[Pluto]

You are correct, Forest. I hadn't gotten that far into the project when I had made that post, sometimes I get ahead of myself. Thanks for the response!

We switched from diesel to electric before bed last night and luckily I got up to pee about 20 minutes later because the new unit ended up boiling over. I heard a bubbling sound and went to check l, finding a cloud of steam and a large puddle of transfer fluid.

We shut off the system immediately and I called John Carrillo as soon as possible this morning. According to him it was more than likely due to an air lock in the system. We did our best to prime and purge each of the heating zones and had heat coming from each of them, but apparently an air lock can still happen.

I had to take off work today and drive back to St George to buy the rest of the transfer fluid they had (6 gallons) at campingworld. We reprimed the each zone again and are keeping a closer eye on the temps.

He also said that it could be a faulty thermostat switch, so I pulled the one from our old unit, per his suggestion, and will try switching it out later this week.

For now we're going to stick to running the diesel burner since it is shutting of correctly.

Fingers crossed ?

[Richard]

Ty, I am sorry the Beckett conversion was a stumbling block.

This may have been what you were looking for. https://www.hydronicheatingwarehouse.com...rness-375d

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Someone can correct me if I am wrong but these style aqua hots do not require the special transfer fluid, you can use just regular green coolant. I need to flush my system as mine does not look really good. The transfer fluid is required in the newer aqua hots because the use a heat exchanger for the domestic water heating and there is a possibility the transfer fluid can get into the drinking water so it’s non toxic. These older aqua hots just have a coil wrapped around the outside of the boiler chamber so no chance the coolant can get into the drinking water.

[Pluto]

Jeff, the unit that we replaced used regular green ethylene glycol antifreeze.  The remanufactured unit that we installed has the newer style tank and requires the GRAS propylene glycol heat transfer fluid.

After the boil-over and the six gallons I bought yesterday to refill the unit were  at a little over $700 in boiler fluid alone. 

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Jeff, the unit that we replaced used regular green ethylene glycol antifreeze.  The remanufactured unit that we installed has the newer style tank and requires the GRAS propylene glycol heat transfer fluid.

After the boil-over and the six gallons I bought yesterday to refill the unit were  at a little over $700 in boiler fluid alone. 

Ahh I see, so they reman those units and make them like the new ones with a heat exchanger?

[Pluto]

Thanks for the link Richard that probably would've helped with adapting the beckett controller to the new unit. I'm glad we decided to go back to OEM, it think it looks a lot cleaner and should be easier to diagnose any future issues with the help of the Aquahot shop manual.

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I'm not for sure on the design of the new unit, but I think the heating coils are inside of the tank instead of around the outside. Which is why the no-toxic fluid is required.

[Pluto]

We were able to get the living room thermostat working like it should, once I actually understood how it works. The bedroom one is still not working, but we have a new one on order.

I also swapped the AC thermostat switch out and now it's shutting off consistently at 208 degrees like it should.

I'll update when we get the new bedroom thermostat, but I'm comfortable calling this project complete!