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  1. #1
    Join Date
    Feb 2012
    Location
    New York City
    Posts
    106

    VRV or VRF + hydronic heat

    Apologies if this has been posted before, wasn't having much luck with my searching. I'm designing a job where we may be using a combination of a VRF with perimeter or radiant floor hydronic heat. Most VRF controls only sequence a non-VRF heat source as backup. I'd want the perimeter or radiant to sequence first with heatpump as backup/warmup.

    My understanding is that these are the only ways of combining hydronic heat with VRF.

    1. Use a VRF to BMS gateway and poll each VRF zone for setpoint, temp, and mode then use the BMS to enable and control the hydronic system. The user interface is the VRF controller interface or a home automation system talking to the BMS.
    2. Use a VRF to BMS gateway to provide setpoints and schedules to the VRF system and push a lower than requested heating setpoint to the VRF system while using the higher setpoint for the hydronic system. The user interface is the BMS controller interface or a home automation system talking to the BMS.
    3. Use standalone controls for both. Size perimeter heating for a smallish part of the load and use an aggressive reset schedule that will prevent simultaneous heating and cooling. This sizing strategy is not really forbidden for strategies 1 and 2, but not necessary either.
    4. Some VRF system that will provide the require sequencing internally that I haven't found yet.

    Any other ideas?

  2. #2
    Join Date
    Jan 2003
    Location
    USA
    Posts
    1,648
    Option 4 would be first.

    Option 3 This is a nightmare. They could / will be fighting each other at some point. Can you get VRV / VRFs with standalone thermostats? If so this may be a great option.

    Option 1 & 2 are equally bad. The gateways on these systems are horrible from what I have seen.

    Option 5 Forget about VRF / VRV. Use fan coils, VAVs, swamp coolers, burn barrels, anything else.

    Option 6 Live with the current sequence.
    Propagating the formula. http://www.noagendashow.com/

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