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Home heating efficiency?

L

LBaker

Jan 1, 1970
0
I hope this group could help settle a debate in my household. My wife
insists on turning the thermostat back in the morning when she leaves for
work. I say it should stay at a constant temperature, as it runs longer in
the evening to get things warmed back up when she turns it back. What say
you all?
 
S

SQLit

Jan 1, 1970
0
LBaker said:
I hope this group could help settle a debate in my household. My wife
insists on turning the thermostat back in the morning when she leaves for
work. I say it should stay at a constant temperature, as it runs longer in
the evening to get things warmed back up when she turns it back. What say
you all?

The local utilities here in Phoenix have said for years
"if you can vary the temp by more than 8 degrees for more than 8 hours you
can save more than 5%".

I installed a set back t-stat years ago and it does help the power bill. I
tried it the manual method but that did not help at all. I would forget a
lot of the time.

My stat has 4 programs per day, I allow the temp to fall after 9 pm to 5 am
then come on for 2 hours and then off again until 4:30 pm. I had it hooked
up to an X-10 module when I was traveling a lot so I could call from the
airport and have the house almost where I liked it by the time I got home,
about an hour. It does not get real cold in Phoenix, so your operation will
vary.
 
P

PCK

Jan 1, 1970
0
LBaker said:
I hope this group could help settle a debate in my household. My wife
insists on turning the thermostat back in the morning when she leaves
for work. I say it should stay at a constant temperature, as it runs
longer in the evening to get things warmed back up when she turns it
back. What say you all?
your wife`s opinion is based on science and common sense
your`s is not
 
L

LBaker

Jan 1, 1970
0
SQLit said:
The local utilities here in Phoenix have said for years
"if you can vary the temp by more than 8 degrees for more than 8 hours you
can save more than 5%".

I installed a set back t-stat years ago and it does help the power bill. I
tried it the manual method but that did not help at all. I would forget a
lot of the time.

My stat has 4 programs per day, I allow the temp to fall after 9 pm to 5 am
then come on for 2 hours and then off again until 4:30 pm. I had it hooked
up to an X-10 module when I was traveling a lot so I could call from the
airport and have the house almost where I liked it by the time I got home,
about an hour. It does not get real cold in Phoenix, so your operation will
vary.
We have a ground source heat pump. The backup heat coil kicks in when
anything above a 3 degree increase is called for. So the auto units won't
work unless we go with a 2 degree differential and I can't imagine that
would save much. We also have a substantial amount of ceramic flooring which
does store some heat. It just seems like it runs much more when trying to
warm things up again....
 
L

LBaker

Jan 1, 1970
0
PCK said:
your wife`s opinion is based on science and common sense
your`s is not
My opinion was based on what I was told by the HVAC contractor that
installed the GSHP...
 
L

LBaker

Jan 1, 1970
0
LBaker said:
I hope this group could help settle a debate in my household. My wife
insists on turning the thermostat back in the morning when she leaves for
work. I say it should stay at a constant temperature, as it runs longer in
the evening to get things warmed back up when she turns it back. What say
you all?
I should have given a little more information. We have a ground source heat
pump with a heat recovery system for hot water needs. The water heater is on
a timer so that it is only on during peak periods. So the heat pump is also
warming our water during the day. The house has a full southern exposure so
we are getting some passive heat. Location is southern Pennsylvania...
 
S

Sylvan Butler

Jan 1, 1970
0
I hope this group could help settle a debate in my household. My wife
insists on turning the thermostat back in the morning when she leaves for
work. I say it should stay at a constant temperature, as it runs longer in
the evening to get things warmed back up when she turns it back. What say

If you heat with an air-source heat pump, you are right. Anything else,
she is right.

sdb
 
L

LBaker

Jan 1, 1970
0
m Ransley said:
she is right
Is she? I just found this.

"Ground source heat pumps operate most efficiently when left at one
set-point year around. If
you desire a cooler temperature for sleeping, you may lower the set point a
few degrees, however
the heat pump may take more time to "recover" from changes in the heating
setpoint than a fossil
fuel burning furnace."
 
M

m II

Jan 1, 1970
0
LBaker said:
My opinion was based on what I was told by the HVAC contractor that
installed the GSHP...


In all probability, your wife is a lot smarter than an HVAC contractor.




mike
 
J

j.b. miller

Jan 1, 1970
0
You can save around 10% by setting the stat back when you're not home or
alseep.
I run mine 70 daytime, 60 off hours.

In my remote energy control business, I set buildings(most are
manufacturers) back to 45F. They're properly zoned out ,failsafe,etc. and
enjoy saving a minimum of $1000 per heating month( 8 months of the year).
This contrary to the 'experts'( the HVAC guys,the ring bearing 'engineers')
the local gas company....
I've done this for the past 20 years and everyone's happy so far...

