Sidearm heat exchanger reverse heating

[blakey]

We went away for the weekend and I thought I would let the new backup propane furnace run instead of asking someone to load the OWB. I don't think the propane ever came on and my electric water heater with a sidearm reverse heated the 400 gallons out at the OWB. This was enough to keep the house warm. I set the thermostat to 18C and the propane is set to kick in 2 degrees below that. We had one cold night of-12C in that time and I can see the electricity usage spiked. I was monitoring the thermostat when we were away and it was always 18.0. I did not expect that. Next time I will likely shut off the breaker to the water heater although it's not terrible doing this just for a couple days. We were gone for four days and the wood lasted for two.

 

[jblnut]

Same thing happened here when we left last winter for a week. I left the circulators on so the water heater was heating the stove and then the water went to the shop and it was warm enough that the shop LP boiler never fired. So my water heater in the house was essentially heating the shop

I put a ball valve in the bottom of the water heater so I can shut the side arm off without flipping the breaker on the water heater and having an ice cold tank to heat up when we get home. Side benefit is that I can flush the water heater out better now that I can stop water from coming through the side arm during the flush.

You live and you learn lol

 

[rancher2]

If I get lazy in the off heating season and don't keep the temp up on my Garn. My propane water heater starts up and it will in turn heat the 2000 gallons of water in my Garn. I should just unplug the propane water heater so it won't come on but its nice to have a back up if I get busy and don't get the Garn fired. I normal heat my domestic water year round with wood.