alpha

[fitz1]

how easy is it to change dhw diaphram on an alpha cb24x.

 

[gas4you]

I think the plate heat exchanger has to come out first. Not too bad a job but a bit more fiddly.

 

[fitz1]

diaphram is 25 +vat.i need an idea of time scale.is it 20 min baxi type change or a2hr worcester type.

 

[gas4you]

I'm not an expert on these but the last one I did took about an hour if I remeber rightly. Also need new 'o'rings for plate he to be safe.

Paul Barker probably does this in half the time and maybe has some time saving tricks

He's the Alpha man

 

[nickso]

1/2 hour for someone whos done it a lot.

probably 2 hours for someone who hasnt.

 

[Paul Barker]

Isolate f/r cold feed, drain boiler only, take the pump off, leave it hanging, undo only the 1/2" fibre washer union on the dv manifold diaphragm housing to heat ex, remove diaphragm housing screws hold it together against the spring might need a tap to shift it then it'll fly off. replace diaphragm careful (very careful at this moment) that the diaphragm housing doesn't pinch any part of the diaphragm. If diaphragm doesn't seat properly square at tthis moment it will leak after all your good work. The nut on top to the plate is an absolute sod to light up that it to angle it right and psoition it right and get the nut started. Non of them line up easily, sometimes the other two unions have to be loostened to allow sufficient positioning flexibility to get the one you are doing started.

Replace pump.

Need new 1" pump washers, one new 1/2" washer. The pump washers don't come in kit so get those yourself.

If you head the warning about arrangeing diaphragm square on and you have strength and dexterity to position the union with the dv which won't make it easy for you, the job is 1/2 hr start to finish. If it goes wrong for me, which it sometimes does it takes another 1/2 hr to repeat with more care, and probably loostening more unions.

It is easier than a worcester junior harder than a baxi 80/105e.

 

[gas4you]

I thought that it looked like the pump would have to come off on first inspection, but after reading the sertvice manual I followed this and took the plate he off.

Just goes to prove there are more ways to skin a cat when you now how

 

[nickso]

i do it by removing the plate h/e like dave.

i see no value in removing the pump as doing it that way usually leaves the other unions on the plate h/e leaking anyway.

oh yeh and, paul, you are a brave man to isolate an alpha with the F/R valves. dont think ive ever seen a set of them tampered with that dont leak .....even the ones left well alone will leak if you breathe on them.

 

[gas4you]

And at over £40 + VAT for the pair are quite expensive to replace.

Re post last night are these the same as Baxi's and cheaper as well?

 

[Paul Barker]

i do it by removing the plate h/e like dave.

i see no value in removing the pump as doing it that way usually leaves the other unions on the plate h/e leaking anyway.

oh yeh and, paul, you are a brave man to isolate an alpha with the F/R valves. dont think ive ever seen a set of them tampered with that dont leak .....even the ones left well alone will leak if you breathe on them.

I haven't had a leak from an iso valve on a in warrantie boiler, but in an older boiler you would not trust them. It just facilitates screw removal better and I find pump removal a piece of cake.

Not removing the plate is only a problem in respect of the strength needed to hold it into position for geting the thread started on the one connection you have undone. Many times that is relatively easy for standard gas fitter grip abilities, when it isn't loosten the others, which don;t leak if they were in good condition but if they weren't you would remove the plate and renew the washers anyway. The red o ring should always be renewed when you go this far, and sometimes the ones at the top of the pipe where it goes into the primary heatex on the cb range has to be changed due to the disturbance, or if inspected can be seen to have leaked, so wants changing anyway. It has to be the manufacturers part or it won't last long.

 

[nickso]

we get the giannoni kits and i find them very good for keeping sealed for a long time after removing the plate h/e.

btw i have very little faith in the manufacturers fibre washers. they seem to leak far too often and too easily.

 

[avidfan]

Had a within guarantee visit from an Alpha service tech the other day and got talking to him about the diaphragms on the CB range (wasn't you Paul). He told me that it was a false economy to change just the diaphragm as you you can't be sure that anything else needs changing. He said he always changes the complete dv. Seems a bit expensive, but this is what he said.

 

[Paul Barker]

Yes we were told to change the whole dv, but I have only had one in warrantie boiler that needed the primary side changing, so I have adapted my technique to changing the diaphragm as they stock us with 5 diaphragms and one DV, and on the Biasi training day the gadger Mike someoneoranother really ramed it in about reconditioning parts like the dv not just changing them, but he also made the point that you shouldn't leave in a part that didn't fix the boiler as you could be introducing a new fault. So I now work to the minimalist principle of geting the exact fault fixed and leave everything else well alone.

 

[Gasguru]

Giannoni diverters often run for 10 years or more before sticking (and thats on old systems full of muck) so unless its required I'd just change the front end.