Gas and Oil Home Heating Furnaces - Furnace Igniting

I turned the gas off to my pilot and the main on my forced air furnace for the summer. The furnace is probably original to the house so 40 years old.

The pilot is lit but the thermostat will not make the furnace come on. I can manually turn on the burner at the furnace but the fan will not turn on.

If I take a reading with a volt meter at the thermostat what should I get?

Any ideas?

First, be sure you have power to the furnace. The pilot will work without power being present. If you have 110 volts ac to the furnace, look for the thermostat wires inside the furnace. They are small wires and usually are not inside a covered box since they carry low voltage. Especially on a unit the age of yours. You should see at least one of them connected to a transformer with two terminals. Read voltage across them and you should get 24 volts ac. Let us know how that goes and if you haven't uncovered the problem by then, we'll go further.

I am getting 24 volt at the furnace.

To date I have had to manually turn the furnace on and then turn the manual switch off once the blower is on. At this point the thermostat takes over and shuts the burner off at temp.

I have changed the termostat but this has not helped. At times I am able to jump the 24 volt at the furnace and start the furnace but this does not work at all times.

It seems that the gas valve is sticking and keeping the sysem from operating.

What willa gas valve cost with a repairman?

My own personal opinion..........................


Furnace is 40 years old.. I think it's time to put it to rest... It's had it's FULL life in, and has past it..


Your fuel is being wasted big time on this.. I'd say at best your getting maybe 50+% out of it. where a new one is 80 or 90%.


My question for you.. Do you own a car that is 40 years old??

If you pull the t-stat you should get 24v at red to white. If you do get the 24v, jumper these 2 wires together and see if she fires up. If you don't get 24v or it don't fire post back.

By the way, Jay I have a 63' Impala...LOL:D

When you say you are manually getting it to come on, exactly what are you doing?

By the way, Jay I have a 63' Impala...LOL


LOL Ok, you got me there Matt.... BUT! Do you driving it everday going to work, grocery shopping.. going out on a road trip out of state??

I finally got a repairman in today. The gas valve is bad but it is extinct. They will have to do some modifications to put a in new valve on. I think I am leaning towards a new furnace instead of a couple hundred $s into a valve. Any suggestions on what to stay away from or what a 120k BTU unit should run installed?

What are the better filter systems out there for a family with 2 dogs?

Few things to do..


Call at least 3 diffrent dealers to give you a bid on a new system.

Ask them to do a heat load/lost

Duct maybe needs to be cleaned??

I would do your own home work on a free down load of the heat lost/load program and figure out what you need for size.

http://www.hvaccomputer.com/main.asp

90% of old furnaces were WAY oversized! if your old one is 120k, I bet your new one will only need to be about 80k.

Type of system..

Trane, Rheem, York are my personal choice.

90% rating for northern states and 80% for southern states (don't know where you are from)

If budget allows, go with two stage furance, and also look in to variable speed fan

Air filter would be the April Air Space Guard Media filter, or the April Air 5000 for people with allegery.

I don't know if you have Central Air? If so, and it's old change it out as well since your doing the job.. If no, do it anyway.. adds a value to the home for resale.

Good luck! :-)