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Tekmar 304V and L722U aquastat

SuperTech Member Posts: 1,639
I was given a Tekmar 304V zone valve control recently and I'm trying to figure out the best way to wire it for my indirect tank.
I currently have the it wired up like a heating zone and it works but I have an L7224U aquastat and the matching outdoor reset controls. I'd like to see the zone panel have priority control on the indirect and the duu function on the aquastat turned on to recognise a call for DHW. I've read the manuals for the aquastat, indirect and zone control and unless I missed something I don't see how to accomplish this.

Eventually I would like to install another circulator for the indirect and have that controlled by the same equipment


  • STEVEusaPA
    STEVEusaPA Member Posts: 4,963
    edited November 2018
    The problem is your mixing applications. You could try to wire the indirect aquastat to zone one, set the dip switch for zone one/priority to 'On'. But you need to send a signal from the control to the boiler to tell it it's domestic hot water, otherwise your reset control with both prevent the boiler from targeting a higher temperature, and won't allow DHW production during WWSD.
    So you'd have to use the diagram that shows wiring the indirect aquastat to zone 1 AND wiring a separate circulator to DHW at the bottom (304V-3 in the manual).
  • SuperTech
    SuperTech Member Posts: 1,639
    edited November 2018
    But even if I have a separate circ for DHW I would still need to let the L7224U know that there is a call for DHW, by connecting the panel to the aquastat ZR terminal somehow. Perhaps the two components don't work together?
    HVACNUT Member Posts: 3,917
    It looks like you can put the indirect on zone 1 priority in the board but you'll need the Honeywell DHW module and temp sensor to wire into the Enviracom so the aquastat can override ODR.
  • SuperTech
    SuperTech Member Posts: 1,639
    I just figured it out a few minutes ago. I have the DHW module for the outdoor reset. I switched to Tekmar to priority and just ran a wire from the priority pump terminal from the 304V to ZR on the L7224U. Set the duu function to on. My boiler temperature was 153 degrees, turned up a thermostat and the pump ran without the burner. Turned up the indirect and it over ran the space heating call and opened the DHW zone valve and switched on the burner simultaneously. Boiler heated up to 180 and I turned the tank back down to 120 and space heating resumed. I should have figured it out sooner. An occasional run up to 180 degrees should help keep my chimney warmer and to prevent condensate formation.
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