Keeping our RV water system from freezing

Question

Hey folks, we are about to be taking our 2009 Thor Jazz 2780BH into colder weather (Sunriver, OR) to do some skiing. I've been watching the weather for a few weeks and it typically gets into the single digits (F) at night and into the 20s during the day.

First, I apologize for the lengthy post. I know that every RV is different so I want to describe ours as well as possible.

I've been doing my research and I think I have a good handle on what needs to be done, but I'd like some feedback. I don't think pictures will do much good so let me explain how the water system is in our rig.

1. All water lines are enclosed in the underbelly, EXCEPT for water lines to the sink and toilet, which run through the forward storage compartment. That compartment is heated. ALSO, the water pump, city water, and fresh water lines all sit in the rear storage compartment by the water heater. That compartment gets heat from the water heater. It gets mild residual heat from the electric water heater but it stays nice and toasty if I use the propane heater. I plan to just use propane in Sunriver.

2. We have 4 holding tanks. Black (which we don't use since we have a composting toilet); Grey from the bathroom, which sits in the forward storage compartment; Grey from the kitchen sink (galley) which is in the back storage compartment; Fresh, which is in the underbelly underneath the rear compartment. There are two heating ducts that run from the rear storage compartment into the underbelly right above the fresh water tank and also into the compartment that holds the galley tank, so I'm 99% sure that those tanks are heated. However, the fresh water tank isn't insulated or heated on the bottom. The bottom of it froze last night, but not severely (it thawed out as soon as sun hit it).

So that's the setup. Now for the questions.

There are two weak points that I've found. The first is the drain pipes coming from the black (doesn't matter), grey, and galley. Once they exit the underbelly they freeze. It was in the 20s last night and I had to thaw them out with an electric heater this morning. I could wrap them in heat tape, but I'm wondering if RV anti-freeze in the tanks would be a better option? Anti-freeze would protect the entire tank + the drain pipes, whereas heat tape would only protect the pipes. I also found people recommending rock salt. Would that work better than anti-freeze?

Second question: I prefer to use our fresh water tanks instead of campsite water. It's just less of a hassle and I don't have to worry about hoses freezing. As I said above, the fresh water tank is heated but the bottom of it is not insulated. I'm thinking that I'll build an insulated box to go right under that section and then put a work lamp in it. Do you guys think that would work, or is there a better solution?

P.S. - I know that there are more in depth solutions, like insulating all the tanks, etc. However, we plan to sell this rig in February so I don't want to spend a lot of time or money on it.

Thanks in advance for the help.

wyotraveler · Answer

I have seen TTs where they sprayed foam over the tanks that were exposed. Instead of a box spray foam may work as well. Also may be easier and cheaper. Grey water line. I would wrap aluminum tape (Walmart paint dept) to distribute heat then wrap heat tape around grey water line. Just a couple of ideas.

rekoj71 · Answer

I like the foam idea but think that gluing some 1 inch sheet foam like they sell at HD for walls might be cheaper than the spray stuff, but might use the spray glue to stick it. They also sell Liquid Nails caulk like adhesive for foam board but would want to be sure it would bond to the poly tank bottom.

Not sure on the discharge tube. The above idea is probably the best but a little costly for such a short trip, though you might be able to remove it and use it again somewhere. If you use antifreeze or rock salt (no experience) I would be wary of over diluting it as you fill up the tanks.

jayspi · Answer

WyoTraveler wrote:I have seen TTs where they sprayed foam over the tanks that were exposed. Instead of a box spray foam may work as well. Also may be easier and cheaper. Grey water line. I would wrap aluminum tape (Walmart paint dept) to distribute heat then wrap heat tape around grey water line. Just a couple of ideas.Thanks, those are great ideas. I think I will put aluminum tape followed by heat tape around the grey and galley lines. I did some more ready and I don't think anti-freeze would help much. If the tank is empty then the anti-freeze would just go into the bottom of the line and stay there. It wouldn't circulate through the rest of the pipe. If the tank isn't empty then the anti-freeze wouldn't make its way down into the pipe.rekoj71 wrote:I like the foam idea but think that gluing some 1 inch sheet foam like they sell at HD for walls might be cheaper than the spray stuff, but might use the spray glue to stick it. They also sell Liquid Nails caulk like adhesive for foam board but would want to be sure it would bond to the poly tank bottom.Not sure on the discharge tube. The above idea is probably the best but a little costly for such a short trip, though you might be able to remove it and use it again somewhere. If you use antifreeze or rock salt (no experience) I would be wary of over diluting it as you fill up the tanks.I'll drop by Lowe's and check out their sheet foam. As I said above, the only potential problem is that I might not be able to tape the underbelly back up if I put insulation on it. It feels like the tank pushes right up against it with no give.I might just put heat tape on the grey and galley pipes and then use a hose instead of fresh water. It's an extra hassle but if it saves me from getting a cracked fresh water tank it would be worth it.By the way, this won't be a short trip. We'll be in Sunriver for 3 weeks and then probably move down to South Lake Tahoe for more skiing. At least that's the plan...we'll see how the DW handles the cold :)

golden_hvac · Answer

It sounds like you will have full hookups. I don't know if the campground water will be on at all the sites, I know someone at a campground in Paso Robles CA where it normally does not freeze and the hoses are exposed, did reach 26F and many hoses froze, because there was no provision for protecting them.

Here in Portland the winter I did spend in a RV park, the water hookup was under a 10X15" heavy plastic cover along with some wall insulation that was 15" wide and 3.5" thick. I would add water to my tank on warmer days, and drain at the same time. The coldest that winter was 26 overnight, but most days where above freezing. We can have 8-10" of snow, but winters like that are rare.

I might consider some 2" thick foam wall insulation, and as you have described it, it seems like there is a underbelly, and the tank is sitting directly on that, and the steel supports under the underbelly. Getting something in between would be impossible. But by cutting some 80" long boards to fit snugly between the steel supports (install only while parked and remove before moving) it might do the trick, and keep the tank above freezing. 2" is about R-19, and heat will stay above it.

If that is not practical, I have a bunch of 4' wide Reflextix insulation that I cut to length and hang from each window shade - mostly to keep it dark inside, but also to insulate my windows, and single pane front windshield. It is easy to cut, R-4 insulation, so it will slow the heat loss. By cutting some and gluing it to the underbelly, with contact cement, it should stay for the duration of your trip at least. Make sure to both glue and tape all the sides well, so air will not get under the edge and literately blow it off the tank. (imagine it inflating like a balloon)

As for keeping the tank from getting cold, you might want to rig up some tubing from a hot water connection to the tank inlet. They do sell a fitting that will replace your faucet bubbler, and has a garden hose fitting on it. Then you can use your 25' long fresh water hose to pump hot water into the fresh water tank. Fill it with 6 gallons about 4 times, and the tank water will become warm. Then it will not freeze overnight. Together with some insulation to keep the heat in, and you will be OK.

Good luck,

Fred.

time2roll · Answer

Selling in Feb?  I would try to do nothing or just minimal like Styrofoam and duct tape.  Maybe a hose adapter on a faucet to get warm water into the fresh tank to hold you overnight.  Try the antifreeze in the waste tanks a bit or just do as before to thaw it out to dump.

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Keeping our RV water system from freezing

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