How long does it take waste tanks to freeze in winter?

[HappyCamper1962]

We camp year round across the US. Most winter camping has been in the southern states so far. This is my first TT with heated tanks - at what point (temperature and duration) would it be necessary to heat the tanks to keep them from freezing?

[Reverse_snowbird]

At or below 32 degrees F?

[HappyCamper1962]

Originally Posted by Reverse_snowbird

At or below 32 degrees F?

Um, Yes, pretty sure about that. But like at home, it has to stay there for a period of time before any damage is done. We've camped in sub-freezing temps but they were only holding for a few hours, never heated the tanks. Just planning ahead, when would I need to be concerned. I guess I could just heat them when freezing temps are expected just to be safe.

[Reverse_snowbird]

Originally Posted by HappyCamper1962

I guess I could just heat them when freezing temps are expected just to be safe.

Sounds like a plan. Read somewhere that they only turn on below 42 degrees.

[Oaklevel]

We do not have heated tanks and been camping in the mid to upper 20s overnight with no freezing. They will be kept somewhat warm by the heat from the trailer.

Personally to be safe you can turn them on below 32 but probably would not need them to much below that.

[TitanMike]

Most tank heaters don't heat until the temp is near freezing. Only precaution is to not have them on if tanks are empty.

How fast the Gray/Black tank will freeze depends on how cold it is and how much wind. Also if the belly has a full cover, insulating the tanks to a point, or not.

My experience has been that it has to drop significantly into the teens for longer than just a "plunge" during the night to freeze tanks and do any damage. There's often enough residual heat to keep things from freezing right away. Lots of wind, or if you are driving can accelerate things though.

[bigmurph]

I camped in my Flagstaff last January. It was below freezing for all three days. The lows at night were in the signal digits and the highs were in the 20s. My tanks didn't freeze but my calves did. I may install valve heaters this year. I did use my tank heaters. Thought that it would keep the valves warm enough but I think the fact that they are 10" from the main tank and out in the open allowed them to freeze.

[richp]

Hi,

Take a look at the drain valve on your fresh water tank.

On my Silverback, the hose hangs down 9-10 inches, with the valve at the bottom. That leaves a relatively thin column of water hanging down in the exterior air temperature. My low point drain valves are inside
a compartment, but they could be another vulnerable point on some rigs.

I have dealt with this by slicing a section of pool noodle and enclosing the entire hanging assembly -- valve and all. Worked last winter going to and from Quartzsite in January, from northern illinois.

FWIW.

Rich Phillips

[Flybob]

The first place to freeze unless it is fully heated is not the tank, but the drain line just prior to the dump valve. This is the smallest volume of liquid and hence the least amount of stored heat energy. It is also the most vulnerable and the tanks itself has some flexibility while the drain pipe and valve does not.

[JohnD10]

Buy some heat tape from Home Depot or Lowe's.

Comes in several different lengths.

I used some on my 5'ver last winter as my drain lines are exposed under the camper after having one freeze up.

Kept them for two months after that and no more freeze up!

Also, a heated hose if you plan to be hooked up to city water, however, the ends of these still freeze, so yet another trip to Home Depot for more heat tape.

That helped, but I still had issues with that so I resorted to running off of the fresh water tank for most of those two months.

Keep an eye on your outside shower...mine froze up and required complete replacement!

[Cold Lake Kid]

I would be more concerned about the lines and fittings, with any water in them.
I had one night, of below freezing, that split the fresh water inlet fitting to my toilet.
Dry camping and I was not heating the motor home overnight.

[Larry-NC]

Originally Posted by Flybob

The first place to freeze unless it is fully heated is not the tank, but the drain line just prior to the dump valve. This is the smallest volume of liquid and hence the least amount of stored heat energy. It is also the most vulnerable ant the tanks itself has some flexibility while the drain pipe and valve does not.

Yup! Replaced the gray water plumbing last summer because that's where it froze. Two pieces of pipe froze and split. I had to replace them and two elbows and the flange on the gray water slide valve. We had winterized the system and were using bottled water. The only use was brushing my teeth, but all the water drained to that lowest point. Guess I'll brush in the bathhouse next winter.

Larry

[JohnD10]

Originally Posted by Larry-NC

Yup! Replaced the gray water plumbing last summer because that's where it froze. Two pieces of pipe froze and split. I had to replace them and two elbows and the flange on the gray water slide valve. We had winterized the system and were using bottled water. The only use was brushing my teeth, but all the water drained to that lowest point. Guess I'll brush in the bathhouse next winter.

Larry

I typically pour enough RV antifreeze (pink stuff) down the black and gray tanks to fill the drain pipes up to at least the tanks so that this will stop the freezing from the exposed drain pipes.

Even if running water in the tanks, the pink stuff in there will help stop them from freezing between dumps.

[Larry-NC]

Originally Posted by JohnD10

I typically pour enough RV antifreeze (pink stuff) down the black and gray tanks to fill the drain pipes up to at least the tanks so that this will stop the freezing from the exposed drain pipes.

Even if running water in the tanks, the pink stuff in there will help stop them from freezing between dumps.

Good idea, but it would probably take a gallon for the gray tank (long run) and a gallon for the black tank (shorter, but larger diameter).

What I did instead this winter (winter after I repaired/replaced the pipes) was to simply connect the Blueboy and leave the gray valve open. There's enough salt in the black tank to prevent problems.

Larry

[pmsherman]

Rigs with tank heaters usually have heating pads located on the waste tank drain pipes too. As already pointed out, the drain pipes are the weakest point in the system and usually freeze first. Since these pipes are rigid plastic, they'll crack when water in them freezes.

Turn on your tank heaters whenever the temperature is below 40F. The thermostat in them should prevent current draw until the temperature drops to the "turn on" point. Don't forget that it's a lot easier to keep something warm than to warm it up once it gets too cold.

We do a lot of travel in below freezing temperatures. I added 300W of gutter heater strip to all of the plumbing pipes and the water filter in the basement compartment that isn't heated. It's powered from the 1kw inverter I installed that also powers the fridge while we're driving. The rest of the plumbing lines are located inside the rig where the temperature doesn't get below freezing.

Phil

[JohnD10]

Originally Posted by Larry-NC

Good idea, but it would probably take a gallon for the gray tank (long run) and a gallon for the black tank (shorter, but larger diameter).

What I did instead this winter (winter after I repaired/replaced the pipes) was to simply connect the Blueboy and leave the gray valve open. There's enough salt in the black tank to prevent problems.

Larry

Maybe a half a gallon to fill those drain pipes under the RV to the tank, and this can be somewhat dilluted as well.

Just having the antifreeze in there will keep those drain lines from freezing up.

Worked for me in below zero temps for weeks this past winter in Denver!

I'd rather spend a few dollars on antifreeze to keep those drain lines open than to replace them after they spit open from freezing.

Plus, I think enough heat tape to wrap around the drain pipes was around $40 at Home Depot, which I ended up doing once I realized that the cold was not going away anytime soon.

[mwdilday]

I've never had a tank freeze. I have had the drain pipes freeze when we were on the highway with 9 deg temps. That was a mess.

[rsdata]

I typically pour enough RV antifreeze (pink stuff) down the black and gray tanks to fill the drain pipes up to at least the tanks so that this will stop the freezing from the exposed drain pipes.

Even if running water in the tanks, the pink stuff in there will help stop them from freezing between dumps.

this is a great tip... thx