Gas furnace or electric heat pump
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Egon
Epic Contributor
It's best if all the plans are in place beforehand so systems are compatible and installation at a later date is easy.
Egon /forums/images/graemlins/grin.gif
Egon /forums/images/graemlins/grin.gif
Volfandt
Veteran Member
Potatoe, potato. Tomatoe, tomato /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
Perhaps I should have stated that the "heat transfer" decreases as opposed to "efficiency" decreases but in accuality either works for me /forums/images/graemlins/grin.gif
Bottom line is that the HP needs a backup heat source to kick in or it will run all day & night and never meet the thermostats demand at approx 30 degrees outside temp /forums/images/graemlins/grin.gif
</font><font color="blue" class="small">( The problem that occurs is that the capacity of the heat pump (number of BTUs delivered) drops. This is due to the reduced temperature difference between the vaporizing freon in the outside unit and the outdoor temperature, reducing the amount of heat that can be absorbed from the air. )</font>
My system utilizes Puron as opposed to freon and as I stated I feel it runs quite a bit more than the old freon based HP it replaced but wiith that said, it uses much less electricity.
My outside unit's coil is atleast twice as large as the original unit, and the inside "A" coil has roughly the same area as the originals straight coil. Could it be that the combination of a larger outside coil plus Puron as the refrigurant makes it more efficient, err ahhh, I mean use less electricity?
Volfandt
Perhaps I should have stated that the "heat transfer" decreases as opposed to "efficiency" decreases but in accuality either works for me /forums/images/graemlins/grin.gif
Bottom line is that the HP needs a backup heat source to kick in or it will run all day & night and never meet the thermostats demand at approx 30 degrees outside temp /forums/images/graemlins/grin.gif
</font><font color="blue" class="small">( The problem that occurs is that the capacity of the heat pump (number of BTUs delivered) drops. This is due to the reduced temperature difference between the vaporizing freon in the outside unit and the outdoor temperature, reducing the amount of heat that can be absorbed from the air. )</font>
My system utilizes Puron as opposed to freon and as I stated I feel it runs quite a bit more than the old freon based HP it replaced but wiith that said, it uses much less electricity.
My outside unit's coil is atleast twice as large as the original unit, and the inside "A" coil has roughly the same area as the originals straight coil. Could it be that the combination of a larger outside coil plus Puron as the refrigurant makes it more efficient, err ahhh, I mean use less electricity?
Volfandt
Cityboyfarmer
Gold Member
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</font><font color="blue" class="small">(
Bottom line is that the HP needs a backup heat source to kick in or it will run all day & night and never meet the thermostats demand at approx 30 degrees outside temp /forums/images/graemlins/grin.gif
</font>[color:"blue" class="small
)</font>
If your heat pump system cannot satisfy the thermostat at 30 degrees OAT it is either too small, improperly charged or incorrectly installed. Many contractors do not understand proper heat pump installations and heat load/loss calculations. The design of your duct system can make a massive difference in your heat pumps operation and your overall comfort. Heat pump refrigerant charges are critical and the old rules of thumb used for AC do not apply.
A properly installed heat pump will warm your home and satisfy the stat at outdoor air temps (OAT) in the low teens. Another factor affecting heat pump operation is how well insulated your home is along with what type of windows and doors you have.
So let's not be too quick to compare all heat pumps performance to one persons experience.
Bottom line is that the HP needs a backup heat source to kick in or it will run all day & night and never meet the thermostats demand at approx 30 degrees outside temp /forums/images/graemlins/grin.gif
</font>[color:"blue" class="small
)</font>
If your heat pump system cannot satisfy the thermostat at 30 degrees OAT it is either too small, improperly charged or incorrectly installed. Many contractors do not understand proper heat pump installations and heat load/loss calculations. The design of your duct system can make a massive difference in your heat pumps operation and your overall comfort. Heat pump refrigerant charges are critical and the old rules of thumb used for AC do not apply.
