furnace replacement vs. heat pump

Not my experience in TN w/ the air-exchange unit prior to putting in the ground loop (after 15+ yr on a builder-grade, cheapie initial).

It would occasionally, yes, but nothing nearly like that frequency and generally, even though E TN is pretty humid, winters "aren't so much" and icing really wasn't much of an issue (until the unit developed leaks later in its life cycle, but that's a failure problem).

Reply to
dpb
Loading thread data ...

I depends on what your definition of "efficiently" is. If he means that the heat pump will generate more heat for the house than the electric energy used to run it, it's true. But the coefficient of performance drops with the temp. It might be 4 at 40F and 2 at 0F, meaning that at the lower temp you're only getting half the heat per kwh that you were getting at 40F. You're also getting considerabley less heat period for the same reason. I think that's often the biggest problem, that when you need it the most, it has the least capacity to deliver the heat. That's when heat pump systems typically have resistance heat or another source kick in. IDK if mini-splits have that too or not.

Reply to
trader_4

Good point on the geothermal possibility. Only problem is the ones I've seen details on, the payback was so long it just wasn't practical. But if you have high cost propane, it would be worth looking into.

Reply to
trader_4

On 10/10/2014 9:58 AM, trader_4 wrote: ...

Simply to add if OP comes back...

Cooling efficiency is indicated by the seasonal energy efficiency ratio (SEER), which is the total heat removed from the conditioned space during the annual cooling season, expressed in Btu, divided by the total electrical energy consumed by the heat pump during the same season, expressed in watt-hours.

The HSPF rates both the efficiency of the compressor and the electric-resistance elements. The most efficient heat pumps have an HSPF of between 8 and 10.

"Energy Star" units must have SEERs of 12 or greater and HSPFs of 7 or greater. When comparing units w/ electric resistance backup, check their steady-state rating at -8.3C (17F), the low temperature test setting. The unit with the higher rating will be more efficient.

In warmer climates, SEER is more important than HSPF. In colder climates or in the OP's operational scenario the higher HSPF should be the target if were to stay with the electric resistance emergency heat. Of course, if go to gas/propane for that, HSPF is not applicable.

Reply to
dpb

I bet they also put in a new thermostat and, also the heat pump has electric backup.

I replace an old oil furnace in a rental house with a heat pump with electrical backup. Just like we have in our mfg home. Both in Central Oregon. Ours worked quite well and was the cheapest heat around.

The new installation used a new programmable thermostat. I had the company replace our home thermostat with a similar new programmable thermostat.

The electric bill at the rental was now outrageous. Working with the electrician and the heating company, we discovered a one degree difference between the house temperature and the thermostat set temperature would not only turn on the heat pump, but turn on the backup electric heat elements. The renter's parents have the same system and their backup comes on with a two degree difference.

The renter was setting the night temp 5-10 degrees cooler than the day temp, so when the trigger time arrived, both the heat pump and the electric backup came on and stayed on until the house warmed up.

Same thing on our home heat pump with the new thermostat.

The solution is to set the thermostat so a constant temperature is maintained day and night. Ours is set to 72 degrees. this is also the most economical use of heating. Once everything is up to temp, the heat source only has to maintain that temp.

I do not see any option in the thermostat manual to set a specific temperature difference value.

Don't blame the heat pump. It's the thermostat.

Paul in Central ORegon

Reply to
Paul Drahn

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.