Vaillant Ecomax 824/2 E hot water problem

[gm3suz]

I have a Vaillant Ecomax 824/2 E, which was installed about 5 or 6 years ago but in the last few days there has been a problem with the hot water supply. The problem is that after I run my bath as normal I jump into the bath and find out the water is nearly cold, ouch. When I investigated I found that the hot water fills OK for about 2 minutes and then starts to go colder and colder. I can see this when I look at the water temperature on the boiler, it starts at about 70 C and then rapidly goes down and down until it's nearly cold. Turning up the heater temperature has no effect but if I run the water at low volume, the water stays hot but it takes ages to get a decent hor bath. I noticed this fault in a similar Vaillant boiler in another forum and the guy had changed the water diverter valve and some kind of sensor, to no avail and the problem had still not been resolved more than a month ago.
Would appreciate any help on finding what the fault is, TIA

 

[ColJack]

are your radiators on at the moment?

do they get hotter when you run the hot tap for any period of time?

if the diverter valve is sticking part way then all that heat is getting put into the rads and not the hot water..

 

[Agile]

A simple test to se if its a failed diverter valve is to turn off the rads and wait until thye have cooled.

Then turn on a hot water tap and run for several minutes and see if the rads warm up.

The older diverter valves had smaller holes about 4 mm whereas the later modified ones had 6 mm holes. ( A few of the older type were also made with the 6 mm holes ).

A fairly easy job to replace for someone competent with water parts on a boiler.

Tony

G8ABQ

 

[Happyplumber]

it is very likely to be the divertor valve,i have seen this problem a couple times where the boiler fires up intermittently.YOu reset it then once again as you use it,will start again


there you go

merry xmas

 

[gm3suz]

Thanks for the tips guys, I ran the hot water for 10 minutes and the radiators cooled by 2 or 3 degrees, when I turned the hot water off the radiators came back to their normal temperature in a couple of minutes. I will try the other suggestion tomorrow, turning the radiators off, letting them cool down and try running the hot water and see if the radiators heat up, as someone suggested. In the meantime I will check on prices for a Diverter valve, the 6mm holes one.

 

[Agile]

Do the test as I ( not someone ) suggested.

When we know the result we can give further advice.

Tony

 

[gm3suz]

Thanks Tony, I will do as you suggest tomorrow, HANE and 73's, Dan

 

[gm3suz]

Regarding the test that Tony mentioned, I ran the hot water for 10 minutes, with the radiators turned off and got the following results. The hot water temp at the boiler was 80 degrees C, after 2 minutes this had reduced to 46 degrees C and it remained at that temperature for the remainder of the 10 minutes.
I monitored the radiator temperature at the same time and after 10 minutes the pipe leading to my first radiator was warm, not hot and the body of the 1st radiator was cold. The pipe from the boiler to the radiators, next to the boiler was warm, not hot and the return pipe was almost cold.