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Rick Mather
Rick Mather, HVAC Technician
Category: HVAC
Satisfied Customers: 3634
Experience:  35 years experience, HVAC
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Connecting a Honeywell R845 switching relay to a HoneyL7248C

Resolved Question:

<p>I'm installing a new Burnham Oil fired bolier that came with a Honeywell L7248C Controller.  The house has an existing Honeywell R845 switching relay to controll the second zone in the house. The wiring digram shows the leads coming from the #1 and #4 terminals on the R845 going to the ZC and ZR terminals on the L7248C.  However, there are no terminal srewon the L7248C where the labels are for the ZR and ZC contacts.  Is it possible that those terminals are shared with the B1 and L1 terminals next to them?</p>
Submitted: 5 years ago.
Category: HVAC
Expert:  Rick Mather replied 5 years ago.

Rick Mather :

Fig 5 and 6 clearly show those terminals

Rick Mather :

Fig 10 shows wiring for R845a

Customer:

Hi Rick,

Customer:

I agree, but alas, they do not exsist on box itself.

Customer:

they are labed but there is no terminal screw for Zr or ZC.

Customer:

on figure 10 on the upper left corner of the box for the controller is says "L7224"

Customer:

figure 12 shows "L7248L" which shows no terminal screw for ZC. I don't see any diagram specifically indicating "L7248C"

Customer:

here's a pic showing the labels for ZR and ZC but no terminal screws. Not sure how this this works but I need to step away for a bit. I'll leave this chat window open in hopes you can help.

Full Size Image

Customer:

your back!

Customer:

Can you see my problem?

Rick Mather :

The only choice would be to too get new aquastat that has the right terminals other wise you can wire r845 as just relay and hope boiler has enough heat to heat zone

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