Furnace cycles on/off before reaching temp

[GregThomp]

I just moved into a house in Los Angeles that has a gas-fired forced air heating system on the roof. The problem is that the system cycles on and off (sometimes in cycles only a minute or two long) before reaching the set temperature. I'm a first-time homeowner so I don't even know for sure whether this is unusual, but it sure seems so. The result is that it takes a very, very long time for the system to heat up the house. And it seems incapable of heating it any hotter than 70-71.

(I should also say that I have no way of knowing for sure when the *heating element* is on -- I only know when the fan is on, because I hear it. But I assume that the fan runs when the furnace runs. I did try leaving the fan on all the time to see if that helped, and it didn't.)

As a new homeowner I am covered for a year by some kind of appliance insurance policy and a guy came out and replaced the thermostat (the new one is a White-Rodgers). Alas, he didn't stick around long enough to make sure that solved the problem, and it didn't.

I'd be grateful for any thoughts.

Best,

Greg Thompson

[e5husmc]

If you just someone come out to fix it and they didn't call them back out.
Does the furnace run for a long time then cycles through some shorter cycles before it runs a long time again?

quote:Originally posted by GregThomp

I just moved into a house in Los Angeles that has a gas-fired forced air heating system on the roof. The problem is that the system cycles on and off (sometimes in cycles only a minute or two long) before reaching the set temperature. I'm a first-time homeowner so I don't even know for sure whether this is unusual, but it sure seems so. The result is that it takes a very, very long time for the system to heat up the house. And it seems incapable of heating it any hotter than 70-71.

(I should also say that I have no way of knowing for sure when the *heating element* is on -- I only know when the fan is on, because I hear it. But I assume that the fan runs when the furnace runs. I did try leaving the fan on all the time to see if that helped, and it didn't.)

As a new homeowner I am covered for a year by some kind of appliance insurance policy and a guy came out and replaced the thermostat (the new one is a White-Rodgers). Alas, he didn't stick around long enough to make sure that solved the problem, and it didn't.

I'd be grateful for any thoughts.

Best,

Greg Thompson

GH

[GregThomp]

I have called for them to come back. I just want to have some idea of what I'm dealing with.

In answer to your question, I'm not really sure. This morning the furnace did run for a longer than usual time before cutting out, I think. Still, it only raised the temperature from 62 to 63 before bailing.

Since I changed the airfilter I *think* it is also running somewhat longer.

Someone in another forum said the problem was probably a dirty flame sensor -- a common problem, apparently.

Hopefully, we'll find out.

Best,

Greg T.