Another freezing water line question

Much depends on your floor plan.. For example on my Class A I have water lines on both sides of the coach.. Currb side has the kitchen sink, water heater, water pump, LInes then do both up from the tank and down to the "Wet bay" and across, this is a heated bay on my RV so the lines have only forzen twice both time s well below 15 degrees (11 and 6)
Then they come back up inside the coach to the half bath, and along the driver's side wall (Inside) to the main bath, then wrap around the rear end (Still inside) to the shower.

You need to find 'em. but most of 'em are inside.. All trailers I've owned or worked on were the same way, Mostly inside.

My 30 foot Class C does not have a winter package of any kind. No insulated or heated holding tanks, or thermal windows. No closed underbelly. Vinyl floors. There is no outside shower, and all of the plumbing is inside the coach. In the below picture (at my brother's house) the big door that is next to the red marker light is a pass-through that runs right under the bed. Between the pass-through and the rear wall is the fresh water tank (also under the bed). The little door, above and to the right of the pass-through, is the water fill/shore water. Below the water fill is the water pump.



I've been doing this for 6 winters now, on the Olympic Peninsula, with no problems with freezing water lines.

Our Class C has an all season package where ALL water (fresh, grey and black) is heated by:
(1) the propane furnace AND
(2) engine heat (radiator hoses plumbed to a rear heater) while enroute.

You have to check each unit, as generalizations don't work.

Many TT model lines, and some lower cost fivers, will have plumbing outside heated space. This is harder to check than it used to be because buyers want "enclosed underbelly" so even entry price models will have a sheet of fabric or plastic hiding everything under the floor.

Premium towable lines, particularly fivers built for the full-timer market, will plumbing in heated space, though that might be below the floor. Some lines actually have heated basements containing utilities, also serving to make for warmer floors. Carriage used to do this for their Carri-Lite and higher model lines, but not for lower priced model lines. At Northwood, heated basement space used to be one of the differences between the Arctic Fox and the lower-priced Nash lines.

My 5er has no exposed water lines.

If it's cold enough I doubt incan light bulbs would do much.

Keep in mind, that the low point drains are exposed from where they come out under the floor to the drain valve.

Jack L

Our 5th wheel is 4 season rated due to attic roof vents, 2" walls with DOW Blue solid insulation blocks, enclosed underbelly and heat source for waste tanks/fresh water tank.

Water pump and hot/cold pumping is all inside 5vr

We have been in -19*F temps.
No frozen lines or tanks but did open kitchen lower cabinets doors so heat from furnace went inside cabinets
Furnace maintained 66*F inside (could have done higher) but we used a 1500W space heater when sitting in living room to supplement furnace.

Only issue...propane. Had to fill a cylinder every other day to keep up with demand. :B

I would have to think that units that advertise three or four season capability would be fairly well protected, but the seasonal units, and the light units would certainly not be so well insulated.

My fifth wheel is top quality. The water pump is accessible behind an inside cupboard door and all plumbing is not near un-insulated walls.

For a Class C the fresh water tank and pump are generally inside the heated space. Waste tanks are not.

I replaced the cold air return grate for the furnace with dual window fans. That allows me to heat 100% electrically.