ideal isar water temp drop

[680312]

ive noticed when i run the hot water for a while the temperature drops from 57c to 39c then the boiler fires back up reaching 57c again.it's a right pain when having a shower.
Also on a couple of occasions there's been a different code in the idle position but reverts back to normal when running and then resting.
it looks a bit like this
l l
_. any ideas

 

[twgas]

cycling on hot water is very often due to restrictions in the plate heat exchanger.

 

[idealnumber1]

seen this once before two lines
changed user control fixed it

 

[onlyfitidealboilers]

PHX blocked, why on earth why a user display repair this fault

 

[kevplumb]

why on earth why a user display repair this fault

you put the temp on with a marker pen so it dont change

 

[Homesafe]

Whos the real Ideal expert only a fistfight will tell .

But TBH, limited as my knowledge is, what has a user control got to do with the temp. control?

 

[idealnumber1]

Whos the real Ideal expert only a fistfight will tell .

But TBH, limited as my knowledge is, what has a user control got to do with the temp. control?

user control with two lines meant it was damaged possibly by water inside the user control, on the boiler i was at,changed control worked fine.
another way too check is too take off the control and fire boiler for dhw,this will result in the boiler running at its maximim,then check flow and return pipe to see which if they are getting hot,usually return pipe gets hot when blocked plate