Per everybody's suggestions, we started the empty holding tanks with a couple gallons of anti-freeze, then waited until they were real full before dumping. It worked great!The problem was the bathroom pipes.The walls, floors, and cabinets with the bathroom pipes are in the back rear of the RV. They are completely sealed and unheated. There is a heat duct in the bathroom, but zero heat in the plumbing enclosure.We dodged around western Montana and managed to camp no colder than 30 degrees F. We also had the good sense to unplug the electric space heater and run the furnace so the duct put out heat. No help.The toilet line froze. The bathroom sink had almost froze thru when I turned it on and cleared it with warm water. I suspect the shower froze (but when we got around to showering, it was warm enough that water ran. However, the shower P-trap froze and it wasn't until my wife shower filled the pan with warm water that the p trap thawed and flowed.Our leak appears to be the screw on hose connection for fresh water. It was on its last legs and I have a replacement part on hand at home. I think the cold weather pushed the spring loaded seal to its end of life.I am still going to install holding tank heaters and blankets.I am also going to install a new supply connection and shower faucet, and, when I do so, wrap the lines with pipe insulation as much possible. Additionally, I am going to "Y" one of the rear furnace ducts and route it into the plumbing enclosure to warm the pipes.My cold weather plumbing problem wasn't where I expected it to be. Go figure.

Sorry about the freeze up.One reason the window fans work is that warm cabin air is circulated before the cavity gets too cold.I agree adding a Y is a good plan.

there wasn't cabinet doors that could be open to the plumbing. Also are you saying no colder than 30 degrees and things froze. I find that hard to believe:(

If applicable, consider installing pairs of little 4" round louvers to allow air to circulate between walls or compartments that have concern of freezing so that warm air gets into where the pipes are located. Place them far apart to get flow-through action.Something like this.....Some are sold with screens so you don't let in insects.You might even find some with closures.

Ron makes a good point. Just having warm air isn't enough. There has to be some place for it to flow.

I,m sorry to hear that things froze at that temp. I once did the same as ron.dittmer suggests and added a 12v computer fan at one duct, it allowed the space fill with warm cabin air which vented out the opposite end. I also re-routed water lines off the outside exterior wall (so they don't touch the wall) and was able to wrap them in foam tubes.

Sub-freezing Weather UPDATE --- We froze the pipes!

pianotuna
Nomad III
Oct 11, 2018
Sorry about the freeze up.

One reason the window fans work is that warm cabin air is circulated before the cavity gets too cold.

I agree adding a Y is a good plan.
dave17352
Explorer
Oct 11, 2018
there wasn't cabinet doors that could be open to the plumbing. Also are you saying no colder than 30 degrees and things froze. I find that hard to believe:(
ron_dittmer
Explorer II
Oct 11, 2018
If applicable, consider installing pairs of little 4" round louvers to allow air to circulate between walls or compartments that have concern of freezing so that warm air gets into where the pipes are located. Place them far apart to get flow-through action.

Something like this.....

Some are sold with screens so you don't let in insects.

You might even find some with closures.
pianotuna
Nomad III
Oct 12, 2018
Ron makes a good point. Just having warm air isn't enough. There has to be some place for it to flow.
bobndot
Explorer II
Oct 12, 2018
I,m sorry to hear that things froze at that temp.
I once did the same as ron.dittmer suggests and added a 12v computer fan at one duct, it allowed the space fill with warm cabin air which vented out the opposite end.

I also re-routed water lines off the outside exterior wall (so they don't touch the wall) and was able to wrap them in foam tubes.
time2roll
Nomad
Oct 12, 2018
My old thread to circulate hot water

System has since been updated to generally run the pump while the furnace is cycled on. Or a switch to run continuous.
GordonThree
Explorer
Oct 12, 2018
time2roll wrote:
My old thread to circulate hot water

System has since been updated to generally run the pump while the furnace is cycled on. Or a switch to run continuous.

X2 for this. It's a bit technical but really works well.

My system is tied to outdoor temperature, the colder the more frequently it runs. When it's operating it runs until the hot and cold lines reach the same temperature.
SDcampowneroper
Explorer
Oct 12, 2018
Fans and open cabinets will work for sub freezing temps, for cold, say singles to below 0 f you will have to do more.
First, block most or all fridge lower vents. Foam pipe insul. is perfect for tucking in and removing as the weather changes. Absorption fridges have to have a warm condenser, so when outdoor temps drop below 40 f it wont work well unless you help it by blocking the air flow. Seems backward to warm a fridge to help it, but it is correct to keep the outside condenser warm. I go further, placed an in/ outdoor thermometer above the condenser, changed the blockage daily to maintain + 40 to 100f temps.
not an easy quick fix, but for the long term open the underbelly, heat trace lines, pump, tanks then insulate with cut to length 5w / ' elec. heating cable available at any box store. Place the thermostat where you can plug into 120v ac or into an 12v dc -120vac inverter then when on the road the inverter via your tow will heat the plumbing. . I also used old waterbed heaters under the tanks.
Pianotuna, Bobs Your Uncle, and I have been there. I meen -40 and colder there. We made it comfortably, except when Bobs socks were frozen to the floor!
Max
pianotuna
Nomad III
Oct 12, 2018
Add Moving Sue and PhotoMike to that shortlist. I believe they did it with no shore power as well.

I have to recuse myself from the list--my lowest temperature was only -37 c (-34 f).

Don't forget the butter (for the popcorn) from Bobs Your Uncle.
ReneeG
Explorer
Oct 12, 2018
Whizbang, the RV in your signature and your description of freezing pipes reminds me of one of our nights camping in late Sept in Western Montana at Bannock State Park. It was freezing weather and a Class C, the only other one in the campground ran their generator off and on all night I'm assuming so they could run their furnace. We set our furnace to 45, but it never kicked on as it didn't get to that temp inside our FW. In the morning I turned on the catalytic heater.

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