Issue with UH8-RF v2

[athlonoc]

Hi,

 

I’m looking for some help / advice to see if there is anything further, I can do.

My property is a newbuild of 2 years and was fitted with the following

 

UH8-RF V2 wiring centre

5 NeoAir v3 stats

 

Connected to Mitsubishi ASHP heating system.

 

All has been fine until the last few days where I noticed I could hear the system was pumping water around and at times, I could see the ASHP was running.

At the same time I noticed the Wiring Centre UH8 was lit up on a specific zone.

When I checked the stats I noticed two of them had battery warning icons up.

 

So, I simply replaced the batteries expecting this to solve the problem. However, things started to go downhill from here.

It became obvious that the pairing was no longer right as I was not able to call for heat with all the stats ( testing purposes ). All stats would have a flame but not all the lights on the UH8 would lights up.

 

So, I reset all five zones after powering down the UH8. I was able to pair successfully 4 of the 5 zones but one wouldn’t pair. So, I used a spare stat to see if that could pair, which eventually it did after several attempts, but then I noticed one or two of the other zones would no longer call for heat.

I then used one of the three spare zones on the UH8 in case zone 5 had developed a fault.

I’m now experiencing intermittent control, when calling for heat.

 

I can manually push any of the zone buttons on the UH8 and they light up.

I have now on three occasions, powered down the UH8, reset the master RF button so it flashes quickly. Then reset all 8 zones so they all flash quickly, then one by one repaired with my 5 Neoair stats. In the past when setting up it worked fine and always paired within 5 to 10 seconds, and all would call for heat.

 

I have replaced all batteries in the stats.

I have reset all the stats.

I have reset the zones on the UH8

 

But I am left with some of the zones not lighting up when the stat is calling for heat.

 

My questions are:

 

Is there anything further I could try?

Is it possible that the RF communication device on the UH8 is now faulty, or the UH8 wiring centre in total.

 

 

No other RF or Wifi devices have recently been installed that might interfere. Certainly not for over a year and everything was working fine until the battery symbol on a couple of the stats were showing and the flow pump in the loft could be heard running.

 

I’d be very grateful for some expert advice.

[MikeSharp01]

30 minutes ago, athlonoc said:

I’d be very grateful for some expert advice.

Are you close to a neighbouring property that might be causing radio interference?

 

I notice that the data sheets on the U8 show a set of engineers DIP switches that can be used to test the zones maybe this could be a way of eliminating some issues although it looks and feels like an RF comms issue doesn't it. Don't attempt an internal playing with power on unless you know what you are doing though. The manual I found here: https://www.theunderfloorheatingstore.com/cdn/shop/files/UH8-RF_V2_Datasheet.pdf?v=16128903087641331176 

[athlonoc]

40 minutes ago, MikeSharp01 said:

Are you close to a neighbouring property that might be causing radio interference?

 

I notice that the data sheets on the U8 show a set of engineers DIP switches that can be used to test the zones maybe this could be a way of eliminating some issues although it looks and feels like an RF comms issue doesn't it. Don't attempt an internal playing with power on unless you know what you are doing though. The manual I found here: https://www.theunderfloorheatingstore.com/cdn/shop/files/UH8-RF_V2_Datasheet.pdf?v=16128903087641331176 

Thanks Mike,

I'm going to assume that no interference from neighbours as I live in a well spaced out area with 8 other houses and all have the same setup. No one else is having this issue and mine has been fine up to this recent point where I had a batter icon on two stats and then noticed things with the system were running when not called for. I think might order a new UH8 centre and then see if the problem still exists. As with so much it will be a process of elimination. 

[JohnMo]

I would leave it alone for a couple of hours and see if it fixes itself.

 

Are you running weather compensation?

 

But some alarm bells

You have ASHP which is great, but your house is zoned and this will mean inefficient running

 

If you need thermostats flow temp is too high.

 

If you have zone it may also mean you have a buffer again driving inefficiency.

