Alpha CB28 Problems

[ekcopyephilips]

Hi all

Im about to fit a diaphfram (excuse the spelling) kit to my Alpha CB28 boiler that it not firing up unless the hot taps are full on.

Im aware i need to remove the heat exchanger and divertor valve to do this, but is there anything else i need to be aware of before i start to do the job ?

Also while i have the heat exchanger off, should i give it a clean out, as ive heard that clogged ones can cause hot water problems, if so what product/method should i use to descale/clean it ? White the unit is apart should i drain the cyclone of any derbis, should i also clean out the cold water inlet filter ??

Any help would be welcomed

Many thanks

Mike

 

[Kristoflampie]

These diverters have a strong spring in the diaphragm section so dont lose the bits !! and be very careful you put it together in the way it came apart. Also the 0 rings to the cold main connection are very suspect and leak more often than not so new ones and silicone grease to put the rings in with are a good idea. The mains connection will rise up on the o rings to its retaining screw when the main is turned back on so make sure its located correctly and tight or it will blow off . New washers at all the connections and you should be okay, all the bits come in the service kit aprt from the o rings.
Good luck....... dont get wet!!

 

[ekcopyephilips]

Hi everyone

Fitted the diaghphram kit this morning, started at about 8am, so i guess it took me 4 hours. It was fairly simple to do, access is limited so take off the front and sides too if you can, although it can be done with the sides in situ.
The faulty initially was no hot water unless the hot tap was fully on, this was confusing as the fault was appearing intermittently, the old diahgpram was roton and just starting to split. upon reasembly everything works fine, boiler now fires with a slow flow of hot water and thermostatic mixer shower now happily works again.
I would advise anyone who has not done one of these before and is thinking of doing so to start as early as possible in the morning and have good sharp tools and spanners available. This way you will avoid damaging any parts.
i've uploaded some pics for you to see as the Alpha CB24/28 boilers seem to be increasingly cropping up on here with faults. This boiler is only years old !!!
Hope this is of help to everyone.

Mike

p.s. Pics are in my album - i presume you can all see them

 

[nickso]

job well done. 4 hours isnt bad for your first go.

now that you have disturbed it the boiler may start leaking in places that you haven't touched. open it up in a week and check everything. the big nut on the left of the diverter can sometimes be a real pain in the arse to seal for any reasonable length of time. also check regularly for leaks on the mains water side as if it leaks there it usually rusts the tiny screws making them hard to get off again.

 

[ekcopyephilips]

Hi Nick

you must be telephathic

even though i didnt touch it, once it was all back together there was a small drip from the DHW outlet manifold. I found this to be quite loose, so tightened it right up. Odd how it didnt manage to leak before.

I was also surprised to find that even though east anglia is a hard water area there was no scale in the heat exchanger, absolutely nothing !

Mike

 

[Agile]

The plate hE does not get hot enough under correct working conditions to deposit lime scale.

The propblem is caused by rusty dirt which formed as oxidation of the steel on the inside of the rads.

I donk know how hard you tried but the way to check it quickly is to fill with water and shake it out from the flow in port. usually a few flakes come out.

If yours was really clean then you are really lucky!

Tony

 

[ekcopyephilips]

Hi Tony

I did wash out the F &R ports on the heat exchanger and a fair amount of rubbish came out, nothing huge, just the size of tea leaves, i guess this is enough to block it totally in time.
The whole system was drained down and has fernox added in 2007, so im hoping this will stop any further corrosion.
Should i have undone the bottom of the cyclone ? I was tempted but as i didnt have a new washer for doing it up again i left well alone.
Maybe it needs a power flush in time. Whats involved with one of those, is it something i can do myself ?

Mike

 

[nickso]

if its working fine right now leave it alone. if it develops problems in the future come back and ask.