Another Central Heating Issue

[MMarve]

Triggers broom.....

But in theory these components should last another 8 years

Yeah, I'll remind myself of that next year when I'm replacing the PCB board, pump and whatever else is left!

On that subject though, we bought this house 3 years ago and have serviced the boiler each year. But unless the book just wasn't filled in, it looks like it hadn't been serviced once by the previous occupiers. Would not having a service for the first 5 years of its life really make a difference and mean things like the PRV, Expansion vessel and diverter valve would have a shorter life expectency?

 

[Harry Bloomfield]

Triggers broom.....

But in theory these components should last another 8 years

Yeah but, look how long triggers broom lasted

I never begrudge minor parts replacement, things don't last forever.

 

[Harry Bloomfield]

Yeah, I'll remind myself of that next year when I'm replacing the PCB board, pump and whatever else is left!

On that subject though, we bought this house 3 years ago and have serviced the boiler each year. But unless the book just wasn't filled in, it looks like it hadn't been serviced once by the previous occupiers. Would not having a service for the first 5 years of its life really make a difference and mean things like the PRV, Expansion vessel and diverter valve would have a shorter life expectency?

Very unlikely. A service might have picked up on them showing signs of failure earlier.

 

[Gasguru]

Expansion vessels normally fail through lack of maintainance...lazy installers don't check the air charge when servicing and customers don't bother with annual servicing.
As a consequence the PRV often operates...
The diverter valves on these fail for fun - normally leaking due to system water not being made from unicorn tears.
Constant topping up the pressure and diluting the inhibitor from a PRV dripping is a sure fire way to get contaminated system water.
Vaillant haven't made a robust diverter since their CombiCompact models back in the 90s.

If the cylinder appears to be heating ok then then that would indicate the diverter is ok but perhaps it's hard to tell as you've been using the immersion heater instead.

 

[MMarve]

Expansion vessels normally fail through lack of maintainance...lazy installers don't check the air charge when servicing and customers don't bother with annual servicing.
As a consequence the PRV often operates...
The diverter valves on these fail for fun - normally leaking due to system water not being made from unicorn tears.
Constant topping up the pressure and diluting the inhibitor from a PRV dripping is a sure fire way to get contaminated system water.
Vaillant haven't made a robust diverter since their CombiCompact models back in the 90s.

If the cylinder appears to be heating ok then then that would indicate the diverter is ok but perhaps it's hard to tell as you've been using the immersion heater instead.

Thanks very much, that is very useful to read. And yes, we probably have been relying upon topping up the system pressure too much for too long so I'll mention about maybe needing to topp up the inhibitor as well.

One last point which had totally slipped my mind but as we discussed the diverter valve and I guess helps to confirm it is that a week or so ago we had about a period of about 10-15 minutes when no hot water would come to the kitchen tap when demanded. It came out of the blue and I reset the boiler, left it as distracted by something else, came back and suddenly it was fine again so never gave it a second thought. It's been fine since as well. But in hindsight, I think that points to an issue with the diverter valve if it was not sending hot water the other way when it should have been.

For the record though it does seem to be fine supplying hot water to the cylinder as I turned off the immersion yesterday and we've had a hot bath for the children yesterday and showers for me and my wife today with no sign of cooling water coming through. But I guess if we left it, it could just be an intermittent problem, once every so often when it randomly doesn't "divert" correctly.

Thanks for all your help!

 

[wannocks]

Although if your boiler is an 831 its a combi so some of your taps may be supplied by the boiler and some by the cylinder.
It sounds like your kitchen is supplied by the boiler and the bathroom by the cylinder.

 

[MMarve]

Although if your boiler is an 831 its a combi so some of your taps may be supplied by the boiler and some by the cylinder.
It sounds like your kitchen is supplied by the boiler and the bathroom by the cylinder.

Quite right. The kitchen tap is the only "on demand" tap from the boiler. The bathrooms are all fed by the cylinder. I know there's been a lot in the thread to follow but I did put that in the opening post.

For full disclosure, the boiler also supplies hot water to the kitchen tap and then also to a Megaflo Unvented hot water cylinder that is used to supply hot water to 2 bathrooms.

 

[MMarve]

Just to close this out, after a day of not having the immersion heater on, we did finally start to run out of hot water in the cylinder (thankfully whilst my wife was in the shower )

And then yesterday afternoon we had the replacement diverter valve fitted. All sorted and we have a lovely toasty house again now.

Thanks all