Heat Pump or Conventional Boiler

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mkgrady

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Massachusetts
My friend is building a ranch house in Massachusetts. It will have a full basement and it will have central AC. His plumber is suggesting a gas burner with conventional baseboard forced hot water heat. Since he will be installing ductwork for the ac does it make sense to just skip the burner and just go with a heat pump and ac in one unit? I understand this is pretty typical in warmer climates but only recently have heat pumps been effecient in the northern states.
 
The only thing that would stop me are high electric rates here in the northeast.

Now, why is he installing ductwork and not using a furnace as well? :huh:
 
I would go with a heat pump with electric heat backup for emergency heat. Makes no sense to do 2 different systems.
 
peter d said:
The only thing that would stop me are high electric rates here in the northeast.

Now, why is he installing ductwork and not using a furnace as well? :huh:
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Good question. It doesn't make sense to use baseboard forced hot water. Maybe I misunderstood. Let's assume the burner is only to heat a hot water coil in the air handler and that hot water baseboard is not what he is actually doing. Let me revise the question to: does the boiler make sense or should it just be a heat pump?
 
ptonsparky said:
Two different systems is nuts.

Gas backup has an advantage of small generator for heat when needed.

That said I am all electric with a pump and dump and low rates. We do have a gas fireplace that would keep us from freezing to death for a day or two.
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You are saying go with heat pump with gas hot water coil as backup only? good point on small generator being able to power system during outage. He is going with a small 7 kW standby generator.
 
Hot water heat is much more uniform in maintaining the interior temperature than forced air and as a result more comfortable. Even more so if you adjust the system water temperature as the outside temperature changes. If I was building and had the money to install two systems I would.
 
... I'm told the heat pump is good a few degrees below zero. ...
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So far I have not seen any specs listed for the heatpump, nor any heat loss calcs for the house. Without reading the specs and running the heat calcs, it is all just guessing.

... Two different systems is nuts. ...
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Okay. And I will ask, How is it you know that?

Boilers and hot water baseboard is pretty efficient. Gas is is often inexpensive ($/BTU) compared to electric heat. Heatpumps lose efficiency quickly when the ambient gets cold. If the plumber has installed very many HVAC in the area, she may have the best anecdotal information.

So, I'll ask, All these statements that were made, How is it you know this?

Seriously, if I were building a house, I would not want anybody's guesses.

ice
 
I would not consider any system that has duct work. That's what opening the windows are for.

Ground source heat pump is an expensive install with some maintenance issues. The compressors are ~ 15 yr expected lifetime. People like them but it's not for me.

For similar money I would start with the foundation built similar to European Passivhaus standards. All the concrete, footings, slabs, walls are wrapped in 4" or more rigid foam board. This gets your heat loss down to a very small number and the thermal mass is a battery or flywheel for heat. Most of the year the foundation will heat and cool the house passively with house appliances and electronics supplying enough supplemental heat.

With the low heat loss and modern insulated coated windows, the A/C system could easily be one or two small window units or a small minisplit.

For heat, gas, methane, is the best fuel and a modern condensing boiler with indirect DHW is a no brainer. People like the newer heat pump DHW tanks also.

If methane gas is not available, I would be installing a modern high end European pellet boiler, Windhager / Froling. That system is made for radiant but conventional baseboard hydronic or European style low temp radiators, heat emitters, are also in view. An essential element imo is outside air temp hot water reset of the HW distribution temp.

The added foundation insulation has the fastest payback of any option with no maintenance issues. The heat penetrates the mass evenly, no drafts or temp differences anywhere in the house. I have 2" rigid foam board under my slab and exterior to the foundation walls. It works perfectly. If it's 40 deg out I really don't have to fire the boiler for several days once the slabs are up to temp. In this weather of 20 deg, if I don't fire the boiler for three days the house will drop to ~ 61 - 62 but it would take another three weeks of January weather for the house to drop below 55 without firing the boiler. The insulated foundation is an effortless heating and cooling system. Next time it will be 4" minimum rigid foam board.

Myself, I would never build a conventional uninsulated concrete foundation.
 
We are used to forced air heating and A/C systems sharing the same ducts and registers, but that is really a compromise.
Ideally A/C will use supply ducts high on the wall or in the ceiling while heating will have the supply ducts at or near floor level.
 
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