Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Programming Honeywell 7248C

Joe Plumb
Joe Plumb Member Posts: 7
Just installed a Weil McClain UO-4 boiler with electronic aquastat 7248C. The boiler is supplying heat  to two baseboard zones via one pump and two zone valves,  and one Plus 60 indirect fired water heater also on separate pump.

I am trying to adjust the low limit on the control but it is not allowing me to program beyond the high limit. While scrolling through the menu it will not display anything but boiler temp, Fahrenheit,  high limit, and two separate thermostat settings. Therefore the pump for the indirect will run constantly while the boiler remains at 110 degrees. The boiler does come on when there is a call for heat and runs up to high limit. Could there be something wrong related to  the ZR terminal; possibly the electrician wired into the control from the indirect incorrectly.

Please help!!


  • billtwocase
    billtwocase Member Posts: 2,385
    cold start

    There is no ZR, or low limit on that control. It should be all zone valves if you are using that control. T-T will bring it on and run it to high limit
  • Big Ed_4
    Big Ed_4 Member Posts: 2,696
    edited April 2010
    Add an End Switch

    At this point pic up a low cost RIB( Brand name ) relay and wire it into the voltage of the indirects circulator .This relay can power up either 24 V or 110 V , just read the directions as to use proper leads and voltage coil... On the contact side use the normally open leads to wire to TT ,So when the indirect sends juice to the circulator it will also power up the relay and make TT , You can also use the normally close side to kill the heat if you want , to make it priority , ... $20 and your done ... I keep a few RIB's on the truck , great relay in a fix ...
    I have enough experience to know , that I dont know it all
This discussion has been closed.