Removing Hard-Water Scaling from Boiler Pipes

Billy_13

Thanks Hot Rod.
I was considering looking for a different contractor, but I didnt know if it was just me being out of my mind.


When I explain to the contractors about not being able to add DI feedwater or boiler conditioners to the water, is there a specific part or parts I should refer to... or just tell them we have hard water issues and see what they recommend?

Thanks again for all the advice.

Billy_13

Removing Hard-Water Scaling from Boiler Pipes

I installed a whole-house water filter this weekend and when I cut into the cold-water line, I found scale buildup on the pipes. I have no way of knowing how bad the scaling is in the boiler or the supply/return lines, but I would think it would be worse due to the effects of heating hard-water. A previous technician told me during my annual fall maintenance I should never add any chemicals to the boiler water for any reason. He also stated that since the "fill water" comes straight from the cold water line, it would be impossible for me to add any chemicals even if I wanted to. Is there any type of maintenance or process that can be done to descale the existing hard-water buildup? If so, what is it called so I can call around to ask if any of the heating/plumbing companies will do it?

Thanks for any insight. And yes, we're still celebrating here in "Six Pack" Pittsburgh.

hot_rod

Is this

a closed loop, pressurized hydronic system? If so it should not be taking on additional water. Once the system is filled, purged, and pressurized there should be not additional water required.

some installers like to add a conditioner, basically it is an o2 scavanger, ph biffer and film provider.

Plenty of systems run plain old tap water without problems.

It depends on how much your system holds, how hard your water is, etc.

If it is taking on water on a regular basis, you may have a leak?

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Billy_13

It is a closed-loop hot-water boiler system (225k BTU Utica). It uses a large compression tank rather than the newer expansion tanks. It was installed back in 1988. We purchased the home in july 2007. We usually have to drain the compression tank once a season when the tank is full and the pressure-relief valve drops the boiler pressure from 30 psi back down to 15 psi.
We also tend to vent/bleed the first cast-iron radiator off the supply side about once a week if that makes a difference.

We had our water tested and they said the water hardness was between 15-20 GPG. They recommended a water softener; but I am holding out until I feel its necessary.

hot_rod

Any noises from the boiler?

usually when they start to scale inside you hear about it. Often perculation sounds, like an old water heater or coffee pot.

I have used Hercules Sizzle to clean out boilers that had taken on excessive hard water (radiant leaks in the slab) It quiets them right down and no doubt increases the heat transfer efficiency. Be sure to follow the dilution rate on the bottle, it is safe for boilers and even DHW tank cleaning.

Consider changing to the proper sized bladder type tank, a good air separator and fill valve (like Caleffi And be sure the system is leak free.

If the boiler has a low water cutoff switch, consider shutting off the fill valve after everything is purged and quiet. That will determine if you have a small leak somewhere.

12- 15 grains hard is not ideal for boiler filling. Consider buying some DI water to blend in with your tap water after you clean and flush the system.

Softened water may be better than hard water if you are sure the system backwashes properly and you are not adding chlorides.

The boiler installation usually gives you the acceptable range for hardness, ph, and chlorides.

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mark ransley

Its a closed system, Im in Chicago and when they removed our 30 yr old boiler it was like new inside. Adding water is not good and should not be needed, You should not need to bleed a radiator except the top one maybe in fall as you turn it on. I a have a 3 story plus basement and I run maybe 12lb cold and it wont go to 25 hot, a too small exoansion tank made it go to 35 so we added another one with a new boiler. Scale will pop as it fires, fix it so you dont bleed it and add water. I would not add anything or worry except for the tank, pressure, and why you bleed air out of a radiator weekly. Keep it sealed.

Billy_13

No Noises

The tech that did the annual maintenance this fall told us to stick with the compression tank. He said the bladder tanks fail too often.

I asked the tech about being able to use RO/DI water (or the addition of a boiler additive) in the boiler and he said there is no way to add makeup water to the boiler. The current setup has a coldwater pipe going straight into one of the return lines. The tech told me there was no way I could add anything (DI water, boiler additive, or otherwise) to the water. I am stuck only being able to add the water from the coldwater line that is piped to the boiler.

I am positive there are no leaks. The venting issue is most likely due to an inadequate Air Separator or lack there of. I asked if I should install one of the B&G Enhanced Air Separators, and I kinda got the deer-in-the-headlights look.

Any thoughts, or am I just out of my mind?

hot_rod

a good hydronic contractor

should be able to make an air problem disappear. If what he is doing doesn't "foix" the air or flooded expansion problem... guess what. Change the plan.

A properly sized and installed air separator, expansion tank, and fill valve should solve all of these problems. Keep adding fresh water to that boiler WILL lead to other, more expensive, problems.

Maybe get a second opinion? And a copy of "Pumping Away" form this website. Read it, and give it to your installer. It clearly explains how to set up and pipe a quiet, troublefree hydronic system. It's ok to change away from older components. A properly sized and installed bladder expansion tank should last many many years.

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hot_rod

typically

the system will have a boiler drain on the boiler, or a drain valve somewhere. if you do decide to use a cleaner or conditioner it could be injected at that drain.

If some re-piping will take place, I like to add a good ball valve with a drain cock on both sides. This assures everything you flow into the system can be washed back out. Webstone makes a ball valve with a purge cock built in for this use, or the installer can fab one up.

It's nice to have a ball valve to inject into. Some time injecting into a boiler drain will lift the washer off the stem!

This picture shows one of my methods to use a Webstone valve with a pump flange. Now you have isolation for the pump, and a nice fill/ purge point.

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