potterton performa 24 h/w problem

[pil]

Hi all,
I have trawled through a lot of the problems for these boilers but dont seem to have seen one with the exact symptoms as mine.

As i say, its a 6 yo potterton performa 24 which worked ok till sunday when the hot water side started to play up, cutting in and out and barely getting past "warm". I checked the pressure on the gauge which is at 1.5 bar, water flow to the taps is good (flow at tap has always needed to be lowered to maintain a good heat) and also the central heating side works with no problems whatsoever. Regardless of whether the switch is at just "h/w" or "c/h AND h/w", the light comes on for around 10 seconds (boiler can be heard firing up) and back off for around the same time each time demand is made from the taps. The overheat trip does not operate at any time during any of this but, having tried the h/w several times, there are now noises from the boiler each time before it switches itself off again in exactly the same way. I have also checked the isolation valves at the base of the unit by the way.
Any ideas??

 

[kevplumb]

sludge in plate h /ex

 

[pil]

seems pretty conclusive then! Thanks, new one ordered......will let you know how it goes!

 

[namsag]

Cost around £40 dont throw old one away clean it out with white vinegar or x800 and keep it as a spare for next tie

 

[pil]

does the flushing route work with any success then?
Im a mechanic by trade and very rarely does flushing a vehicles cooling system actually make any difference, thats why i was going to replace rather than repair! If it does often work i shall give that a go first. Best commercially available descaler then anyone??

 

[kevplumb]

fernox ds 3

i did once put some in my van to clear heater blockage it worked a treat

had to flush it out a couple of times tho

 

[Agile]

Citric acid ( DS3 ) or even 10% hydrochloric acid if you are careful.

This works very well if you know how to do it. But it is messy and a bit dangerous too!

The car desludgers are not acidic and I agree they dont work well. But with aluminium components its probably advisable not to use an acid on the engine.

Isolating a car heater and using an acid should be fine if the heater is still copper like they used to be! Perhaps they are plastic now?

Tony

 

[pil]

Thanks for the idvice guys, shall attack it on saturday and will post the results after a nice hot bath!!

 

[pil]

really must stop thinking too much! It states that it works at 60-80 degrees for 4 hours or so. with the exchanger remover, how would you go about doing this??
As its a combi i cant do it in sit can i ???