Vaillant Turbo Max 837E Hot water issues

[Andy63]

Hi looking for advice please

Have Vaillant Turbo Max 837E boiler, the dial temperature set at 42 degree (on 10 clock where as used to be 2oclock if you know what I mean), however when water comes out the tap it continues to go warm, hot, boiling hot, cold, within 10 seconds it can go from 28 degree to 51 degree, then back up to hot and down again, it is the same in our Aqualisa "off the wall" electro thermostatic shower, in the shower the water is hot, really hot then really cold with no warning (not great for the kids)

Been fobbed off for years its the heat exchanger as also have problems with central heating side, have had it changed and no difference
Is this the thermostat (PCB) ?
I pay British Gas homecare nearly £40 a month and not getting anywhere

Can anyone give any suggestions ? Many thanks Andy

 

[Stu-B]

There’s no logic here, if you’ve been paying nearly £500 a year then you’d expect it to be repaired, keep ringing BG until it’s repaired, for that cost they can afford to change every part in the boiler until it’s fixed (which is pretty much what most do from what I’ve seen)
Or cancel the BG contract, get a new boiler with a 10 year warranty and it’ll save you money, chances are you could get it installed for around £2K if it’s a fairly straightforward install, so that’s a saving of around £3K over the life of the boiler. Plus you’ll have the reassurance of a working appliance.

let us know how you get on 👍🏻

 

[Andy63]

There’s no logic here, if you’ve been paying nearly £500 a year then you’d expect it to be repaired, keep ringing BG until it’s repaired, for that cost they can afford to change every part in the boiler until it’s fixed (which is pretty much what most do from what I’ve seen)
Or cancel the BG contract, get a new boiler with a 10 year warranty and it’ll save you money, chances are you could get it installed for around £2K if it’s a fairly straightforward install, so that’s a saving of around £3K over the life of the boiler. Plus you’ll have the reassurance of a working appliance.

let us know how you get on 👍🏻

thanks for the reply
I really wanted to know have I got an argument with them about the water going from one extreme to the other, and could it be the PCB grasping at straws
Just to let you know that not all parts are covered by the monthly fee that I pay

 

[Stu-B]

It’s clearly not performing as it should, sounds to me like it’s overheating somehow which is why the temperature skyrockets, then goes cold as the overheat device cuts the boiler out, maybe blockage or pump or thermister out of range or like you say pcb. Hard to say without being stood in front of it. A quick google tells me these boilers were made between 2002 and 2009, so maybe it’s cone to the end of its life now, what parts won’t BG change?

 

[Andy63]

It’s clearly not performing as it should, sounds to me like it’s overheating somehow which is why the temperature skyrockets, then goes cold as the overheat device cuts the boiler out, maybe blockage or pump or thermister out of range or like you say pcb. Hard to say without being stood in front of it. A quick google tells me these boilers were made between 2002 and 2009, so maybe it’s cone to the end of its life now, what parts won’t BG change?

Thanks we have had various F number faults over the years and every time the engineers say its heat exchanger (not covered quoted £300+) , and that a power flush at £2500 needed (declined) We got the heat exchanger changed (not BG) and nothing has changed When boiler was fitted all the pipes radiators etc brand new, not saying it wont fur up
The old heat exchanger wasn't dirty, had few specks of grime
The boiler shuts off and fires up again whilst the hot tap is running hot to cold to hot etc it will be this that probably kills the boiler!
Have booked another engineer for next week

 

[Stu-B]

You’re going round in circles with this now and it needs a fresh set of eyes on it, Mayberry a friend of a friend or someone will take a look?