ALPHA CB 24/28 BOILER.
Hi all,
I had some trouble with my Alpha cb24/28 boiler over the past few months, firstly the boiler lost pressure when the heating was switched off and we had to refill it using the water fill loop before switching the heating back on,it was then usually ok for the rest of the day until we switched the heating off and again it would then empty!
We also had an issue with the hot water in as much as it stopped working altogether a few months ago, no sad loss as we only shower and have a dishwasher so no real need for tapped hot water.
I had a plumber round a couple of weeks ago and he told me the pressure vessel had gone along with a pressure release valve and it would cost me £350+ to put it all right or he could fit a new boiler for £1100.
Well I pondered this over and thought I would do some searches of the net for this problem,one such search brought me here which gave me some pointers as to what the real problem was, so thanks guys wether from this site or the others!
I will give a brief run down of what was happening and then how I fixed it!
THE CAUSE.
1. No hot water (got worse over weeks then none at all).
2. Central heating boiler would only hold pressure when the heating was switched on and running.
THE FIX.
1. Purchase a DHW diaphragm kit from any good merchant, PART No(ALPHA 3.013389). I paid £31 for one but you can get them slightly cheaper.
HOW TO FIX.
Turn your mains power to the boiler off, turn your cold water supply off at the mains.
Remove the two self tapping screws from the front panel and the front panel will drop down (still attached!) revealing the pipework etc underneath the boiler.
Place a bowl underneath the boiler to catch any dribbles of water you may get.
You will see a small red knob at the front, turn/push this and it will empty the pressure from the boiler.
To the right of the boiler you will see the pump, there are two pipes coming from it, one on top and one bottom,firstly completely undo the top pipe (large adjustable spanner!),when the top pipe is fully undone then undo the bottom pipe, there should be a little water escaping but not torrents just whats left in the pump.
Carefully remove the pump to the outside of the boiler and out of the way,leaving the electrical wire attached.
To the left of where the pump was situated you will see the DHW flow valve, again this has two pipes going into it,one pipe in the top and one in the bottom. The valve is in two parts and is screwed together with 4 cross head screws, you are going to remove the side of the valve closest to where the pump sits!
The top pipe goes into the DHW heat exchanger, undo the top pipe completely. Now remove the four cross head screws from the DHW valve.
Remove the half of the DHW flow valve casing you have unscrewed, you will find a rubber diaphragm and large spring inside, on inspection the diaphragm will be perished with holes in it? .
In the kit you brought there will be loads of washers etc and a tube of liquid grease, clean all the seated areas of the DHW valve up, liberally,grease both sides of the valve up and the diaphragm where it will sit on the valve.
Carefully replace the new diaphragm into the situated side of the valve and replace (not forgetting the large spring!!) the opposite casing you removed, when you have seated the valve halves together then replace the four crosshead screws you removed, as the valve is sprung loaded then tighten the screws up alternately making sure the two halves of the valve go back together evenly and fully.
Ok, thats the DHW valve back together and about to work as it should again.
Reconnect the top pipe to the DHW valve and tighten, I used new fiber washers (1 of) when replacing the DHW pipe and the pump pipes which can be brought as a kit when you buy the diaphragm for £10, they looked ok but I replaced them any way!
Refit your pump in reverse to how you took it off, again using new fiber washers (2 off).
Thats it basically, refill the boiler with the fill loop until the pressure is in the green (after first turning your mains water back on!).
Try your hot water, turn all the hot taps on firstly to bleed any air through then just wait for hot water to come through.
PRESSURE KEEPS DROPPING.....read on.....
Locate your pressure vessel, which like mine maybe at the top rear of my boiler, it has a valve on top of it pretty much the same as the one on a car wheel.......
........turn the heating off and wait for it to be stone cold, taking a car foot pump, fit it to the valve and pump 0.8 bar into it in total! I pressed the valve firstly and emptied it before starting, I also used a digital car tyre type pressure gauge to check for the correct pressure as they read in bar as well as psi.
ok with the pressure up to 0.8 bar, take a look at your pressure gauge at the front of the boiler, it should be reading somewhere in the green segment, if it is higher then simply, gently turn/press the red knob (front of boiler) until it reads in the green.
That's it!!
very long winded explanation I know but if you print it out and follow then if your problems are the same as what mine were this will fix it for less than £40.
I am not an engineer and only moderately handy with tools and the whole job took me approximately 1 hour to complete with no prior plumbing experience etc!
Let me know if it helped!
