changing outside thermostat setting

[nladan]

I live in Tennessee. I have a Tappen duel fuel. The outside thermostat is currently set towards the high range. Now that propane costs are much higher and electric is about the same as it was last year, I would like to adjust the outside thermostat to use the propane only when it is colder out.

The outside thermostat was set about 37 [factory setting?], I believe. Could or should it be lowered to, say 34?

Can this be done without fear of messing up anything?

Thanks.

Nladan

[dhvac]

you can only set it as low as the heat pump is able to keep up if you set it too low then you will be cold

if you do not know what the capacity balance is then you might want to get professional help

or you could adjust it and just take a chance

[nladan]

Thank you for your reply.

The booklet that came with the unit has a formula for figuring out the most effecient setting for electric and propane prices.

I have a single stage heat pump split unit duel fuel.

If it doesn't keep us warm, I will set the outside thermostat where it was.

I just wanted to be sure that I wouldn't cuase the heat pump to freeze up or do some other damage if I lower the outside thermostat.

Is it possible to do damage? (Other than cold fingers?)

Nladan

[dhvac]

you will not hurt it by turning it down as long as thats all you do and you dont short any wires while in there

[nladan]

Thanks.

I asked a tech on a tune up call if he could change the setting of the outside thermostat, because the cost of LP had gone up.

He said it shouldn't be changed as it was factory set. It might cause the HP to freeze up.

I was suspicious that he just didn't want to do it.

Thank you for your input.


Nladan

[Black Adder]

Heat pump will not "Freeze up" that's what a defrost cycle is for. 34 degrees sounds a bit cold, try it and see if it keeps up to temp. Change it back if it doesn't, won't hurt the unit at all.

[wyounger]

Originally posted by nladan

He said it shouldn't be changed as it was factory set. It might cause the HP to freeze up.

Bogus. It's going to freeze up one way or another; that's why heat pumps know how to defrost themselves.

You can determine the balance point on paper until you're blue in the face, but if you have the time and the interest, you'll probably get the best results experimentally by just creeping down the balance point setting until it can't hold the setpoint when you're near the balance point setting; then back off a little. Even if your calculations are perfect, you can't expect the outdoor stat to have perfect calibration. And even if it was perfect, just being built into an operating heat pump is going to bias its perception of outdoor temp a bit.

[nladan]

Thank you so much for your info. It is great to have this resourse.

Three more questions, please. How can I be sure I have a Duel fuel thermostat vs the fossle fuel kit?

Which is the most expensive option? By how much?


Nladan

[Black Adder]

What make and model is your thermostat, do you change the balance point on the thermostat? Is there a seperate control in the furnace (fossil fuel kit)?

[nladan]

<What make and model is your thermostat, do you change the <balance point on the thermostat?

The make of the inside wall thermostat is Simplecomfort Model # 2210.


<Is there a seperate control in the furnace (fossil fuel kit)?

There is a dual fuel kit. I am not sure if there is a seperate control in the furnace. I am not sure what to look for.


There is a thermostat in the HP. It was set at about 38 degrees.

Nladan



[Edited by nladan on 10-28-2005 at 10:27 PM]