[Nickfromwales]

On 05/07/2025 at 12:40, athlonoc said:

Thanks Mike,

I'm going to assume that no interference from neighbours as I live in a well spaced out area with 8 other houses and all have the same setup. No one else is having this issue and mine has been fine up to this recent point where I had a batter icon on two stats and then noticed things with the system were running when not called for. I think might order a new UH8 centre and then see if the problem still exists. As with so much it will be a process of elimination. 

Is the UH8 mounted quite low? I would first try extending the wires and mounting it as high up as is possible. 

[SimonD]

On 05/07/2025 at 11:04, athlonoc said:

Hi,

 

I’m looking for some help / advice to see if there is anything further, I can do.

My property is a newbuild of 2 years and was fitted with the following

 

UH8-RF V2 wiring centre

5 NeoAir v3 stats

 

Connected to Mitsubishi ASHP heating system.

 

All has been fine until the last few days where I noticed I could hear the system was pumping water around and at times, I could see the ASHP was running.

At the same time I noticed the Wiring Centre UH8 was lit up on a specific zone.

When I checked the stats I noticed two of them had battery warning icons up.

 

So, I simply replaced the batteries expecting this to solve the problem. However, things started to go downhill from here.

It became obvious that the pairing was no longer right as I was not able to call for heat with all the stats ( testing purposes ). All stats would have a flame but not all the lights on the UH8 would lights up.

 

So, I reset all five zones after powering down the UH8. I was able to pair successfully 4 of the 5 zones but one wouldn’t pair. So, I used a spare stat to see if that could pair, which eventually it did after several attempts, but then I noticed one or two of the other zones would no longer call for heat.

I then used one of the three spare zones on the UH8 in case zone 5 had developed a fault.

I’m now experiencing intermittent control, when calling for heat.

 

I can manually push any of the zone buttons on the UH8 and they light up.

I have now on three occasions, powered down the UH8, reset the master RF button so it flashes quickly. Then reset all 8 zones so they all flash quickly, then one by one repaired with my 5 Neoair stats. In the past when setting up it worked fine and always paired within 5 to 10 seconds, and all would call for heat.

 

I have replaced all batteries in the stats.

I have reset all the stats.

I have reset the zones on the UH8

 

But I am left with some of the zones not lighting up when the stat is calling for heat.

 

My questions are:

 

Is there anything further I could try?

Is it possible that the RF communication device on the UH8 is now faulty, or the UH8 wiring centre in total.

 

 

No other RF or Wifi devices have recently been installed that might interfere. Certainly not for over a year and everything was working fine until the battery symbol on a couple of the stats were showing and the flow pump in the loft could be heard running.

 

I’d be very grateful for some expert advice.

 

Yup, been there seen it and done it. I've lost a lot of hair in the process. I had a customer's house where the neostats would repeatedly pair fine up until the 10th stat and the last ones would refuse to pair, or would pair and then not work correctly. This was after replacing the wireless hub. I doubt it's the UH8, but more a tendency of the neoair stats. Why they can be problematic, I don't know.

 

When you reset everything, did you proceed to repair from the closest stat to the furthest stat and do this methodically?

 

It's worth calling Heatmiser tech support as they will help you through the process while to try to repair and get everything up and running again.

[Temp]

Google tells me they operate on 868MHz which is also used by some burglar alarms. I don't think having a burglar alarm on the same frequency should cause a problem but I suppose it might be something to check.

[athlonoc]

Hi again,

Update with a problem.

 

So I didn't bother with UH8 after all. I powered down everything connected to the central heating system. Ecodan unit, UH8, stats, Heatmiser Neohub.

Then after a few hours I powered up and repaired everything and it seemed to go ok. All stats paired fine with Switch and the UH8. The Neohub connected to all stats and could control the rise and fall in heat. The HW came on and off in accordance with its schedule.

