Does My Boiler Need Chemicals?

Chemicals used to treat diseases of fish

I was wondering about boiler chemicals and how many contractors (if any) were using them on brand-new systems. Do we need them?

Hydronic systems are closed to the atmosphere, so what are we treating? I also wondered about the water we’re using. Is that any different these days?

So I asked some contractor friends and one said, “I think all new heating systems need, at the very least, to be power flushed. A cleaner would be even better because it would help cut the oils, greases, and fluxes, but how much of that is in there really depends on how careful the pipefitters are.

“As for treatment and fill-water, it really depends on the quality of the job-site water. I look at hardness, pH, total dissolved solids and chlorides at the very least. I'm not sure how many city- or rural water systems supply water that meets the specs boiler manufacturers and tank manufacturers insist on these days. When hydronic systems combine copper, brass, iron, steel, plastic, aluminum alloys and various stainless alloys, the issue of water quality becomes much more important.

“I also think potable water quality nationwide is changing, not to mention the chemicals they add at treatment plants, and how they work in hydronic systems.”
Which got me thinking about the domestic hot-water copper tubing in our house on New York’s Long Island. We’ve replaced the same length of pipe twice in three years. The water ate right through it. Scary stuff.

Another friend commented, “I have been using Rhomar products for the last 10 years in systems that have a lot of rubber radiant tubing and it’s been a great help.

“As for treating a new system as part of the install, it depends on the system. If it’s an old cast-iron or steel system, I’ll treat it. If it’s a newer system with copper fintube radiators I won’t.

“I am starting to make the switch to Fernox because their compressed-gas applicator bottles make getting the chemical into the system a lot cleaner and faster."

And then there was this from another contractor:

“I would not recommend makeup-water purification without first having everyone understanding that we are about to shift the chemical equilibrium of this system, regardless of whether it's in good shape or bad shape. Taking an old scaled- or corroded boiler and swapping it over to treated water is going to have a very real and very immediate impact that can be interpreted as bad. Long-term water purification is good but who is going to maintain it?

“Motivation is key here. If you have a boiler or a system that has failed a few times from corrosion you might have a client that is willing to play ball with you. But if you show up and see an impending disaster, and this is the first time it’s happening, or if the owner is new, then selling chemicals is going to be very difficult.”

So bring an open mind and a lot of questions to all of this because it can get messy.

Water treatment

I asked a guy I respect for some treatment rules of the road and here’s what he had to say.

“Unless there was a problem, I would only check for hardness in the water and its pH. If I can keep the pH at 8.5 I know I can eliminate iron corrosion at 82 degrees C. That’s a big deal.

“I would also keep the hardness in bicarbonate form less than 10 parts per million. If there’s no copper piping in the system, I treat hardness and pH with straight caustic. For me, caustic is like a one-stop shop and it’s pretty cheap. It will take all the carbon dioxide out of water in exchange for carbonate, and it will remove temporary hardness in exchange for more carbonate. It also converts permanent magnesium hardness to milk of magnesia, sodium sulphate, table salt and salt peter.

“If there’s copper in the system, I won’t use caustic; I’ll use phosphate. High pH in soft water with sulphates and nitrates can eat copper’s oxide layer, which is never a good thing.

“And since hot water systems don't cycle up in concentration like steam boilers will, it is not something I would habitually watch.”

And speaking of steam (should you work on those systems), keep the pH of the water between 7 and 9. A pH of 10 won’t allow the pipes to corrode, but if the pH gets to 11, the water will foam and that will ruin the steam.

Easy sell?

From another guy I respect:

“I am a strong believer in water treatment. I carry pints of Fernox F3 cleaner on my truck and sell them when I do a boiler cleaning. People like the idea of a clean system, inside and out. I to go back a week or so later and flush it out and add the F1 inhibitor. It's an easy sell and people get lots of benefits from it.

“I have also had success using these products on non-oxygen-barrier systems and open, wood-boiler systems. When checking the inhibitor levels several years later, I have found the water clean and clear.

“Every new system I install gets some form of treatment. They deserve it. Ask yourself one question: When you replace a component in a hydronic system, did it fail from the inside or from the outside?

“I read old books about the pioneers that first explored these rolling hills and valleys where I work. We have turned much of this land into an overpopulated, industrial wasteland. Those old books describe clear blue lakes and crystal-clear rippling brooks filled with trout. Those very same brooks are now called cricks and they are void of fish, just brown and dirty.

“We are polluting the water, above and below ground. There are a few contractors in the area that are using the treatments. There would be more using it if someone told them about it and explained how it works.”

We just did.

Did you know? 

People add glycol to hydronic systems and then forget to tell anyone. The glycol gets old, diluted, useless and very corrosive. Check the water’s pH on every job.

A plant worker was told to add one scoop of a chemical to the system every day. Lest he forget, he added seven scoops each Monday. Whoa!

You can buy a tester that measures pH, Total Dissolved Solids, conductivity, salinity and temperature. Great tool to have!


Leave a comment

Related Posts

Circulators or Zone Valves

Back in my rep days, half a lifetime ago, I sold Bell & Gossett circulators. We didn’t have a viable zone valve available at the time, and when the factory finally showed...

Published on 01/25/2023 1:02 PM by Dan Holohan
Posted in Hot-Water Heating
Adventures in Pumping

I read somewhere that the most prevalent machine in the world is the electric motor. I thought about that for a while and it made sense. Just look around.

Published on 12/07/2021 11:47 AM by Dan Holohan
Posted in Hot-Water Heating