Boilers - Home Heating Steam and Hot Water Systems - Air in system?? From where?
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radioconnection
11-30-07, 01:40 PM
I've been tracking down a slow pressure loss in my hydronic heating season. Being we're going into the colder weather, taking the system off line for extended pressure tests on each of the three zones isn't practical right now.
I have one zone turned off (ball valves on the supply and return) and I suspect it may be the zone with the leak since the pressure appears holding above 20 psi (set on the high side for now).. I had also, on Grady's suggestion, closed the air vent caps on the HiVent and on the Honeywell Spirovent. I'm noticing that when I open either cap I get a quick "pfffffttt" of air escaping. So, I assume air is getting into the system somehow? I tightened the flanges on the pump return ports, but I am wondering what else besides a leak on the pump suction side would cause this?
Pete
Pete
I have one zone turned off (ball valves on the supply and return) and I suspect it may be the zone with the leak since the pressure appears holding above 20 psi (set on the high side for now).. I had also, on Grady's suggestion, closed the air vent caps on the HiVent and on the Honeywell Spirovent. I'm noticing that when I open either cap I get a quick "pfffffttt" of air escaping. So, I assume air is getting into the system somehow? I tightened the flanges on the pump return ports, but I am wondering what else besides a leak on the pump suction side would cause this?
Pete
Pete
NJ Trooper
11-30-07, 02:19 PM
How long has it been since you added _any_ water to the system ? I'm still venting a little air here from the drain/refill that I did in August when I worked on this one...
radioconnection
11-30-07, 02:28 PM
Full water exchange in the summer, when I repiped both boilers. All three zones were drained, along with both boilers. I have the VanWert valved off right now, but there is considerable water in the CI baseboards and piping.
Hmmm. I'll wait and see if it slows down as time progresses.
Grady also suggested it might be gases from chemicals in the water reacting with the various metals in the system.
Pete
Hmmm. I'll wait and see if it slows down as time progresses.
Grady also suggested it might be gases from chemicals in the water reacting with the various metals in the system.
Pete
NJ Trooper
11-30-07, 03:11 PM
That's possible too... you are on well water so you may have even more trapped gases than city water which is heavily 'processed'. I'll close off my air valve and see how much I'm getting still, for comparison sake, as I'm on well also.
xiphias
11-30-07, 06:31 PM
Hmm. I looked at the PSpiping pics. It is possible, I suppose, that one or both air-letter-outers are functioning as air-letter-inners. You obviously would have to be creating a huge differential to drop the pressure far enough. And since I'm certain you are pumping away, that seems unlikely.
But 0.5psi/wk (is that what it is?) sounds like a water leak somewhere.
But 0.5psi/wk (is that what it is?) sounds like a water leak somewhere.
radioconnection
11-30-07, 06:38 PM
Hmm. I looked at the PSpiping pics. It is possible, I suppose, that one or both air-letter-outers are functioning as air-letter-inners. You obviously would have to be creating a huge differential to drop the pressure far enough. And since I'm certain you are pumping away, that seems unlikely.
But 0.5psi/wk (is that what it is?) sounds like a water leak somewhere.
I suspect a leak in zone 3, and I am trying to prove it right now. Fortunately this zone is well insulated, and very easy to heat! I have the return and supply valved off, and so far I am not seeing a drop, but it hasn't been long enough to prove it to my satisfaction. If the pressure holds for two or three weeks, I'll be more convinced.
I was wondering if that could happen--sucking air back in through the floats... But, I have both vents capped and the air is still being captured in the vent bodies. The pressure seems to be holding so far, but this will take a bit of time to sort out since the pressure loss is so gradual.
Pete
But 0.5psi/wk (is that what it is?) sounds like a water leak somewhere.
I suspect a leak in zone 3, and I am trying to prove it right now. Fortunately this zone is well insulated, and very easy to heat! I have the return and supply valved off, and so far I am not seeing a drop, but it hasn't been long enough to prove it to my satisfaction. If the pressure holds for two or three weeks, I'll be more convinced.
I was wondering if that could happen--sucking air back in through the floats... But, I have both vents capped and the air is still being captured in the vent bodies. The pressure seems to be holding so far, but this will take a bit of time to sort out since the pressure loss is so gradual.
Pete