Set Up Indirect Water Heater Using Honeywell L7224/L7248 - HVAC - DIY Chatroom Home Improvement Forum

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Old 09-30-2012, 08:49 AM   #1
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Set up indirect water heater using Honeywell L7224/L7248

I have an older cold start Weil McLain oil fired boiler with a newer L7224/L7248 controller (the old controller died 2-3 years ago). Until recently I ran a separate oil fired Bock water water heater, but it is nearing the end of its life and I decided to set up an indirect water heater to save on oil and burner maintenance costs. My boiler system is set up with a single circulator pump. I have a spare zone that I plan to hook up to the indirect tank, which originally went to a basement heating zone that I never used. Think it will work if I simply just hook up the thermostat wires to the aquastat on the indirect tank, however, I would like to set up the indirect water heater zone such that it is prioritized over the other 4 house heating zones if possible. I see that there is a ZR terminal on the L7224/L7248 controller, but I am not quite understanding how to wire the indirect tank zone such that it will be prioritized. Would appreciate some advice.


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Old 09-30-2012, 09:14 AM   #2
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a line voltage aquastat will be necessary that will send L1 power through to the ZR terminal with a demand for heat on the dhw zone. You have to go into the settings of the new L7224/L7248 to setup the priority on the ZR circuit.

see more here: pdf file

page 8 for a schematic
page 5 for adjusting control settings

You should install a separate circulator for the dhw zone.


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honeywell l7224/l7248 , indirect-fired hot water

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