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MurphyMan · 02-06-2019, 07:07 AM

2005 Class C Outlook. We are in southern Illinois.

We got our motorhome out of storage, purged the antifreeze, and got it ready for a trip South. Unforeseen circumstances dictate that we stay for a while, and that is going to include some brief weather maybe down to 15 or 20 degrees. If we keep it in the driveway, plugged into the shore power, and run the propane, how much cold can this machine take before I start damaging plumbing from freezing?

I can keep the thermostat set to 45 or 50, and leave the cabinet doors open that have plumbing in them. There is a tank heater on the gray and black water, though I've never used them. I'm a particularly worried about freezing in the black water discharge bay, as that is unheated. I think we're only going to have the cold weather for a day or two before it warms up to above freezing. I hate to have to go and re-winterize the whole thing again.

So, what temperature can our Class C withstand?

Persistent · 02-06-2019, 07:29 AM

Tanks with only a little liquid in them are not in danger. Water expands about 10% by volume when temperature drop from 38 degrees to 31 degrees. If the tank is full and there is no room for expansion the tank will burst. If the tank is nearly empty, it will simply shift the ice around.

Pipes with water in them are full. If the ends of the pipe freeze there is a sealed chamber between the frozen ends and or valves. The pipes or valves will burst. Any sealed chamber like a pump will burst.
PECS water pipe will expand instead of bursting, but fittings and valves will probably burst.

Persistent · 02-06-2019, 07:45 AM

A black water flush system with water in it may be at risk depending on its design. It is possible all the water in it simply drains into the tank when it is disconnected.

Hikerdogs · 02-06-2019, 08:46 AM

I would set the thermostat at 55* to be safe. The furnace forces air into the lower compartments. That being said if the furnace doesn't cycle often enough to move the cooler air in the compartments you do stand a chance of freezing the PEX tubing. The small volume in the PEX will be the first to freeze.

We regularly camp in temperatures between 15* and 30*. When we leave the thermostat at 55 the compartments stay between 38* and 40*.

We purchased a Lacrosse wireless weather station and 2 extra remote sensors to monitor key areas.

https://www.lacrossetechnology.com/w...ather-station/

The main unit is the bedroom with one sensor in the water compartment, one in the fresh water tank compartment, and one exposed to the outdoor ambient temperature. If the temps in these compartments get near the freezing point we bump the thermostat up a couple degrees.

It does take a fair amount of propane to keep everything warm on the colder nights. Our tank has about 18 gallons of usable volume. If temperatures stay in the 15* range I doubt it would last a week.

As for the black flush system, ours doesn't have a back flow preventer, so when the hose is removed the water either drains into the tank or out the hose connection. There is nothing left in the pipe to freeze.

pmoroney · 02-06-2019, 09:23 PM

I put the window washing fluid in my holding tanks ( gray and Black)when it got cold here in Idaho before we left to go south, it will not freeze or damage anything.

my 2cents

Patrick

Mudfrog · 02-06-2019, 09:24 PM

Make sure water tanks are empty. Open all faucets inside and drain the water as best you can at the lowest point. I sometimes do this on ours via the outside shower since it is down low. Drain the hot water heater too. If you're plugged in, then you might try running a 1500 watt space heater inside with the cabinet doors open. It probably wouldn't keep up so you could still leave the furnace set down around 40° for back up. For water bay compartment, a 100 watt incandescent bulb would probably work well to keep the plumbing inside from freezing. I would check it periodically though to make sure it hadn't burn out.

I would think this would work for what you're expecting but who knows, it might be better to go ahead and winterize again if there's a chance temps could fall and remain below 20° for a longer than expected period of time.

AFChap · 02-07-2019, 07:58 AM

You are on the right track. In addition, as mentioned above, I would open the low point drain and open a faucet inside. After the drain has totally quit dripping then I would close the faucet and the drain. Also, I would put an incandescent light bulb in an auto trouble light/spotlight housing/can light or something like that in the unheated compartment that has water fixture. An incandescent bulb in a small space puts out a considerable amount of heat. Just ensure that the bear bulb is not touching or extremely close to anything that could be flammable.

