Oil fired water heater thermocouple/ thermostat replacement


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Old 02-26-19, 05:04 AM
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Oil fired water heater thermocouple/ thermostat replacement

Hello I am replacing some components on my oil fired water heater and have a question about the electrical connection. The feed electrical coming into the thermocouple/ thermostat ??? The old one that I took off had a blue and black wire. The new one has the blue/black wire attached to where you select the temperature of your water cool/hot/hotter but it also has 2 black wires coming from a black device in the box. It’s a 120V incoming from my disconnect to the heater. Can anyone tell me the proper way to connect the electrical?

Thanks
 
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Old 02-26-19, 09:11 AM
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It wouldn't be a thermocouple on an oil fired unit.
A thermocouple is used to hold a gas valve on in the presence of a flame.

Possibly an aquastat ? Controls firing based on water temperature.

Can you post a picture or two of what you have there....... How-to-insert-pictures
 
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Old 02-26-19, 11:34 AM
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It is an aquastat. A white Rodgers/ Emerson dual aquastat. 11D73-3 I cannot find a wiring diagram anywhere. There’s 4 wires. Two black and a black and blue. I have 120V coming in and then another set of wires going to the burner.
 
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Old 02-26-19, 07:24 PM
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I'm guessing this is a John Wood water heater ?
Their manuals all say to check the wiring diagram that came with the burner.

That aquastat appears to only be used in that brand of water heaters.
I'm probably going to need pictures as I'm not familiar with that water heater.
 
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Old 02-26-19, 07:55 PM
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Here’s the aquastat connected. The 2 black wires are the ones I’m unsure about.

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Last edited by PJmax; 02-26-19 at 09:04 PM. Reason: enlarged picture
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Old 02-26-19, 09:08 PM
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It looks like that aquastat serves two functions. It cycles the burner based on water temperature. The other function is over heat protection. It would break the circuit on overheat.

That means you would have a series loop. No particular order....... power in to one switch. Power out of first switch to second switch. Power out of the second switch to the burner.
 
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Old 02-27-19, 03:25 PM
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Thanks for the input! Appreciate the help
 
 

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