New GUY with alpha cb24x boiler. I know!!!!!!!!!!!!!

[richie rex]

Hi all, I am new on here and at the end of my tether with this boiler.

It was fitted around 10 years ago by a jobbing builder type and was little used but never worked properly.

It used to switch off half way through a shower which would entail running downstairs and battering it. This seemed to work for a while.

Then the transformer tried to detach itself from the PCB. I managed to resolder that and also found a switch faulty up at the top right of the boiler.

Now everything worked except it lost pressure every time the heating was used and had to be refilled. It would appear that it has never had an expansion pressure vessel fitted. I cannot find one to pump up.

So now the switch that should operate when the water flows over 2.5 litres/min does not operate until the tap is virtually full on and so the water never gets really hot. I have ttried the black plastic switch that controls this function and it works perfectly when operated by hand, letting the plunger out and stops when I press the plunger up.

So, what causes the switch to operate, I know it is initially the flow of water, but what releases the plunger on the switch and how can I mend it, many thanks and Happy New Year to all. :dunce2:

 

[jtsplumbing]

Cuck it on the scrap heap !!

 

[brightcrow]

i believe there is a bladed sensor or Direct Hot Water (DHW) switch which screws into one of the pipes internally. see

http://www.alpha-innovation.co.uk/custom/upload/instructions/Old%20models/CB24%2028%20Installation%20and%20Servicing%20Inst.pdf


Tend to agree with JTS... scrapheap best place for it!

 

[wheeto]

Slightly off topic, but section 3.4, page 6 says:

"For horizontal flues ensure there is a slight downward slope towards the terminal."

Really?

Edit: D'oh,just seen this isn't a condensing unit! Ignore me...

 

[Alpha man]

Hello new guy, you either need a new divertor valve or diaphragm which is in the DV, possibly a flow switch as well,

The expansion vessel is at the rear of the boiler and only accesable from the top of the boiler,

Had it serviced recently?

 

[richie rex]

Thanks for the quick replies, scrapheap is a no no. not heavy enough to weigh in.

Alpha man, is the expansion vessel a standard fitting. Is it there or is it an option, ie internal or external. I understand the need for one to absorb the pressure increase when the water expands. Mine just blows it out of the vent pipe, unless it freezes up like last year, then I got a very high pressure reading!!!!!!!!!!!

The electrical switch on the flow valve works ok. I have tried it while removed and the boiler kicks in and out.

could it just be a diaphram. would a service clear the problem? many thanks for all replies.

 

[Alpha man]

If its leaking from the relief valve outside, the vessel is empty and it needs recharging (normally checked on every proper service), the relief valve needs changing, when was the HW flow switch last replaced?

A service will possibly only cure the vessel problem, the diaphragm is a wear and tear item and PRV will need replacing due to lack of charge in the vessel.

Hope that helps,

Were are you based?

 

[richie rex]

Hi Alpha man, I am in Middlesbrough.

The vessel has never been charged as far as I know. The relief valve operates at around 2.8 - 3 bar and lets the water out. I have always had to refill it when the heating cools down.

It seems to me that the diaphram is now not operating the flow switch until the water flow is higher than before.

If I could find the valve, I could pressurise the vessel. about 0.8 bar I believe.

So would a diaphram and a pump up get me going?

Service then maily for the gas side!

 

[Alpha man]

You'll need a new 3bar PRV, diaphragm repair kit or worst case a divertor valve and recharge the vessel,

Best bet would be to get a GSR engineer in to do the lot in one go, will be cheaper and done once, (Hopefully) LOL.

Goodluck!

 

[richie rex]

Thanks for your very prompt reply and information. I still think if I could find the pressure vessel and change the diaphram, that could cure it. But anyway, I am on the look out for a good local engineer in the meantime. Many thanks again.