Erratic hot water with new shower

[bensonhedges]

Hi, this is my first post so I hope you can help. We have just had a new bathroom installed - part of which is a Hudson Reed A3003 shower, fed from a Gloworm Swiftflow 80 boiler, which is approx 10 years old, maybe more. 9 times out of 10 it is fine but every so often the shower will get hot for a few seconds and then run cold. Nothing we do (which mostly consists of leaving it for a bit then trying again) will make it run hot. Then the next day it is fine again. The rads are hot and have no problems. Is it just that the boiler cannot produce enough hot water to feed the shower's demands? If so, why is it fine most of the time?

We have had a quote of £2300 to install a Worcester Bosch 28i condensing boiler. Will this fix the problem and is it a fair price?
Thanks very much.

 

[GasMan1965]

Cant comment on the quote as not seen the job so dont know whats involved but will sort the problem if the boiler you got now is the problem (probably is).

Good boiler but would go with the 30CDI

 

[bensonhedges]

The job is pretty much a straight swap - the current boiler vents through the wall but there is a blocked off roof vent from a previous boiler which they can re-use, and need to fit the condensate drain (?)
Do you know why it might only fail occasionally though please?

 

[GasMan1965]

Do you know what the boiler is doing when it happens?

 

[bensonhedges]

Well, it's working fine as in the radiators are hot - being about as technical as a cabbage that's all I can really tell you. Sorry - not being much help I know. Am grateful for your replies so far.

 

[bensonhedges]

Would anyone else be able to comment on this please?

 

[AshaDPlumber]

A new boiler would probably solve your problem, it's irelevant that the rads are hot, as when you get a bigger sized boiler the majority of the size is to give you flow rate. This is the problem your having the boiler cant genrate hot water fast enough. Look for litres per minute when getting your new boiler