Do I need a Heating Engineer ?

Leodogger

SGM1 wrote: »

JWhite wrote: »

Could still be several other things on boiler. If the boiler is shutting down then that would indicate a fault with it not the shower? Would have thought the boiler should get upto temp and maintain it?

The boiler doesn't shut down when having a shower or using the hot water, it shuts down obviously when we are not using it but comes on occasionally when nothing is being used during the day but the plumber says this is normal which I find strange as I thought it only should come on when you turn a tap on to heat the water, we don't use the central heating during the day either.

onomatopoeia99

If you stand next to the boiler while the shower is on full, does it sound like it is kettling? I don't mean herding protesters, I mean making a noise like a kettle.

One possibility is a partial blockage in the primary heat exchanger from a buildup of sludge or scale, and the reduced water flow means the boiler can't modulate the temperature properly. This can lead to it shutting off completely with a fault code.

I went through this with my Vailant almost five years ago, the plumber that came out had no idea and replaced the secondary heat exchanger (aka "the plate") and the diverter valve, neither of which did anything. I eventually fixed it by adding a litre of Fernox X800 to the central heating for a couple of weeks, as he wanted to replace the entire main heat exchanger at that point, which was almost as much as a new boiler!.

I'm not a plumber, just someone that had a faulty boiler!

sk240

It sounds to me like your temp setting is too high on the boiler, and the shower is rapidly trying to control the temp, with that the cold is also fluctuating with eth shower switching from hot and cold.


There is no need on a combi to have a set point above 50'C as you have no stored water volumes.


Try reducing the temp and try it again.

Leodogger

Our plumber did suspect that at the outset and asked if we knew if the system had been flushed when the boiler was fitted but we didn't know as it was an old lady that lived here and moved north, but anyway he quickly changed his mind and said that the thermal plate (heat exchange plate?) probably needed changing and he changed that and something else, might have been the diverter valve, I can't remember but it cost £400 and made no difference whatsoever.

How do you add the Fernox X800 to the central heating system ?

Leodogger

sk240 wrote: »

It sounds to me like your temp setting is too high on the boiler, and the shower is rapidly trying to control the temp, with that the cold is also fluctuating with eth shower switching from hot and cold.


There is no need on a combi to have a set point above 50'C as you have no stored water volumes.


Try reducing the temp and try it again.

We tried turning the boiler down slightly, from 51c down to about 47c and turned on the shower full at its hottest, the boiler immediately went up to 70c and slowly cycled down to the mid to high 60's and the shower was red hot. After a few minutes we turned off the shower and waited for the boiler to go back down to 47c and after a few minutes it is still 54c, whether it will settle lower I don't know but we feel the temp on the boiler seems to fluctuate too rapidly up and down every time a water source is used. I would have thought that the temp should stabilise after a minute or two to a set temp but it never does, it goes up and down like a yo yo when any water source is used.

Just tried the taps again, turned them on full and the temp is fluctuating from very hot to hot and back to very hot.

I have come to the conclusion that we need a Vaillant engineer.

Does anyone know what their charges are like ?

SGM1

JWhite wrote: »

SGM1 wrote: »

The boiler doesn't shut down when having a shower or using the hot water, it shuts down obviously when we are not using it but comes on occasionally when nothing is being used during the day but the plumber says this is normal which I find strange as I thought it only should come on when you turn a tap on to heat the water, we don't use the central heating during the day either.

It's just the preheat function which is a waste of time really. Turn HW stat to min and back to normal setting, should turn it off

southcoastrgi

Do you know what else he changed ?

What's the heating work like ?

Leodogger

Well it seems to work OK. As the rads have stats on them they obviously only come on when the hall stat kicks in when the temp in the hall is low enough.

I am not sure, but I think it could have been the diverter valve. I have sent the plumber a text to say it is still not working but as usual he has failed to contact us. He never returns a call unless I speak to him personally and then he fobs me off saying he is doing other jobs.

This is why I am thinking of getting a Vaillant engineer in but I might be paying for nothing if it turns out it is the shower that is the problem.

How long do showers normally last, ours is a Grohe but I reckon it could be as much as 8 or 10 yrs old.

southcoastrgi

But you said it's doing the same thing with the taps ?

Leodogger

Yes it is, the temp at the taps fluctuates slightly when it has been running a bit.