Alpha CB28 boiler problem - advice please

sevenonine

My problem Alpha CB28 boiler is still limping along. I've been told in this forum that the expansion valve may need replacing, for which I need a Corgi registered engineer. I've been trying to find someone but without success due to the intervening Christmas season.

Online I've been in touch with a couple of companies but I need advice on the following -
1. what is a reasonable call-out charge and is it additional to the total cost, if I agree to the work going ahead?
Also, how to get a couple of quotes if I'm charged a call-out charge each time? And by the way, why is a call out charge based on the engineer being Corgi - shouldn't he be qualified anyway?

2. What is the likely cost of replacing (a) the expansion valve – is this the same as the pressure valve?
(b) the filling loop, VAT extra

System

Look here for a Gas Safe Registered engineer. By law, only GSR engineers can work on gas appliances.

https://www.gassaferegister.co.uk

Most plumbers/engineers will not charge for a quote: however, if you are asking one to come out during Christmas and the New Year then they are likely to want an Emergency Callout payment in addition to labour and parts.

PS

Gas Safe Register replaced CORGI as the gas registration body in Great Britain and Isle of Man on 1 April 2009 and Northern Ireland and Guernsey on 1 April 2010.

sevenonine

Hengus wrote: »

Look here for a Gas Safe Registered engineer. By law, only GSR engineers can work on gas appliances.

https://www.gassaferegister.co.uk.

I understand why there may be a charge during this period but I tried in early December2016 - one company quoted £95 + VAT just to investigate a leak.

The boiler still heats the house but I am prepared to wait and get some quotes. I don't want to get a new boiler unless this one is beyond repair, especially as it's still working. I 've been told it might be just the expansion valve and even if a power flush is would work, it might be more acceptable than a new boiler cost.

sevenonine

Any chance I can get someone to chat re my boiler prob. As I've said it is limping along - I use the filler loop to fill when the arrow moves out of the green (safe) area and into the red area. I also make sure I've turned off the filling knob. Is it still safe if the arrow moves up to the 2 mark when the shower is used. I was told by the plumber who did the power flush in Sept 2015 it was OK. The arrow moves to the green area when the system cools.```

Rubidium

You seem a little confused and your description is not too clear. The system pressure when cold should be between 0.75 Bar and 1.25 Bar, this is the green segment shown on the pressure gauge. If yours is dropping down to the red area, that is less than 0.5 Bar and you have a leak either in the boiler or in the central heating circuit e.g. a weeping radiator valve resulting in the system needing to be re-pressurised to 1 Bar again. If this leak can be located and fixed then the boiler should then be fine and could continue to works for many more years.

If the pressure when cold is set to approx 1 Bar in the green segment and it rises up to 2 Bar then that is fine.



The pressure release valve PRV will operate if the system pressure exceeds 3 Bar but from what you have said it doesn't rise that high. This should only operate in a serious fault situation but if it has operated then it may need replacing as they often won't fully seal after being triggered.

There is no such thing as a expansion valve, it is referred to as the pressure vessel, this pressure vessel is what absorbs the rise in system pressure from 1 Bar when cold to 2 Bar when hot.

Hope that helps.

Mr.Generous

Its going to cost me a bit less than £200 for a new expansion vessel and pressure release valve on a Worcester Bosch, I am going to help remove kitchen door, hold stuff, pass tools etc to keep price down.

sevenonine

Rubidium wrote: »

Apologies for my late acknowledgment of your response. Many, many thanks for your wonderfully clear explanation and for correcting the name of this connector(?): “pressure vessel“. I plead ignorance as a lay person, with no knowledge of the workings of this boiler which is vital to maintaining my comfortable existence!

[If yours is dropping ….to less than 0.5 Bar and you have a leak either in the boiler or in the central heating circuit... resulting in the system needing to be re-pressurised to 1 Bar again.] This does arise, only occasionally, and I have been opening and closing the release of water until the arrow returns to the green area. Obviously, I'm don't feel capable of identifying the origin of the leak.

[if the system pressure exceeds 3 Bar...] I admit that on occasion it may reach 2.10 – eg when I've been showering but the arrow returns to the green area shortly - it's still worrying.

[If this leak can be located and fixed then the boiler should then be fine and could continue to works for many more years.]

I would much rather it can be fixed and I now have, at the very least, some insight into the working of the boiler but it's proving difficult to get anyone to come.

May I finally refer to my earlier post that when showering, the water runs cool for a few seconds – is this a side effect of the leak?

Again, many thanks for your advice.

sevenonine

Rubidium wrote: »

You seem a little confused and your description is not too clear. The system pressure when cold should be between 0.75 Bar and 1.25 Bar....
I have had to reset it to the green area, several times a week.

If the pressure when cold is set to approx 1 Bar in the green segment and it rises up to 2 Bar then that is fine..... but from what you have said it doesn't rise that high.
In fact it rises to 2.5 (when heating and shower operating) but reverts to green area when turned off.

The boiler is still useful though it needs a good degree of tinkering, ie to move it to the green area - and the leak means loss of water; but I can't get anyone to look at it (they always want to sell me a replacement). So I am now looking to get a new boiler. I have been given good advice in this forum on various boiler brands - Intergas and Ideal - and in the process learned a lot about how these boilers operate, which as a non-tech I appreciate. So far no one has recommended Alpha. I've asked a boiler site to send me details of this brand and installers.

Would appreciate your input too on what boiler you would recommend.