This is a fairly common topic. There is a lot of posts on this subject.
How cold do you plan to camp? Does your Micro have an enclosed underbelly? Do you plan to have an electric site?
We camp below freezing most years each spring and fall. We do not have any tank heaters, nor an enclosed underbelly. So far we have not froze up anything. The coldest overnight temps has been about 20 degrees, with the daytime highs on those days in the low 30s. I have to admit, I was a little concerned we would freeze up the tank that two nights (5 day dry camping trip). Normally we camp with overnight lows in the mid 20's with the daytime highs above 40 degrees. If you are going to camp for extended time below freezing (daytime highs are close to or below freezing) I would recommend dry camping.
Except for the tanks and FW tank low point drain, all our plumbing runs inside the TT.
- In the cool weather we make sure our FW tank is full, do not keep any hoses connected to the TT. The hoses will freeze first, and will take hours in the morning to thaw out. Disconnect your hoses, drain them, and coil them up and put them in your store hold.
- Keep cargo hold doors closed and latched.
- Cabinets with plumbing running through them, keep the doors ajar to allow a little more heat to access the plumbing.
- FW tank, fill it full of water. Water has a lot of thermal mass, and freezes slowly from the top down, and will take a long time to freeze once the air temp reaches 32 degrees. Think about puddles.
Normally in cold weather the DW likes having an electric site. So we tend to heat with electricity, normally it keeps our TT nice and toasty during the day, and at night the TT can cold off a bit (we have a hybrid with tent ends). At night if one of us gets up to use the bathroom, we might turn on the gas furnace for a few minutes to help warm things up.
As for tank heaters. They are a silicone flexible pad. They have a tendency not to stay attached to the tank, due to the poor choice of adhesive. Most people say do not use them if the tank is empty. We use these pads at work on many of our processes, and we have not had any issues with them failing due to a lack of being attached to something or an empty tank.
Pipe fittings tend to be the first thing to fail if the plumbing freezes. The pex tubing can flex a lot and tends not to fail. The FW and waste tanks are big, if they are full, there is a lot of thermal mass, and will take a long time to freeze. Water Heater, if it is not being used, make sure to bypass it, and drain the tank. If your using it, it will not be an issue.
FW tank low point drain valve; I have been surprised, I have not damaged this valve. I am sure the water has frozen within this cheap valve many times.
If your daytime highs are going to be close to or below freezing, I would recommend draining the system, and dry camp.
Have fun cool weather camping