Wiser not turning off boiler? Newbie question

[Timothy2Tim]

Hi All,

I've just installed my new Wiser system, 2 zone hub, room thermostat and 2 wiser TRVs to begin with. This replaced a standard Drayton 7 day programmer with wireless thermostat.

My boiler is a heat only boiler and open vented system. I replaced the wireless themostat with a manual one and left it on full power to avoid having to change the wiring.

Anyway, my problem is that the wiser system never seems to turn off the boiler?

I'm looking at the app and all the devices are showing the temperature in the room is higher than the desired temperature. But the boiler keeps coming on and heating the flow temperature back up to 60degrees. The only radiators on are the towel warmers in kitchen and bathroom.

I'm about to leave the house for a few hours so selected the away "Moment" in the app but the boiler is still coming on every now and then. When I come home I will have very warm towels!

My old controller would turn the boiler off when the main room thermostat (in the hall) reached the desired temperature.

Does the Drayton Wiser system not work the same way?

I've got the room thermo in the Hall and TRVs in my Office and Living Room.

Edit: Forgot to mention: Hot water is also off in the app. Won't turn back on until 8:30am so it's not that firing up the boiler.

Sorry for a long post, thanks for any info received.

Tim

[PhilHornby]

You're suspicions are correct - it's not working correctly. ☹️

The Wiser system commands the associated iTrvs to open (unless hot water only) and then activates the appropriate Relay to energise the motorised valve(s). If the Wiser says it's OFF, but it's still energising the motorised valve(s), it would have to be a dodgy internal relay (pretty unlikely), or a wiring issue. I had to swap the backplate on mine, because the previous controller wasn't Drayton. Assuming you didn't, perhaps yours isn't completely compatible?

Are you certain it started with the Wiser install? ... something like a stuck motorised valve might give the same effect. Mine comes on unexpectedly when the Hot Water stat does its once a week anti-legionella cycle, which always takes me by surprise, because its timing is unpredictable.

[Timothy2Tim]

Yes, the Drayton 7 day programmer was definitely turning the boiler off at 4:30pm because I can see on the boiler the flow temperature and it was going down to 20c when I left the house. With the new one it's still at 60c 😕

[PhilHornby]

I had a look at the Wiser wiring diagram and the Drayton LP112 etc wiring diagram and both look the same. The wallplate(s) are described as "Industry Standard". You wouldn't expect there to be any issue there then.

Is it something to do with this :-

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@Timothy2Tim wrote:

I replaced the wireless themostat with a manual one and left it on full power to avoid having to change the wiring.

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There's a slightly confusing note in the Wiser instructions that says:-

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Note: If there is an existing wired thermostat connected via the wallplate, this must be disconnected, i.e. remove the thermostat wires from the wallplate.

(I don't quite understand the logic of their statement, but that's what it says. I would have thought that would have broken the circuit to the valve. Maybe they actually mean remove it and rewire the wallplate accordingly?)

Didn't you have a Receiver unit of some kind wired to the wallplate? (for the previous wireless thermostat). Wouldn't the Wireless thermostat itself just have been wired to Live & Neutral? Is your new manual roomstat short-circuiting the Wiser somehow and suppling a constant heating demand signal?

What happens if you remove the Wiser Hub from the wallplate...does the boiler stop firing?

[Timothy2Tim]

Yes, you were right.

The wireless one has a receiver which fits to the same type of backplate as the wired one, I took them off to compare and noticed the wired one doesn't have all the pins that are wired up, so I guess they not as interchangable as I thought.

The wired one just had L N and SL but the wireless one also had COM.

Using the Drayton installation sheets I have now removed the thermostat completely and linking the two correct wires in the terminal box has now fixed the issue.

So I think it's all steam ahead now.

Many thanks for your help 😃