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Posted by John Gilmer on September 26, 2009, 6:48 pm
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> Last I heard, setback stats don't work with heat pumps, because they
> put out so little heat, if you let them fall behind they can't catch
> up. Was this true? Is it still true?
The main problem is that if the temperature drops too far below the set
point the system will call for expensive resistance heating to catch up.
One "solution" (which I have used) is to disconnect 2/3rds of the electric
auxilary strip heaters. (There are still there but on a second breaker.
Were the heat pump to fail and I NEEDED the resistance heating I could just
flip a breaker and be back to normal.)
A secondary problem is that the heat "pump" is more effective/efficient when
the outside air temperature is closer to the room air temperature. If you
turn the setting back at night the system will try to catch up when the
indoor/outdoor temperature is at the daily maximum.
I don't have much science to back me up but I decided that setting the
system back was more trouble than it was worth. Among other things, our
"outside unit" doesn't have a heater to keep the oil warm enough to function
well. Thus, our system depends upon regular operation to ensure reasonable
lubrication on start up.
Some very sophiscated/efficient systems come with the fancy thermostats as
part of the package. They automatically "do the math" and find the most
efficient way to accomplish the set back (which you determine). In you
just have a simple heat pump, I wouldn't use an offset thermostat for
heating OR cooling.
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Posted by mm on September 26, 2009, 8:51 pm
On Sat, 26 Sep 2009 18:48:10 -0400, "John Gilmer"
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>> Last I heard, setback stats don't work with heat pumps, because they
>> put out so little heat, if you let them fall behind they can't catch
>> up. Was this true? Is it still true?
BTW, I heard about this 25 years ago when I was getting a setback stat
for my house and offerred to put one in my girlfriend's house. She
told me that they didn't work with heat pumps. Later after I didn't
like her anymore, I talked to her ex-husband and he told me how she
would turn the heat down when she left for work a half hour before he
got up, and he was thin, and cold every winter morning because of what
she did. She had said that she was paying for the heat so she was in
charge of it. She made more money that he did.
She seemed very nice and accomodating at first, but her first husband
said the greatest day of his life was the day the divorce was final.
Met her two husbands and 2 major boyfriends all at work. But at least
I was smart enough not to marry her.
More at the bottom.
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>The main problem is that if the temperature drops too far below the set
>point the system will call for expensive resistance heating to catch up.
>One "solution" (which I have used) is to disconnect 2/3rds of the electric
>auxilary strip heaters. (There are still there but on a second breaker.
>Were the heat pump to fail and I NEEDED the resistance heating I could just
>flip a breaker and be back to normal.)
>A secondary problem is that the heat "pump" is more effective/efficient when
>the outside air temperature is closer to the room air temperature. If you
>turn the setting back at night the system will try to catch up when the
>indoor/outdoor temperature is at the daily maximum.
>I don't have much science to back me up but I decided that setting the
>system back was more trouble than it was worth. Among other things, our
>"outside unit" doesn't have a heater to keep the oil warm enough to function
>well. Thus, our system depends upon regular operation to ensure reasonable
>lubrication on start up.
>Some very sophiscated/efficient systems come with the fancy thermostats as
>part of the package. They automatically "do the math" and find the most
>efficient way to accomplish the set back (which you determine). In you
>just have a simple heat pump, I wouldn't use an offset thermostat for
>heating OR cooling.
Isn't a heat pump as good as any air conditioner when used for
cooling?
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Posted by Ralph Mowery on September 26, 2009, 9:00 pm
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>> I don't have much science to back me up but I decided that setting the
> system back was more trouble than it was worth. Among other things, our
> "outside unit" doesn't have a heater to keep the oil warm enough to
> function well. Thus, our system depends upon regular operation to ensure
> reasonable lubrication on start up.
I don't have any thing to back that up either, but I still feel like most of
the energy saving things are just like the things you add to your car to get
beter milage. Just something to sell and make you feel good about it.
I have a heatpump and set it to one temperature in the summer and another in
the winter. Almost never change it unless something unusual hapens.
Sometimes in the fall and spring I do have to change it from heat to cool in
the mornings and evenings for a few weeks.
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Posted by mm on September 26, 2009, 9:14 pm
On Sat, 26 Sep 2009 21:00:08 -0400, "Ralph Mowery"
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>>> I don't have much science to back me up but I decided that setting the
>> system back was more trouble than it was worth. Among other things, our
>> "outside unit" doesn't have a heater to keep the oil warm enough to
>> function well. Thus, our system depends upon regular operation to ensure
>> reasonable lubrication on start up.
>I don't have any thing to back that up either, but I still feel like most of
>the energy saving things are just like the things you add to your car to get
>beter milage.
Well, no longer talking about heat pumps, talking about oil furnaces
etc. it's true that a lot of what you save when it's not as warm at
night or in the middle of the day, you lose when you finally have to
warm a colder place up. But the entire time the house is colder, it
is transmitting less heat to the outside (in the winter), and when
warmer in the summer, accepting less heat from the outside.
Considering that my seback stat has lasted 25 years so far, the outlay
per year was small.
It's not a new notino. My mother, at least since 1946 but probably
before that, always turned the stat down from 68 two or four degrees
when we went to bed, and she just tolerated the cold when she woke up
in the morning, until she had adjusted the stat and the house warmed
up. And I did too on weekday mornings when I got up almost as early
as she did.
I have no doubt that turning down the stat (or up in the summer) save
energy for the homeowner and society**. The advantage of the fancy
stat is not that it adjusts the temperature, one can do that manually.
It's that one doesn't have to wake up cold in the morning (or hot in
the summer for people who use AC)
**Plus the balance of payments to oil producing countries, plus the
pollution, the fuel waste disposal costs, the added heat to the
outside in the summer and even in the winter. There are a lot of
costs to wasting heating and cooling.
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> Just something to sell and make you feel good about it.
>I have a heatpump and set it to one temperature in the summer and another in
I haven't thought much about heatpumps. I've just read Tony's post
that they are designed to work with them now and it will take me a few
years before I come across enough info to reach a conclusion. And
since I don't have a heat pump, and only have about 30 years to live,
I may well be dead by the time I reach the conclusion. Please come to
my hospital room and I will try to tell you what my conclusions are.
show/hide quoted text
>the winter. Almost never change it unless something unusual hapens.
>Sometimes in the fall and spring I do have to change it from heat to cool in
>the mornings and evenings for a few weeks.
In a period like that, I would just open the windows and take life as
it comes.
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Posted by Ralph Mowery on September 26, 2009, 10:22 pm
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>>Sometimes in the fall and spring I do have to change it from heat to cool
>>in
>>the mornings and evenings for a few weeks.
> In a period like that, I would just open the windows and take life as
> it comes.
With the hay fever and allegories my wife and I have , we have not opened
the windows in about 30 years for any heating or cooling. Well one
Christmas or Thanksgivings day we did open the doors as it go too hot in the
house with all the family and cooking.
We are in a mild climate area so the total electric bill is around $ 150 per
month. We do have a heat pump and about 1800 sq. ft.
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> put out so little heat, if you let them fall behind they can't catch
> up. Was this true? Is it still true?