A properly installed heat pump will warm your home and satisfy the stat at outdoor air temps (OAT) in the low teens. Another factor affecting heat pump operation is how well insulated your home is along with what type of windows and doors you have.
So let's not be too quick to compare all heat pumps performance to one persons experience.
Volfandt
Veteran Member
Semper Fi....
73-77 Winger /forums/images/graemlins/wink.gif /forums/images/graemlins/grin.gif
I've had three differnet brands of HP's over the last 23 yrs.
1st one was a Rheem package unit. It was 1.5 ton and conditioned 1000 sq ft. Once the temps dropped below freezing the only time the HP's outside fan unit would cut off was when it was either in defrost or the strip heaters kicked in. I could easily tell. Ran this way for 7 yrs. Was working that way when I bought the house and after I sold it.
2nd was a Sears branded 2 ton split system that conditioned 1800 sq ft in a new built house. Once the OST dropped below freezing it too rarely quit running except for when defrosting or when the electric heaters kicked in. Also easy to tell. Ran this way for 13 yrs until the inside coil deteriorated and started leaking.
3rd and present is a 2.5ton Carrier split system that conditions approx 2500 sq ft (expanded the abode) and it not only runs more in heat mode but also in AC mode too. It utilizes Puron as opposed to freon and I'm becomeing of the opinion that it's not as efficient as freon. The Carrier uses less electric in AC mode but since I run a gas furnace as backup, the electric usage when heating is much less but that could be because of no 220v resistance heaters kicking in now and the furnace draws no more than 10 amps surge.
In my non professional opinion, if the HP isn't water source or ground source, it will struggle to heat once the OST drops below freezing but even at athat it is the best most economical choice. At least that has been my observations with three different units at two different houses.
Volfandt
73-77 Winger /forums/images/graemlins/wink.gif /forums/images/graemlins/grin.gif
I've had three differnet brands of HP's over the last 23 yrs.
1st one was a Rheem package unit. It was 1.5 ton and conditioned 1000 sq ft. Once the temps dropped below freezing the only time the HP's outside fan unit would cut off was when it was either in defrost or the strip heaters kicked in. I could easily tell. Ran this way for 7 yrs. Was working that way when I bought the house and after I sold it.
2nd was a Sears branded 2 ton split system that conditioned 1800 sq ft in a new built house. Once the OST dropped below freezing it too rarely quit running except for when defrosting or when the electric heaters kicked in. Also easy to tell. Ran this way for 13 yrs until the inside coil deteriorated and started leaking.
3rd and present is a 2.5ton Carrier split system that conditions approx 2500 sq ft (expanded the abode) and it not only runs more in heat mode but also in AC mode too. It utilizes Puron as opposed to freon and I'm becomeing of the opinion that it's not as efficient as freon. The Carrier uses less electric in AC mode but since I run a gas furnace as backup, the electric usage when heating is much less but that could be because of no 220v resistance heaters kicking in now and the furnace draws no more than 10 amps surge.
In my non professional opinion, if the HP isn't water source or ground source, it will struggle to heat once the OST drops below freezing but even at athat it is the best most economical choice. At least that has been my observations with three different units at two different houses.
Volfandt
kenmac
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I have installed many heat pumps over the years , rheem goodman trane just to name a few. I don't know what brand you are installing , but the ones I've installed won't produce comfortable heat below around 32-35 deg. the air is just not warm enough for some folkes.I have even had to change the setting for the aux. heat to come on at 40 deg out side temp for a good many of my customers
Sigarms
Super Member
Curoius
Is that with the strip heat "on" for heat in the low teens?
Is that with the strip heat "on" for heat in the low teens?
Sigarms
Super Member
Puron is R-410A ( a refrigerant just like R-22).
Puron is Carrier/Bryant "brand name" only.
Technicality (sp?) I know, but...
410A has nothing to do with the S.E.E.R rating (although coil size does in relationship to the condensing unit and vise versa).
Puron is Carrier/Bryant "brand name" only.
Technicality (sp?) I know, but...
410A has nothing to do with the S.E.E.R rating (although coil size does in relationship to the condensing unit and vise versa).
