Pellet Stove Efficiency Question

[MtnXfreeride]

Hello, I am trying to calculate out costs for comparing a ductless heatpump to a pellet stove. I would likely be using both systems to avoid oil.. but as far as my preference when temps get very low and the heat pump becomes less efficient would be affected.

Anyway, my energex pellets say they produce 9000BTU/s per pound, but with pellet stove efficiency averaging 76%, I am really only going to get ~6840BTUs/Ib correct? Or is that efficiency already calculated into their number?

 

[john193]

Currently there isn't a set standard on testing stove efficiency, or pellet BTU per pound. The EPA is in the works of setting up efficiency standards for stoves, but assuming a 76% efficiency is a fair number. It's also what the EPA assumes all stoves are.

I would take the number on the pellet bag with a grain of salt. And you are correct on your math. You will utilize about 3/4 of the energy to heat your room.

 

[Pelleting In NJ]

If you hve not yet purchased your heat pump, consider the Mitsubishi Mini-Split AC/Heat pumps, specifically the "Hyperheat" models which give full rated heat output down to an outside air temp of 5F.

 

[moey]

Id suggest a new mini-split and a used pellet stove. Get the best of both.

 

[MtnXfreeride]

Thanks for the quick reply. If this is the case than a heat pump along side my pellet stove should save me a lot of money and pay for the heat pump in just a couple years.

If you hve not yet purchased your heat pump, consider the Mitsubishi Mini-Split AC/Heat pumps, specifically the "Hyperheat" models which give full rated heat output down to an outside air temp of 5F.

Hitting that target BTU output means nothing if it takes 4000 watts to do it. Efficiency is very important. I look into the hyperheat ones you sugested, i had not come across anything but Fujitsu that can work in cold weather climates yet.

**edit** I did a calculation for that hyperheat. At 5F the 6300 watts it uses to generate 32K BTUs per day with electric in Maine is $15.84 while pellets at $6/bag and 77% efficiency would cost $16.62 ... so at least at those temps it would never pay for itself.
At 17F it uses 5600 watts.. which is a little better at $14.78/day
At 47F outside it would cost $8.97/day to run.

Realistically my stove cannot burn pellets fast enough to put out this much heat.. and the heat pump wouldn't be at 100% all day either. I think the Fujitsu pumps were more efficient. I think though these would be great for the end of fall and end of spring where it dips just low enough to need light heating.

**edit** the hyperheat heat pumps aren't efficient enough for state rebates, so they are out of the question.