problem with boiler: Alpha CB28

sevenonine

I have an old Alpha CB28 combi boiler on which the needle drops just below the green (safe) area. I toggled the loop switch to get it above the green area and the water filled but the needle swung to well beyond 1.5 bars, which I believe is the optimum area. It's now at 2 bars. How can I get back to the 1.5 bar? The switch doesn't move anti-clockwise or should I try it clockwise (to the right), which I thought I had done to fill the water.

I don't really know much about boilers and was shown this process by a neighbour who had earlier adjusted the boiler for me; unfortunately the neighbour is not available at the moment.

Is it safe to use the boiler to heat the house and for showering - as long as the needle is above the green area?

Or should I get a gas engineer in!

Browntoa

If you have a bleed valve for a radiator you can release pressure that way , you'll need something to catch the water like an old towel

CashStrapped

When was it last serviced?

Read this:

https://www.williamsmithheating.com/184_PressurisingYourSystemandExpellingExcessAir.html

Browntoa

http://www.diydoctor.org.uk/projects/bleedrads.htm

carguy143

Hi.
I also have an alpha boiler and find the running pressure can be varied by turning up or down the boiler temperature.

The instruction guide for your boiler recommends the pressure is at 1 bar when cold. When running, the working pressure could be anything between 0.5 to 2.5 bar. There's a safety valve that releases pressure if the boiler reaches 3 bar.

Here's a link to the instruction guide.

https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.alpha-innovation.co.uk/custom/upload/instructions/Old%2520models/CB24%252028%2520Installation%2520and%2520Servicing%2520Inst.pdf&ved=0ahUKEwjQgNuK4Z7QAhWKL8AKHerkBk4QFggaMAA&usg=AFQjCNGRds33Y4udVKqjiEzakuMclk-4hA&sig2=V_blaLwR9cWtEYtLUoGtXA

sevenonine

Browntoa wrote: »

If you have a bleed valve for a radiator you can release pressure that way , you'll need something to catch the water like an old towel

Thanks Browntoa I have just bled the valve and got the needle to move to the upper end of the green area - which gives it ample space to move within the green area. I'm going to turn on the heating and see how the needle moves.

I last had a power flush done in September 2015 - the engineer took some 3 hours and charged me £280 - he also caused an overflow which he tried to hide by using up 2 tissue rolls!

Can you suggest a reliable website to obtain another power flush or for advice on getting a new boiler. So far I think I can carry on with the present boiler.

carguy143

If it's the cold pressure that's too high you could always connect the filling loop to the boiler and place the other end in a bucket and slowly open the valve to drain water that way.

sevenonine

carguy143 wrote: »

Hi.
I also have an alpha boiler and find the running pressure can be varied by turning up or down the boiler temperature.

The instruction guide for your boiler recommends the pressure is at 1 bar when cold. When running, the working pressure could be anything between 0.5 to 2.5 bar. There's a safety valve that releases pressure if the boiler reaches 3 bar.

Here's a link to the instruction guide.

https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.alpha-innovation.co.uk/custom/upload/instructions/Old%2520models/CB24%252028%2520Installation%2520and%2520Servicing%2520Inst.pdf&ved=0ahUKEwjQgNuK4Z7QAhWKL8AKHerkBk4QFggaMAA&usg=AFQjCNGRds33Y4udVKqjiEzakuMclk-4hA&sig2=V_blaLwR9cWtEYtLUoGtXA

Thanks, this is valuable advice; I thought it had gone too far at 2! It's now between 2-2.5 and I hope it doesn't get to 3. I am always a bit worried when it strays outside the green area but you say it is safe even at 0.5.

As an "ing!nue" this forum has helped me sort this problem out - if indeed the boiler will carry on performing as before.

Any advice on getting a power flush until I can research availability of a replacement boiler?

carguy143

sevenonine wrote: »

Thanks, this is valuable advice; I thought it had gone too far at 2! It's now between 2-2.5 and I hope it doesn't get to 3. I am always a bit worried when it strays outside the green area but you say it is safe even at 0.5.

As an "ing!nue" this forum has helped me sort this problem out - if indeed the boiler will carry on performing as before.

Any advice on getting a power flush until I can research availability of a replacement boiler?

The green zone is the ideal pressure range when cold. I think mine even says on the gauge that it's only accurate when cold.

I'm not sure if the link works for you or not but if you google your boiler make and model the first result that popped up was the instructionsd manual. I've not got a clue about flushing unfortunately as I've only been in my first house around a year. I just know what I do about the boiler as I spent a lot of time tweaking the boiler and radiators working together to get the house consistently warm in all rooms.

macman

Why on earth do you think you need a new boiler or a power flush? All that is happening is that the filling loop valve is not closing off fully when you turn it off, so water continues to flow in and the pressure mounts. Either the valve is not quite correctly set to 'off', or you need the filling loop replacing. About £15 last time I bought one. It's a simple 10 minute plumbing job to replace that: you don't need an RGI, as the work is external to the boiler and does not involve the gas supply.
Don't let the pressure continue to mount, because if you do, the PRV will lift to release the pressure and then you'll probably have to replace that as well, which is a job for an RGI (though not a major one).

sevenonine

macman wrote: »

Why on earth do you think you need a new boiler or a power flush? All that is happening is that the filling loop valve is not closing off fully when you turn it off, so water continues to flow in and the pressure mounts. Either the valve is not quite correctly set to 'off', or you need the filling loop replacing. About £15 last time I bought one. It's a simple 10 minute plumbing job to replace that: you don't need an RGI, as the work is external to the boiler and does not involve the gas supply.
Don't let the pressure continue to mount, because if you do, the PRV will lift to release the pressure and then you'll probably have to replace that as well, which is a job for an RGI (though not a major one).

Thank you for your above comments - I wish I'd returned to this page sooner but had to deal with other problems. You're quite right: I ought to replace what needs replacing rather than getting a new boiler and you've probably correctly identified the problem; but it'll be difficult finding a plumber in the first place and then telling him what needs to be done as he'll suss I'm a novice. What is the PRV (some kind of valve)?

At present I run the boiler for short periods - 15 mins - and the needle goes just past the 2 mark. When at rest it is in the middle of the green area. Does this mean the PRV will need replacing?