Freez prevention

[Jerry Liebler]

It has been really cold, for here, the last couple of days.  I tried to make my bus not need winterising of the fresh water system.  The plan was to keep it minimally heated with the heat pump, a couple of electric 'cube' heaters and backed up by the Webasto when the temp inside gets down to 45.  My fresh water tanks are under the twin beds, my hot water heater is on the original floor and under the forward extension of the upper floor.  My freshwater plumbing is along the walls just above the floor.  Well after the first 8 degree night I had no hot water & found a frozen cold water pipe leading into the water heater.  OH SH--.  Well I cranked up the Webasto and got it thawed with no damage but I needed a permenant solution.  I think I have got one.  I had installed a solenoid valve at the end of my hot water line returning the water to the tanks to allow warming up the pipes without wasting water.  This I'm hoping is my solution to the freezing problem.  I scrounged a couple of time delay relays and another relay from my collection of treasures (AKA junk boxes) and built a relay oscillator.  The parts I had allowed me to set it up to open the valve for 5 seconds, then wait for 195 seconds.  Assuming my 5.7 GPM pump delivers 5 GPM through all the pipes I now have an average of 1/8 GPM of hot water circulating back to the tank.  It's been running for about an  hour and the tank temperate has only gone up a degree (I've got about 100 gallons in the tanks).  Right now my tank temperature is 55 and the spot that froze is also reading 55 with the infrared thermometer.  Tonight is going to be another cold one so tomorrow morning I'll check the temperatures again & hopefully be pleased.
Regards
Jerry 4107 1120

[gumpy]

Interesting solution. Will this also take care of the manifold and other fresh water lines to sinks, toilet, shower, etc?

[Jerry Liebler]

Craig,
     It will help but I'll still have to keep some heat on.  I have no manifold but use  'Tees' off of a 'main line'   
and individual ball valves at each fixture.  The problem I was having was the lines to & from the water heater pass through an unheated space between the original floor and the extended upper floor.  I 'tweaked' the timers a bit and now have the valve open for 4 seconds and closed for 196 (estimated average flow now 1/10 gallon per minute) and the cold water temperature has risen from the 54 I first measured to 62. but it's all of 20 outside right now, the real test will be overnight, the forcast low is 8 again.
Regards
Jerry 4107 1120