Taco switching Relay wired to L8418 High Limit Relay


Old 02-28-13, 09:04 AM
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Taco switching Relay wired to L8418 High Limit Relay

I would like to add a Taco 6 zone switching relay to my heating system.
Wiring looks very straight-forward. T-stat leads come in, 120v input power, individual circulator power & boiler output power. Plus, I like the idea of having my indirect wired to zone 6 for "Priority heating".

However, my oil boiler has a Honeywell L8418 aquastat relay wired with a high limit shut-off & a low water cut-off.
I was planning on using the 120V output "Boiler" lead from the Taco relay and feeding the L8418 to retain the same function, when the Taco relay signals for heat. However, the 8418 is also switched by 24v thermostat control as "a call for heat by the t-stat starts both the burner & circulator"

Can I splice the 120V boiler output @ the Taco relay into two feeds, add a 24v transformer to one & continue the other feed to power the 8418?
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Old 02-28-13, 09:14 AM
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I don't think yer thinking correctly...

First, let's know about your system. I know you've posted before but I don't remember...

You have zones with circulators? NO electric zone valves?

If so, you won't be using the boiler 120VAC output at all, just a jumper as shown in the install for 'cold start' boiler.

All you will need from the taco to the 8148 should be a pair of thermostat wires from the taco ENDSWITCH to the T T terminals in the 8148.
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