6 times per hour versus 3 times per hour

[Jayn123]

I have an 80% efficiency forced air furnace. I think it is oversized for the temperatures I keep my townhouse at. When we had single digits in NJ it was still cycling 6 times per hour and I don't know if it even made it to

2nd stage by running 15 minutes or longer. I changed the setting on my Honeywell thermostat to 3 times per hour. That way, there are only 3 start-ups per hour. Even at 3 times per hour I don't even think it made it to 2nd stage on those really cold days, except in the morning when the thermostat setting went up by a degree.

I like 3 times per hour, because it seems to me that only 3 start-ups per hour would be less wear and tear. Just was wondering if there is any harm in 3 times per hour versus 6 times per hour for an 80% furnace? Would the longer running time (mostly in stage 1) be causing more wear and tear on the burner or heat exchanger, or not?

Thanks,

J.

[Tony Hwang]

Hi, You said your furnace is over sized. What is the size of furnace and your house? I'd rather concern myself with comfort level than wear of furnace. I didn't know 80% furnace came in multi stage model. If you want to see if 2nd stage coming on at all, while furnace is running you can check 2nd stage control lead marked W2.

I upgraded to 110K BTU 2 stage VS 98% furnace replacing single state 80% eff. 120K BTU one. The old furnace used to run mostly 3 times an hour during cold winter days. My house is 2700 Sq. St. 2 story located in Southern Alberta. New one cycles about at same rate including 2nd state. It gives more even temp. in the house(that's what wife noticed)

BTW, they don't sell 80% furnace any more up here. You can only install high efficiency furnaces for new houses or replacing old furnaces.

[Jayn123]

The house is around 2100 square feet and the finished basement is around 800 square feet.

The furnace is 110 K BTU forced air. It uses a single stage stat, and normally the furnace doesn't make it to the 2nd stage until after 15 minutes of running in the 2nd stage. Everyone I talked to wanted to put in a 110K furnace. I normally keep the thermostat only at 67 during the day, and 66 at night.

My furnace has a VS motor as well.

J.

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Jayn123 wrote:

Hi, You said your furnace is over sized. What is the size of furnace and your house? I'd rather concern myself with comfort level than wear of furnace. I didn't know 80% furnace came in multi stage model. If you want to see if 2nd stage coming on at all, while furnace is running you can check 2nd stage control lead marked W2.

I upgraded to 110K BTU 2 stage VS 98% furnace replacing single state 80% eff. 120K BTU one. The old furnace used to run mostly 3 times an hour during cold winter days. My house is 2700 Sq. St. 2 story located in Southern Alberta. New one cycles about at same rate including 2nd state. It gives more even temp. in the house(that's what wife noticed)

BTW, they don't sell 80% furnace any more up here. You can only install high efficiency furnaces for new houses or replacing old furnaces.

[Tony Hwang]

nt Hi, I see. I have a 1000 sq. ft. finished basement as well. Our winter is much colder than yours. My programmed temp setting is 70/65. Our NG price is ~3.00/GigaJoule floating rate, electric power is 8 cents/KWh fixed for next 5 years.

[MLD]

I have a 90+% efficient (condensing) furnace and it operates in a very similar manner. That is, the colder the day the more cycles it goes through and many times it does not get to the 2nd stage heat and increased fan speed. That's the way it is supposed to work--provides a more even, consistent heat with minimum in-house temperature variation. The only adjustment that I have control of is the time the system stays on Stage 1. I have it set on 10 min--if the thermostat isn't satisfied after 10 min the

2nd stage gas valve kicks in and the fan ramps up to it's high speed setting. I don't think that you truly understand how your system is designed to operate. MLD

[grumpy]

It depend if your Tst looking diferance of temperature or at the time???