Using Evohome Hot Water kit and Vaillant Unistor

[bruce_miranda]

I have a Vaillant unistor and as far as I can tell it has a dry pocket for a temperature sensor, which is currently used up by the 230 volts temperature sensor thermostat that goes into my wiring box. The thermostat knob is on the unistor itself.

There is another thermostat on the unistor which i guess is for the electric immersion heater.

Has anyone moved from this configuration to using the evohome hot water kit.

[top brake]

please consult with a professional installer that is certified to work on G3 unvented cylinders

[bruce_miranda]

Believe or not my Gas Safe plumber who installed the cylinder knows nothing about the evohome.

[top brake]

Believe or not my Gas Safe plumber who installed the cylinder knows nothing about the evohome.

No problem I do believe it. Youlearn.honeywelluk.com is the answer

[bruce_miranda]

I've got an answer from Vaillant in regards to my uniStor. Because mine is a 1st generation unistor, it doesn't have a free dry pocket for a NTC sensor. There are two pockets and they have the sensors for the immersion heater in the first one, and the second one has two sensors for the primary heating and it's thermal cut out.

Vaillant have told me to remove the sensors for the primary heating and thermal cut out and use that pocket for the Honeywell HW kit. This is exactly what they suggest you do when you are installing their own VR10 sensor. I actually don't like the sound of this. So am going to try and keep the current sensors in place and push the honeywell sensor into the hole. I wan't to use the thermostat of the cylinder to switch the motorised valve off as a fail safe. Vaillant themselves think my idea is a good one and have asked me to report back if I am successful in doing this or not. They said I can use either dry pocket for the honeywell sensor as long as I can confirm that all sensors are making good contact in the tube and picking up the temperatures as needed.

[bruce_miranda]

This turned out to be easier than ever.

I didnt need to remove anything. I just inserted the Hot water sensor into the pocket that had the immersion heater sensor (green wire).
Now, because I've not removed anything i can still use the cylinder's own thermostat (two black wires) as a fail safe to shut the zone valve.