m90f 28s , problem with dhw

[stpxh12]

Hi All
I have problem with a Biasi M90f 28s combi boiler. CH is o.k but it
has just started to play up on the dhw .water starts hot but after a short time the boiler cuts out and restarts again, water is then only warm, this can happen quite a few times when tap is running, doesnt seem to matter it if ch is on or off. any ideas anyone?

 

[Agile]

Its probably a rather blocked plate HE.

On DHW the temp guage should not go above about 65C. If it goes much higher then thats probably the problem but it can be other things.

Tony

 

[stpxh12]

Hi Agile

many thanks for the reply
the temp always seems to be between 60-65
is there any way to test the HE or is it a case of
having it removed and cleaning it

 

[Agile]

The definitive test is to measure the flow and return boiler temperature on DHW and it should be only 10-15 degrees.

If its blocked it will be higher or much higher.

Tony

 

[stpxh12]

Hi All
Quick update
CH now starting to play up as well,
temp gets to 50-55 and cuts out
will not get any hotter than that.
any more ideas

 

[Agile]

It sounds as if you may have a dirty system.

Have you looked at bthe colour of the system water?

Or the CH sensor is going o/c when it gets hot. You could monitor the voiltage across it during boiler operation and see if it suddenly jumps up on heat up.

There are so many simple checks to be done on a boiler that its easy to identify the problem in front of the boiler.

You may be better asking Kevinthegas to come out to you before it stops completely.

Tony