Forced air furnace takes long time to heat up house

[ColdBuffalo]

I live in Buffalo, NY. Outside temps are about 25 degrees Fairenheit. I have a vacant home that I am selling, and keep the heat at 45 until I have a showing. Before a showing, I go over to the house and turn the heat up to 68 degrees. The furnace is a 27 year old forced-air Bryant, and the house is about 1600 square feet, with carpets in all the rooms except for 1 bedroom, which has a wood floor. It takes about 2.5 to 3 hours to get the house up to 68 degrees. Does this sound normal? Should it be taking this long? What could be the problem? Thanks!

[LazyPup]

that does not sound unusual at all. We must remember that when a house is occupied the furnace basically only needs to reheat the air in the structure between cycles while the basic structural materials will remain fairly constant temp.

When the house is left unoccupied for an extended period of time with the temp turned down to 55 the structurals materials are now cooled to 55 as well, therefore as the furnace begins heating the house a considerable portion of the energy is being immediatel absorbed in to the structural materials.

[Phelps]

I concur. I have seen many condos that I work on that have furnaces at the low end of the sizing requirements. They only put out like 106 degrees heat at around 70 degrees. But at 45 degrees, due to the rise in the furnace, it will be putting out much less than this at first because the icy cold return air is moving past the heat exchanger.

That is why I like my furnace. I have the older non-hi-efficiency type and have measured a high temp of 180 degrees at the register. Ahhhhh. I sit by it after I am frozen from being outside. Ahhhhh. And I can warm my place up from 53 set back to 78 degrees in probably 1/2 hour. Ahhhhhhh.

[Hube]

That is why I like my furnace. I have the older non-hi-efficiency type and have measured a high temp of 180 degrees at the register. Ahhhhh. I sit by it after I am frozen from being outside. Ahhhhh. And I can warm my place up from 53 set back to 78 degrees in probably 1/2 hour. Ahhhhhhh.

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Phelps;
You are quite fortunate, but are risking a 'fire' with a heat temperature like you claim.
Most safely installed furnaces have a temperature of approx 120 degrees maximum at the register.
In your case of 180 at the register, this would be a "far out of whack temperature" within the immediate vicinity of the supply plenum, and in most modern, "safe " installations, it would 'trip ' the High Lmit, thus preventing any potential dangerous situation within the home.

"aaah" could very quickly change to " ooooh" at your given 180 temperature

[Phelps]

From what I can see in my heat exchanger area is that all looks fine. But I do have a CO detector plugged in.

I like to test heat at the various rentals I work on, with the various furnaces and find many between range of about 118-142 degrees depending on the btu rating. The ones that are like only 40,000 only put out like 106, and the ones that are about 75,000 put out about 142. Unless my thermometer is off some. It's a Pryrex.

[HayZee518]

I was born in Buffalo and if your house is anything like I've seen especially in Black Rock - none of those houses are insulated. My aunt had a williams burner with one stat in one apt that controlled the heat for both tenants.