Glow-worm second annual service

sevenonine

I am revisiting my previous thread relating to my Glow-worm boiler which is only 2 years old but has developed a defect that occurs in older units: the sudden rush of cold water during showering. In a recent annual service I mentioned this to the serviceman who suggested the shower unit itself might need descaling - I thought this was nonsense. I also asked him whether he had used any chemicals during the service but he said no.

I've looked at my old posts in this forum, where the first annual service mentioned the addition of the following:

* Descaler : will be fitted to the new boiler to help prevent the build-up of damaging scale within the boilers heat exchange and other water components.

* Mains Chemical Flushing: your new system is carried out using Sentinel chemicals, this will quickly remove any existing sludge deposits.

It seems obvious to me that these additives should have been included in the recent servicing. Would I be right to ask the installer of the boiler whether this should have been done in the recent service and included in future procedures?

Kitchen_Sink

sevenonine wrote: »

I am revisiting my previous thread relating to my Glow-worm boiler which is only 2 years old but has developed a defect that occurs in older units: the sudden rush of cold water during showering. In a recent annual service I mentioned this to the serviceman who suggested the shower unit itself might need descaling - I thought this was nonsense. I also asked him whether he had used any chemicals during the service but he said no.

I've looked at my old posts in this forum, where the first annual service mentioned the addition of the following:

* Descaler : will be fitted to the new boiler to help prevent the build-up of damaging scale within the boilers heat exchange and other water components.

* Mains Chemical Flushing: your new system is carried out using Sentinel chemicals, this will quickly remove any existing sludge deposits.

It seems obvious to me that these additives should have been included in the recent servicing. Would I be right to ask the installer of the boiler whether this should have been done in the recent service and included in future procedures?

You can ask, but these chemicals are often designed to last a lifetime (assuming there has been no leakage, drainage or flushing etc.)
You put them in and forget about them

sevenonine

Kitchen_Sink wrote: »

You can ask, but these chemicals are often designed to last a lifetime (assuming there has been no leakage, drainage or flushing etc.)
You put them in and forget about them

If these chemicals don't need to be repeated, what is the probable cause of the cold water rush - sometimes lasting almost 2 minutes - and how can it be prevented recurring?