use (in a house) and we have run into the high-rise scenario a few times.

Pete Caruso
A newborn with muscle. - I'm paid to sell the rAy boiler.

The WALL is not the place for sales talk.

If you go to and take a look at rAy and have questions about it, I'll answer either here or privately. [email protected]

Anybody out there who has used them have anything to say?


Tim Smith replies:
Per Dan's request re: why we like which one - The TT Prestige has been flawless for us over the last 3 years, period. No failures of electrical components. Hardly any build up on gas side in heat x after 3 yrs. Just a little that we lightly brush off and flush out. Set up is quite easy. Venting to a 100 ft except the 250mbh unit. Low pressure drop, much lower than all others on this units water side. Tech support, been good for set up questions but other than that have not needed. Putting one in my house as I type this.

Paul Rohrs replies:
Good info Tim Smith. Okay, so the Prestige DOES require servicing the HX over the course of time. I was being led to believe that this heat-exchangers "Self-Cleaning" design trumped the need for cleaning like EVERY other modcon out there to include the Viessman. No doubt, it sounds like the Viessman is a very well put together boiler but I have yet to install one or have my customer request its installation because of a "Green" mindset.

We have enjoyed a lot of success with the Lochinvar Knight. Well thought out design, software with reset, setback, and fuel conserving options that can be easily tweaked.

Standard software also handles sequencing multiple boilers for a huge potential of staging, rotating, and minimum fire capabilies on very large systems.

"American Made" still means a great deal to me. The Knight also has a support team just outside of Nashville that is readily accessible. As with any boiler, reading the manual and adhering to industry standards and guidelines will keep you off of the phone (IMHO).

I will say to answer the "Best Boiler" question. It is a boiler that has been properly sized and installed by a professional contractor that has been factory trained.

John L replies:
Wow, The Ray looks like a Robot!

Pete Caruso replies:
Like a good robot...rAy is easy to "talk" to, does what you tell it to, can do many things, and is reliable.

TDH replies:
For those of you not completely sold on stainless or aluminum,you may want to look at rAy.A cast iron condensing boiler made right here in the USA.

kal replies:
"and is reliable" ? based on how much field experience???... also it seems like the heaviest boiler per sq-ft out there – the single section hx is twice as thick as a regular cast iron section of same size, better buy a powermate hand truck and the question is why? - as a modcon - it has enough electronics and moving parts to make it on par with all the others as far as reliability goes, the way i see it is, that the hunk of cast iron buys you two things:
1) a low loss hx, allowing you to pipe a load straight through without the extra pump for pri/sec (ie more green), 2) the mass acts as a buffer tank for the small loads Perhaps a possible third advantage is less likelihood for cold shock stress fractures which plagued early stainless steel hx’s – but we really havent seen those on the newer designs if either of these two requirements don’t fit your design, then, i cant understand why you would want it – at 4grand street price for 199kbu, it's not exactly a bargain, – you can buy a triangle tube prestige 250kbtu for less and it also has a low loss hx, and if you have an indirect with it, and run it hot, and mix-down to 120 for domestic use – then you can use the excess heat of the storage tank for those small loads – so you have “green” for a lot less, not to mention a lot lighter, with a good track record to boot i dont know, maybe all you rAy lovers know something i dont, i'm all ears!!

NRT.Rob replies:
I don't know about reliable, but one thing I like about the prestige is the water content which adds mass as well and is always helpful. I don't see why you'd ever want to limit a mod/con to running at DHW temperature or higher in order to use a storage tank as a buffer. In that case, you really want a separate buffer so you can run at lower temps.

kal replies:
You would need stage it since the indirect is there anyway, just run it a little hotter, and use a seperate aquastat that opens on cooler (i use a johnson a419 which allows any combonation) and when the tank is above 160, the heat demand routes through the closed aquats contact to a relay, that runs the indirect pump, and
the load pumps of course, and as the tank cools down, it opens the line to the relay, the relay drops out, the indirect pumps goes off, and the relay's normally closed contacts now route the demand back to the boiler - simple, this way, you dont run the boiler out of modcon mode when not needed - just runs a little longer when making hot water anyway - so for the cost of an a419 and a relay ($100) - you have a ready heat source for those "short time" loads - i am in brooklyn NY, where there really isnt room for a buffer tank, so every trick helps

jimmy replies:
This sounds interesting to me. I'm across the bridge in SI, but space is equally limited in the older houses. Exactly what did you do to make this work for you? I have a Triangle 110 with a smart 40 in an old house, gravity conversion. Any ideas?

