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Small Cabin Forum / Off-Grid Living / Thoughts on in floor heating
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# Posted: 25 May 2021 11:27

Hello all. We're hoping to put up a new home. Since we're in AK I'm trying to figure out the best options for heat.
Fuel oil is the energy source. 28x40 single story home. With a 4' crawl space.
Looking at a unit made by toyo. Parts, services available locally. They have a boiler and on demand hot water unit in one .
From the bottom up. The poured concrete 4' foundation walls and rim joists around the floor joists 1 foot in will be 6" spray urethane.
The heat tubes would be placed on top of the 3/4" TnG plywood floor.
After the plywood is nailed off . Install all the bottom plates for all walls inner and outer. There will be 2 bottom plates essentially. The walls bottom plate will nail down to this plate.
Lay out reflex foil on the floor then Install the heat tubes. Then pour light weight cement over the tubes. And screed off level with the plates.
Ending up with a flat floor ready to stand walls.
Lots of smart folks here so you're input is welcome.
Thank you

# Posted: 25 May 2021 15:52

I have no direct experience with that but I've seen it done with good results.

Just curious, why not just go with slab on grade? Seems better for in floor heat to me. I friend in Anchorage added a large garage to his house and that's what he did. Nice thing is the garage floor stays dry even in the winter when pulling in cars with snow on them.

# Posted: 25 May 2021 18:03

My daughter and her husband did a very similar system for the log home they built. The difference being the hot water boiler is wood fired and sits 25'-30' from the home. They absolutely love it. Their home is in Eastern Oregon, in Oregon's coldest town with a record low of -54F.... commonly between -20/-30F every winter.

I would say the only drawback they have had is that it is a complex system with several zones, pressure regulators, back flow preventer/s, hot water heat exchanger and a gas fired backup on demand hot water heater. Of course numerous valves and fittings. My SIL installed it all himself so he knows it back and forward. The wall in the utility room is "decorated " with plumbing, valves and guages. All quite orderly. When they are gone during the winter his father keeps an eye on the wood furnace and the system. My SIL was here at the cabin a couple of years ago in the spring when his father called with a problem. I would say it took an hour on the phone to direct him in how to solve the issue.... I think he had him switch it over to gas. By his frustration you could tell talking someone through this was not fun! But I don't think they would do anything differently... it's been in operation maybe 10-12 years with very little down time. Their wood furnace takes 3' wood and burns for days, thermostatically controlled by the hot water heating system.

# Posted: 25 May 2021 18:51

For one, comfort is marvelous, especially for a geezer like me with creeky ol bones and buggered up joints.

Mine is within an FPSF Slab which is wrapped in 4" of foam so it is a different beast as the thermal mass regulates & distributes the heat a bit differently.

Any Radiant heating system can work a treat if there is mass that can collect & distribute the heat. Zones are important for anything pretty much over 500 sq feet. The Thermal Shell of the building is critical, like any structure, insulation and healthy air movement rules.

It is very easy to make a "sick house" if you heavily insulate & make it air tight and do not provide for a fresh air exchange system. This applies to any climate zone.

# Posted: 26 May 2021 09:28

Hello all. NorthRick I've thought about slab n may do that still. I , we like the crawl space for the storage space n ease of maintenance to fix things. A place to put water pressure tank n such. Although you have me thinking.
Nobadays, I really like that name, yes the different zones can get confusing, labels help. When I wire in an electric panel I take a piece of the wire casing n write the zone on it such as master bedroom. Then slide it over the black hot wire before I put it into the breaker. Each breaker is then identifiable by its label.
Steve S . I'm trying to get our home super insulated. And you're absolutely correct on having a sick house because it can't breathe. And can make the occupants sick too. It has to breathe . I will plan on making sure I have fresh make up air . I was thinking about running some 4" plastic pipes under the frost line for that. So the outside ambient air can be warmed up before entering the house. Its a fairly small area so I think I can get by with a passive system, and not need anything mechanical.
Thanks folks

# Posted: 26 May 2021 10:01

I can easily recommend The Radiant Company out of Vermont with regards to Radiant systems. Lots of valuable info, ideas & methods and they can design it too with zoning etc. Have a LOOK and see and you can buy the whole "kit" or parts of it. I must say, that getting a fully pre-assembled & tested plumbing system with valves, pumps etc was a real bonus.

Running lines underground present many issues and most notoriously is damp/mould control which is a nightmare to deal with. There are ways to deal with it but none are easy and most often it creates other issues. Do very seriously consider the cons, there are many.

Most common solution is an Air Exchanger system and in the commercial world there are a myriad of choices for the different climate zones and they can get crat expensive too. Of course this requires an air distribution system to get stale air out while exchanging it with fresh & pre-conditioned air. Preconditioning meaning either pre-warmed or cooled pending on zone. Your 40x28 Structure presents difficulties with that, especially without a central (air) heating system. Depending on your roof structure and build method, there may be several options available to you.

The AK Temp Range from 32F to 92F means you do not get "deep" winters but that summer heat with Humidity into the 75-80% certainly creates comfort issues. That also highlights that bring in exterior air via underground will not be suitable for your region, not without extensive control systems.

You would gain more efficiency & temp control of the house if you build it so that it does not pass heat/cool from the house to the outside. Thermally broken walls and roof can indeed make things much more liveable and even consistent internally to the house. The use of a Cool Roof system and Rainscreen siding provide such thermal breaks between the outside environment and the shell of the structure. I've done so and the results are amazing, my climate zone I see -31F to 104F and humidity to the mid 70%s so it is somewhat more noticeable due to the extremes.

hope it helps

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