Water loss and sound piping

chuckadoo

How much water loss is typical for a system with “good”, no major return leak, piping? Is there a rule of thumb for gallons over time per btuh? 

Jamie Hall

I don't know of a correlation with BTUh, but a really good system will not need much more than a gallon of water per month, even on fairly large (for a residence) systems. Anything more than a gallon a week and it's time to start finding the leaks...

chuckadoo

We’ve had a new 900,000 BTUh replacement (4 mos. old), in a 30 unit apartment. One pipe steam. Seems like the feed comes on at least once a day, if not more. Installer said they tested for leaks in the return, but didn’t find any. I should have asked what their test method was. I assumed capping both ends and pressurizing? I am hoping to talk management into a VXT, to give something for them to see, as words are passing right through😂 (vxt literature says residential, but I couldn’t imagine it would not work here??). On a system this size, how many gallons a month should I start to worry about boiler longevity?

Jamie Hall

I don't see why a VXT wouldn't work on your system, though it's likely that the normal warranty wouldn't apply.

That said, the feed comes on once a day, more or less? Any idea how much gets fed at a shot? Not that it really matters... with that much feed, that poor boiler is going to die an early and messy death. (Just to give you an idea, Cedric -- the boiler in the main place I care for -- is only slightly less than half that size. Last time I had to put a gallon of water in him was back in January sometime... so even if there was a correlation with boiler size, that would mean sometime in February, maybe, for yours)(I'll grant you, though, one pipe systems lose more than two pipe).

You have a leak. Or leaks. Where, I wouldn't care to say. If the installers really did pressure test the wet returns, it would be a steam leak, and those can be a bit hard to find, since the steam disappears immediately. However, I wouldn't be so quick to say there was no leak in the wet returns. As we are getting into warmer weather, you may be able to use a simple trick to find out: Add water to the boiler to somewhat above the Hartford Loop level, and let it sit there, turned off. If the water drops at all, you either have a leak in a wet return or in the boiler below the water line (don't discount that, either). If that raises suspicion, drop to the boiler water level below the Hartford Loop, again with the boiler turned off. If the water level is now stable -- wet return leak. If it still drops -- boiler leak.

Otherwise, start looking for vents and valves which are leaking steam. It really doesn't take that many to add up to a problem, and in an apartment building you may never know.

Also check the operating pressure -- if it's over 3 psi, it's very likely that you have leaking vents. It shouldn't be over 2 psi.

chuckadoo

Thanks! how much time would you let the water level “sit there”? Time for one more question? Another apartment has a condensate pump whose vent is beginning to spit. I assume a radiator trap, as it is spitting just a small amount of air/water. There are no hot/cold complaints from any units. Any tricks on narrowing down which is the culprit? 

Jamie Hall

How long to sit there? Couple of hours -- assuming that you carefully marked the water level and don't have to play the "well... hmm... maybe..." gamie!

That condensate pump and any associated traps is the first place I'd look. Thing is, the "air" which that vent is spitting isn't air -- it's steam, or perhaps at best 100% saturated air. Not saying that that could be all of it -- probably not -- but it surely is some of it (consider that a drip every ten seconds is two gallons a day, roughly).