P
Pilgrim Tim
Hi, I'm after some advice on converting my current CH system to Wiser smart system. In particular, looking for advice on whether I can use the Wiser Hub without using Wiser's specialist Underfloor heating controller.
Current set-up
• System boiler (Vaillant ecoFIT pure 630) with unvented hot water tank. Gas fired.
• 3 channel controller (Hortsmann ChannelPlus H37XL) controlling Hot Water, Upstairs radiators (1st zone) and downstairs UFH (2nd zone)
• Upstairs heating – 7 radiators (5 of which are controlled by non-smart TRVs). One wired Thermostat as master controller.
• Downstairs UFH – Wet system. 5 loops controlled by 4 wired Thermostats (Drayton). This covers 4 separate rooms (one room has 2 loops).
Proposed set up
• Purchase Wiser Kit 3 plus 5 smart TRVs
• Channel 1 on the Wiser Hub to control upstairs central heating. Replace all existing TRVs with smart TRVs. Smart thermostat would control heat to the 2 uncapped bathroom radiators. This is straightforward and I don’t need advice on this.
• Channel 2 to control hot water. Again, seemingly straightforward.
• Channel 3 to control downstairs UFH. Single Wiser Thermostat would act as the master switch to turn the UFH on/off via the zone valve. Existing wired thermostats would be retained to control the heat in each individual room (provided, of course, these temperatures are lower than the set temperature on the master Wiser thermostat). I am aware that this means that I don’t have smart control over individual temperatures for the UFH zones but I would at least be able to control remotely whether the UFH is on or off.
Comments
• I am aware that the best/proper way of incorporating UFH into the Wiser system is to use the Wiser UFH controller. I am trying to avoid this, however, as it would require me to buy the controller and 4 additional Wiser room thermostats (at a total additional cost of over £550). This would make the project uneconomical for me so it either my solution above or nothing.
• Having done a little bit of research on this, the only potential downside I have found to my proposed set-up is that the Wiser Hub is not suitable to control UFH because the load compensating algorithm is designed for radiators. In other words, it will start to switch the demand for heat on and off as it gets close to the required temperature, whereas underfloor works best with a simple on/off algorithm. To solve this problem, I would propose to set the Wiser room thermostat at a temperature that is well above the temperature that is set on the individual wired room thermostats so that this on/off scenario does not occur.
• This way, the Wiser Hub and Wiser room thermostat is simply acting as a master on/off switch for the UFH. So there would only be a call for heat on the boiler for the UFH if (1) Channel 3 on the Hub is set to “on”; (2) the ambient temp is below the master temp set by the Wiser room thermostat; and (3) the ambient temp in at least one of the rooms controlled by the existing wired thermostats is below the set temp.
• I am aware that there are compromises with this approach, principally no smart control over individual temperatures for the downstairs UFH. I’m prepared to live with that compromise, however. Provided that it works.
Can anyone confirm that this set-up should work in theory? Is there any reason why this set-up would not work?
Current set-up
• System boiler (Vaillant ecoFIT pure 630) with unvented hot water tank. Gas fired.
• 3 channel controller (Hortsmann ChannelPlus H37XL) controlling Hot Water, Upstairs radiators (1st zone) and downstairs UFH (2nd zone)
• Upstairs heating – 7 radiators (5 of which are controlled by non-smart TRVs). One wired Thermostat as master controller.
• Downstairs UFH – Wet system. 5 loops controlled by 4 wired Thermostats (Drayton). This covers 4 separate rooms (one room has 2 loops).
Proposed set up
• Purchase Wiser Kit 3 plus 5 smart TRVs
• Channel 1 on the Wiser Hub to control upstairs central heating. Replace all existing TRVs with smart TRVs. Smart thermostat would control heat to the 2 uncapped bathroom radiators. This is straightforward and I don’t need advice on this.
• Channel 2 to control hot water. Again, seemingly straightforward.
• Channel 3 to control downstairs UFH. Single Wiser Thermostat would act as the master switch to turn the UFH on/off via the zone valve. Existing wired thermostats would be retained to control the heat in each individual room (provided, of course, these temperatures are lower than the set temperature on the master Wiser thermostat). I am aware that this means that I don’t have smart control over individual temperatures for the UFH zones but I would at least be able to control remotely whether the UFH is on or off.
Comments
• I am aware that the best/proper way of incorporating UFH into the Wiser system is to use the Wiser UFH controller. I am trying to avoid this, however, as it would require me to buy the controller and 4 additional Wiser room thermostats (at a total additional cost of over £550). This would make the project uneconomical for me so it either my solution above or nothing.
• Having done a little bit of research on this, the only potential downside I have found to my proposed set-up is that the Wiser Hub is not suitable to control UFH because the load compensating algorithm is designed for radiators. In other words, it will start to switch the demand for heat on and off as it gets close to the required temperature, whereas underfloor works best with a simple on/off algorithm. To solve this problem, I would propose to set the Wiser room thermostat at a temperature that is well above the temperature that is set on the individual wired room thermostats so that this on/off scenario does not occur.
• This way, the Wiser Hub and Wiser room thermostat is simply acting as a master on/off switch for the UFH. So there would only be a call for heat on the boiler for the UFH if (1) Channel 3 on the Hub is set to “on”; (2) the ambient temp is below the master temp set by the Wiser room thermostat; and (3) the ambient temp in at least one of the rooms controlled by the existing wired thermostats is below the set temp.
• I am aware that there are compromises with this approach, principally no smart control over individual temperatures for the downstairs UFH. I’m prepared to live with that compromise, however. Provided that it works.
Can anyone confirm that this set-up should work in theory? Is there any reason why this set-up would not work?
