Propane off-grid heat

[Shrubsteppe]

Hello All.
I am in Central WA. 2000' on side of mtn. Building a 1200 sqft workshop/garage w/ 600 sq ft LOFT studio spartment.
I am 100% off-grid Solar + propane. Well water.
Opinions pls. on propane heating options for LOFT space. The 4 winter months avg 10 - 15° F. (Lows -10).
First I'm going to insulate the s**t out of it!
Then... Rinnai, Martin ? direct connect wall mount propane heater?
Additional Radiant floor heat set-up?
I can site all mechanicals in garage space below loft and just run up piping.
Garage will be insulated also.
Wife and I will be lliving here for 2 yrs. while I build main house. She won't commit if I can't promise her "warm" winters.
Appreciate ideas.

 

[gmcgeo]

empire makes a DV35 direct vent wall mounted lp heater that does not need power to run. but you can add a blower to it giving more distributing heat.

example https://www.amazon.com/dp/B0044FTR5G/?tag=atomicindus08-20

These are amazing, and good for something like you are doing that will be temporary.

 

[Shrubsteppe]

Thanks for Empire suggest.
I figure @ 30,000 btu unit for 600 sqft would be good when it gets too cold. I'm thinking a blower is an option, help if it was 12v. But then again I have a 10Kw solar setup for the main house which I can utilize until its built. After we move into house I just need reliable lp heating for the loft when kids visit during winter.

 

[thammel]

Why not just do a ceiling hung propane heater? The key will be making it super insulated as you say you plan. Be sure that the door separating the apt from the downstairs is well sealed and insulated. And you'll also want to insulate the garage ceiling that is below the apartment. You will be fine.

 

[Shrubsteppe]

another option, thx.

re: "insulate the s**t out of it".
as in closed cell spray 5" x r6.7/", ext sides & 1 inner wall + floor of loft., 6" roof

 

[Jackfre]

Depending upon how your power set up performs you may want to check out the Rinnai EX22. From low, 8200 btu, to high fire 20,500 on LP, it draws 33-56W. The EX38 is not as efficient on the power side running about 120W on high. The DV 35 will make heat and consume no power, but from a feature standpoint it cannot compare to the Rinnai. Cheap heat or cheap heater. I believe the optional blower on the 35 is in the power range of the EX38 and it does not do a really good job. With a really well insulated space I’d take a shot at the 22 and see how it does. You might be pleasantly surprised.

 

[Shrubsteppe]

Thx
Rinnai was on my radar. Researched EX22 as per your suggest. This fits the requirements! Being off-grid I'm always looking for low W usage to the extreme. This seems very efficient and user features will work well for my wife.
I will have a low W ceiling fan also help to circulate heated air.

 

[Bretny]

You would be suprised what a $20 box fan on low would do to move air in a small space like 600sqft.

 

[HoosierBuddy]

Sounds like a very cool project.

I like the options above.

I went with radiant floor heat in my bonus room above the garage, but only because I was doing in floor radiant in the main garage below. If you are doing that, in floor radiant might make sense in the loft BUT i'd highly recommend you go with one of the systems that get's your loops into or above the subfloor if you do. I went with recommendations about stapling the pex to the bottom of the subfloor and insulating underneath that, and it is not very responsive. Litecrete would be the best option to create a heat sink. What I run into is the water returning to the boiler from that zone is still hot. Even where I've used aluminum heat transfer plates clipped around the PEX, you can't get enough heat out of the pex on a cold day to hold temp.

So what I did....and what you should do REGARDLESS of your primary heat is to also get an inexpensive ventless, thermostatically controlled propane heater as backup. I've got one that will "catch" my bonus room when the temperature plummets and the floor heat can't keep up. Yours would mostly be to serve as a backup if you don't have power available, as these units do not require AC power. Just a couple of batteries in the heater and the remote t-stat that you change about once per season.

I HATE ventless heaters as a primary heat source. But as a backup, they can save your ***. You'd just set the thermostat a couple of degrees under your primary heat thermostat. If your power fails or the primary can't keep up....it'll kick on.

My ventless heater might run an hour a day during the coldest part of the winter to supplement my in floor heat. When we've had rare power outages it easily keeps the bonus room (and connected bath) comfortable.

PHil

 

[gmcgeo]

There are in floor furnaces made by Empire also. need 120v to them but they do amazing at camps.

Also there is a empire RH50 these are more then you ever will need in heat but work with no power

 

[Nosferatu]

We use one just like this: https://www.amazon.com/dp/B00S04VOB2/?tag=atomicindus08-20

 

[Shrubsteppe]

Thx all.
I'm getting good suggestions.
Somone just recommended a Micro-CHP. Now THAT is intriguing! Provide my elec. + heat during cold months, PV elec. during summer. Turn the garage into a power station to feed main house.
I see its more popular in Northeast. I don't know if I can find an installer here in WA.

 

[PoorUB]

The Rinnai is a great heater, but do you want to be able to heat without 120 power? Then one of the Empire heaters is a better choice.

 

[HoosierBuddy]

MicroCHP systems like Yanmars reportedly run $40,000 to $60,000 installed for 5kw. Maybe something homegrown would make more sense. I’m picturing a liquid cooled generator where an auxiliary radiator is mounted inside an air handler in the loft. It’d give you free heat when the generator was running. ???

 

[jives]

First responded to this post duplicated in the main garage section. Anyway, here is my $.02. First questions is what is to be done with the room after you move out. Garage office? Rental space? Mother-in-law apartment? In other words, how much use will the space get? Will it be occupied full time, or only on occasion when the kids come? While the mechanicals are in the garage, you still have plumbing water that needs to be kept from freezing.

If part time or sporadic use you still need to keep the space warm to prevent freezing of pipes, so what is going to be the most efficient and mindless way to keep the space at 55 deg when no one is there? Radiant? Wall mount propane? Keep in mind that the bath may not warm with a single wall mount propane in the room.

We have a dual wall-hung unit that provides both domestic hot water and radiant hydronic heating. The plumbing is complex, more so than I would want in a loft apt.