[Lukeman123]

Recently moved into my newly built 2000 sqft home, it is all one level open in the middle of the house bedrooms on one end of the house and rec room on the other end. I have a ductless heat pump in the middle of my house for heat aswell as an in floor heat system heated by an electric boiler. I was wondering what other people think on the best way to heat my house between the two systems. I am thinking the heat pump would be cheaper to run but where I live (nova scotia) we have half price electricity from 11pm till 7am so I can heat my slab with half price electricty and the warm slab will heat my house the next day . So I am not sure what way would be best ????

 

[user_12345a]

Depends on the efficiency of the heatpump, how it performs in cold weather. Would have to see the performance data-sheets.

Heatpump should supply between 1.5 to 3 kwh of heat, the electric boiler is 1:1.

The heatpump will always be more efficient than the boiler, but after a certain point may not be able to keep up. Newer units may do this better than old ones.

A good strategy is to set the boiler to a lower temp than the heatpump and it comes on as needed as supplemental heat. Unlikely that a single ductless unit will be able to heat the house on its own, but it should be used to cut the heating bills.

There are actually heatpump boilers out there - how well they work, I have no idea what so ever. Probably more common in europe than anywhere else.

 

[beenthere]

1/2 price electricity, may not be all that cheap. Depending on what full price is.

 

[Lukeman123]

Even with electricity half price at night and the ability to store heat in the slab it would be better to heat as much with the heat pump as possible?

 

[user_12345a]

Even with electricity half price at night and the ability to store heat in the slab it would be better to heat as much with the heat pump as possible?

The inverter driven heatpump is far more efficient than electric resistance heater at all times.

The efficiency of the heatpump varies with outdoor temp but the COP will always be above 1. The electricity consumed by the compressor gets absorbed by the refrigerant and gets supplied to the house and any heat which gets picked up by the outdoor coil is free.

When the heatpump isn't on due to extreme cold (different units may perform differently in extreme cold, some may shut down below x temp), then you should pre-heat the slab during off peak periods.

Heating directly with electricity isn't cheap at all unless the electricity is used to run a heatpump. Heatpumps, especially the central air style ones get a rap for being expensive to operate, but really it's the reliance on electric backup in cold weather which makes them expensive.

The inverter driven asian mini-splits are variable speed, fine tuned to adjust themselves to deliver as much heat as possible from the outdoor air. Some may maintain nameplate capacity down to -20c or lower. Old ones are rated at 7c or so and drop off below that.

 

[zootjeff]

Recently moved into my newly built 2000 sqft home, it is all one level open in the middle of the house bedrooms on one end of the house and rec room on the other end. I have a ductless heat pump in the middle of my house for heat aswell as an in floor heat system heated by an electric boiler. I was wondering what other people think on the best way to heat my house between the two systems. I am thinking the heat pump would be cheaper to run but where I live (nova scotia) we have half price electricity from 11pm till 7am so I can heat my slab with half price electricty and the warm slab will heat my house the next day . So I am not sure what way would be best ????

Regardless of the price, heatpump heat is 3 to 4 times cheaper than electric heat. COP or coefficient of performance is that metric. The only problem is that when it is really cold out, the CAPACITY of the heatpump is what the problem is. The heatpump may work really hard and not generate much heat, but the heat it does generate is still cheaper than the floor heat you describe. But it isn't enough and you have to help it with something..

 

[zootjeff]

Even with electricity half price at night and the ability to store heat in the slab it would be better to heat as much with the heat pump as possible?

Yes it is.