Regards,
Paul
Hi all,
I had some trouble with my Alpha cb24/28 boiler over the past few months, firstly the boiler lost pressure when the heating was switched off and we had to refill it using the water fill loop before switching the heating back on,it was then usually ok for the rest of the day until we switched the heating off and again it would then empty!
We also had an issue with the hot water in as much as it stopped working altogether a few months ago, no sad loss as we only shower and have a dishwasher so no real need for tapped hot water.
I had a plumber round a couple of weeks ago and he told me the pressure vessel had gone along with a pressure release valve and it would cost me £350+ to put it all right or he could fit a new boiler for £1100.
Well I pondered this over and thought I would do some searches of the net for this problem,one such search brought me here which gave me some pointers as to what the real problem was, so thanks guys wether from this site or the others!
I will give a brief run down of what was happening and then how I fixed it!
THE CAUSE.
1. No hot water (got worse over weeks then none at all).
2. Central heating boiler would only hold pressure when the heating was switched on and running.
THE FIX.
1. Purchase a DHW diaphragm kit from any good merchant, PART No(ALPHA 3.013389). I paid £31 for one but you can get them slightly cheaper.
HOW TO FIX.
Turn your mains power to the boiler off, turn your cold water supply off at the mains.
Remove the two self tapping screws from the front panel and the front panel will drop down (still attached!) revealing the pipework etc underneath the boiler.
Place a bowl underneath the boiler to catch any dribbles of water you may get.
You will see a small red knob at the front, turn/push this and it will empty the pressure from the boiler.
To the right of the boiler you will see the pump, there are two pipes coming from it, one on top and one bottom,firstly completely undo the top pipe (large adjustable spanner!),when the top pipe is fully undone then undo the bottom pipe, there should be a little water escaping but not torrents just whats left in the pump.
Carefully remove the pump to the outside of the boiler and out of the way,leaving the electrical wire attached.
To the left of where the pump was situated you will see the DHW flow valve, again this has two pipes going into it,one pipe in the top and one in the bottom. The valve is in two parts and is screwed together with 4 cross head screws, you are going to remove the side of the valve closest to where the pump sits!
The top pipe goes into the DHW heat exchanger, undo the top pipe completely. Now remove the four cross head screws from the DHW valve.
Remove the half of the DHW flow valve casing you have unscrewed, you will find a rubber diaphragm and large spring inside, on inspection the diaphragm will be perished with holes in it? .
In the kit you brought there will be loads of washers etc and a tube of liquid grease, clean all the seated areas of the DHW valve up, liberally,grease both sides of the valve up and the diaphragm where it will sit on the valve.
Carefully replace the new diaphragm into the situated side of the valve and replace (not forgetting the large spring!!) the opposite casing you removed, when you have seated the valve halves together then replace the four crosshead screws you removed, as the valve is sprung loaded then tighten the screws up alternately making sure the two halves of the valve go back together evenly and fully.
Ok, thats the DHW valve back together and about to work as it should again.
Reconnect the top pipe to the DHW valve and tighten, I used new fiber washers (1 of) when replacing the DHW pipe and the pump pipes which can be brought as a kit when you buy the diaphragm for £10, they looked ok but I replaced them any way!
Refit your pump in reverse to how you took it off, again using new fiber washers (2 off).
Thats it basically, refill the boiler with the fill loop until the pressure is in the green (after first turning your mains water back on!).
Try your hot water, turn all the hot taps on firstly to bleed any air through then just wait for hot water to come through.
PRESSURE KEEPS DROPPING.....read on.....
Locate your pressure vessel, which like mine maybe at the top rear of my boiler, it has a valve on top of it pretty much the same as the one on a car wheel.......
........turn the heating off and wait for it to be stone cold, taking a car foot pump, fit it to the valve and pump 0.8 bar into it in total! I pressed the valve firstly and emptied it before starting, I also used a digital car tyre type pressure gauge to check for the correct pressure as they read in bar as well as psi.
ok with the pressure up to 0.8 bar, take a look at your pressure gauge at the front of the boiler, it should be reading somewhere in the green segment, if it is higher then simply, gently turn/press the red knob (front of boiler) until it reads in the green.
That's it!!
very long winded explanation I know but if you print it out and follow then if your problems are the same as what mine were this will fix it for less than £40.
I am not an engineer and only moderately handy with tools and the whole job took me approximately 1 hour to complete with no prior plumbing experience etc!
Let me know if it helped!
Regards,
Paul
