Systems Help Center
Hot Water
- Air Control and Elimination
- Antifreeze
- Beyond the U.S.
- Boilers
- Circulators
- Combustion
- System Conversions
- Diverter-Tee Hot Water Systems
- Fill Valves
- Gravity Hot Water Systems
- Indirect Hot Water Systems
- Indoor Air Quality
- Insulation
- Loop Hot Water Systems
- Primary-Secondary Pumping
- Radiant Systems
- Radiators
- Sizing Systems
- Thermostats
- Zone Valves
- Compression Tanks
- Low-Water Cutoff
- Water Quality
- Hot-Water Zone Off a Steam Boiler
- Troubleshooting
- Hot-water-system pressure
- Piping
- Water Hammer
- Corrosion
- Snowmelt Systems
Hot Water 90 Articles
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Where to Find Used Radiators
Here are some places to find used and refurbished radiators in the United States and Canada.
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Three Hydronic Radiant Heating Myths
Myth #1: It’s bad for people with heart conditions
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Commercial Domestic Hot Water
My company does not do a lot of commercial work but one specialty niche we have is servicing the boilers and mechanical systems in the turn of the century apartment...
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The return pipe that was a supply
The heating business has a way of humbling you. After more than 25 years of running service calls on all types of heating and cooling systems, I had managed to...
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The cold, hard truth about snowmelt systems
Washington, D.C., is not exactly the Arctic Circle, but we have installed a surprising number of snowmelt systems over the years, everything from walkways and front steps to a 28,000-sq.-ft.
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Troubleshooting air and compression tanks
Ah, air! It's grand for living creatures, but often a problem for hydronic heating systems.
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Do I need to flush an old radiator from time to time?
No. Hot water radiators operate within a “closed” system where there’s little or no corrosion taking place.
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Where does the air vent belong on a hot water radiator?
Each hot water radiator should have an air vent at the top, on the side opposite the inlet pipe.
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Does a two-pipe steam radiator have to have a steam trap?
No, but it has to have something to keep the steam from entering the condensate return lines.
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What’s the difference between a steam and a hot water radiator?
It’s the way the radiator sections go together. They may be nippled together at both the top and bottom, or just at the bottom.
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The best place to install a cast-iron radiator
Q: If I decide to move a cast-iron radiator, where should I reinstall it?
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What’s the best way to disconnect, move, and reconnect radiators for floor repairs?
First, take care with those old pipes. Make sure you’re using two wrenches when you’re loosening the union connections.
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Can I successfully cut down the size of an antique cast-iron radiator?
Maybe. It all depends on how the long-gone manufacturer assembled the radiator. A cast-iron radiator goes together in sections, like a loaf of sliced bread.
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PEX for Hydronic Distribution Piping
PEX is a viable option for a variety of hydronic distribution-piping applications on both residential and commercial projects. With its durability, flexibility, range of sizes, system-performance characteristics and labor-saving benefits, PEX need no longer take a back seat to traditional metallic materials in the design and installation of a distribution piping system.
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How to Remove an Old, Threaded Fitting Video
A Wallie, Bio, posted this video as a part of a great thread that Delta T, another Wallie, started. He posted:
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Threaded Copper Tubing
A discussion on The Wall:
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Dissimilar-metals and electrolysis corrosion
I asked this question on The Wall:
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Tips on Radiant Heat and Wood Floors
The wider the boards, the greater the chance for trouble. Stick with boards that are no wider than three inches. Wide wood can warp.
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Air in a hot-water heating system
Air is the enemy in a hydronic (hot-water) heating system. It blocks the flow to the radiators. It rattles around and annoys customers.
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Watch the tailpipe
Start your car on a cold morning and walk around to the tailpipe. See that water dripping? That’s the way a high-efficiency, condensing boiler works.
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Grocery store radiant
A great place to understand radiant heating (or to explain it to your customer) is your local grocery store. Stop first in the gadget aisle and pick up a thermometer.
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Why closely spaced tees?
Primary-secondary piping systems call for the tees that go off to the secondary circuit to be close together, ideally not more than six inches apart.
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Discovering Water Hammer
Discovering that water hammer has moved into any hydronic system, be it steam or hot water is never fun, but finding the cause of it sure can be.
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Radiator colors
Ever wonder why so many of the old radiators you see are painted silver? Back in the day, they were mostly plain grey metal, but then the Spanish Influenza arrived...
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Pumping Away Piping
This is an excerpt from Dan Holohan’s book Pumping Away and other really cool piping options for hydronic systems.
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Water quality with high-efficiency boilers
The majority of the hydronic boilers we install today are low-mass, modulating condensing boilers. Sure, we still install a few atmospheric cast iron boilers on occasion, when budget, venting or...
