We are in the middle of planning to replace our gas boiler with an Air to water heat pump. We plan to go for Daikin Monobloc heat pump with a buffer tank. We have underfloor heating, controlled using Heatmiser controller on the ground floor. We also have radiators on first floor and domestic hot water tank, both controlled through the Evohome. The radiators have HR92s fitted, with Zoning. We have BDR91s connected to the S-Plan to control respective valves. We also have CS92A to control the DWH with temperature sensor installed.
The system has been in use for the past few years and we are quite happy with the performance.
Our preference would be to continue to use Evohome to manage the heating configured with the Heat pump - the installer has agreed to configure it to work with Daikin. We are going with Daikin Domestic Hot Water tank as well, so Evohome should ideally control the DWH as well.
Having read the user manual and the forums, i have a few questions. Hope you can get these clarified. As the property is efficient with a heat loss of around 5Kw, the design is for an 8KW monobloc pump, with a buffer tank. We are retaining the existing radiators on the first floor.
1. Usages of TRVs for managing radiators.
We understand it is better to run the radiators at lower temperatures and for longer, and without zoning. We normally set the temperature on TRVs to 20 deg, with it coming on for couple of hours every day. May not be ideal for heat pump. Its a 4 bed detached, with rooms all close-by. We could retain the zones to one or two, based on the room layout. Considering one valve is controlling the whole heating circuit to all radiators, does Zoning make any difference, in the context of the Evohome setup. And should we leave the radiators on always to 20 deg with a fall back temp of 18? Any specific settings we should make on Evohome to optimise this. Evohome uses the latest firmware.
This reflects our current setup, though we have TRVs fitted in the radiator loop.
- Existing setup
- evohome-SPlan.jpg (87.23 KiB) Viewed 213 times
We plan to replace the BDR9A with BDR91Ts as we want to use the extended parameters while configuring them with heat pumps. We also plan to use Evohome to control the DWH cycles. We would leave the heatmiser to control water underfloor heating on the ground floor. The picture here looks close to the expected configuration.
- Heat pump setup
- Evohome-Heatpump.jpg (53.97 KiB) Viewed 213 times
What would be the ideal configuration for Evohome, using the BDR91Ts, if we want to manage DWH and the radiators in the most efficient way. Say leaving the DWH in re-heat mode to keep the temperature around 45-50 deg and the radiators around 18-20 degs.
Basically do we have one BDR91T control the heat pump (set as heat pump relay) and a second one to control the secondary pump ( set as appliance relay) - depicted in the setup above? And how do we setup the DWH control, connecting the CS92A and thermostat, in this configuration.
Or do we set one BDR91T to control the heat pump with the other two BDR91s to control the S-Plan Valves, alongside the CS92A with temperature probe as it is currently being setup? This possibly is much closer to our current setup.
Didnt find any literature on this setup and so the post.
Hope you can help.
Thanks,
Salil