Odd Behavior -sightglass drains in 20 seconds...

srmaietta

Hey everyone, I've had my system on for the past two weeks or so, its been doing minimal work but everything seemed fine. Its a two pipe system that runs as a one pipe (the rads drain back into the feed side.) I insulated everything I could last season, and replaced vents, got it pretty well tuned, it ran all season almost silently and we had a steady heat. This will be our second winter in this house. (Turn of the century queen anne in northern NJ.)

Anyway today I noticed more than usual noise down there and investigated. I saw no water in the sight glass and so just barely cracked the fresh water feed (Feeds from the hot water tank) and noticed the water level jumped right back up in a few seconds. Turned off the feed. Boiler kicked back on, and the sight glass water level went from half way to zero showing in under 10 seconds....

I turned off the system and let it calm down for 10 minutes and then switched it back on. Water level was around 80% up the sight glass. In literally 30 seconds the level was down to zero and the LWCO kicked the system off again. Pressure gauge was fluttering around 1 psi (usually runs at 4-5 ounces). Within 1 minute of the boiler being off the water level had come right back up.

Any ideas of things I should look at / investigate?

thanks
~Steve

srmaietta

few more notes.
-no leaks found anywhere.
-only vents besides the radiators are on the returns, close to the boiler. One big "vacuum vent" per side of my system -they were venting like crazy during this episode.
-my LWCO and lower drain are clean.
thanks in advance...
~Stv

srmaietta

So I let it run a bit more -i'm too curious to leave it be. Its short cycling on the water cutoff. The water level drops, turns off, water returns in 15 seconds, kicks back on, on and on. . .
So what is forcing the water down and out into the returns? (and then back again)

Fred

So I have to ask, why is a 2 pipe system operating like a one pipe system? Is the second pipe and trap still in place on each radiator? Have other system components been removed? Post som3e pictures of the current piping, near the boiler, along the mains and returns and around a couple radiators.
Your boiler is not really short cycling. It is being shut down by the low water cut-off because it senses a water level below what is safe. Has anyone done any work on the boiler or piping recently? Are there any gate valves on the mains or elsewhere on the system that may have been closed? How long does the boiler run (from a cold start) before the water level drops?

neilc

plugged pigtail,
bad pressure readings ?

KC_Jones

Sounds like surging to me. As Fred asked any recent work on the piping that involved pipe dope in any way? Are you running a water treatment this year that you weren't before? Pics of the piping could help as well.

srmaietta

Thanks for the thoughts gents.

Fred - as far as I can assess, it was a vacuum system at one point. Vacuum vents on the returns, plugs in a few of the rads (as opposed to vents.) No traps anywhere in the system. No crossovers anywhere in the system. The radiators are all angled to drain back into the feeds. I replaced a few old broken radiator vents last year, insulated everything I could on the main side (zero insulation when I moved in) and got everything working pretty well.

I just went through and removed all the rad vents plus one of the big vents on the return -the pressure still bouncing up around 1PSI and forcing the water into the returns, short cycling ensues.


neilC -the pigtail is less than a year old and the 0-3psi gauge moves freely -my gut tells me thats fine.

KC -No changes since we shut her down last spring. The last tweak was a part of a bottle of 8-way water treatment that I put in a week or so before the system was fully shut down for the summer layover.... Perhaps that has dredged up a bit of crud, or concentrated a bit over the past few months? I could drain a few gallons and fill w/fresh, see if that helps with the surging.

KC_Jones

Typical reasons for surging, high PH, oil, bad piping or a combination of the above. Another possibility is high pressure pushing water into the returns, but it seems like this is happening too quickly to be pressure.

Fred

I would suggest you let the boiler cool down, drain it completely and refill it. Then run it immediately after refilling it and see what it does. Oddly enough, some of those additives/treatments can cause surging, especially if too much was added. That old adage: To much of a good thing .....

KC_Jones

Fred is correct, since most water treatments adjust the PH they can cause issues if not applied correctly. I put 2 steamaster tablets in mine once, that didn't end well. According to them I should have put a lot more, rare case of not following directions is a good thing.

Erin Holohan Haskell

This article may help: https://heatinghelp.com/systems-help-center/reasons-why-the-water-is-bouncing-in-the-gauge-glass-and-where-to-look-for-solutions/

srmaietta

Drained a few gallons from the boiler -dark purple/brown. Added fresh, boiling now, a lot less surging!! Will do this again tomorrow. Seems like the first few heats this season brought a lot of muck back to the boiler, I probably had a wee bit too much 8-way in there too.

Will report back tomorrow after another flush and few heat cycles.

thanks all
~Steve