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Old Radiator Ratings
If you're replacing a steam boiler, there's only one right way to size that boiler, and that's to measure the radiators. If you're replacing a hot-water boiler, you'll do a heat-loss...
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Let's chat about compression tanks
That I can get excited about compression tanks probably means that I'd be a lousy lunch companion, right? I mean who wants to hear about solving problems with something that...
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What is a thermostatic radiator valve?
A thermostatic radiator valve enables you to control the temperature of that specific radiator, thus giving you greater control of the temperature and comfort of that room or space.
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How do you paint cast-iron baseboard radiators?
When painting cast-iron baseboard radiators, use an oil-based enamel type of paint like Benjamin Moore Satin Impervo for the best result.
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Does my boiler need chemicals?
Here are some tips from contractors about cleaning new heating systems, using boiler chemicals, and water treatment.
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Special Tees
These days, I think the most special tees are the ones designed to make primary-secondary heating systems easier for you to install.
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What is the safe pressure for a hot-water-heating system?
One member responds:
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How many times can PEX freeze before bursting?
"How many times can PEX freeze before bursting? At what temp will it only take once? Will it just expand and contract forever without damaged? Does it get significantly weaker? "I'm...
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The O-S Fitting
I was looking at a photograph of Crosley Field, a grand, Cincinnati, Ohio baseball stadium that burned to the ground in 1900.
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How They Rated Radiators
So go look in a radiator catalog and you’ll see the EDR (that’s Equivalent Direct Radiation) ratings for all those different shapes and sizes.
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What to do with boilers during the summer
I read dead people.
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Banging Zone Valves
Here's Johnny!
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Thermostatic radiator valves
What's wrong with this picture?
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Steam vs. Hot Water
I have a wonderful old ad from Honeywell that goes back to 1909. The headline reads, "Put this sign up." There's a well-dressed man taking down a sign that reads,...
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Don't size a hot-water boiler by measuring the radiators
In 1970, the previous owner noticed wet spots on his kitchen floor, and since they didn’t have a dog, he knew that the family budget was about to take a nosedive.
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Don't size heating equipment with rules of thumb
The World Headquarters of HeatingHelp.com, our humble company, used to be in a tiny store in beautiful downtown Bethpage, here on the Isle of Long.
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When a radiant-heating system goes wrong
Marianne and I were at the 5 PM mass last Saturday. We like going to that mass because it allows us to be lazy in bed with newspapers and coffee...
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Radiant heat and wood floors
More and more radiant systems going into existing homes as retrofit projects. On many of these jobs the tubing winds up getting attached to the underside of the wood floor.
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The first radiant heating jobs
Each morning, when I sit at my desk, I give a moment’s thought to the broken copper pipes that are buried in the concrete slab just below my feet.
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Types of PEX pipe
You have options when it comes to the tubing you bury or staple up on a radiant job.
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Oxygen-diffusion corrosion in radiant heating systems
Whether you’re doing radiant floor heating or hydronic snowmelt jobs, it pays to give lots of thought to this oxygen-diffusion corrosion business.
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Levittown radiant heating systems
I grew up in Hicksville, Long Island (don't laugh!) and I spent a good part of Junior and Senior High School sharing a classroom with Billy Joel, and that is...
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Understanding primary-secondary pumping
Primary-secondary pumping has become pretty popular nowadays, especially with boiler manufacturers. They love it because it offers a simple way to protect their boilers against low-temperature return water and the...
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Primary-Secondary systems sometimes overheat
The ceiling was 14 feet above the parquet floor and there was an electronic scoreboard hanging on the wall that would have made Michael Jordon smile.
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Why your boiler needs a low-water cutoff
There was no water in that boiler and yet the burner just kept running because there was nothing on that boiler that could shut it off.
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Loop system hot-water heating Q&A
Q: What's loop hot water heating? A: It's the simplest method of heating with hot water. Each zone consists of a single loop made up of the pipe and the radiators.
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Bubble-foil insulation
On this subject, I'll direct you to Robert Bean's HealthyHeating.com site, where he makes his case very well.
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Basics of Indoor Air Quality
We of the Hydronic Realm often don't think too much about Indoor Air Quality, but that mindset is obsolete.
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Indirect hot-water heating Q&A
Q: What's "indirect" heating? A: It's a method of heating the old-timers used to warm fresh air before it entered a building.
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Honeywell Heat Generator
My run-in with Mark Honeywell (and the day I met his Heat Generator)
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Orifices and gravity hot-water heat
Gravity hot-water heating is both the simplest and the most complicated system ever to come driving down Hydronic Highway. It’s simple because it has so few moving parts.
