ariston euro combi help

[wacomuk]

Hi all

I have a problem with my ariston euro combi. The prolem is with the hot water, If i turn the hot tap on fully the water will run hot cold hot cold. If i turn the tap down to a trickle the water will stay hot. Its taking 45mins to run a hot bath

The combi is about 7 years old. i have a book with it. The books says its a A/23 MFFI - A/27 MFFI TYPE C BOILER

does anyone have any idea whats wrong

 

[ChrisR]

A Genus??
Constantly getting tripped up on ariston numbers but it has a plate secondary heat exchanger I think. They block, as do the main heat exchangers, which causes what you have to varying degrees. Also temp sensors and gas valves can contribute. Clean it first and diagnose from there. Search for "acid"!

 

[chrishutt]

Just had the same problem with this boiler. I changed the plate to plate heat exchanger but the old one wasn't that badly sludged. Distinct improvement but burners still cut down to low flame when HW temp was only 38C or so.

Then I changed the main temperature sensor (on CH side, just to left of heat exchanger) and performance was much improved! The old sensor had quite a coating of the black stuff which might have caused the problem, but new ones are quite cheap so it didn't seem worth messing around cleaning the old one.

Try a new sensor first, but take a look inside the plate to plate while you have the boiler drained down.

 

[wacomuk]

today I drained down the system and put in sentinel X400 sludge remover, its been in about 2 hours so far and there's no change to the water.

after I refilled the system I had a look for the domestic plate heat exchanger (its at the bottom of the boiler at the back) I turned the hot water on and put my hand on the heat exchanger, the top inch felt hot and the bottom was cold to warm ish. Im thinking most of it is blocked!

Ill leave the X400 for a week or so and see what happens if it does not clear ill have to have a go at taking the heat exchanger out

 

[wacomuk]

does the hot water constintly flow through the domestic heat exchanger or does it only flow when the hot water is turned on.

 

[Agile]

Why am I dealing with a boiler which I am pretty certain is an A23 MFFI but it does NOT have a plate HE but a four pipe main HE ( which is leaking! ) ?

Tony