Hot Water turning on but heating isn't
Hi all
Complete novice here and British Gas had no idea how to fix it either.
I have a V3+ kit with two separate zones for my underfloor heating and then the rest of the house is controlled by TRVs. The underfloor heating is connected to a wired thermostat.
Initially, everything was working fine for a few months.
For the last few months ago (yes I've waited too long), I would be able to turn on the heating from the app, the extension kit light would turn on and indicate it has received the message but my boiler doesn't fire. I can even hear the TRVs whirring and signalling they need heat.
Curiously, hot water is working fine.
It was around the time I disconnected my old Honeywell wired thermostat as I thought the main Tado wireless thermostat was doing the job. I can't be sure this triggered it as it was summer and we weren't using the heating everyday.
I've since reconnected the old wired thermostat and it still doesn't work.
The underfloor heating is working fine.
Any suggestions? Need help to avoid a very cold winter for my family.
Boiler is Vaillant Ecotec Plus 637
Comments
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You should have two dedicated zone valves dedicated to the CH and UFH flow. One may turn on the UFH and another which turns on the CH pump and radiator feeds. Check both those zone valves. Make sure both actually activate when requested. You should be able to feel them open and close.
The fact that this system did work once suggests that one of those valves is having trouble.1 -
You state you have two UFH zones. It is possible that one the UFH wiring centres is actually in control of all heating, informing both the Tado starter kit, and is also is the primary driver for the boiler. It really depends on how your fitters wired in the UFH services.
Would you describe more fully how your system is laid out, ie:
* how many zone valves and how they are assigned,
* how many UFH manifolds and how they are linked to wiring centres,
* whether the tado extension kit talks directly to the boiler or to a UFH wiring centre.1 -
Thanks for replying.
To your second point, the heating was working fine throughout the house when it suddenly stopped.
To answer your first question, the CH zone valve is de-energised. The hot water and UFH zone valves are moving freely.0 -
It's a brand new valve and I believe the British Gas team checked it and said the valve itself was fine, but no power was getting to it.
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OK. Did the British Gas team manage to work out what point actually powers that valve?
I presume it is a 2 port valve. They should be able to trace the origin of the live feed to the valve. There should be a grey wire going to the valve. It needs to be traced back.
Normally a two port valve, when it receives a call for heat, (i) opens the water supply to the CH feed side (ii) on completing its step to open, it then provides a switched live feed to the pump and boiler.
Now British Gas should be able to tell you if the UFH wiring centre is actually controlling power to the call for heat, or whether the tado controller is wired to provide that power. The trace back should answer this.1 -
Sounds like a broken wire/bad connection given that it did work previously then stopped and the engineer has said that no power is going to the valve.
I would double check all wiring connections on the CH side. What can be really useful (although not very safe!) is to open the wiring centre and wireless receiver and use a mains tester screwdriver on the terminals while also turning on/off the CH. The screwdriver will light when power is present. Start at the wireless receiver to verify that power is applied to the CH terminal when CH is turned on and then work from there.
Remember to shut off the power if you do need to re-make connections!
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Slightly different set up here, but I recently had a similar problem with my CH 2 port valve. Per @davidlyall 's suggestion, check the wiring. Turned out one of the valve connections in the wiring centre was loose (not sure how as it had worked fine for years) and no power was getting to that valve on the call for heat. If it's not a loose connection, my money would be on the valve as everything else sounds to be working. So I'd be looking at the valve spindle next. Quite common for them to seize over the summer when not in use. I now take the heads off both valves at this time of year, spray in a little WD40 and move the spindle with some pliers. Pop the heads back on and all's good for another year. Takes about 30 minutes.
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Thank for your replies everyone, I've been on night shifts so haven't had a chance to try these.
We have three zone valves, one assigned to UFH, on HW, on CH.
The British Gas engineer stopped short of troubleshooting as he said they are not supposed to fix Tado, only Hive.
I'm unsure how to check if the wire is damaged.
