Downstairs underfloor heating now working

confusedt

Had working heating system for a year and today the downstairs underfloor heating stopped working. Got pretty cold so not good timing. Have wired thermostat and wireless receiver. All showing as connected on the app and heating but no heat is coming. Radiators upstairs are working as normal as is the hot water. I did update phone today so not sure if that's got anything to do with it? Have tried resetting it all and switching off mains to boiler. Nothing working. Any suggestions? Everything lit up as normal

davidlyall

@confusedt

Firstly, your phone update won't have affected that so no need to worry about that.

I assume your downstairs UFH is controlled by the wireless receiver and upstairs by the wired thermostat and that both of these control motorised valves to direct the flow appropriately

I would be be checking the following

1. is the wireless receiver applying power to the CH terminal when heat is called?
   If not, it could be a stuck relay in the wireless receiver. Turn off the power and try tapping the casing gently to free the relay.
   If there is power on the terminal, turn off the power and ensure the wire on the terminal is securely connected then go to the next step
2. Check that the UFH motorised valve has power on the permanent live (brown) AND is getting power on the heat demand wire (can't remember the colour - grey I think) If no power there, you have a wiring issue
   If there is power and you can hear the valve operating, it should then apply power on the orange wire which tells the pump and boiler to fire. If that doesn't happen, it's likely a fault with the motorised valve unit
   If the orange wire is energised, check the connections in your wiring centre

If you're not confident in any of the above, get a heating engineer in to check

confusedt

Thanks David, that's very helpful. So I have 4 wired thermostats downstairs for underfloor heating and a wired thermostat upstairs for the rads. When upstairs calls for heat it all kicks in and works as it should. Likewise with the hot water. There is no sound coming from valve when the ufh calls for heat although the receiver lights up and app is telling me its heating. Looks like I need to go to screwfix to get a voltage pen!

policywonk

@confusedt UFH manifolds are usually hosted and defined by a zone valve. Was one implemented for the CH heat going to the UFH manifold? If so, the zone valve head may have failed. Is one there? Do you know how to check that? When they fail they prevent the boiler firing when there is a call for heat.

confusedt

Yeah there's one, was a drama when it was installed because the electrician didn't understand the need for 2 (1 for rads and 1 ufh). How do I test that its working. There is a 3 way switch that doesn't seem to change when the ufh ask for heat. Cust services are saying i need to take a photo of inside the receiver so maybe a stuck relay? Really hope the valve doesn't need changing as in awkward place.

confusedt

Thanks again for the advice

policywonk

Taking a photo will reveal nothing IMHO, unless you take shots of each switched state.
1 Have a look at this video:
https://youtu.be/2jZ33ZCmoyE?feature=shared
And try it out.
2. Turn off all other rooms. Then turn off the UFH areas. The boiler should shut down.
3. Then only turn on one room with UFH. You should see it hear the valve turn and within a min, the boiler starts. If it doesn't, this is the most likely part to fail.
4. If convinced, take a note of the valve model number. Purchase a new head. There are more youtube videos explaining how to swap the head. Takes 10 mins to mechanically replace it without touching the plumbing, another 30 mins to swap the wires in the wiring centre. If still stuck come back.

confusedt

Thanks policywonk, I did find this video previously and the zone valve was moving freely. Tado finally came back and said configuration wasnt correct as all on one zone control rather than two. They then did something and all downstairs started to work but upstairs i couldn't control, since then downstairs has stopped again. Do you still think this could be zone valve related or just tado not having a clue what's going on? They said in a message it may have been caused by my phone update which is worrying

policywonk

Do your have a multimeter, or a electrical testing screwdriver? Each zone valve has five wires: four of which operate at mains voltage, so be careful.
* The motor is driven by brown and blue.
* When the valve opens it relays the voltage from the grey wire to the orange wire. This means when it does not have a call for heat the orange wire shows no voltage. When the valve opens it shows 230v.
When you force it to call for heat, if the valve opens, that orange wire relays the call for heat to the boiler and the pump. If the orange wire is not at 230v it means that either the valve wasn't told to open or it was told but it didn't complete the opening process.
So if you shut down everything and just open one zone by kicking up demand in that zone, the valve should receive a request to open. You will feel the motor turn and you will hear it move. Then the orange wire will go live.
If this doesn't happen, write down the model, take a photo of it and get a replacement head, fit it and all should be well.

If it isn't, complain to support and tell them you don't have heat. It will escalate. Keep us informed.

policywonk

@confusedt Some questions, ones that may help us more than a little in working out whether all is as it should be:

• Whats the exact model of your boiler?
• What exact Tado components do you have now in your home and what role do they individually play?
• Are the underfloor heating thermostats wired thermostats from Tado?
• What did you find in your investigations following my previous post?

confusedt

Thanks Policywonk. I wasn't about yesterday but will check what you said. I have little confidence as since tado reconfigured it the light doesn't even come on when the downstairs calls for heat. I have a Greenstar Life Gr8300iw 30 S Ng one year old boiler, 4 tado wired thermostats downstairs via the receiver, and one tado wired thermostat wired to zone valve for upstairs radiator. I can't see it's a wiring issue as worked perfectly fine for nearly a year. If they hadn't reconfigured it I would probably have just changed the motor on that valve but as the light is not coming on now...I've been passed onto another team, this was yesterday afternoon and no response so far. I would get a heating engineer out but again I'm pretty sure it's something tado have done.

confusedt

All wired thermostats. Hot water, rads upstairs on one zone, and downstairs underfloor heating with 4 thermostats. Underfloor heating has come on a couple of times in last 5 days, once randomly, and once when tado reconfigured it, unfortunately this didn't last for long. Just glad we have working rads upstairs!

confusedt

Ok, so tado have reconfigured it, I think to back where I started, as all zones are now initiating the light on the receiver independently. However still no heat downstairs. I have noticed that the downstairs zone valve is only going across half way and not moving freely, this is the same with upstairs one but the upstairs one can be moved easily right across when powered. So it seems that the downstairs zone valve is not being powered. I have looked at the wiring centre and it hurts my head and they're all level connectors so not just about my voltage screwdriver in this instance - or maybe you were saying to check in the zone valve itself?

policywonk

Yep, know what thats like.

Breath in, look at this video - it is excellent. How to Repair a Motorised Central Heating Valve It shows you how they work and describes you have to do to check that the physical valve is turning fully. If it isnt able to fully turn you have to arrange a full valve replacement with a plumber. If it is able to fully turn then move the lever to fully open, lock it in - and the boiler should fire when the power is turned on, driving that zone because the zone will inform the boiler that there is a call for heat.

If it isnt the valve body you have two options. The cheaper option is to replace the motor.

Find the model number, go to a plumber's merchant and get a syncro motor. It looks daunting because you have to crimp wires. They will sell you the crimping tools. It is remarkably simple.

Now you may not like having to crimp wires, your next option is to replace the whole zone valve head - the box with all the bits inside it:

• Follow this video. How to renew a motorised valve motor or head. No draining down.
• Replace the valve head. It means that you have to replace where the wires go into the wiring centre - slowly, carefully. As long as power is isolated you should find this easy. It is easier than it seems.
• If this deters you, get a heating engineer in to replace the head. Give him the model number of the motorised valve.

Let us know.

confusedt

Replaced valve yesterday as no response from. Tado, apparently with their specialist team. Underfloor heating is working, so happy about that. Upstairs still working but this isn't showing up on the receiver. Weirdly now old zone valve removed the mechanism is working exactly how it should be probably wasted.£60, but hey got heating downstairs! Thanks again.

policywonk

Come back if they don't help. May be away for a week but will try...