I finally got the hot tub up and running off of the Tarm last night!!
I made a heat exchanger based on nofossils design and put it in series with the electric one. I disconnected the 230 vac heater and ran a wire from one leg to a relay and the other side of the relay to the neutral. So when the tub thinks it’s turning on the heater it’s actually turning on a relay which in turn is acting as a thermostat back to my control panel and turning on the spare circulating pump just like a heating zone. I have 1200 gallons of storage so I should be able to go quite a while between firings.
One problem I ran into was that they apparently only switch one side of the heater circuit and I initially hooked up to the non switched side. This caused the pump to not shut off and I hit the overheat limit on the tub over night. I swapped it over to the other leg this morning and its running fine, turning on and off just like it’s suppose to.
It actually heats up about twice as fast as the electric heater.
The other problem I had was the TACO pump that I saved when installed the Tarm last fall must have been seized up. I got no flow and it got wicked hot just sitting there. That might explain why the living room never got very warm. Of course I found that out at 10:30 at night when I made my final connection. A quick trip to Home Depot yesterday for a new one, and I’m up and running.
It’s going to make a huge difference in my electric bill. I turned the tub off over a month ago in preparation to switching over and my electric bill from mid April to mid May was down by 33% or about $58. That’s with overnight lows in the 40’s and 50’s. I can only imagine what the savings will be next January!
Now the next step is to hook up those solar panels so I don't even have to build a fire until fall!!
I’ll post some pictures tonight.
I made a heat exchanger based on nofossils design and put it in series with the electric one. I disconnected the 230 vac heater and ran a wire from one leg to a relay and the other side of the relay to the neutral. So when the tub thinks it’s turning on the heater it’s actually turning on a relay which in turn is acting as a thermostat back to my control panel and turning on the spare circulating pump just like a heating zone. I have 1200 gallons of storage so I should be able to go quite a while between firings.
One problem I ran into was that they apparently only switch one side of the heater circuit and I initially hooked up to the non switched side. This caused the pump to not shut off and I hit the overheat limit on the tub over night. I swapped it over to the other leg this morning and its running fine, turning on and off just like it’s suppose to.
It actually heats up about twice as fast as the electric heater.
The other problem I had was the TACO pump that I saved when installed the Tarm last fall must have been seized up. I got no flow and it got wicked hot just sitting there. That might explain why the living room never got very warm. Of course I found that out at 10:30 at night when I made my final connection. A quick trip to Home Depot yesterday for a new one, and I’m up and running.
It’s going to make a huge difference in my electric bill. I turned the tub off over a month ago in preparation to switching over and my electric bill from mid April to mid May was down by 33% or about $58. That’s with overnight lows in the 40’s and 50’s. I can only imagine what the savings will be next January!
Now the next step is to hook up those solar panels so I don't even have to build a fire until fall!!
I’ll post some pictures tonight.