kal replies:
my favorite is the knight, but since none of them are a fraction as reliable as a cast iron with a standing pilot, i
always insist on redundancy, and a dealer with good service, i have wallce-ennace of long island to depend on for my knights and they are great - this is very important i just did a 7000sqft fancy house with radiant and snowmelt, the works, and it was done with two cast iron standing pilot boilers (oh the waste!) but i could not counter the owners argument that they are the most reliable hands down, so i piped them primary- >vari-speed-injection->secondary to protect the boilers and have a nice day!!! he doesnt care if 20% of the energy is going up the flue - cause he knows, that for the next 30 years, he wont know from a dead boiler!!! stick that in your pvc flue and smoke it!!! -- of course
the guy has a full building automation system for everthing else - i cant wait to gloat when he hits a light switch and nothing happens, that will give him orders upon orders of magnitude more grief than any modcon ever could ;)

roy downeaster replies:
I gotta tell you the Munchkin by Heat Transfer with the Vision controls is the greatest. no maintenance, no problems five years

Tim McElwain replies:
Wow lots of opinions!

kal replies:
there wasnt enough mentioned about servicability...i get called in to solve those real bum jobs that go south that we had nothing to do with - i have too many picture to post, from a Weill McLain ultra vented with galvanized thin flue, raining acid all over the place, to a NTI boiler that had it's intake piped 4" off the ground and sucked in a
plastic bag, so how well a boiler stands up to stupid abuse and how easy it's to diagnose & service should also be on the table!!!

this is why i like the knight's so much, the plain English display - that tells you in 2 seconds if you have a Call For Heat, a Call For Domestic hot water, what the temps are, and even what the fan speed and flame sense current is, right on the display - not to mention the ease with which it all disassembles - trust me, it did not go unnoticed at Weill McLain - just look at the changes they made to the ultra, from moving the electric terminals in front of the flue to the English language display - sounds familiar? (they should have added a water PH sensor – cause it’s the one thing that can make an aluminum HX go south real fast)

Rick replies:
They must all be pretty good! If all these people took the time out of their busy day to write. I'm glad there is so much quality in our industry...

roy downeaster replies:
Serviceability for my Munchkin Mod - Installed 2005, hung from ceiling of equipment room with unfired Ultra-Stor DHW storage; no service PVC flue - no cleaning; out of harms way for stupid-proof. My control system is "VISION-1" with outdoor reset; gives me 140 deg DHW and lower temps for my underfloor and baseboard zone heating.

john replies:
weil ultra series 3 hands down

Tim McElwain replies:
Add the Ray was at Mestek and the Reed Institute for a great morning yesterday (Oct 10) going over the new cast iron, condensing Ray boiler. It looks like a great product with some great features for ease of set up and service.

I like the down firing feature for maximum condensing performance and minimum boiler damage from acidic condensate. Those cast iron sections are specially designed for the condensing process, by the way it is not some magic type of cast iron just regular everyday cast iron, in fact it is recycled. They have been running this in their commercial KN series for sometime now with very few problems. The SmartCycle feature monitors energy use rather than bowing to out door reset technology for more accurate actual room temperature control with the IAR (Indoor Air Reset) feature for up to 8 zones. You can, as an option use outdoor reset is you so choose. There to the best of my knowledge based on what I saw no need for other external control systems even with multiple boilers setup.

No codes on the digital display but English and this can handle up to 16 individual units. Multiple unit’s set up is simple with the master boiler interfacing with the others and controlling firing with a simple phone type connector.

Simple to convert from natural gas to LP with just the turn of a screw, it also adjusts automatically to altitude changes for you guys up in the Rockies. It does require you to have a combustion tester for determining correct firing setup and is very easy to do with an actual new access panel on the latest version for ease of reaching the gas valve adjustment screws. It uses direct spark ignition with rectification as a flame proving system with a Fenwal control, which is easy to take microamps with, as you do not have to disconnect any wires using FC+ and FC- connectors.

Another nice feature is the steel mesh intake filter to keep out airborne contaminants. It can be removed by the homeowner and washed and put back in place very easily.

The AFUE is 92.7% at 199,000 BTUS and has a 5 to 1 turndown ratio with the ability to change the top end BTU with a low end to 40,000 BTU's. The boiler holds not quite 5 gallons of water. It will operate at from 3" W.C. to 14" W.C. gas pressure. The valve is a Dungs valve from the Netherlands, which gives very accurate and simple control with negative pressure gas technology. The vent is with AL-29-4C with at least four different manufacturers vent
material accepted for venting. It also has a special at the boiler connector required for vent connection. Finally I am a boiler and furnace I & O freak, as I love to read manuals and other than my Bible this is my favorite pastime. The manuals are excellent easy to follow and there are three separate ones:

  • 200i Boiler Manual
  • 200i Control Manual
  • 200i Vent/air Manual

I suggest you all take a look at this one and add it to the many real fine boilers we are seeing on the market today.