Cityboyfarmer
Gold Member
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As I said before, there are many variables. In a home with lots of windows or standard insulation, I'll agree that below freezing temps will cause those HP's to struggle. Another variable is what indoor air temperature are you trying to achieve? If you are trying to maintain greater than 70 degrees when it is below freezing, you will need supplemental heat. A heat pump will never achieve the warm air temps at the supply vents a gas furnace will.
If you allow your ambient temp to drop, say overnight to 60, then in the morning you want to raise the temp to 68 with OAT's below freezing, you are going to need strip heat. If you want to achieve a stable 68 degrees continually, you need to "set it and forget it". A well installed HP can "maintain" a comfortable IAT well below freezing. It cannot heat a space as fast as gas. If you have kids running in and out of the house leaving doors cracked, you will need supplemental heat.
I installed my heat pump up in my home to operate in three stages. It is a 10 SEER 4 ton heating 2200 square feet with at least 1 return in each room. Now I have seen builders put 3.5 ton units and smaller in homes this size with only one or two filtered returns. Your duct system makes a massive difference in system performance. Those small HP's will not heat as well as my 4 ton. When the summer OAT approaches 100, these small units will not cool as well either. Manual J allows for up to a 25% size increase over the cooling load for HP's.
Stage 1: Heat pump only with 1 degree temp drop.
Stage 2: Heat pump + 10K strip heat with 2 degree drop.
Stage 3: Heat pump + 10K + 10K with greater than 2 degree drop.
The stages drop out in the same order. I set my system up in this manner because when I want heat, I want heat now. I like to sleep a little cooler at night and bring it up in the morning. 99% of the time, once I have achieved 68 IAT, the HP will maintain it. Electric bill runs between $150-$200 a month.
Now, I retract my statement about HP's maintaining IAT's in the teens. Temps that low rarely happen in Georgia, so I have little HP experience below the 20's. I can say, however, that my HP has done its job for the last 6 years.
If you allow your ambient temp to drop, say overnight to 60, then in the morning you want to raise the temp to 68 with OAT's below freezing, you are going to need strip heat. If you want to achieve a stable 68 degrees continually, you need to "set it and forget it". A well installed HP can "maintain" a comfortable IAT well below freezing. It cannot heat a space as fast as gas. If you have kids running in and out of the house leaving doors cracked, you will need supplemental heat.
I installed my heat pump up in my home to operate in three stages. It is a 10 SEER 4 ton heating 2200 square feet with at least 1 return in each room. Now I have seen builders put 3.5 ton units and smaller in homes this size with only one or two filtered returns. Your duct system makes a massive difference in system performance. Those small HP's will not heat as well as my 4 ton. When the summer OAT approaches 100, these small units will not cool as well either. Manual J allows for up to a 25% size increase over the cooling load for HP's.
Stage 1: Heat pump only with 1 degree temp drop.
Stage 2: Heat pump + 10K strip heat with 2 degree drop.
Stage 3: Heat pump + 10K + 10K with greater than 2 degree drop.
The stages drop out in the same order. I set my system up in this manner because when I want heat, I want heat now. I like to sleep a little cooler at night and bring it up in the morning. 99% of the time, once I have achieved 68 IAT, the HP will maintain it. Electric bill runs between $150-$200 a month.
Now, I retract my statement about HP's maintaining IAT's in the teens. Temps that low rarely happen in Georgia, so I have little HP experience below the 20's. I can say, however, that my HP has done its job for the last 6 years.
kenmac
Super Member
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What back up heat do you use when the unit goes into defrost mode? gas OR elec strips ? I don't know of any h.p. that will heat in defrost mode no matter the size of the unit ,duct work, how well house is insulated. We have about the same temps. here as you have in GA. When the unit goes into defrost you have to have something to offset this. You maybe able to handle the cold air that is put out when the unit goes into d. f . mode , but most people can't. Thats why I don't know of any H. P. units that can stand alone . My parents live in FL. and they have elec. heat strips for back up .
