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Community and Q&A

ERV Stuck on Boost

mpsterner | Posted in Mechanicals on

I have a Renewaire ERV EV Premium L. It is ducted with boost switches in the bathrooms to boost the CFM exhaust upon hitting the timer button. 

The switches are all stuck on “green” or on and the system running on boost around the clock. 

I’ve been waiting for my HVAC contractor to get back here to fix this for 6 months now and I cannot get them back here, so I am wondering if anyone can give advice on how to troubleshoot this. 

Thank you!

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  1. Expert Member
    Akos | | #1

    What exactly is wired? How many PBT and PBL? Are there any toggle switches also wired into the boost circuit?

    Can you also post a picture of the accessory terminal on the unit. Did you try disconnecting the wires on the accessory terminal and does the unit go to low flow?

    1. mpsterner | | #2

      Hi Akos,
      I am not sure what PBT/PBL are, I assume push button timers??? There are 3 bathrooms all with the same switches (as shown in pic). No other switches that I know of.

      Pic of accessory terminal attached.

      If I disconnect the wires, the unit goes down to low flow, yes.

      If I reconnect only one switch, it does the same issue as with 3. The green light turns on on the switch and stays on low, but then once I click the button once, it turns on boost and stays on boost forever.


  2. Expert Member
    Akos | | #3

    One of the push buttons needs to be a timer. The rest of the push buttons connect to this timer. Take a look at the diagram here:

    I would turn off the power and pop off the cover plate and see what you actually have. The PBT and PBL look the same from the front.

    1. mpsterner | | #4

      Thank you. After review, they are all PBL, there is no PBT switch.

      I've ordered one and will replace one of them with a PBT.

      That said, according to the diagram, I need to wire the PBLs through the PBT, then go to the ERV with the 2 PBT wires. I think I can still achieve this (even though behind sheetrock) since they have 4 wire line... All PBLs should be connected and run to the PB terminals on the PBT, then run the PBT to the ERV unit...

      Does that sound right?

      1. Expert Member
        Akos | | #5

        I think the simplest would be to leave the existing as is and mount the PBT at the unit. Connect the existing boost wiring to the PB terminals on the timer switch and run a new wire from the timer's RC terminal to the ERV.

        Honestly I can't blame the HVAC installers for messing this up. All other manufacturers simply wire all the pushbuttons in parallel and connect to the ERV exactly how the techs set it up. Renewair's documentation is also not clear enough, there should be a big bold caution not to use a PBL by itself.

        1. mpsterner | | #6

          Thanks so much for your help! I'll proceed like that. Appreciate it as always.

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