alpha ocean 280e boiler fault

[jacko007]

Hi guys, Please bear with me on this as I am a newbie.
My dad has an alpha ocean 280e gas boiler approx 18 months old that has a really annoying intermittent fauly that no one has yet managed to resolve. Basically it fires up absolutely fine to provide both heat and hot water. However after showering for a few minutes the water turns luke warm and then a few more minutes pass before it returns to hot again. Strangely, it may do the above in the morning but can work fine later the same day. So far only the main flow switch has been replaced but engineers called out to have a look at it seem to want to try and replace as many parts as possible to try and elimate the problem (ie, they don't know what is causing the fault) Any advice or help that anyone can give would be much appreciated.

 

[namsag]

Firstly for a 280e 18 months seems 2 years to young .
Is it only doing it on hot water if so diaphragm going or plate heat exchanger is partially blocked

 

[gas4you]

I would say even older than that

I would agree that the plate HE is blocked to some extent though and the boiler is going to overhea, cooling down, then starting again.

 

[jacko007]

Sorry, checked the age of boiler I thought he had it replaced 18 months ago but apparently not, it is about 7 years old! He said ithe heating does cool down aswell as the water but it's only because the boiler is shutting itself down for the few minutes before starting up again. Also, extremely unlikely to be a blocked heat exchanger as we live in an area with soft water.

 

[gas4you]

Don't mean the domestic side of the plate HE, but the system side of it.

 

[jacko007]

Dave,
Thanks for replies, but how does the system side of the plate h.e. get blocked? Sorry you've lost me there

 

[gas4you]

General sludge and carp build up due to the system not being cleaned properly and treated with inhibitor at time of boiler installation.

 

[jacko007]

Dave,
I've spoken with my dad. He says the system has been regularly serviced and is spotless ie the water in the system is very clean and there is no sludge or dirt build up in the boiler.

 

[spacethegas]

how would he know this ?

 

[jacko007]

I guess he saw it when it was being serviced. He has had engineers out to try and resolve previously but they seem to be taking a stab in the dark with it.

 

[Gasguru]

If it cycles in heating mode as well it's often due to a duff flow thermister (goes open circuit when it reasches a particular temp.). Easy to confirm and easy to change since it's in a dry pocket.

 

[jacko007]

Thanks for the info. It's a very peculiar fault as it's so intermittent. Works fine on some occasions but more often than not it plays up.

 

[grittishbass]

if the orange fan running light is on when the boiler goes cold, get a corgi engineer to remove & thoroughly clean the fan blades/air pressure tubes as a common fault with this model is not enough air pressure in the boiler