Off grid heat question

[tmshort]

I have an off grid cabin in the Rockies. We shut the place down and drain pipes etc when we leave. There are times where there is a month or so where no one is there.
It is all PEX, and even though we drain the pipes there is still some water that freezes.
The basement has a 300 gallon holding tank, when we have really cold spells this freezes.
We arrived yesterday, and with the cold weather lately it took forever to get things thawed out and functioning.

We have solar with batteries, but not enough to run any kind of electric heat. I do have a 1000 gallon propane tank.

I'd like to put a propane heater of some sort in the basement just to keep it above freezing and am interested in thoughts on what would be best as well as safe to run when the place is unoccupied. We have starlink and robust wifi as well as cameras and other monitoring, so I can keep an eye on things remotely.

Thanks in advance...

 

[4x4Pete]

To avoid heating the place when nobody's there, maybe a more thorough draining would do the trick? Compressed air to blow the lines out?

 

[PoorUB]

I'd like to put a propane heater of some sort in the basement just to keep it above freezing and am interested in thoughts on what would be best as well as safe to run when the place is unoccupied. We have starlink and robust wifi as well as cameras and other monitoring, so I can keep an eye on things remotely.

Do you have electrical service, or some other source for power, wind generator, solar? Oops! Solar!

A Reznor or Modine shop heater will work if you have a place you can vent out the exhaust, but they consume a bit of electricity.

There are other heaters that will work, but watch out on how they vent. Some will direct vent right out the wall, but you can not go up and out. Most need 120 volt.

Some small heaters do not use electricity, will vent straight up with B-vent, but you need to find a place to run the venting straight up through the roof.

 

[ipgenie]

If your solar is 12v, you could use an RV furnace. They are all propane fueled, direct vented and DC powered and most are compatible with smart thermostats. If you use a higher voltage system, a buck converter and 12v battery would be needed.

Edit to add that they can also be found cheap at wrecking yards. Last one I bought was $25 from a couple year old motorhome that had been rolled. Should produce plenty of heat to keep a basement above freezing. They vent directly through the wall but are low profile and can be mounted near the ceiling.

 

[Northislander]

Williams propane direct vent wall heater

 

[PCustoms]

How well is it insulated?

Make sure to vent a propane heater, otherwise the moisture will wreck havoc.

 

[HoosierBuddy]

Williams propane direct vent wall heater

Martin makes them as well.

This is the proper solution. Get a propane direct vent that doesn't require power. Install properly and set the t-stat as required to protect against freezing. Monitor with an ap of some kind.

This will be more effective if you give some thought to insulation.

 

[cvairwerks]

You might be better off looking at a stock tank heater, rather than trying to heat the entire basement.

 

[tmshort]

Thanks for all of the input.
Currently looking at the direct vent options. Does anyone know of a unit that can be controlled remotely, or do they all have a piezo lighted pilot and built in thermostat?

Also, altitude may be a factor - the cabin is at 10,000'; some of the units say "up to 2000' altitude".

 

[PCustoms]

Wow, where do you have a cabin at 10k?

 

[tmshort]

You might be better off looking at a stock tank heater, rather than trying to heat the entire basement.

We had considered something like this, but we don't have a ton of electrical reserve. Certainly not enough to run a resistance type heater.

 

[tmshort]

Wow, where do you have a cabin at 10k?

It is in central CO, Leadville / Buena Vista area.

 

[PCustoms]

It is in central CO, Leadville / Buena Vista area.

I'm jealous, that sounds pretty damn cool. I need to get myself out west sometime...

 

[cvairwerks]

We had considered something like this, but we don't have a ton of electrical reserve. Certainly not enough to run a resistance type heater.

They come as small as 750 watts. You only need to keep the water over about 33F.

 

[dcg9381]

If your solar is 12v, you could use an RV furnace. They are all propane fueled, direct vented and DC powered and most are compatible with smart thermostats. If you use a higher voltage system, a buck converter and 12v battery would be needed.

They go through propane for sure. Once the start cycle fails, they likely do not auto-reset without intervention.

How about a simple "ventless" deal mounted on the wall? Ventless would be better. At 10k elevation, that might be a little tricky.

10K BTU is .45 gallons propane per hour though...

 

[LopezBart]

10K BTU is .45 gallons propane per hour though...

Burning a gallon of propane yields 91K BTU; it would be more like .12 to .2 gallons/hr depending on efficiencies, etc.

 

[dcg9381]

Burning a gallon of propane yields 91K BTU; it would be more like .12 to .2 gallons/hr depending on efficiencies, etc.

Thanks.. I'm going drop using the AI answers. Seems like it confused gallons with pounds. Your calculation is right.

 

[LopezBart]

Thanks.. I'm going drop using the AI answers. Seems like it confused gallons with pounds. Your calculation is right.

As you saw, don't trust AI. It's simply wrong too much of the time. These systems hallucinate frequently... try asking questions on a subject when you know a lot about; you'll wonder why anyone would trust these systems.

 

[Firebrick43]

We had considered something like this, but we don't have a ton of electrical reserve. Certainly not enough to run a resistance type heater.

They make resistance immersed heaters to hook up directly to a solar panel. No batteries, no inverters.

It doesn’t take much to keep it thawed out of there is any insulation on the tank. I would still drain the lines.

A panel or two hooked to one would suffice

DC Water Heater Elements | Missouri Wind and Solar

Choose from a wide variety of submersible DC water heating elements for direct connection to your batteries or solar panels. Great for RVs, heating stock tanks, or converting your AC water heater. Don't forget to add a thermostat.

windandsolar.com

 

[Jacko264]

Is the tank insulated?
can you insulate insulate and more then build a box round the tank
how cold does it get?
G

 

[u3b3rg33k]

We had considered something like this, but we don't have a ton of electrical reserve. Certainly not enough to run a resistance type heater.

have you considered a dump load for the solar into the 300gal tank? presumably it's insulated, it should not take a ton of kWh to keep it at 33F. also maybe heat trace on some lines you can switch on for easy startup.

 

[NUTTSGT]

How often are you there ? How often can you get the LP refilled and how ?

 

[Jackfre]

Ahh, Leadville! 10,000 elevation. I would suggest a Rinnai EX-22. It modulates from 8200-20,500 And draws from 33-52 watts. Direct Vent requiring only a 2.75” hole in the wall for the vent which is included. You will have to de-rate for the elevation and you MUST have a differential pressure manometer to do so. Ther are many of them in the Leadville area.

 

[tmshort]

In answer to some of the questions:

- the tank is not currently insulated.
- we have some work to do on insulating the basement, but overall it is not terrible. about 2/3 of it is below grade, the rest is 2x6 with R19 batts.
- I really only need a few degrees of heat ... I have remote temp sensors there. The temp hovers around 32, and drops lower at times when the OAT is much lower. Even getting it to a consistent 35 would solve the problem.
- was not aware of the DC heating elements. this is an interesting option for keeping the tank from freezing...

Thanks for the Rinnai suggestion - researching that more now.

 

[locomotiveman]

OFF-GRID?? Simple. EMPIRE propane-fired direct vent wall heater with a Milli-Volt thermopile wall thermostat. I have similar situation and it is heavenly ( and SAFE!! ) I have the DV-215