Vaillant warm water

[standardbum]

Hi all

I'm having a problem with my Vaillant Turbomax VUW GB 242/2-5 which seems to be a common problem but I'm unable to find an answer to my specific problem.

The problem is the DHW doesn't get very hot. The CH is fine and heats perfectly. I have measured the DHW temperature and it's about 40 degrees. If I reduce the flow to just before the boiler switches off, it gets to about 48 degrees but the flow is very slow and really unusable for the kitchen tap. The kitchen tap is below the boiler on a lower floor.

The flames in the burner are high and blue. The DHW temperature gauge gets to about 80 degrees. The dial is set to maximum. The DHW HEX gets very hot; so hot it cannot be touched for more than a second. The pipe from the HEX to the DHW does not get hot at all. The radiators do not heat up when on just DHW demand so it cannot be the diverter value.

I have removed the HEX and have used 3 different de-scalers on it, and even left it over night with de-scaler inside it. Black deposits do come out of the the unit but nothing, I would say, that I should worry about. There is no pressure loss on the CH.

I really think its the HEX scaled up but before I replace it at about £75 I wanted to see if anyone else had any ideas or anything else I can check as I will be replacing the whole boiler next year.

Thanks....

 

[Agile]

There are two sides to the plate.

To properly clean them you need to know what the problem is and what is the appropriate chemical to use to clean it.

It sounds as if you need to just buy a new one!

Tony

 

[standardbum]

Yeah, i thought that was going to be the answer.

Thanks for replying Tony.

Just to confirm, from my original post, would you suspect the HEX is blocked, choked etc - there's nothing else I should try first?