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?