Gas boiler and central heating help please

[MikeMusic]

Have a problem at work (I run the company so my problem) with a blockage on the combi boiler.

So far I have spent £600 on parts and labour and may still not have the answer.
Probably a mid 90s boiler.

Seems like the system may never have been flushed and I am told the blockage could come back if the system is not flushed, that's another £350

I've never had to fork out this sort of dough for boiler problems

Is this all kosher ?

[Oldpinkman]

Have a problem at work (I run the company so my problem) with a blockage on the combi boiler.

So far I have spent £600 on parts and labour and may still not have the answer.
Probably a mid 90s boiler.

Seems like the system may never have been flushed and I am told the blockage could come back if the system is not flushed, that's another £350

I've never had to fork out this sort of dough for boiler problems

Is this all kosher ?

Not by any means by choice - combi boilers are a bit of a specialist subject of mine. Mine is oil - but the wet sides are the same as gas in principle. I know a good boiler engineer I could totally trust who probably covers Surrey (ex British Gas) if you need another professional opinion.

There is no requirement to routinely flush a combi boiler or the system it is connected to. It obviously makes sense to run appropriate system protection chemicals in the system, and because this is a bit less completely simple to do than it is for a gravity system it sometimes gets over looked (note to self - this is DESPERATELY overdue). Most boiler engineers I know would flush a system (powerflush) prior to installing a new boiler - cost £300+.

A blockage is, I suppose, possible, but really shouldn't occur if you have a system that was flushed prior to installation and you have maintained it with appropriate system additives. But there are oh so many things can go wrong with a combi. In the final analysis, my insoluble mystery - which we referred to as "dead mouse" since it resembled an intermittent blockage, was down to an airlocked system pump.

So - what were the symptoms? Did you lose both hot water and heating? Was the burner firing? Is this a domestic boiler in spite of the fact that it is "at work"?

Which parts have been changed and why?

[Audioman]

It's likely straight as a combi is going to be more sensitive to muck in the pipes. £350 if it's a powerflush of the entire system sounds very reasonable. BG charge about £600 for domestic systems.

[MikeMusic]

Not by any means by choice - combi boilers are a bit of a specialist subject of mine. Mine is oil - but the wet sides are the same as gas in principle. I know a good boiler engineer I could totally trust who probably covers Surrey (ex British Gas) if you need another professional opinion.

There is no requirement to routinely flush a combi boiler or the system it is connected to. It obviously makes sense to run appropriate system protection chemicals in the system, and because this is a bit less completely simple to do than it is for a gravity system it sometimes gets over looked (note to self - this is DESPERATELY overdue). Most boiler engineers I know would flush a system (powerflush) prior to installing a new boiler - cost £300+.

A blockage is, I suppose, possible, but really shouldn't occur if you have a system that was flushed prior to installation and you have maintained it with appropriate system additives. But there are oh so many things can go wrong with a combi. In the final analysis, my insoluble mystery - which we referred to as "dead mouse" since it resembled an intermittent blockage, was down to an airlocked system pump.

So - what were the symptoms? Did you lose both hot water and heating? Was the burner firing? Is this a domestic boiler in spite of the fact that it is "at work"?

Which parts have been changed and why?

Thanks. I'm getting the feeling that combi boilers are a difficult breed.
This unit was built around 1995. I have no idea of the service history of the boiler before 2009 when we moved in. May have been looked after or not.

We had a minor problem, forget what it was, Jan 2012 which was fixed and all ok

This year a visit from the water company to say we have to conform to regs.
We called in a guy who seemed highly competent when working on one of our guy's boiler and system at home.
He fitted the item he said was required. Affinity Water disagreed saying amongst other things
"The reg's require the back flow protection device (double check valve) to be connected to the supply pipe when the filling loop is disconnected"
He came back and did the work
Couple of days later I turned the boiler on to double check all ok before winter.
Noticed after a few minutes the rads still cold. So turned it off. I think everything was running, certainly sounded like it
Called plumber back and he said "blockage" He spoke to the manufacturers and they advised the remedies.
So far we have at least a micro switch and a "VOKR 6025 complete pump"
There is another part to come.
Yesterday he said he thought this new part to come tomorrow or Monday should fix the problem but a good move would be to flush the system as the items/blockage/s could come back and block again.
I have no idea what chemicals we may have on the system. I should take more interest I know now.
We only run rads from the boiler.

