Help... Boiler questions

tbird6391

I've been watching this thing more closely the past few days. 2 concerns have arisen.

(1) Burner: What I noticed on 2 occasions is the boiler comes up to temp, burner shuts off. A moment later the burner kicks back on for a second then goes back off. The gas Co was here a couple days ago to replace the noisy meter and I mentioned this to the tech (older guy, seems to have been doing this a while). He called it something like "burp" or "fart" and didn't seem overly concerned.

It don't seem right to me. Normal? Bad gas valve? Thoughts?

(2) Leaks? After the burner shuts off, there is a faint whistling coming from someplace in or near the boiler - can't tell exactly where. It lasts only a couple seconds. What could this be? Leak?

I bled the radiators a few weeks ago and got more air out on the second floor than ever before (like a minute or so from each radiator). Today I checked again and there was some more air in them, maybe 10 seconds worth per rad. There was no air on the first floor either time.

The circulator pumps were replaced about a year or 2 years ago. I remember bleeding them shortly after and not much air then.

The system always has a good pressure reading, doesn't move on its own other than a slight increase when it gets hot. the gage responds, I bleed a few rads, check the gage then fill back to 12-15 psi.

Leaks? Or just the air in the fill water coming out? don't really understand how the pressure would stay up if a leak was present.

Thanks.

Ironman

How about posting some pics of the boiler and its near piping?

tbird6391

Hi Bob
Here's some pics.
I had heard some random gurgling in the pipes over the last year, where they go up to the second floor. I thought it had something to do with the toilet up there since the drain pipe is in that wall. More noticed this past fall, when the heat started coming on. Since the massive bleeding I haven't noticed it. Thinking it was some trapped air from when the pumps were replaced?
Water that comes out from bleeding is pretty black.
Thanks.

Paul S_3

if the pumps were replaced recently....with the type of system you have they definitely introduced air in the system....sometimes you may have to bleed some left over air shortly after but not 2 years later....maybe the pressure gauge is a little off try raising it to 15 or 18 to ensure pressure at top of system and see how that goes.....after the pumps were replaced everything heats fine ? what kind of pumps were removed?

aircooled81

Wheres the expansion tank? I saw the prv entering the (return?) piping? Compression tank can release air back into the system if not set, and expansion tank can leak air back into the system.
PAul s was right too, if the top of the return doesnt stay positive, an auto air vent could pull air back in... Or even a leak.

tbird6391

If you look at the second pic you will see the tank up in between the joists with sheetrock around it. I didn't do it this year, but previously I shut the tank from the system, drained it completely, then re-opened the valve. So it should be about half full of water at 14 psig. There's an air scoop or whatever it's called on the supply out of the boiler (top front) that feeds it. No auto air vents, just the bleeders on the radiators

There is some pressure on the second floor which is evident when bleeding. I did 3 of the 4 radiators before it bled down and I had to go top it off again.

Maybe I should try a few more psi. To be safe I'd have to make sure the expansion tank has enough air in it. Next week it should warm up enough to shut the burner off.

The old pumps were original b&g. There was some hum in the pipes, and a mismatched motor on one. Had doubts about how much longer they would go. My intentions were to have them rebuilt and put back. The Tacos work ok, but seem to flow faster, so that makes a different noise. Heat was good after pump installation.
Thanks
Rick

JUGHNE

Does this burner have a standing pilot light, always on?
Does it ever get blown out that you have to relight it?

tbird6391

It does have a standing pilot, but never had to relight due to blowing out.

aircooled81

Check that compression tank, see if its water logged.
After you reset it (post if you want the how to) get some soap bubbles and check the sightglass and valve if you have, for air leaks.
Short cycling due to air entrainment in the boiler is a viable cause. If the compression tank is water logged, or the airtrol is clogged up, your hottest water at lowest pressure is in the boiler, where air can seperate and log.
The huge burps of air in your loop probably came from there. Check that tank.

kcopp

The "leak" is more than likely just the boiler and burner settling down/ contracting after the burner shuts off. Think about it.... that metal is exposed to direct flame then it is not.

The burner on/of/on again sounds like a control issue more than anything else.

The B&G circ was prob the best circ to leave on there... at least for the big zone. The pump curve for that is better suited for the piping and radiators.

The expansion tank should act as an "air separator". No other automatic air vents/ Hy-vents should be added to the system. Its not uncommon to need to bleed out radiators once a season.