Heatmiser one zone offline

[s3dave]

Please any advice and help would be much appreciated.

I have UFH on all 3 floors of the property controlled through a Heatmiser Neostat system. It is 5 years old and has never given me an issue. On each floor I have a UH2 wiring centre, with Neostat Programmable Thermostats and I have a WiFi gateway Neo Hub; so I can monitor the system online from the app. Up to now I would highly recommend the heatmiser system, over the past 5 years it has been faultless and the app very easy to use and control each zone and change profiles. However I now have an issue.

Not sure how relevant, but sometime overnight the RCB tripped. Reset it and all circuits back online ok. I then noticed my thermostat display in the kitchen was blank. On the app it showed kitchen “Off Line”. The rest of the system was behaving perfectly.

I have performed the following faultfinding:

1. Swapped the Thermostat face between the kitchen and another zone. Kitchen thermostat display worked in the other zone and the thermostat fitted into kitchen display was blank.
2. I took off the thermostat (and backplate) and input 240V measured
3. As the UH2 wiring centre on the kitchen floor has only 3 zones used, I swapped the Kitchen wiring across to the empty zone – no difference. On the kitchen circuit no 240V was measured on the trigger (S/L) wire.

I also checked the wiring centre that connects the UH2’s from each floor and nothing obvious seen (this has no electronics and simply joins the 3 x UH2 wirings centers and then links to boiler/pump etc; this can be discounted anyway as the other 2 zones on the kitchen floor work satis.

I am now at a loss as to why the kitchen zone is not working. The only 2 things I can think of is the kitchen thermostat backplate has developed a fault, or I have a broken wire somewhere between the kitchen thermostat and the UH2. Any suggestions would be most appreciated before I go to the effort of swapping the thermostat (including backplate) from the kitchen with another zone to see if the fault moves.

[WyrleyD]

Can't help with your actual problem but when I had a problem with my Heatmiser wiring centre I found the Heatmiser Helpline very good and very patient whilst we stepped through everything. It does sound like either a backplate or wiring issue though. All my thermostats are battery and not mains, I did have an issue in the summer whilst we were away, two of the thermostats batteries ran out and because they couldn't communicate the heating switched on and was running full blast during that hot spell and we returned to a house that was nearly 50c!!

[GranpaB]

Interesting this as we had two of these doing our up and down zones.

It turns out they are crap as within a couple of years or so they failed again, so had two nests fitted and been fine ever since.

[s3dave]

Thanks for comment. Backplate changed and everything working ok.

[Jambo85]

Yeah the back panels do seem to fail periodically - either total failure or the relay goes and it appears to work fine but the room doesn't get warm! I've got more than 10 though and I've had them for about 8 years IIRC, happy enough with a couple of failures all things considered.

[Pistom]

Another Heatmiser Neo failure here when the power went off. When the power came back, one of the thermostats is just blank.

[Jambo85]

Almost all my V1 stats have now failed at about 8-10 yrs old, haven't had a V2 failure yet, fingers crossed. I did contact support, they gave me a discount code for buying a replacement, worth a shot.

I tried replacing the two most likely suspects, the relay and the power management chip, but neither fixed the issue. The power management chip was a pig to desolder as well as it is connected to a massive heatsinking plane on the PCB.

If buying a replacement on eBay, I'd make sure to get a V2.