Kal replies:
the ray is a very pretty girl...just don’t try to lift her over the threshold, as you will get a hernia forthwith!!, did you even try to move it 1"? the new lochinvar 1.5million btu “sync” weighs less!!, I was able to move it an inch as I wanted to walk off with it at ASHRE, I know that a MultipleBoilerSystem is built-in, but the design doesn’t scale up very well, for the space limited light commercial or fancy home, I cant tell you how many 10,000sqft homes I go into with a 2 by nothing boiler room, and you even have to fight with the home owner for every inch of that, as they want to put the central vacuum in there, and an air handler hanging from the ceiling, and a whole host of other stuff!!! They have a 6 car garage and no boiler room – fancy that!!! They have fake fireplaces bigger than the boiler room!!! mestek, should also offer, the same exact design with cast aluminum, the extra thickness they put in their cast to handle condensing over the long term - should also handle low water ph that plague aluminum boilers, seen a big commercial one sold in Europe that does just that, they could easily make a 5 section 1million btu one, and it would still weigh less than the 200k one of the cast iron, they could run it a lot cooler than the cast iron, it would be made out of recycle soda cans, they could paint it green and add an ECM boiler pump, just need to come up with a good name for it… maybe “Hope” as in “ray” of “Hope” ;)

tim: you are right about the manuals – the ray’s are some of the best I have seen!!! I also love the read manuals – I seem to know them better than the company techs, I have caught many a tech support manager – not to mention some of those really awful manuals out there, but we would a need a whole nother thread with a thousand entries to even scratch the tip if the iceberg

Jed replies:
No heavier than a 3 or 4 section cast iron pin boiler, but with much smaller "delivery clearances". You've done those, haven't you, Kal?

But the Ray has so much more punch.

Kal replies:
yeah, but it was much bigger... and i didnt look like a wimp getting a bunch of guys to lug it ;)

Mad Dog replies:
The one you get free to "try out" on a job. Not many get "deals" like that.

Tim McElwain replies:
Some questions from Minnesota. I have been looking at the “Ray” boiler recently and I like several features about it. I noticed where you had recently responded on the Wall with some comments regarding the Ray.

I hope you do not mind if I ask you a few more questions separately here. With this boiler being relatively new into the market place I am trying to a shot at some due diligence here..

First of all, did you get to see one in operation? What did you think? My real question here is how stable was the flame down at 20% input?

ANSWER I did spend some considerable time in their lab with a unit firing from full input down to minimum with very good combustion test results and good flame stability, also very quiet even at full input.

This boiler can cover a very large range from 200 to 40 Kbtuh and there is a good chance that definitely into thru and after both shoulder seasons my application will be running near the 20% mark. My load calculations are right around 110kbtuh at a -20 deg F day.

ANSWER The other great feature with this unit is you can field adjust the high end BTU down to match heat load, that is down from full input to say 100,000 and set the parameters to fire there.

Everything I could read about the boiler I really liked. The weight I consider a plus and IF there is no increased corrosion of the CI due to the flue gases it may prove to be a great option for several users.. When I see pictures of the interiors of several heat exchangers ---- mainly SS, I wonder why the so called coffee grounds or particles are forming first of all, and more importantly --- will they corrode the HX from the burner chamber?? If you have some thoughts on what forms these deposits and do you think they are or could be a problem over time?

ANSWER I have several opinions on deposits inside both SS and cast aluminum units
1. It may be due to very low intake combustion air temps when outdoor temps drop below 20 degrees.
2. The possible increased amounts of Ethyl Mercaptan (odorant) utilities use in very cold weather.
3. Failure of homeowners to have annual cleaning done on equipment.
4. Improper set up with combustion analysis, even though it was done it should be rechecked after the brand new unit has been running a season.
5. Improper venting and the possibility of cross contamination of CO2 into air for combustion.
6. Failure to remove all of the acidic condensate at shut down and with that high temps held in the unit at shutdown.
The Ray by the way has a circulator post purge on shut down to cool the water and drop chamber temperature to prevent that from happening.


My last question is with regard to your comment on the CI sections themselves.. I realize that these same units are being used in their KN series, but you went on to say they have had “very few problems”. Can you share the problems that you are aware of regarding the CI castings?

ANSWER They recommend on old systems a complete flushing of the system as there may be iron particulate from the old cast iron boiler being removed out in the piping system. This could be a problem later on with reaction to cast iron in the Ray. This by the way can actually happen on a lot of new equipment. My take is when installing a new boiler flush the system four times with high pressure clean water. Then use water treatment to insure good metal to metal reaction.

Tim McElwain replies:
Will be getting my Ray for my training center tomorrow will let you know if I come up with anymore.
Date: October 26, 2008 04:49 PM

Tim McElwain replies:
Ray arrived all 500 + pounds of her, one thing for sure it will survive an earthquake.