Only get hot water when the heating is on

[freedonian]

Hi All

Please can you offer some advice with this problem

I have an Alpha CB28X Combi boiler

The hot water only comes on when the heating is on.

A plumber friend, said it may be the flow regulator or diverter valve???

Any help would be gratefully received

Best regards

 

[gas4you]

First and easiest thing to check is the horseshoe flow switch on top of the DV.

If you remove this the boiler should fire instantly for HW. If this is ok then it sounds like the diaphragm perished.

 

[freedonian]

First and easiest thing to check is the horseshoe flow switch on top of the DV.

If you remove this the boiler should fire instantly for HW. If this is ok then it sounds like the diaphragm perished.

Thanks very much for your almost instantaneous reply. Unfortunately I can't find those things in my instructions.

Is there any chance you can take a look at

http://www.alpha-boilers.com/produc...8_installation_and_servicing_instructions.pdf

and refer to the boiler schematic on page 5

Regards

 

[Agile]

Its better shown in Para 8.26 and labelled as the DHW flow switch!

Tony

 

[freedonian]

Ok

Removed the DHW Switch and you're right the boiler fired up straight away for the heating and hot water.

So my next question is where is this diaphragm that you say has perished?

And how easy is it to replace if at all.

Regards

 

[gas4you]

To the right of the flow switch you will see the diaphragm housing. About 3" diameter.

You need to remove this to be able to replace the diaphragm.

This needs you to drain the boiler and remove the plate HE before you can remove the assembly.

The diaphragm kit includes all the new fibre washers for the plate HE.

DON'T isolate the boiler with the ch valves under it, they will leak.

 

[Agile]

Because this is one of the diverters which often leak from other places its one of the boilers where I usually recommend the client that we replace the whole unit rather than just the diaphragm.

Of course its up to the client if they choose the cheaper alternative but many do accept my advice as the labour charge is the same.

Tony

 

[freedonian]

OK

Thanks for all your help

I'll order the new kit and have a go

I'll post when I've done it, (probably next week depending on when the kit arrives)

Thanks and regards

 

[nogoodatfaultfinding]

2 Points on this issue.

1. I may be wrong on this but is it not now against regulations for a non gas safe registered person to remove a boiler cover and

2. Dont for the love of god try this yourself mate, its easy when you know how but if you get it wrong your in for a world of pain with leaks ect, its not the most expensive of jobs to get your local engineer to do if you can find one that will do it.

 

[Agile]

He did ask how easy it was but Dave did not comment.

Its certainly more difficult than most boilers but not as hard as a CDI.

The usual advice from RGIs is that its not a task to be undertaken lightly.

But of course that depends on your level of skill.

If you would rplace the cylinder head on your car then you will not have much problem. If you would not then you might get into difficulties.

If you must do it yourself then do it early in the week in case you need professional help to complete.

Tony

 

[freedonian]

Thanks for the warnings

I'll take it very slowly and carefully. If at any point I feel I'm getting in too deep I'll call in a professional.

Alpha quoted me in the £246 and British Gas £150 for fixed price repair.

That's why I'm here. I do heed your advice and won't be doing any thing silly to save a few quid.

All the best

 

[nogoodatfaultfinding]

Every time im called out to an Alpha Combi with hot water problems i pray its just the black flow switch fault (which is a really common fault) as i have changed a couple of diaphrams on these and struggled like hell due to where they are situated and also due to the heat exchanger needing to come off.
My advise mate is to get a local engineer out or call Alpha (although i beleive they are now part of homeserve who would rather condemn every boiler than fix it) to see how much to sort your problem.
Try to fix this at your peril as i know engineers with 20+ years experience who would not go near this job due to the complications of putting the thing back together without leaks.
And please do not think i am scare mongering as i really am not.

 

[freedonian]

Ok I appreciate the advice

I'm not going to touch it.

I'll just have to bite the bullet and call a professional in.

Thanks to everyone for all your advice

Bye

 

[Agile]

BG would normally put in a new diverter valve and as they cost about £130 then the whole ( difficult ) job done for £150 must be a bargain.

Tony

 

[gas4you]

This is a harder than most diaphragm change, especially for a diyer.

I have yet to have any problems with leaks after replacing a diaphragm on this boiler.

I always use the new seals supplied with the kit though.

Can't remember the price of the kit, but I think it works out at about £90 + VAT ish for the complete job.