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Should fill valves be left open or closed?
Now there’s a question for you. The feed valve’s job is to, well, feed. You figure out the height of the hydronic system from the point where the feed valve...
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Diverter-Tee Q&A
Q: What's the principle of the diverter-tee system? A: This system lets you supply hot water to a radiator and return cooler water from the same radiator by using a...
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Converting from steam to hot-water heat?
In the case of one-pipe steam, the air worked its way out of the radiator air vent.
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How to run a hot-water zone off a steam boiler
Q: Is it possible for me to use the condensate in a steam boiler to make a hot water zone? A: Sure! Heating professionals have been doing this for years...
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Why compression tanks waterlog
When hot water heating was new (and this goes back to the turn of the century) the Dead Men installed gravity systems because Homer Thrush had not yet invented the circulator.
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Why some compression tanks fail
Packaged boilers have been popular for a very long time and they sure do make a contractor’s life easier.
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Some gravity-hot-water systems didn't have compression tanks
It all started when a friend called to tell me about this old gravity hot-water system that had him baffled. “There’s no expansion tank anywhere on this job,” he said.
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Gas-Pipe Sizing Chart pdf
Which is just that!
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Using vacuum gauges to tune an oil burner
Vacuum Gauges Paint a Picture for You
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Why you should never dead-head a circulator
When I was still young and very wet behind the ears I worked for a manufacturers representative in New York City and we sold Bell & Gossett pumps to wholesalers.
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The Point of No Pressure Change
In 1994, I wrote a book called, Pumping Away, which I began by remembering the late, great Gil Carlson. Here's what I wrote:
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The Hidden Costs of Hidden Pumps
Let's face it; there's an awful lot of old equipment out there that's wasting energy, and the average consumer is starting to wonder what to do about it, or at...
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Sizing circulators for old gravity-hot-water heating systems
When servicing old hot-water heating systems that originally circulated by gravity, but now use circulating pumps, I began to notice a lot of oversized circulators.
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Net Positive Suction Head
I was lucky to have had as one of my teachers the late, great Gil Carlson.
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How to Size Circulators
"When you're sizing circulators, or even when you're just looking at a hot water job," he said, "you should imagine that you're inside the pipe, rolling from one end to...
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Adjusting the flow rate for an old gravity-hot-water system
A hot-water stumper
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Boiler Ratings Explained
There's the Input rating, the Gross Output rating (which some call the D.O.E. Heating Capacity) and then there's the Net Output rating. You pick one or another to size a boiler.
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Thermocouple Testing Procedure
I am often asked about troubleshooting a thermocouple on gas systems. This will be a permanent reference that will give a step-by-step procedure:
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Modulating-condensing boilers
A question asked on the Wall, "Who, in your opinion, makes the best modulating-condensing boiler?"
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How to have a boiler replaced
"We haven't had decent heat since that heating contractor left our basement."
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Considerations when using constant circulation
A question asked on the Wall, "What do I need to consider with a hot-water system running on constant circulation?"
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Boiler Failure after Two Years
The boilers (and there were 20 of them) were laying out there in the parking lot, not far from the boiler room door.
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Heating in France
I was in Paris one chilly November, where I had the wonderful opportunity to explain American-heating practices (such as they are) to the folks who run most of the huge...
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Heating in Russia
“I’m pretty sure that’s a district hot water system over there,” I said.
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Wood, Solar and Other European Lessons
I first went to the big ISH fair in Frankfurt, Germany in 1991 with two buddies, and I think we three were joined by only about 17 other Americans that year.
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A Different Way to Pipe
I was raised by Bell & Gossett and gobbled up the writings of the late, great Gil Carlson for a lot of years.
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Antifreeze for Hydronic Systems
In response to a person on the Wall who asked, "Can I add antifreeze to my heating system?"
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Mixing passive and active heaters can lead to problems
Sometimes, you just have to think like air.
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Gravity Hot Water Heating Q&A
Q: How long has gravity hot water heating been around? A: Gravity hot-water heating began quietly in the United States between 1875 and 1885.
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Why Some Compression Tanks Fail
Packaged boilers have been popular for a very long time and they sure do make a contractor’s life easier.
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Lochinvar's SHIELD™ commercial water heater Video
Here's an interesting new product from our friends at Lochinvar.
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Wall-hung boilers (and all that comes with them)
Here they are, high to low, in order of sales during 2006: United Kingdom, Italy, France, Germany, Russia, Spain, China, Netherlands, Turkey, Ukraine, Romania, Poland, Belgium, Czech Republic, Hungry, Austria,...
