gas furnace won't fire, part 2

[Redlocks]

The other day I reported:

My gas furnace won't fire. The pilot is lit. When I turn up the > >thermostat, I hear a single click that is usually followed a few seconds > >later by combustion, however today it won't fire.

I should add it is an American Standard gas boiler (hot water/radiator) that is probably 35 - 40 years old.

The first pro to arrive at my house said it was the gas valve, but didn't have the part and decided it wasn't worth his time (no charge). The second pro was with a subsidiary of the local utlity company. He got the furnace to ignite and the heat is on ($79 no parts needed), however he said the circulator pump was rusted in place and recommended getting a plumber.

Now in the 16 years that I've been in the house I don't ever recall hearing a circulator pump in operation. This might sound like a stupid question but do I really need to get this fixed?

The heat feels good!

Thanks.

John

[HaHaHa]

Not hearing the pump is actually a good thing. Look at it yourself, it's somewhere near the boiler with a pipe going in and another going out.

Aside from the boiler providing the heat, the pump is crucial on getting that heat to where it's needed - from the boiler to the radiators and back.

[e-mail]

[Art]

If you do get it replaced, you might also have the expansion tank replaced if you still have the original and have to bleed it every year. The new ones are small and do not have to be bled.

[Gary R. Lloyd]

If your tank has to be bled every year, the problem is not the tank. Neither type of tank should need annual bleeding.

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software

[Redlocks]

I've never bled the expansion tank. I didn't know what is was for until 3 years ago. I might tap on it once or twice a season to make sure it sounds empty.

John

[m Ransley]

In 30 yrs we never bled our tank and still dont, tanks do not have to be bled and should not be. They need air not water for Expansion.

[m Ransley]

If you loose the air bubble and have to drain something is wrong with your system and it will not have expansion capabilities and can overpressure. Water in it when cold - tank is to small, or it does not drain properly- blockage, or bad autrotrol valve, or bad auto feed, over filling system. Pressure - altitude gauge may be bad if you rely on that for monitoring and manualy feed. Often pressure relief will release on even a partialy full tank from overpressure on a fully hot boiler, your relief valve could be bad also. Maintain overpressure and boilers do not last. Start with a new presure gauge and set boiler to right level.

[Art]

Perhaps not every year but if you have an old tank that doesn't have a bladder between the air and water, eventually you lose the air bubble and you have to bleed it.

[Gary R. Lloyd]

The expansion tanks most likely to leak air are those with a glass tube level indicator. The service tech is supposed to open the hand valves, check the level, then close the hand valves. If the hand valves are left open, air will eventually escape past the upper glass tube gasket. Seems like I have to close hand valves everywhere I go, because the guy who was there before me left them open.

Gary R. Lloyd CMS HVACR Troubleshooting Books/Software