Another way to save on energy is to have a 'mud' room built or a wind
break(3 sides,no door on the prevailing wind side). Did this 8 years ago and
according to the math on the records I kept, I've saved another 8%. It all
helps...

Jay in Greensville,Ontario
 
W

William P.N. Smith

Jan 1, 1970
0
LBaker said:
I hope this group could help settle a debate in my household. My wife
insists on turning the thermostat back in the morning when she leaves for
work. I say it should stay at a constant temperature, as it runs longer in
the evening to get things warmed back up when she turns it back. What say
you all?

I say a setback thermostat will make you both happy. It'll save some
(*) money when you aren't home and everything will be at 'comfortable'
when you get home, so you won't be chilly for a while after you turn
it back up. Plus you'll never forget to set it {down,up}, and you'll
keep your wife happy. 8*)

(*) Sure, it's all YMMV, an electric ground source heat pump with
radiant flooring is different from a fossil-fueled forced hot air
system, but you can't help but save _some_ money. You might also try
setting the thermostat down a single degree and see how that helps,
and if you notice... We keep our thermostats at 64 overnight and
during the day, and 67 mornings and evenings, and we are rarely cold,
as we get used to it. The computers keep the office at 67. 8*)
 
M

Mark Mitchell

Jan 1, 1970
0
She would be correct in her assertion.

The difference of indoor temperature from outdoor temperature causes the
heat exchange or loss.

The warmer home will exchange or loss more heat to the outdoors, while the
cooler home will not loose as much.
 
S

SQLit

Jan 1, 1970
0
LBaker said:
longer
We have a ground source heat pump. The backup heat coil kicks in when
anything above a 3 degree increase is called for. So the auto units won't
work unless we go with a 2 degree differential and I can't imagine that
would save much. We also have a substantial amount of ceramic flooring which
does store some heat. It just seems like it runs much more when trying to
warm things up again....

Sorry you forgot to mention your on an ground source heat pump. I assumed,
falsely that you were using conventional means to heat and cool..
She is right.
 
D

daestrom

Jan 1, 1970
0
LBaker said:
Is she? I just found this.

"Ground source heat pumps operate most efficiently when left at one
set-point year around. If
you desire a cooler temperature for sleeping, you may lower the set point
a
few degrees, however
the heat pump may take more time to "recover" from changes in the heating
setpoint than a fossil
fuel burning furnace."

But keep in mind, 'more time to recover' doesn't automatically mean it uses
more overall energy. For example, say setting back at night you avoid
cycling the heating system at all. Then in the morning, a fossil fuel unit
takes about 30 minutes to warm the house back up whereas a heat pump may
have to take an hour. But if the set-point is left up all night long so
that the heat-pump cycles 10 minutes every hour for 9 hours, it would run 90
minutes.

So the heat pump takes longer to recover (an hour to warm the house up vs.
30 minutes for fossil fuel), but you save 30 minutes worth of running (just
60 minutes in morning vs. 90 minutes throughout the night).

Of course, YMMV, and this is just an example.

daestrom
 
D

daestrom

Jan 1, 1970
0
LBaker said:
We have a ground source heat pump. The backup heat coil kicks in when
anything above a 3 degree increase is called for.

Now THAT makes a difference. If the backup is just resistance heating, and
it kicks on when you bump the thermostat back up to 'normal', then you are
right and she's wrong.

But why would the backup heat coil kick in at such a minor set up?? Are you
sure this 'backup heat coil' is resistance heaters or is it another valve
opening in the freon circuit?

If it is a resistance heater, I'd look for a way to change this setting. It
provides a faster heat recovery, but you can walk into a warm house by
programming a regular set-back thermostat to 'set-up' a half-hour before you
get home. Resistance heating is probably the *most* expensive way to warm
up the house after a set-back.

daestrom
 
D

daestrom

Jan 1, 1970
0
Sylvan Butler said:
If you heat with an air-source heat pump, you are right. Anything else,
she is right.

Not if electric resistance heaters kick-in for 'quick recovery' when the
thermostat is set back up to normal. Having the controls switch to
resistance heaters probably wastes whatever savings he would have realized
from setting down for 8 hours. Especially if the house has a lot of thermal
mass so the temperature only drops four or five degrees in 8 hours.

daestrom
 
M

m Ransley

Jan 1, 1970
0
We do not know what his gas or electric costs are to say electric is
overpriced, although for most it is. Or what kicks in for backup, when.
Bottom line setbacks save if the cheapest fuel is used.
 
M

m Ransley

Jan 1, 1970
0
At first you did not say GSHP. that is the most efficient heating
system, but even a 2f reduction will help if a less efficient backup
does not come on. You could try reseting it for 3 but when it is colder
out you realy dont want the backup comming on if it is another heat
source of less efficiency. Experiment, normaly setbacks save, but for
you it wont if a more expensive secondary fuel is used. It depends on
your GSHP capacity to recover, Btu required for your home. So outdoor
temps will change the situation
 
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