biasi m90f hot water problem

[stevig2003]

i moved into my home 2 years ago and have never had any major problems with my boiler
i noticed a few months after moving in that the system pressure on the boiler was low, i checker in the instructions for correct pressure and topped it back up .i have been doing this for the last 2 years at least once a month and could not find a leak anywhere.
after some decorating around the boiler in the kitchen i found a small constant leak, fixed it and now the pressure has been about the same for 3 months.
The problem i have is the hot water side of the system is getting colder
i use to have to only turn my mixer shower half a turn and it would be
red hot . now i have it fully open and it seems only warm
if i slow the hot water down at the tap it gets red hot but the faster it comes out the colder it gets. could it be something to do with the heat excanger getting blocked? also the boiler has just recently started whisterling .
i had an engineer out and he said i had to contact biasi because he encountered the same problem before and biasi had to come out and alter the flue ie cut a small square in it , how can this be when it has worked for 2 years perfect but just started playing up now.
i work with portable oil fired boilers so have a little knowledge of water systems but not enough any help cheers stevig

 

[Agile]

Your plate heat exchanger is getting blocked and needs cleaning or replacement.

Your engineer is a total idiot! What he was describing is related to a completely different model to yours!

There are two different whistles on your boiler. One is during hot water delivery only and the other is on full power which is usually on hot water but can also be on heating as well if the boiler heating output has been left on maximum and not matched to your heating load.

Tony

 

[stevig2003]

spot on thanks for that.
i have heard of something called a power flush would that clean the system.
i i guess if you think about it if the hex unit is getting blocked up you would have to slow the water flow down to get a decent heat transfer my shower has only on and off from cold to hot i cant control the pressure like i said if you slow the water down at the hot water tap it gets hotter .
how much would u normally get charged for a system clean just so i dont get ripped off.

 

[Agile]

We charge £136 to fit a ready cleaned plate heat exchanger and that includes a few minutes running water through the rads to drain. Thats usually enough for most systems.

A full power flush is about £350 extra.

A chemical clean is about £180.

Neither of the above two will clean the plate HE.

You have not talked about your boiler whistle though!

Tony