... After you insulate and seal the bay from draft intrusion, you can probably heat it with an incandescent or quartz halogen light bulb, a small cube heater, or even a blower pushing warm air from the interior of the bus. In my case my propane furnace is in the same bay as the tankage and plumbing and it throws of a lot of heat. The key is probably the insulating and sealing, if only because it's the hardest to do well.
Yeah, my fresh tank, water pump, and water heater are in the same compartment. I'm pretty sure that two 100-watt light bulbs would keep the temps up above freezing there. I don't expect for my bus to see temps any colder than about 18 deg F so we're not talking severe cold here. I expect to store my bus from about January until April 1st. But I have two issues/questions:
1) There are only about 4-foot runs of PEX from that compartment to the kitchen sink. They pass through a bulkhead and there would only be two feet outside the bulkhead in the undersink area. I guess I could put a 50-watt bulb under there. My bigger question/issue is that there are another 12 feet or so of pex (cold and hot) that lead up to the toilet, bathroom sink, shower upstairs. They pass behind the kitchen cupboard/pantry cabinet, up the wall to the bathroom area over head. Since my bus will be unattended/unheated (except for the small heat sources in the tank compartment and under the sink), how much danger am I of freezing those pipes up to the upstairs bathroom? I don't remember if I have a cavity that I could blow warm air in that would cover all the pipe areas, the faucet locations, the toilet internal piping and valves, etc.
2) What would one do for grey/black tanks? I would assume that I could dump them before winter. If I use any water/ put anything into the tanks (I'd assume 4-6 gallons, at most) over the winter, would I need to worry about the tanks freezing enough to crack the tanks, etc? If go, for 4=6 gallons, could I pour a couple of gallons of RV antifreeze into each tank and feel safe for 18 deg conditions? (It wouldn't be convenient to dump the tanks every time I leave the bus, but it's *possible*, just very inconvenient.)
I work out of the country for about 6 weeks over the winter. The electric supply to my bus is pretty dependable at it's storage location so I wouldn't worry about the heating sources in the tank compartment and under-kitchen sink.
So, I think that I have a few options --
1) I have a "winterization" port into the water pump. I drain fresh tank, put a funnel onto the winterization port, and pump in non-toxic RV antifreeze until antifreeze runs from all the faucets (kitchen sink, bathroom sink, shower head, toilet), then drain the waste tanks. Then I just shut the bus up as well as possible and don't worry about freezing. I could continue to do this but it's not entirely convenient for short visits to the bus before spring thaw.
2) Put in isolation valves to the water lines to upstairs, winterize that part of the fresh circuit with antifreeze, and keep a few gallons of fresh in the fresh tank, install the low-wattage heat sources I talked about and just use the water in the kitchen sink. (Actually, this doesn't help much - I'd still have the inconvenience of walking up to the storage office to use the bathroom and take a shower; I have a key so that's available 24/7 but it feels like a long walk in cold, rainy weather.)
3) Try to arrange heat sources and methods of circulation that would keep warm air all the parts of the fresh circuits. The drawback to this is that a severe winter storm sufficient to cut the power off for a few days would leave the system in danger.
What I've done in the past is just "winterize" the system and live with the inconvenience. I'm not at the bus much in the dead of winter and while not having water/waste systems isn't entirely convenient, it's liveable for the amount that I need it. And I really, absolutely DO NOT want
to have to tear out walls, etc. to repair cracked water pipes, water heaters, toilet valves, etc.
Any advice??? Thanks, B Henderson NC USA