Last week, I sanitized the fresh water system on my 2011 Keystone Montana 3400RL 5th Wheel. Now this cold snap will bring temps down to 25 degrees tonight. I used the Thetford system to sanitize ...
Like others have said.You are fine..I wouldnt even run furnace.Unless your below 25 all day.Your prolly talking a few hours at night at 25 then sun comes out and warms above 32 quickly.It needs to freeze solid .. Dont worry.Run furnace if it makes you feel better.
This happens to me every yr at least once after I dewinterize.Never a problem yet.I open all faucets and lower drain points.Throw some antifreeze in the traps for further piece of mind.