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Thermostatic radiator valve w/ monoflo

I am assuming this is a no no. I have always hear you need to pipe through where a radiator or baseboard once was if it used monoflows. I was working on an apartment building that was banging systematically every few seconds during a cycle. There was air in a few of the units which was weird because if the whole building was bled and running. A few of the units have trv's installed. I drained down the expansion tank and bled a few of the units. I was wondering if anyone else has experienced banging on a hot water system? I know this could be air or steam but we did not have a no heat situation. Any thoughts? I was actually thinking about bumping up the pressure on the prv. It is a two story apartment building with copper fin tube. Approximately 20' lift from the boiler to the highest baseboard. It is running off of two large b and pumps.


  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    If you run water through a TRV backwards, it hammers when the needle and seat get close to each other.... the use of TRV's on BBR with Monflow fittings is acceptable, however when bypassing the baseboard, the pressure drop increases significantly, especially with B7G MonFlo brand tees. Not as bad with others (taco, thrift, roll your own with venturi fittings).

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.