Hmmm...woke up this morning with no hot water in the bath sink or tub which is at the rear of the trailer. No shore water even though hose had heat tape and insulation. Furnace was run at 71 all night and came on about about every 6 minutes. Outside temps dropped to about 25 degrees where I'm currently parked near Richmond Va. The on board tank is providing hot and cold to the kitchen, but only cold to the bathroom. I opened all the access panels and none seem cold enough to cause freezing so I suppose the hot water pipe running from the kitchen to the bath under the flooring is the one frozen which I cannot access. In hindsight I should have dripped the faucet in the bath.