Alpha CB28X - Is my Diverter Valve Assembly Broke?

[julesg007]

Hi again,

Got the DVA out and the diaphragm was completely sha**ed. It was practically falling to bits, totally water logged and split nearly half was round. Not at all surprised I wasn't getting HW!!!!!

Anyhow, I hope the replacement sorts out my problems and there are no other issues to sort out and if it does the £21 paid for it and a bit of my time seems well worth it.

Your help and guidance are greatly appreciated.

Looking forward to your comments before putting everything back together.

Regards

Jules

 

[Agile]

Tony, was wondering if the is anything else other than just rinsing the HE with clean flowing water to clean it?

Nickso, I am having problems releasing the room sealed cover, have undone the 4 screws as per the instructions, but it seems solid, is there anything I can do to try to release it as I don't want to damage to seal.

Was wondering how to check the expansion vessel pressure?, am only a DIY'er and don't have any specialist tools. Also presume the PRV is the pressure release valve?

Regards
Jules

You need to clean the plate with appropriate chemicals but only IF you are competent to work with Citric acid or HCl !!!

I dont know what you mean by room sealed cover but if its the combustion chamber then you should not be opening it anyway!

Look in the FAQ for repressurising the EXV. You need a car foot pump with pressure gauge.

Tony

 

[julesg007]

Hi Tony,

Thanks for the further advice.

Not to sure about the cleaning fluids mentioned for cleaning the HE, so going to leave it, prior to my problems the other aspects of the boiler seemed to be working OK so having going to assume everything else is also OK.

Was going to give the boiler a general clean, but as I was unable to get to the combustion chamber I am going to leave it. In retrospect I have decided not to get into any areas that involve the Gas side of the boiler.

Will look at FAQ's for repressuring the EXV.

Thanks again

Jules

 

[julesg007]

Yippee, I've got hot water.

Everything went back together fairly easily, but there was a small drip between the 2 parts of the DV - after spliting the DV I found there wasn't a replacement O ring in the kit. So after getting a replacement all is fine with no leaks or drips.

Just a point of interest, I was going to re-pressure the EV as advised but was unable to find the valve. So I spoke to Alpha and they advised that this wasn't necessary and all I needed to do was to set the cold pressure of the boiler (1 bar) using the pressure guage of the boiler. So that's what I done and all seems fine.

So with that done and all valves re-opened, kitchen tap on and instant hot water.

Thanks for all your help it has been greatly appreicated.

Regards

Jules

 

[nickso]

alpha are talking cobblers, the valve is on the expansion vessel. look over the top and between the combustion chamber and the wall is the EV. the valve will be clearly visible if not particularly accessible.

if the water pressure is staying constant when hot and cold then leave it for now. you will need to repressurise it at some point though.

 

[julesg007]

Hi Nickso,

Thank you for the advice.

With regards to the EV, on my particular model it is situated within the room sealed chamber/part of the boiler, and to be honest this is an area which I didn't really want to get into unless I really had to, although I did undo the 4 retaining screws on the cover but it didn't want to release to easily so I left it alone.

I have in the past drained the system and when refilling have just used the pressure gauge, setting to 1 bar and both the CH and HW sides of the boiler seem to be fine. The only problem I have had with the boiler is the current issue concerning HW.

I would be grateful if you could advise why I would need to re-pressure the EV at some stage in the future. As I am no boiler expert I am a little confused as to why I need to do this and what is achieved by doing it.

Thanks and regards

Jules

 

[nickso]

nope, cb28x EV is where i said it is, not in the combustion chamber

if it loses its air pressure then the water pressure will rise significantly during heating, this usually results in pressure loss through the PRV. this is when you have to repressurise it.

 

[julesg007]

nickso,

Must say that I don't recall ever having a problem with keeping the system pressure or excessive pressure, but I have just read something on the issue and basically the manual states that if the pressure exceeds 2.5 bar when operating I need to re-pressure the EV. Now I know about this issue I will keep a closer eye on things.


I agree that the the EV is not in the combustion chamber, but within the room sealed section of the boiler, which the combustion chamber is also in. As stated when I did undo the room sealed chamber cover screws the cover plate didn't want to come free, so I left it as I did read in the manual that you should not damage the seal. Knowing my luck I would have totally buggered it and gave myself even more problems to solve.

Regards

Jules