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Discuss Hot water but no Central Heating with young children in the Central Heating Forum area at PlumbersForums.net

Messages
42
We have a Potterton Titanium Combi Gas Boiler which was setup with the wireless Nest Thermostat last year to provide heat to our radiators, heat up our unvented indirect cylinder to provide us hot water and to heat up our under floor heating in our kitchen.
There is also one tap in the house that is used to provide hot water directly from the gas boiler instead of the cylinder - Something to do with making sure the 'diverter valve' does not fail and has regular use.

The nest thermostat setup has worked flawlessly for just over a year and tonight when I wanted to heat up my sons loft room, the rads would not get hot.
I firstly checked the nest thermostat and it mentioned it had an issue connecting to the link. I tried to reconnect and it connected straight away (this happens from time to time due to the distance of the thermostat and link).

I then went to check the boiler and it was not heating up although powered on.
I checked the single tap that heats up using the boiler directly and this worked instantly.
Going back to the nest, I then attempted to heat the cylinder up, which again worked - boiler was in operation, same applies for the kitchen.

I then tried to set the thermostat to high temperature (23 degrees) and whilst the nest goes orange and says it is heating up, nothing happens at the boilers end.
At closer inspection and playing with the thermostat from getting the boiler to heat up and off, I can clearly hear click at the links end when it is calling for heat yet no impact on the boiler.

What could be the issue and how can I resolve it please?
I have 3 young children and the loft bedroom currently is at 15degrees and dropping!

Attaching a pic of the boiler in hope it explains the setup better
 

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Ted808

Plumber
Gas Engineer
Messages
343
Hi Take a look at the two units on the left, two port valves, turn hw / ch on in turn... they should wurrrr - i suspect one doesn't- the one for the heating, there's a little lever that you can gently push over and hook- the heating will then work- but you need an heating repair person to confirm and repair. ATB
 
Messages
42
Just attempted to change as suggested and called for heat, with no change.
 

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Ted808

Plumber
Gas Engineer
Messages
343
Just attempted to change as suggested and called for heat, with no change.
Turn the power off, then only turn heating on, listen for the gentle wurrr, if not move the lever over and feel the pipe, it should warm up. You will need and engineer if this doesn't work.
 

SJB060685

Plumber
Messages
1,913
As said above. If you can identify which zone valve is for your radiator circuit manually move the lever over and it should hold open. Then bring on HW cylinder circuit through programmer. I can't and wont advise if it's a problem with the boiler as I'm not qualified to but it sounds though it's an electrical fault before the boiler.
 

garygvl

Gas Engineer
Messages
215
looking at the whatsapp image somebody had a load of sockets they needed to use up on the condensate p/work. in the pic you have 2 valves locked open of the three, cant see what the other is doing. you say hw and underfloor is working. if you know which of the 3 valves is the loft leave it locked open but you will only get heat into the loft when either the hw or underfloor puts a demand on the boiler. if both hw and underfloor are upto temp and switched off get somebody to have a bath which will use up hot water firing the boiler again. this will give you limited heating to the loft while cylinder reheats. in the end you need a 'Registered Professional Gas Engineer'/g3 engineer to attend
 

SJB060685

Plumber
Messages
1,913
Exactly what I was getting at Garygvl. Of course the OP will only get loft heat if theres another demand and yes it will be short lived unless things were linked out (obviously I will NOT say what). If I was to have a guess it's the synchronous motor that's burnt out, motor wont turn over and wont connect end switch. The OP needs an engineer from here on out.
 
Messages
42
Thank you for all your responses.
It turned out to be a faulty zone valve (far right).

I have managed to put it in manual override mode and when getting the underfloor heating to come on or/and heating up the cylinder, the rads now heat up as well.

I assume this will not be covered by the warranty of the boiler.

Is the zone valve an easy fix to replace?
How time consuming can it be and roughly how much should parts and labour cost?
 

SJB060685

Plumber
Messages
1,913
It's just the head of the zone valve or maybe even just the synchronous motor inside that needs replacing. Highly unlikely to be covered under warranty. It's an easy fix for an engineer yes, so you'll have to call one out.
 
Messages
42
Thanks for all of your help.
I managed to purchase a HONEYWELL 40003916-001 2-PORT V4043H REPLACEMENT POWERHEAD 22MM 22MM COMPRESSION from screwfix and watched a youtube video of how to change the motor from the old zone valve.
Was very straight forward and although it was difficult getting a thin enough screwdriver to get the case/motor off.
All working again now.

Thank you all!
 

SJB060685

Plumber
Messages
1,913
So it was the synchronous motor like I said?
[automerge]1575758990[/automerge]
That's good. You'll find a lot of so called engineers would just of changed the head, any one worth his weight in gold would of isolated the problem and just changed the motor, cheaper for the customer and a sign they know their stuff. Glad you got it sorted
[automerge]1575758992[/automerge]
That's good. You'll find a lot of so called engineers would just of changed the head, any one worth his weight in gold would of isolated the problem and just changed the motor, cheaper for the customer and a sign they know their stuff. Glad you got it sorted
 
Last edited:

Ted808

Plumber
Gas Engineer
Messages
343
So it was the synchronous motor like I said?
[automerge]1575758990[/automerge]
That's good. You'll find a lot of so called engineers would just of changed the head, any one worth his weight in gold would of isolated the problem and just changed the motor, cheaper for the customer and a sign they know their stuff. Glad you got it sorted
[automerge]1575758992[/automerge]
That's good. You'll find a lot of so called engineers would just of changed the head, any one worth his weight in gold would of isolated the problem and just changed the motor, cheaper for the customer and a sign they know their stuff. Glad you got it sorted
Yes agreed but I have cjhanges the motor and then had to go back to change the head so.***. 50/50 it doesn't always worktrying to save the customer money, and difficult to justify a second charge.
 

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