Hydronic Underfloor Heating

[ddrueding]

New project.

Thoughts:

1. Using a heatpump waterheater should make this more efficient than using a boiler?
2. The thinnest systems I can find are about an inch thick. I'll be installing onto my subfloor (2x6 T&G) and would like to sacrifice as little headroom as possible. Anyone know anything better that isn't electric?
3. We don't have the money to install the flooring we want, suggestions on cheap alternatives to allow us to move ahead with the heating system would be appreciated.

Just getting started on the reading, but personal experiences would be much appreciated.

 

[Pradeep]

No personal experiences with heat pump hot water units or underfloor hot water based systems but:

Where would you be siting the water heater? My only concern would be that it would not deliver enough hot water to satisfy heating demand with just 500W for compressor and fan, without kicking in the additional 1.7KW heating element. Noise of 64db may also be a concern, given a standard electric/gas heater is pretty much silent. Will it also be used for domestic hot water for bathing/laundry etc?

Another option would be to go with a roof mounted solar hot water unit, feeding into a storage tank. You may or may not need some kind of electric back up for extra heat at night, though it doesn't really get all that cold there right? I take it no gas is available?

 

[CougTek]

I know someone who has that to heat his home and I've not heard him complain. Supposed to be quite efficient, but anything in my home producing 64dB at 1m would soon be an ex-thing. I hope you have a garage connected to the house where you can put it and build walls of noise-absorbing materials around it.

At least it only weights 287lbs, you won't need help to install it.

 

[ddrueding]

I have a garage, and it would be installed there. I do have access to natural gas, but I would like to "zone" my house, being able to control whether 3 different zones get heat independently. From my research doing zoning with forced air while keeping the system "balanced" is tricky and expensive.

Besides, underfloor heating is supposed to be the best available; less energy used, more stable temperatures, even heating, no drafts. And I like walking around barefoot already

Being a heat pump with ~80% theoretical efficiency, that 500W becomes 2500W worth of heat. That should be enough most of the time. And our climate is very moderate, so we should be fairly close to optimal.

 

[ddrueding]

Will it also be used for domestic hot water for bathing/laundry etc?

That is one of my thoughts. With the exception of morning showers, all other uses of hot water (dishwasher, laundry) run during the day when it is warm. My hot water heater could use a replacement anyway.

 

[ddrueding]

InFloorBoard is the thinnest solution I've found (5/8" - 15.8mm). That would allow me to put 1/2" of foam insulation underneath it to make sure the heat goes up instead of down.

 

[Pradeep]

No question, underfloor heating is fantastic, had electric underfloor with slate on top at one point, good times.

 

[ddrueding]

I just read that including a solar pre-heater makes the entire system 30% tax deductible.

 

[CougTek]

I thought you had fog and rain instead of sunlight on the West Coast, although I may have read wrong. Are there fog panels?

 

[Pradeep]

I believe that's the pacific northwest area that sees constant rain and fog.

 

[ddrueding]

We get about 200 sunny days a year. Of course, the ones that aren't sunny are the cold ones

 

[Howell]

Both floor heating systems I've seen have been embeded in concrete with tile on top. Very enjoyable.

InFloorBoard is the thinnest solution I've found (5/8" - 15.8mm). That would allow me to put 1/2" of foam insulation underneath it to make sure the heat goes up instead of down.

As best as I can tell they intend for you to install that product aluminum/pipe side up. Hopefully you have something protective in mind to put on top even if its not the flooring you want.

You could mount the insulation under the subfloor, between the joists. That would remove any thickness considerations but would be less efficient.

 

[ddrueding]

As best as I can tell they intend for you to install that product aluminum/pipe side up. Hopefully you have something protective in mind to put on top even if its not the flooring you want.

Indeed. It looks like we'll have to install the flooring at the same time. This means we may only do part of the house now and the rest later.

You could mount the insulation under the subfloor, between the joists. That would remove any thickness considerations but would be less efficient.

I also plan on insulating under the subfloor, using my favorite FoamItGreen.

 

[Bozo]

The only floor heating I've seen recently was hot water pipes put against the bottom of the floor between the joist. Then they were covered with insulation. The water was heated by gas and circulated by a small pump.
This would be easy to zone as all you need is a valve controlled buy a thermostat. When the thermostat calls for heat in that room, the valve opens, the pump starts and the room warms up. When the water in the boiler drops to a set temperature, the gas comes on. Once the room warms up, everything shuts down.

 

[ddrueding]

Indeed. But this house is old enough that the subfloor is 3+ times thicker than modern houses. Now they use 3/4" plywood, my house has 2x6 dimensional lumber. With that much more for the heat to work through, significantly more heat will be lost to the underside of the house.

 

[Santilli]

David:
Shadowbrook used that in the lower room next to the creek.

It worked far better then the overhead, or any other kind of heat we used.

Don't know what Ted Burke used, but, knowing him, you could call him, and he would tell you what he used. DON'T use my name;-)

He pretty much owned the company that put the system in, and, he might tell you what he did, what they did, and if they would do it for you, for a reasonable price.

GS