Intermittent problem - Vaillant Turbomax

[stefan nycz]

Hope you can help with this one. Its an intermittent problem, which makes spot diagnosis by an engineer very challenging.
Two heating engineers have already attended, and not fixed. The first one was a Vaillant specialist who advised that I ring Vaillant to use their fixed price service. The second one (not a Vaillant specialist) assessed the problem, spoke with the Vaillant service team, and replaced the HW heat exchange unit, as well as install a magnet filter unit. The old heat exchange was not badly clogged. Unfortunately the problem still persists.
The facts as follows:
Vaillant Turbomax 828 - 12 years old
The problem is maintaining a consistent hot water supply. Central heating - no problems at all.

Turning on a hot tap does not always fire up the boiler, and does not always deliver hot water when it does - this is the intermittent bit. Sometimes a shower starts lukewarm, gets hot, then goes cold for 3 mins, then gets hot again. Sometimes its fine.

Today is a classic example of what happens. Early this morning the hot water delivery is consistent temperature, and on demand. All hot taps delivered hot water on demand - a steady 72 degrees (as per the boiler reading), and showering was a joy. However, 30 minutes after having had the shower, turning on a hot tap (even all of them at the same time) does not deliver hot water, and the boiler does not fire up. However, with the hot taps running cold water, the boiler is indicating 63 degrees - indicating perhaps a temperature sensor problem? Activating the 'warm start' function sometimes gets the hot water running again, sometimes not.

The fault history indicates 2 x F28 and 8 x F22. Although these seem historic as they have not changed in the past 6 weeks. I have never had a red light lock-out.

I am loathe to use the Vaillant fixed service, as this seems to be a fairly simple problem, and I have already paid out £320 (although the mag filter was included in this). By paying another £300+ to Vaillant, I may as well have had a new boiler installed.
Calling out the heating engineer again may well be at a time that the boiler is working fine, so giving him access to your replies I am sure will help - and hopefully allow a much cheaper solution to this problem.

I hope that someone has faced this issue before, and can offer their advice please.

Thanks

 

[Last Plumber]

Any good Heating engineer should be able to sort that issue for you, However, at 12 years old I personally would avoid throwing money at it. The Boiler is expected to last around a decade and you have passed that point. You will eventually need to replace it anyway and all the component parts in your Boiler have been working for the same amount of time and will have suffered equal wear.
Vaillant are a good make of Boiler and I would not hesitate in having a new one.

 

[jtsplumbing]

Has you know we cant give to much information on boiler repairs, but have you tried a basic check , e.g. when heating system is cold and you run hot water does one of the heating pipes under the boiler start to get hot ? just something you can try and could point to a common problem with combi boilers.

 

[Harvest Fields]

The above is something that you can check yourself and very easy to do as long as all pipes under the boiler are accessible.

 

[king of pipes]

Your engineer should have changed one other part to solve your problem i would have advised a one off fix with valliant you are stuck now any good GSR should be able to sort it but its gonna be £200 + which is i guess you dont want to hear sorry kop

 

[chris watkins]

I had a customer on the phone today "can you come fix our boiler", yes no problem the cost is £149 + parts, fixed price repair (i.e. we don't fix it you don't pay). "OK but what about a discount as I have already payed a guy to come out on Good Friday & he didn't fix it".
Can you guess what my answer was ??
What are these people on, why should we pay cos others don't know what they are doing!!!
OP
Stick with the old girl, few running repairs & tender loving care from a proper engineer who understand her & she will serve you proud for many years to come. These younger model may look attractive but don't let your head be turned, just you try making a claim on that extended warrantee they offer. Much like life the grass may look greener but you just appreciate what you have.
We look after some much older ladies, should never give away their age. (but more than twice yours & going strong)

 

[stefan nycz]

Hi Chris
Thank you for your reply.
I appreciate your comment about customers with a brass neck - it would annoy me as well.
I have contacted the second engineer who attended, and have asked him to revisit and review the info from yourself and your fellow contributors. I hope this will be enough to help him diagnose the problem without too much further delay or unnecessary cost.
Cheers

 

[stefan nycz]

Hi King of Pipes
Your're right - and extra £200+ bill is not what I wanted. However, its the toss up against a new boiler and the reliability (or otherwise!) that it brings.
Either way, thanks for the heads up.
Cheers

 

[stefan nycz]

Hi jstplumbing and Harvest Fields
Thank you for your reply.
I am keeping a log of the everyday issues with the hot water supply, and have asked the second engineer I used to return. Hopefully with my notes, and reading this forum, it will provide enough info for him to make the right diagnosis, and fix it quickly.
From the euphoria of yesterdays shower, today the boiler creeps to 44 degrees then cuts out, back down to 23 degrees, then fires up again. Weird, and totally erratic.
However, I think I have enough for him to work on now.
Appreciate your help.
Cheers

 

[stefan nycz]

Hi Last Plumber
Thanks for your reply.
I agree with your comment that any good heating engineer should have resolved this problem, but I do have some sympathy with the one I used as the problem is erratic, and intermittent.
I have logged daily the weird stuff that it does, and have asked him to re-attend and re-diagnose with the benefit of my notes. Hopefully all will be resolved as a result.
I am loathe to replace the boiler at the moment - although I may well review this if the engineers prognosis is grim!
If I did replace it, I am minded to go for a Bosch Worcester, as they seem to have a marginally better reputation (from a laymans point of view anyway).
Cheers

 

[jtsplumbing]

Hi Last Plumber
Thanks for your reply.
I agree with your comment that any good heating engineer should have resolved this problem, but I do have some sympathy with the one I used as the problem is erratic, and intermittent.
I have logged daily the weird stuff that it does, and have asked him to re-attend and re-diagnose with the benefit of my notes. Hopefully all will be resolved as a result.
I am loathe to replace the boiler at the moment - although I may well review this if the engineers prognosis is grim!
If I did replace it, I am minded to go for a Bosch Worcester, as they seem to have a marginally better reputation (from a laymans point of view anyway).
Cheers

Don't just jump into a Worcester boiler , not quite has good as they make out ! they just spend an large amount on propaganda other very good boilers on the market, I don't favour any particular make , would give some options depending on customer requirements and let them make the choice, Intergas is one you may like to look at,

 

[moonlight]

I not sure this has been suggested above, but is the shower back feeding? some don't have check valves fitted.