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Carloscda40 03-01-2009 06:03 PM

Boiler stays on.
I have an American standard boiler (discontinued).
Now if I set the thermostat to 71 it jumps to 77 and the boiler stays on?

I've bleed all the radiators and at first all air then some water. Now after bleeding them again nothing is coming out?
The gauge on the side of the boiler is at 20psi.

I know it's only supposed to be between 12 & 15?

Now maybe I have to replace the gauge because at first when I taped on it the needle drooped down. But the next thing I know I come back downstairs & water sprayed out the pressure valve?

Replacing the gauge do I have to totally drain the boiler?
And why is the boiler staying on?

Thanks in advanced!

kenmac 03-01-2009 06:07 PM

This may sound like a dumb question.. Is it a water boiler or a steam boiler..?? I have seen people fill a steam boiler with water & water ran out of all the radiator air bleeds. If you have the t.stat set at 71 How does it jump to 77 by it's self ?? I'am missing something here

beenthere 03-01-2009 09:12 PM

Could be the thermostat is not shutting the boiler off.
If you have isolation valves, you don't need to drain teh system.
Sounds like your auto water feed is bad also.

Carloscda40 03-01-2009 10:35 PM

It's a gas Boiler that you fill with water, so a water boiler.
And I don't know why it jumps either?

They say to bleed the radiators to get the air out of them & to purge them with water.

sgthvac 03-01-2009 10:59 PM

Do you have zone valves? If one is sticking it will cause the boiler to keep running. Post some picts. of your system.

Do you have an auto fill valve and expansion tank of some kind? Just a guess, but there are generally 2 things that cause your pressure to rise and open the pressure relief. Autofill valve gummed up and allowing to much water into the system or a waterlogged expansion tank which needs drained. If you have a bladder type expansion tank, the bladder can rupture and become water logged as well and it will need to be replaced.

As stated earlier, post some picts. it will help us out to help you.

Carloscda40 03-01-2009 11:50 PM

Carloscda40 03-01-2009 11:57 PM

And yes there is an expansion tank in the ceiling.
Also the flame under the boiler is not shutting of hence the temp jumping up I guess?
And there sounds like someone is knocking on the pipes?

beenthere 03-02-2009 04:38 AM

You need a meter to start checking componets, to see which one is causing the boiler to not shut off.

Looks like that boiler has had a fair amount of trouble over the years.

kenmac 03-02-2009 07:02 AM

Looks like The t.stat should supply power to tge gas valve on your set up. Mabe t.stat out of calibration, Not level if old mercury type

Carloscda40 03-02-2009 09:46 AM

Yea it's an old one. The burn marks are from last week the left side was full of sut which caused the pilot assembly to go bad. Had it cleaned out and replaced.

The water is from the pressure relief valve.

We have a digital thermostat.

Now with the knocking of the pipes is that because of trapped air?
And to replace the gauge do I have to drain all the water out the system?

satz 03-02-2009 12:50 PM

Knocking of Pipe happens when the plastic tabs they put melts over time. install some brass ones they are expensive but will not cause this problem. The knocking means the pipes are conducting water at high temp and the temp change is fast causing expansion .With no brackets the harmonics are travelling along the pipe banging into stuff.

Test your thermostat , remove the 2 wires for heat and connect them manually the circuit will close and the furnace will start. disconnect and it should shut off. If this happens
you have a thermostat issue.

Check the gas valve .recently mine would not open for 1 zone and all i did was disconnect the power and let the valve plunger completely discharge ,clean and reinstalled to get it to work. I had a soot problem a few days before and i inferred that something got into the zone value blocking it from opening and closing properly.

good luck

beenthere 03-02-2009 03:23 PM

Since I don't see isolation valves.
Your probably going to have to drain it.

While you have it drained, you should install the air vent on the boiler like its suppose to have.

bob22 03-02-2009 03:46 PM

What is the C-clamp holding together (in left side of picture)?

Carloscda40 03-02-2009 03:49 PM


Originally Posted by bob22 (Post 239337)
What is the C-clamp holding together (in left side of picture)?

That was put there yrs ago for what i don't know

Carloscda40 03-02-2009 07:29 PM

OK what i did with the boiler off, starting with the radiator in the front bedroom with someone downstairs. Had them feed water into the system while I went to each radiator and bleed them ti'll water came out.

Set the temp to 72, so far so good.

Spoke to soon, just checked the gauge and it's reading 30?
The manual says 12psi for cold water or 20 to 30 for hot water.

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