Hello Heating Experts.
I'm needing a bit of advice. Moved into this home 4 years ago. Large 4 bed house with a Vaillant Ecotec 635 boiler coupled to a 300ltr sealed system DHW tank and with an existing Solar Thermal system on roof. During this past 4 years we have had several problems. The Vaillant control for heating greatly disappointed us as it was very inflexible and heating a large space constantly at 19 C with a fall back to 17C cost an absoloute fortune in our first winter. We were consuming up to £30 of gas a day! We came from a home where we installed Drayton Wiser smart control so replicated it here fitting all rooms with smart rad stats and immediately saw significant saving and improved comfort. The Wiser controller made the Vaillant single thermostat totally redundant, however we had Vaillant out to service the boiler and they said it wasn't right to have Drayton Wiser controls, threatened to shut off our boiler over an issue about a flue clip so we fired them! They previously maintained this system on contract for 6 years!
Anyhow, all continued OK and bills remained fairly OK, but we had to replace both DHW and CH motorised valves due inoperative or noisy problems.
In February this year we had solar PV installed and then a blistering summer and I was checking on gas use when I noticed we were still consuming gas, just a small amount, but with solar thermal it shouldn't have been using any as the Wiser was set to not follow hot water schedules and heating set down to well below ambient. Subsequently, I finally found a solar thermal engineer to examine and found the system hadn't been working due to a failed sensor. So boiler has been heating hot water all this time!
The solar is now back in operation but here lies the problem:
The Vaillant solar wiring centre is controlling the hot water motorised valve and calling for heat at all times of day or night at its whim. It seems to trigger boiler whenever the stat in tank calls for it. I would much prefer to get this under Wiser control.
Looking at the wiring and comparing to an S plan system, I note you would usually have Wiser Hub, via cylinder stat to power motorised valve, but the DHW cylinder on a solar thermal set up has two NTC stats on the tank, both wired into the Solar controller. The motorised valve for DHW has had the microswitch disconnected and the valve is only fed from the solar control centre. If I press the DHW button on the Wiser Hub, it doesn't switch the valve on, it only triggers when the solar instructs it from thermostat.
How can this be reconfigured to put Wiser in full control of the hot water system? I think it must need the valve microswitch to be put in circuit to provide a switch live control via the upper cylinder NTC stat but not sure how this affects the Solar's need to see what is demanding?
Any suggestions?
Can anyone suggest a wiring plan?
I'm needing a bit of advice. Moved into this home 4 years ago. Large 4 bed house with a Vaillant Ecotec 635 boiler coupled to a 300ltr sealed system DHW tank and with an existing Solar Thermal system on roof. During this past 4 years we have had several problems. The Vaillant control for heating greatly disappointed us as it was very inflexible and heating a large space constantly at 19 C with a fall back to 17C cost an absoloute fortune in our first winter. We were consuming up to £30 of gas a day! We came from a home where we installed Drayton Wiser smart control so replicated it here fitting all rooms with smart rad stats and immediately saw significant saving and improved comfort. The Wiser controller made the Vaillant single thermostat totally redundant, however we had Vaillant out to service the boiler and they said it wasn't right to have Drayton Wiser controls, threatened to shut off our boiler over an issue about a flue clip so we fired them! They previously maintained this system on contract for 6 years!
Anyhow, all continued OK and bills remained fairly OK, but we had to replace both DHW and CH motorised valves due inoperative or noisy problems.
In February this year we had solar PV installed and then a blistering summer and I was checking on gas use when I noticed we were still consuming gas, just a small amount, but with solar thermal it shouldn't have been using any as the Wiser was set to not follow hot water schedules and heating set down to well below ambient. Subsequently, I finally found a solar thermal engineer to examine and found the system hadn't been working due to a failed sensor. So boiler has been heating hot water all this time!
The solar is now back in operation but here lies the problem:
The Vaillant solar wiring centre is controlling the hot water motorised valve and calling for heat at all times of day or night at its whim. It seems to trigger boiler whenever the stat in tank calls for it. I would much prefer to get this under Wiser control.
Looking at the wiring and comparing to an S plan system, I note you would usually have Wiser Hub, via cylinder stat to power motorised valve, but the DHW cylinder on a solar thermal set up has two NTC stats on the tank, both wired into the Solar controller. The motorised valve for DHW has had the microswitch disconnected and the valve is only fed from the solar control centre. If I press the DHW button on the Wiser Hub, it doesn't switch the valve on, it only triggers when the solar instructs it from thermostat.
How can this be reconfigured to put Wiser in full control of the hot water system? I think it must need the valve microswitch to be put in circuit to provide a switch live control via the upper cylinder NTC stat but not sure how this affects the Solar's need to see what is demanding?
Any suggestions?
Can anyone suggest a wiring plan?
