How to change Line voltage to Low voltage Thermostat

Old 12-31-22, 08:02 PM
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How to change Line voltage to Low voltage Thermostat

I am looking for some guidance on installing a low voltage transformer to my heat only boiler system so that I can switch to a smart thermostat. Current t-stat is 120v. / 1 zone / Oil

The system is set up as follows:
Load goes into a junction box
Out of that junction box
1 line to goes to emergency shut off switch
1 line to thermostat
1 line to the Aquastat

Out of the Aquastat
1 line to circulator pump
1 line to a relay box

Out of the relay box
1 line to the burner

At what point do I add on the transformer?

Old 12-31-22, 09:47 PM
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Welcome to the forums.

You need two things.... a relay to switch 120v to the boiler in place of the thermostat and 24vac to run the thermostat. The easiest way to do it is to use a fan center. It's a transformer and relay on one 4" square plate. A 4" square box can be installed where you have room near your controls and the fan center mounts to it. Very easy to wire. One example in the link below. There are other choices. I can help you wire it when you've gotten it.

Fan center (transformer/relay combo)

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