 

Now after about 6 days of seemingly all being good, I noticed the radiators on the first floor were warm. The noise associated with pumping the flow around the system was running. However, the stats were not calling for heat and the control panel didn't have the compressor symbol lit and after checking the ASHP unit, it wasn't running.

So it appears the system was pushing warm water to the radiators ( not the UFH downstairs ), despite it not being heated by the ASHP.

 

So how could this happen?

Is the HW tank sending warm water to the upstairs rads?

I noticed the the Heatmiser switch, was lit up ( boiler and CH1 ) - but not HW light.

 

I've reached the end of my ability to solve and wondered what my be at fault / causing the system to pump warm water from somewhere to the rads without ASHP running and no stats requesting heat?

 

Thanks

Lee

Edited Monday at 16:21 by athlonoc

[JohnMo]

48 minutes ago, athlonoc said:

Ecodan

So you have a heat pump, why all the thermostats?

 

Do you have a buffer or volumiser in the system, where is this actually connected. Is it downstream of the 3 port diverter on the central heating side?

 

Have a feel of the 3 port valve, when doing DHW, the central heating side of the valve piping should be cold, if it got I would suspect the internals of the valve are leaking.

[athlonoc]

1 hour ago, JohnMo said:

So you have a heat pump, why all the thermostats?

 

Do you have a buffer or volumiser in the system, where is this actually connected. Is it downstream of the 3 port diverter on the central heating side?

 

Have a feel of the 3 port valve, when doing DHW, the central heating side of the valve piping should be cold, if it got I would suspect the internals of the valve are leaking.

All these stats were installed in this new build and I had no input. 5 stats for 5 zones for the UFH and 1 stat for the rads upstairs.

Yes there is a 51l buffer in the loft along with the Ecodan controller box and the HW cylinder. I'm not sure but would suggest it's downstream of the 3 port diverter.

I'll go and check and thank you for this.

 

If the diverter port is leaking, would I usually see the switch for the upstairs Central Heating light up? Is it not just the stat upstairs that controls all the rads that would switch that on, even though the stat was calling for heat?

Edited Monday at 18:29 by athlonoc

[JohnMo]

13 minutes ago, athlonoc said:

If the diverter port is leaking, would I usually see the switch for the upstairs Central Heating light up?

No, if it's leaking, past a valve seat you wouldn't get any indication except heating system getting warm.

[athlonoc]

13 minutes ago, JohnMo said:

No, if it's leaking, past a valve seat you wouldn't get any indication except heating system getting warm.

Oh, ok.

So if the switch is on as in the 2nd photo, but the ASHP hasn't fired up as in the 3rd photo, but the pump is pumping warm water around, how can that be? 

Time for a heating engineer to problem solve. I've spend a fortune on this 2 year old system in my new build as it's been nothing but problematic. I've had 2 separate heating engineers round for example to solve the system pressure as it needed topping up every 3 or 4 weeks, which went on for a year or more. No one spotted the leak at one of the pumps and a leak outside by the filter drain. The company that installed went bust. My faith comes from looking at these problems myself and using these amazing forums.

 

So if I can I'd like to understand and solve myself.

Is it therefore possible that the switch is faulty and something other than the stat is turning it on to warm the radiators? If so why doesn't the ASHP come on?

Edited Monday at 18:45 by athlonoc

[athlonoc]

Update:

The response from Heatmiser is one of RF signal issues.

They has suggested that if the batteries went low in one or more neostats, then it might be it activated the failsafe on the stat. They state that every hour it will run for 12 mins to push warm water around the system if it doesn't receive 2 RF signals after two attempts.

It all makes sense, but of course what they couldn't confirm is where the warm water is coming from.

Would it be possible that warmth ( the radiators were not very warm or hot, just warm ) came from heat in the pipes and or the header tank?

Any thoughts, just for an understanding.

 

So far 3 full days without the problem.

 

Heatmiser also suggested that by turning off failsafe which is what I have done to alleviate the issue,  might want to strengthen the RF signal with a boost box or boost plug.