From the size I assume it's domestic

[MikeMusic]

It's likely straight as a combi is going to be more sensitive to muck in the pipes. £350 if it's a powerflush of the entire system sounds very reasonable. BG charge about £600 for domestic systems.

I've looked around and £350 sounds slightly above average for a flush so no as bad as I thought.
BG at £600 sounds about right !
:)

[Oldpinkman]

Sounds kosher Mike. If it were mine I'd get it flushed. The issue with combi's is usually the hot water, not the rads. On the radiator circuit they are not that different (more prone to blockage) than a conventional boiler. The shenanigans with the filler loop won't have anything to do with this (I leave mine permanently connected)

The micro switch would almost certainly be for the hot water. Basically it runs like a normal boiler except it will have a plate heat exchanger (which can block) and a diverter valve, which can block, jam or otherwise fail. The diverter valve usually operates a couple of micro switches - one to fire up the burner (on demand for water) and the other to run the pump (if its not running at the time because the heating is off).

They also have some sort of pressurised expansion vessel and a pressure relief valve. Leaky pressure relief valves can cause airlocks. But if something blocked then a flush makes sense. You might also consider a magnetic filter trap like magnaclean

Of course, although my parents still have their 50 year old boiler, today a 20 year old boiler....

[Gordon Steadman]

Of course, although my parents still have their 50 year old boiler, today a 20 year old boiler....


I just bung another bit of wood on mine - hope that helps:lol:

[MikeMusic]

Thanks Richard. Looks like a flush, another part and fingers crossed

[MikeMusic]

One more question please.

If this doesn't work then a new boiler is on the cards - except the quote was around £2500 if I remember right.
Boilers don't cost that do they ?

[Oldpinkman]

Again - installed - that sounds about right. Well, the big oil boiler combi I was looking at cost about £1900 and then you have installation. Depends how big it is. I guess - if its just your offices you are not looking at running a power shower like we are, so you don't need a particularly high flow rate on the water side. But how many radiators?

Typicaly small gas combi boilers are £750- £1000. Install would be £250-£500 depending on what's involved (if it were a direct replacement it would clearly be much less, because all the pipework is in situ). Cost of supply only, inc VAT on a Worcestor Bosch 550CDi is about £2200.

Like I said - if you have doubts, I know a man who covers Surrey. But £2500 doesn't sound outrageous. Particularly if that included a power flush (which you wouldn't need if you have just had one done)

I only learned all this rubbish because our hot water would fail at 5.45 am when Sue was naked and covered in shampoo, and "I'll get a boiler engineer out within 24 hours" was not an acceptable answer! :(

[MikeMusic]

Again - installed - that sounds about right. Well, the big oil boiler combi I was looking at cost about £1900 and then you have installation. Depends how big it is. I guess - if its just your offices you are not looking at running a power shower like we are, so you don't need a particularly high flow rate on the water side. But how many radiators?

Typicaly small gas combi boilers are £750- £1000. Install would be £250-£500 depending on what's involved (if it were a direct replacement it would clearly be much less, because all the pipework is in situ). Cost of supply only, inc VAT on a Worcestor Bosch 550CDi is about £2200.

Like I said - if you have doubts, I know a man who covers Surrey. But £2500 doesn't sound outrageous. Particularly if that included a power flush (which you wouldn't need if you have just had one done)

I only learned all this rubbish because our hot water would fail at 5.45 am when Sue was naked and covered in shampoo, and "I'll get a boiler engineer out within 24 hours" was not an acceptable answer! :(
Thanks
I had the price wrong. Seems it could be around £1700 but that could be plus plus
Hopefully not required !