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73Electra 225 12-15-2008 12:28 AM

Is my old gas boiler operating properly?
Hi, I have a 50-60 year old gas boiler and I think it isn't working properly. I will give example from today. This evening, set my thermostat to about 61 and my wife I went out to dinner and some shopping. Got home and I put it up to about 64. I then went down into the basement to see just what the boiler was doing. It was on (meaning the burner) for about 10-15 minutes straight, then turned off. I concluded that the room temp upstairs had gotten warm enough to set off the thermostat. The burner was off as was the circulator. I then immediately went back upstairs and bumped my thermostat up two degrees. The whole boiler (burner) came right back on. I don't know a whole lot about boilers, but I was under the impression that the aquastats should be turning off the burner at some point while the circulator continues to pump the heat until the air warms enough. Like when I bumped the thermostat up two degrees, I would think that only the circulator should have kicked in, the burner was just going 15 minutes straight, the water had to be hot enough, no? I am using around 13-16 ccf of gas every three days, which seems like an awful lot. Its a small house with little insulation and the unit is old, but that still seems too much. So, does this sound normal, or do I have an issue with an aquastat or similar?

biggles 12-15-2008 05:14 AM

can't say your not hands on with that thing:thumbup:when the stat calls typical of boilers for HW baseboad/radiators the water coming back to the boiler is what dictates if the aquastat calls or not.....most of the time the ending cycle just before your stat satisfies,and shuts the circ pump the aquastat will be satisfied and it will just be the circ running.the opposite happens when it comes on the cooler water is circ'd back to the boiler and that mix closes the aquastat to run the burner.the stat controls the circ and the water in the system controls the aquastat cycle(when the stat is calling)older boilers maybe yours might be maintaining the boiler temp during the OFF cycle might want to check that out.newer latter boilers have a COLD START design,and do not maintain the water in the off cycle which is a waste of gas and your money.

beenthere 12-15-2008 05:25 AM

A 50 plus year old boiler holds a lot of water.
Most likely, teh boilers water temp didn't reach the aquastat set point.
So teh burner came back on when you turned the thermostat up 2 more degrees.
Normal for old high water content boilers.

3 to just over 5 therms a day, isn't much, depending on several things, including how cold it is outside.

If your aquastat is set to 180 or more. Might want to set it to 140, or 150, if you have cast iron rads.

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