columbia gas boiler fires up, runs for 10-20 minutes, and shuts off.

owhite

I have columbia gas boiler that comes up when I crank up the thermostat, runs for 10-20 minutes and shuts off.

The last time I called the repair guys I know they cleared out the tube that leads to the PSI gauge in the pic. They told me they took the pipe under the gauge off, cleared it out, and then it ran no problem for a year.

The pressure reading on the gauge doesnt budge through the whole cycle of heating up and shutting off. Can someone shout out what role the curling pipe and gauge plays with the operation.

My guess is this some sort of override - it looking for an increase in pressure when the boiler gets hot, and has to register the pressure is increasing. But in my case the boiler gets hot, pipe is clogged, no pressure increase, boiler shuts off.

Here's a pic. I'm talking about the gauge in upper right that links to box with red wire.

Steamer1928

Looks like a re-badged Utica. I have a boiler like this, maybe a little bit older. You really have to keep that whole pigtail-gauge-pressuretrol assembly free of crud. Otherwise the pressuretrol can't accurately tell when to cut in and out and your gauge is also rendered worthless. Mine is doubly sensitive because the assembly is also tied into the top valve of the sight glass.

owhite

thanks - I'm most checking on it's role in operation. So it sounds like it's filled with water, and gets clogged from rust or whatever. But the idea is it's supposed to show an increased pressure as the boiler heats up?

I'm planning on putting the wrench to the gauge, and clearing out the pig-tail with wire and flushing. Sound reasonable?

Steamer1928

Right, the gauge itself doesn't do anything other than show you the pressure exerted by the boiler's operation. I'm sure you've read elsewhere on here that you want a very low pressure for residential heating (under 3 psi). A good cleaning out of the pigtail and making sure the inlets to the gauge and pressuretrol are free of crud should put you in better shape.

-BTW, you might want to move your post to the "Strictly Steam" section; you are currently in the hot water section.

Paul Pollets

the boiler water is extremely dirty. this boiler needs to be cleaned and skimmed. where is the blow down valve?

owhite

blow down valve is on left side. Because of some occupancy issues in the house the furnace has not been skimmed - which I would assume would also account for clogging in the pigtail. There's skimming instructions here: columbia CEG manual -- think these would work?

Jamie Hall

Looks like the pressuretrol (that grey box) is set more or less correctly, anyway. But that gauge is the code required 30 psi gauge, and probably should never even quiver if the system is operating properly.

One important question: after the unit shuts off (which it probably is doing, correctly, on pressure) does it come back on again sometime later?

If it does, then the pressuretrol is doing what it is supposed to do. It will do no harm to flush out the looped pipe, which is called the pigtail, though. It needs to be refilled with water after that, when you put it back on the boiler. The purpose of the pigtail is to provide a water seal between the steam in the boiler and the pressuretrol and the pressure gauge, to protect them.

The purpose of the pressuretrol is to keep the pressure in the system from rising too high -- 1.5 psi is ample for a residential steam system. It turns the boiler off at that pressure. If the thermostat isn't satisfied, and the pressure in the system drops, the boiler should turn back on.

There clearly are some other problems -- that looks dismayingly like copper pipe for the risers, but at least there are two of them and they're good sized -- but we'll get to those later.

owhite

following up, I removed the gauge, cleaned the pigtail with a combination of clearing crud with wire, and rinsing/siphoning out with fresh water. Left some water in the pigtail, replaced gauge, and the furnace is cranking along just fine.

Next step is to drain, possibly skim so it doesnt clogged again.

thanks people.