Fresh water to boiler

gpjazz · April 17

I'm looking for some documentation in writing that I can show a homeowner in regards to the effects of constantly adding fresh water to a boiler system... (I posted this at hvac-talk also)

I'll try to make a long story short... It's a water boiler system with mostly copper piping and baseboard fintube rads. Originally had a 38 year old cast iron boiler but then replaced with high efficient wall hung with stainless ht.exc... Boiler now probably 5-6 years old. Couple years after the install, a leak has developed under the slab somewhere for the basement zone. Copper piping runs under concrete slab and then up to one baseboard rad, then back down under slab and up to next rad, ect ect...
A leak has developed somewhere under the slab and therefore fresh water is constantly being added. At one point the customer was able to actually hear water running into the boiler system, so he shut off the basement zone (ball valve and zone valve) and water stopped running. Open valve again and can hear water running again. But then on occasion, he swears that even with valve open and pressure to basement zone, he does not hear any water running and he assumes nothing is leaking !! So he leaves it on ... I can't understand why sometimes he hears it and sometimes not. I guess it's gotta be from a temp difference and expansion/contraction causing the rate of the leak to change.
But regardless, I tell him it still HAS to be leaking because it isn't gonna fix itself.

Now back to my original question... With all the fresh water being added all the time, he's getting corrosion internally. There is still a little bit of black iron piping near the boiler, and twice he had leaks develop right thru a black nipple. Not at the threaded connection, but the actual nipple corroded right in the middle and got a pinhole leak. He's also got a small leak that corroded directly thru the copper "fastpipe", (Burnham factory fastpipe for primary/secondary) And now he's getting a leak thru the stem of a ball valve too ! I've never seen such a new system with all new piping and valves develop so many leaks. I figure it's from the fresh water and oxygen being added that is causing this mess. But trying to explain this to a homeowner is difficult.

So is there some specific documentation that I can show the homeowner in regards to this?

GGross · April 17

I don't have the specific document you are looking for. @hot_rod has shared some related documents here before and he may have just what you are looking for.

In addition to that, the boiler manufacturer almost definitely has it written in their install manual that the boiler must be hooked to a closed loop hydronic system, you get a big enough leak, take on constant fresh water, and its no longer a closed loop.

You can also quote your customer the cost to fix the problem now, and send a quote to repair the leak and change out all their valves/pumps/boiler. Tell them if they don't fix the leak they will probably have to pay the larger price in about 3-4 years (much sooner depending on severity and water quality), and it will almost certainly fail during winter months because thats when the system is running, and that price is only an estimate it could be much more. Taking on a ton of fresh water will also add air, lowering heat exchanger efficiency and cost the owner more money every month until its fixed, adding to that the possibility of a no heat call due to air lock goes up drastically.

If I were you I would go there when we don't need heat, close off the filling unit, and show the owner how fast the pressure drops, that way you both know the severity of the leak. I would have a hard time thinking you or the owner are actually hearing fresh water flowing through the system, but when adding fresh water you get more air, and that can make some noise in the pipes for sure. No doubt the owner is hearing that air, which is why sometimes it goes away as it circulates through the system.

Derheatmeister · April 17

Check the ANSI H1001.1 and the VDI 2035...The VDI 2035 states that the system fluid makeup should not exceed three times the volume of the system fluid volume over the Life time of the system.
Hope this helps.

hot_rod · April 17

This journal has some good poics of what water can do to a system
https://www.caleffi.com/sites/default/files/media/external-file/Idronics_18_NA_Water quality in hydronic systems.pdf

gpjazz · April 24

Thank you for the information. I was finally able to talk with the customer and make him understand why this corrosion is happening. Now it's time to either isolate or fix the leak to prevent the fresh water being added all the time..

So my next question, is there a recommended additive to put into the system to help "clean it out" and slow down or stop the internal corrosion ??

Intplm. · April 24

The copper is reacting to the concrete slab that it is installed in. An additive is not your answer.

You will continue to have leaks when copper is berried in concrete. The concrete acts as a corrosive to the copper causing the leaks.

You will eventually need to abandon the copper piping and re-route it above the slab.

gpjazz · April 25

Yes I'm aware of that.. The leaking copper buried in the concrete slab WILL BE abandoned / isolated from the system.

My question is about an additive to "clean" the rest of the system ??

Intplm. · April 25

https://forum.heatinghelp.com/discussion/comment/1800076#Comment_1800076

Look up the "Hercules" company. They make many different types of additives and other products for heating systems.

Fresh water to boiler

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