VagabondDoug · 02-07-2019, 06:51 PM

I guess I'm a little obsessive, I open up all the faucets and hook up my compressor to the system and blow out the lines, pump and w/h.. I don't want any water left. Only takes a few minutes.

Ray,IN · 02-07-2019, 09:52 PM

Plastic/PEX lines can withstand mild freezing much better than copper or metal lines. You've received sound advice about setting the furnace temperature at 55°.

Quote:

Originally Posted by VagabondDoug

I guess I'm a little obsessive, I open up all the faucets and hook up my compressor to the system and blow out the lines, pump and w/h.. I don't want any water left. Only takes a few minutes.

You cannot blow ALL water out of a line if it has any dips/low points. To test, go buy a 10' section of 3/8" clear tubing, fill with water, then use your compressed air until you think you blew out(not drain out) all water. Now hold the tubing in the air by both ends and watch the low point for a few minutes.

VagabondDoug · 02-08-2019, 01:09 PM

I understand what you are saying and there is one place in my RV system that didn't clear out and that was a sediment filter near my pump and I had to replace that once due to it not clearing.

I open up all the lines including the low valve on the outside shower.. I close them from the top shower down to the low point.. I have been doing that successfully for 5 years. I live in the Pacific NW where it does freeze.

What I do is in addition to draining the system. Or draining it under pressure.

I would say that common sense means under 40 lbs of pressure to keep from doing any harm.

I started doing it to my drip irrigation system years ago. I shut off, drain and blow out almost all my outside lines. Way easier than repairing them. We have had some periods of extended cold too..

Just what I do, not that anyone else has to do it. I don't like the idea of pumping chemicals in and don't trust just draining it..

MurphyMan · 02-08-2019, 02:05 PM

It got down to 15 last night, and I seem to be fine. Here is what I did to prepare:

Left the main tank full, since it's under the bed.
Opened all the low point drains.
Pulled the slide in.
Closed all the shades and put up the cloth privacy barrier that separates the cabin from the drivers area.
Dumped some RV antifreeze in all the drains. Used a gallon. The tanks were pretty empty anyway.
Opened all the cabinet doors and drawers that had water behind them.
Left the bathroom door open.
Turned on the water heater.
Placed a 100W light bulb in the outside hatch that has a shower.
Turned the HVAC heat to 55 degrees.

I checked on it this morning and all seems in order. I had placed a small bottle of water in the outside shower bay, to act as my "freeze indicator", and it showed no signs of ice. Thanks for all the suggestions. Tonight it's supposed to get down to 12.

Ray,IN · 02-08-2019, 09:35 PM

Murphyman, a tip I learned about the outside shower is; if you have winterized and never open the valves afterwards, the RV anti-freeze is captured in the hoses and hot/cold valves and requires no further attention. When I de-winterize I don't open those valves until I need to use the outside shower, which is normally later in the year.

MurphyMan · 02-08-2019, 09:36 PM

Quote:

Originally Posted by Ray,IN

Murphyman, a tip I learned about the outside shower is; if you have winterized and never open the valves afterwards, the RV anti-freeze is captured in the hoses and requires no further attention. When I de-winterize I don't open those valves until I need to use the outside shower, which is normally later in the year.

Good idea, thanks.

Jim_HiTek · 02-09-2019, 09:22 PM

Just pour a gallon of pink stuff into the drains after dumping. That should protect your drain valves. But you can also put a small heater or even a shop light in the bay with the drain valves to protect them. Or wrap them with heat tape. That's what most do.

I used the pink stuff in the fresh system once. Never again. Took weeks to get that puke taste out of the system. And in a water starved area, it was frowned upon to fill and flush many gallons of water just to get rid of that taste.

I've used the air method ever since. Even those 3 winters I spent in Fairbanks, Alaska. Pipes in an RV are not held in a U shape in one hand. They're mostly flat or a few degrees from zero. Or at some angle. I never worried about water accumulating in the pipes or PVC fittings after I blew out the lines and as it turned out, didn't need to.