I will attach a few pictures and hopefully things will make more sense to you guys. I can try and pay for an engineer but am keen to learn.From the pictures, it is the zone valve on the left that seems like it's the CH and hence not moving smoothly. On the box it connects to it is the third wire on the left. The wires coming out of it seem to have a current but the blue one doesn't. In the picture with the boiler shows a wire coming from above going into the boiler, and another coming out the boiler into the Heatmiser setup.
The boiler seems to acknowledge heat is needed (the radiator sign flashes) but after a few seconds an egg timer flashes and it turns off again.
I hope this information is useful, I'm sorry for not being more helpful.0 -
Any suggestions guys?
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Your photo of the wiring centre for UFH, the Heatmiser box, is it the only one? Your original text suggested that you had two UFH zones, or did you mean one for UFH, one for CH rads? Am confused.
@DM932187's recommendation to unfreeze the valve may help. However my main concern is the power failure. Here are four ideas to check in sequence.
1. Check your contract with BG. They may not have a duty to fix Tado, but their service contract gives them a duty to explain which part is not working,
Ie either the Tado controller is not supplying the request for power, or that the UFH wiring center isn't relaying the request for heat by supplying power to the zone valve.
I should explain. The Tado controller is designed with the extension kit to only handle two zones, one being CH the other being HW. So when three zones are involved, especially with UFH, one of the two wiring centres (the Megaflow or the Heatmiser) should forward the power to *both* the CH zone valve and the UFH zone valve. Now if the UFH wiring centre was set up to do that, then either it's internal relay driving the CH zone valve has failed, or the wire from the UFH wiring centre to the zone valve is badly fitted. The problem with this idea is that your posted photo of Heatmiser wiring centre suggests it not wired for that - if it is the only Heatmiser. The alternative is that the Megaflow wiring centre has a loose connection.
2. Call the boiler company's support team and ask them what causes the timer symbol to turn up. They may confirm that the zone valve is not competing it's switch over.
3. If that's true and if, as I suspect BG, are meant to service it, they should at least confirm that either the Megaflow wiring centre has a wiring fault, or the Megaflow wiring centre has been badly wired or that the Tado controller has a fault. Then you can arrange to have the right item replaced.
4. Force the tado controller to call for heat by pressing the CH button on it and register whether the CH zone valve is activated. If it does turn on that valve, then we can conclude that the Tado controller was not being told to call for heat or is faulty. If it does not then check the Megaflow wiring centre's wires for integrity.0 -
Here is a diagram to help identify which terminals are affected in your Megaflow wiring centre.
https://www.electriciansforums.net/media/unvented-hot-water-cylinder-indirect-heatrae-sadia-megaflow-s-plan-wiring-diagram-in.2565/
According to this
* the Tado controller calls for heat on terminal 4.
* terminals 6 and 9 relay that message onwards if there is a wired thermostat in place not integral to the Tado.
* a link between terminals 9 and 10, then leads to Terminal 10 supplying power to the zone valve.
So... check 4, then 6, then 9, then 10. Somewhere in that sequence there could be a failure.0 -
Thank you @policywonk, I really appreciate the effort you're putting in, especially tolerating my ignorance.
No, sorry for the confusion, I have one UFH zone, CH rads and HW.
I'll check with BG, thank you. I haven't called Vaillant but the guide suggests the egg-timer comes on as part of the anti-cycling function.
I have tried calling for heat to the CH by pressing the button, and the zone valve does not activate. I've checked the wires on the MegaFlo and only the blue wire's circuit is not receiving power. I need to look at your circuit once I'm back home to see what that pertains to. I will check these wires in the order you suggested when I am home.
I thank you once again for your ongoing patience and support!0 -
I've just checked - there's no power to terminal 10 so the zone valve - that's not the wire going into the zone valve though - it's the last wire at the end that says TIMER on it from my picture.
Does this suggest the problem is downflow of the valve?
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With the above knowledge, any suggestions?0
