Dedicated A/C or a Heat Pump Alongside a Gas Furnace?

[farmeratheart]

Hi All,

I will be replacing an existing propane fired forced hot air furnace coupled with a cental air conditioner very soon. My dealer of choice has offered me several options, but the 2 at the top of the list are ...

1) replacement gas furnace (LP) and a central A/C unit both of similar size to what currently exists but with appropriate efficiency gains by new equipment or ...

2) the same gas furnace in option#1 coupled with a heat pump of similar capacity with respect to cooling as the AC in #1.

I think that it would be nice to have another source of heat during the more temperate times of the year so we didn't have to burn LP if the wood fire was out because we weren't home. However, is a heat pump as reliable (and capable) as the central air unit for the A/C portion of the year?

Thanks for any input!

Frank

P.S. Option#2 costs $700 more so the price differential is not prohibitive.

 

[Ed of all trades]

I have heard that the heat pump is very efficient when it is just cool outside. I am thinking of taking out an ac unit and putting in a heat pump myself.

 

[farmeratheart]

I see the heating efficiency of the heat pump from 60F to 40F as a bonus. What I'm less sure about is the efficiency/reliability of the heat pump as an A/C when temps are in the 90-95 range?

Frank

 

[gordyy]

I am a forced into retirement hvac tech I have seen a lot of heat pumps both ground source and air to air, they are as efficient as the regular A/C and work exactly like them for cooling, the temperature they work efficeintly at for heating depends on your local costs for electricity, the efficiency drops as the temp drops, usually they will be able toprovide all your heating needs till around the freezing mark.
In one town in our area they have city owned power distribution that is 75 % of the cost of the rural or for profit utilities there we set them to run down to -10 f as there was still an efficient gain, on rural or the for profit systems we shut them down at 10 f, Your local dealer should be able to answer that question as it has to do with both local electric rates and propane rates. But by all means go for the highest seer rating within reason (some super high efficient units are so cost prohibitive that getting 4% efficiency at a cost of $1000. will never pay itself back. No simple answer to your question but check around if you trust the contractor you are talking to just have a good talk with him and ask him what he would do if it was his place

 

[lilranch2001]

I am a forced into retirement hvac tech I have seen a lot of heat pumps both ground source and air to air, they are as efficient as the regular A/C and work exactly like them for cooling, the temperature they work efficeintly at for heating depends on your local costs for electricity, the efficiency drops as the temp drops, usually they will be able toprovide all your heating needs till around the freezing mark.
In one town in our area they have city owned power distribution that is 75 % of the cost of the rural or for profit utilities there we set them to run down to -10 f as there was still an efficient gain, on rural or the for profit systems we shut them down at 10 f, Your local dealer should be able to answer that question as it has to do with both local electric rates and propane rates. But by all means go for the highest seer rating within reason (some super high efficient units are so cost prohibitive that getting 4% efficiency at a cost of $1000. will never pay itself back. No simple answer to your question but check around if you trust the contractor you are talking to just have a good talk with him and ask him what he would do if it was his place

Thanks Gordy.
I had basicly the same question on my mind as the OP, only also considering ground source

 

[gordyy]

ground source is the way to go IF your going to be there a long time, have the want to tear your lawn to heck and back again and got the $$ to do it upfront although there are some low interest rates now so that might not be as much of a factor as it used to be.
Ground source is considerably higher to install and a whole lot less operating expense however it does require maintance I should say they both do. that is the biggest factor in efficiency the lowest efficient A/C now runs just as cheap as the high if the condensor and evaporator (inside and outside coils) are clean
its just to get a higher rating you need more coil as they are rated on a 2 yr run cycle. spend an hour every 2 months and a 10 seer performs as good as a 14. dont spend the time on maintance it costs in power loss and equipment heats up and burns out. Compressors are spendy
Its like your tractor use it dont check or change oil never clean the radiator it cost real quick

 

[techman]

I do HVAC on the side, and have installed many heat pumps. What was said earlier is not quite true. As it gets colder, the efficiency of a heat pump does not drop much. What happens is that the capacity (amount of BTUs delivered) drops off. At 20 deg F a heat pump is still producing heat at about twice that of straight electric heat.

I would recommend going with a heat pump. It will do you well down to about 25-30 deg F. Below that switch to gas, which today is quite cheap. Have the installer put in a Honeywell IAQ thermostat, with an external temp sensor. You can set that up to automatically switch over to gas when the outdoor temp hits a set value, like 30 deg.

paul

 

[newbury]

<snip> It will do you well down to about 25-30 deg F. Below that switch to gas, which today is quite cheap. <snip>

The OP said LP for gas.



LP is not that cheap.

 

[Redneck in training]

If you have the space for ground loop or pond not too far from the house and/or you can install the ground loop by yourself go for geothermal. It will heat your house regardless of outside temperature, it will do you AC and also hot water during AC season. You can leave your propane furnace in as backup when power is down. Some installers have a horizontal drill that can install the ground loops underground only with minimal ground disturbance. You might be eligible for 30 % tax write off and many utilities have lower "heating electric rate" in the heating season.
Geothermal Boring

 

[LWG]

I live in Maryland, too, and the day I got rid of my heat pumps was one of the happiest days of my life. A heat pump is just a great air conditioner you can run in reverse, unless you go ground-based, which really increases the cost. The problem with the heat pump is that the "hot" air that comes out is about skin temperature. I never felt warm with heat pumps. It felt cold and drafty.