Alpha CB28

[darren wright]

I have an Alpha CB28 boiler. The water in the shower keeps going hot and cold. ie 1 min to get hot | hot for 30 seconds | cold for 45 seconds | hot for 30 seconds....

The engineer that installed it is not sure what to do.

Any ideas?

 

[Paul Barker]

Do red lights a or b or both come on at all?

 

[darren wright]

b flashes green every 10 seconds.

In the kitchen downstairs I have no problem and I also have much more pressure.

 

[Paul Barker]

1/ So that is normal standby mode, what does it do when you are having trouble with your hot water?

2/ You have normal hot water in the kitchen.

Does that tell you something about the shower?

Tried the other taps upstairs?

Isolate cold supply to boiler just underneath and open a hot tap which is on it's own, i.e. not blended and coming out of one spout. Does water come out? Yes? you have a mono or mixer or shower valve that is letting cold mains through to hot water. Go round house listen to all taps including showers that could be responsible. Even if you don't hear anything fiddle with them, adjust them, see if you can get the water to stop flowing from the hot tap. Assuming it is not the shower, now turn on isolation valve under boiler and take a shower.

 

[darren wright]

Paul

I still having problems with my boiler.

I'm not sure how to isolate the supply as you advised below.

It isn't just the shower it also effects the taps (not mixers) in the bathroom.

The pressure is always going below green and I have to top it up every few days - more if I have the heating on. Sometimes I top it back up to within the green markers and when I check later it is upto 3-4 bar.

My installer has taken a look and says there are signs of leaking withing the bolier. He is not sure what to start replacing first - he said he has installed 20 of these boilers in the past and had callbacks on 18. He mentioned the plate heat exchanger. But does not wwant to start changing and charging me for components that may not fix it.

What do you suggest? I have 2 kids under 2 years and want to get it sorted before winter.

thanks

 

[Agile]

I suggest you get a competent engineer who can repair boilers and not just install them.

Its possible the plate heat exchanger is blocked because the installer did not power flush the system.

The leaks need to be fixed because every time its refilled the water contains more oxygen which rusts the rads and cause dirt which can block the plate HE.

If its been leaking like that for more than a few days it may be that the rust produced has blocked the plate HE.

Tony

 

[darren wright]

Thanks

Can anyone recommend a good engineer - I live in Chessington

 

[Agile]

That sounds like Chris R territory.

You can contact him via his profile on this site.

Tony

 

[Paul Barker]

As Tony says you want someone like Chris to it.

They often show signs of leaks but these don't amount to any pressure loss. Tracks of scale where water has been can frighten inexperienced engineers but seldom amount to a problem.

Much more likely a leak in the rest of the system which is easily proved by someone competent like Chris, or possibly but less likely expansion vessel pressure relief valve problem, also easily sussed.

It could quite easily all be sorted out for £100, but may involve more, though a competent service person could tell you within 10 minutes what it is and how much it would cost.

The guy who is scared to start on it and has fukced up 18 out of 20 isn't the one to have round.