Winter water tank heater mod

GSF

I've always wanted to use my TAB 320 water system in the winter at our local ski area instead of lugging water jugs around.  Inspired by a brilliant mod posted by @Gregp, I came up with the scheme illustrated in the attached diagram.  So far, I've tested it in near freezing temperatures here in town and it works well. 

The plumbing was quite challenging because of limited space in the cabinets under the sink and there wasn't enough room for a conventional PEX compression tool.  I found the below item on Amazon and it worked OK with no leaks.   The water tank fill line conveniiently runs through the right bottom edge of the lower cabinet where I added a pvc "T" to connect the hot water output line from the solenoid.

Needless to say, there were multiple trips to the hardware store

https://www.amazon.com/gp/product/B002RBAADC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Solenoid:

https://www.amazon.com/gp/product/B07KCGYQVD/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Thermostat relay:

https://www.amazon.com/gp/product/B08QZ5VRYC/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

I insulated the water tank and undercarriage fill/output water lines with a combination of materials.  I also applied a layer of insulated and reflective auto windshield sunshield material to the entire inside surface of the corrrugated undercarriage cover.

The true test will come this winter.  I'll post a followup in a couple of months.

Geoff

Denny16

So you are circulating hot water back into the water tank to keep it from freezing?

Cheers 

GSF

Yup.  Outside temp got down to 29 deg F here last night and water tank temp was in the low high 40's.  I've currently got the thermostat relay set to start heating at 5 deg C and stop at 10 deg C (it's metric).  To conserve propane and batterry power, I think I'll narrow that to start at 4 and stop at 8. 

GSF

Correction...high 40's not low high.

techietab

Impressive and creative solution.

I just dropped the plastic cover underneath, ran a heavy gauge wire from my battery array to bus bars, and wired up Facon heating pads on all exposed tanks and plumbing. 

GSF

That's way simpler than my setup.  Good job!  I suspect your winters are colder and harsher than out here in the Pacific NW.

We've had some cold nights lately up at the ski area...down to 12 deg F on my last 3 day trip.  Amazingy enough, the fresh water tank temp stayed above 39 deg F, which is my set point temp to pump hot water into the tank.  So the solenoid never needed to open.  I had hot and cold running water just by the regular heating of the living space.  I suspect that if the outside temp gets down into single or negative digits it'll kick in though.

I think this is probably due to the water tank being immediately below the Alde convector that's in the door-side storage space under the seat and partly under the rear storage area where the hot glycol hoses run.  Evidently the floor insulation isn't very good and these features allow heat to leak down into the now insulated undercariage space and tank.