Ariston eurocombi A/23 MFFI help!

[wacomuk]

to flush the system i used a 20L tank / pump / filter /

i used a flushing agent (fernox i think) that the plumbers merchant recommend (i explained what i was doing)

i pumped the flushing agent mixture into where the boiler takes the cold water from, Then collected it from the hot water side, into a filter, back into the tank and so on. I did this while the boiler was on

i hope that made sense

i have done this 3 times for 1 to 1.5 hours a time, each time the hot water temp increased

 

[Gasguru]

i pumped the flushing agent mixture into where the boiler takes the cold water from, Then collected it from the hot water side, into a filter, back into the tank and so on. I did this while the boiler was on

This appears to mean you connected the pump across the cold inlet and hot outlet (15mm connections) of the boiler ie the domestic water side...or secondary side. This will have no effect on the likely blockage on the primary side of the plate.

However even if you did actually connect to the flow and return (22mm connections) your powerflushing will have zero effect on the plate. You must connect onto the boiler pump using an adapter and then set the boiler into DHW mode.

Just remove the plate and inspect/clean it manually - much easier.

 

[wacomuk]

This appears to mean you connected the pump across the cold inlet and hot outlet (15mm connections) of the boiler ie the domestic water side

yes thats what i did

do i need to clean the main exchanger (above the burners) or the small one at the bottom of the boiler (to-wards the back)

if what i did didnt clean the the right bits of the boiler what did it do? and what was all the black sludgy stuff?

 

[Gasguru]

Look carefully at the image posted earlier.

The lower port is the hot outlet connection...pretty clean. Unless you are in an area where scale precipitates within the plates this secondary side on the plate exchanger does not normally require any cleaning.

Now look at the top port...this is the flow connection from the main primary heat exchanger. Note how it is full of debris. The plate is fairly restrictive even when new, with debris like this the pump can no longer shift sufficient water through it.

The primary connections (top) are totally seperate from the secondary (bottom) cconnections. Each alternate plate in the sandwich forms either a primary or secondary flow path.

The blackness you found may just be remaining sludge from the pump left in by the previous user.

 

[wacomuk]

Ok so i need to remove and clean this. When i remove it will anything need replacing E.G washers etc
What cleaning solution should i use?
How long will the cleaning take? (will the boiler be out of action for more than day)

 

[Gasguru]

Good idea to pick up 4 genuine O rings. Most boiler spares stockists should carry them (normally the same as Biasi's).

I suggest you backflow the primary side using the shower hose. Gently banging the plate with a rubber hammer also helps.

When most of the loose flakes are removed use a standard kettle descaler (you can use more aggresive chemicals but take extra care)

Sit the plate in a pan of simmering water on the hob. Fill the SECONDARY side with boiling water (to help heat transfer). Fill the PRIMARY side with the descaler. Advise PPE etc

Give it 10 mins and repeat a few times with fresh descaler.

Whole job should only take an hour or so.

 

[Agile]

The kettle descalers are designed to remove lime scale.

Most blockages in plate HEs are primarily iron oxides with black/brown flakes. There can also be some lime compounds as well but they are usually a greyish colour.

Citric acid ( DS40 ) is good at dissolving oxide flakes but not much good with lime compounds. Sulphamic acid ( DS3 ) will deal with lime based compounds.

Tony

 

[Gasguru]

Can't remember which descaler it is I normally use but it certainly bubbles enough. Anyone tried using Kamco FX2 (phosphoric acid)?