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

[nikdfish]

We installed a heat pump & high eff. propane furnace at our place in the WV eastern panhandle over 10 years back to replace a low eff. (80%?) propane furnace & window AC units. No comparison at all on operating costs. We got through most winters without using much more than one 300 gallon LP tank, sometimes not even that. The heat pump saved loads & was much much cheaper to operate than even the high eff. (93%) LP furnace.

New heat pump units, like the one we recently had installed in our NC place are even better. If you need to "feel warmth" to be comfortable (as opposed to being just being warm), use radiant heat electric units in selected locations while you run the heat pump. They will be tons cheaper than burning propane to heat a house - cost per BTU for resistance electric is cheaper these days than most east coast delivered LP I'm aware of & heat pumps are cheaper than resistance even down well below freezing.

Nick

 

[Retired Iron Peddler]

A heat pump and a gas furnace in the OP is using the gas furnace as the emergency heat source. During extremely cold, the gas furnace would supplement the heat pump and for use during the heat pump's defrost cycle. I have 16kw in heat strips for use as emergency heat and for warming the air when the heat pump is on the defrost cycle. My system only uses the heat strips for supplemental heat if the automatic setback thermostat calls for more than a 2 degree change in the heat setting to quickly warm the air. My heat pump is a high efficiency unit will still produce warm air when the outside air temperature is in the upper teens. I have been very pleased with it's performance, reliability, and the much lower cost of operation compared to LP gas, our only other option.

Bill

 

[wcampbell47]

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.

Years ago a neighbor had a heat pump unit. Thing never worked well when it was cold. We wound up putting an electric heater to blow on the outside coils to keep them from freezing up. The heat strips in the unit did very little to warm the air. He burnt lots of wood that year. Just built a house and elected propane for heat - never considered the heat pump. What I really like is catalytic units that burn propane. Nice and warm spot heat.

 

[Domush]

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.

+1 this post. My last house was heat pump and I'd rather pay more for LP than feel cold all winter long. Save that seven hundred for LP and live warmer and more comfortably for years to come. You mention you have wood heat as well, so there is hardly a worry about price difference anyway.

Sent from my SCH-I500 using TractorByNet

 

[Mickey_Fx]

Had a heat pump installed last yr. VERY satisfied with it. Today's high efficiency HP's are close to 4X as efficient as radiant electric heat. Still something on the order of 2.5X down at freezing. My HP is rated at 40k BTU's and something like 20-25k BTU's at 20ｰ.

Nice seeing a few people referring to ground-source system by proper term as Geothermal is a misnomer. Ground heat doesn't become geothermal until MANY times deeper than these systems are buried.

See someone mentioned SEER rating. That is a rating system for AC's there is a different rating system for heating, HSPF. Heating System Performance Factor.

As for the mention of one brand to buy because it automatically switches on the aux heat when it gets real cold. There are numerous brands that do that. I have the top end model Bryant (sister company to Carrier) and not only does it switch on the aux heat, I can adj the temp at which this happens. I can also specify how often the defrost cycle comes on but that is beside the point.

Where I'm located we are cool/cold and WET during the winter months and if the defrost temp is set too low, the heat exchanger coils freeze up quickly so the defrost cycle has to come on a lot more frequent. Cost more to run the defrost cycle than when temp for aux heat to come on is set a little higher. (My tstat is more of a dedicated computer than a tstat. It keeps records of how often and how long the various components are running) Found out I was using more electric (my aux heat) on defrost than when aux heat is run on low (I have 3 stage heat). Now if you lived where the humidity is low during the winter months, then you can have the aux heat come on at lower temps than I can.

As for a recommendation on which way to go, go with a decent HP, maybe 1 step down from the top model (SEER rating ~14-15) and use the lowest cost aux heat you can for backup.

I sure like the high end tstat I have as it is in communication with all the components connected and keeps records of operation and any trouble codes that might come up.

 

[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

To put the cost of the system in perspective. The geothermal heat pump itself cost about the same as air/air heat pump or regular furnace with AC. The ground loop will add about 5-6K. We pay 4.2 cent/kWh in heating season and 11 cents/kWh in the rest of the year. We heat 3800 sqft and AC about 2400 (garage is heated but not AC). Since we have separate meter for the heating I know exactly what the heating cost is. Last January was the coldest month and we paid $75, year before it was colder so we paid about $100. Our house is single story ranch on slab, has R20 walls, R30-40 ceiling and three pane windows.

 

[yelbike]

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

Sorry in advance, but I'm going to pick on you. You clearly don't know how an air source heat pump works. Heat pumps have the exact same efficiency as an A/C of the same size and seer rating. They work on the same basis except with aa added reciever and a reversing valve in the heat pump.

Dependant on you location and electrical rates, I recommend the highest reasonable seer rating with the heat pump. $700 sounds cheap for the upgrade, I charge $1500-2000. I would recommend an outdoor sensor to control the heat pump. Without an installed outdoor sensor, the thermostat guesses the heat load by monitoring the ON heat cycle. With the sensor installed the heat pump can run later into the fall and earlier in the spring, so you gain more heat pump "season".

 

[kenmac]

JMO Hp is the way to go if your on LP. That being said. The air they produce isn't as warm from the supply as a gas furnace. Will you be happy with an HP ? only you will know. I have had to remove HP'S that other companies installed because, the cust. wasn't happy with the heat the HP produced even though the HP would heat the house to desired temp

 

[yelbike]

All I would do is try and educate the home owner. I would also recommend to run the fan on continous low speed. But some customers.......:confused3:....well you know how it goes!!

 

[kenmac]

All I would do is try and educate the home owner.. But some customers.......:confused3:....well you know how it goes!!

By all means. But, when their use to having that burst of hot air like from a gas FAF. Their just not going to get that with an HP. Just a steady flow of warm air