Hi, My Vaillant turbomax 282e c/h boiler is taking it's time lighting up after you've opened the hot tap. I have mistakenly replaced the flow switch thinking that it was the cause of the problem but still the same. I have now noticed that there is a second microswitch which is also activated by a drop in water pressure on the hot water feed located on a brass component behind the pump on the right hand side of the boiler. This unit must contain another diaphragm and some kind of bleed down jet to create a time delay before the boiler lights.
Can anyone tell me what this unit is called (in boiler-speak) so I can at least enquire about getting another or, better still, give me an indication as to how I can get into it without having to strip down the whole thing. Also, is it likely to be some crud in there causing the problem or, as I've heard mentioned here, is it more likely to be a split diaphragm?
Any help would be greatly appreciated,
Cheers, Martin.

Martin John Goodwin, August 2007

Cheers Andy, now got a diaphragm on order and will give it a try.
Regards Martin

Martin Goodwin, August 2007

sounds like the diverter valve diaphragm has got a split in it. The brass unit is the diverter valve. You can get a diaphragm seperately but 9 times out of 10 the valve leaks when put back together, you may get lucky!
you would need to isolate mains in and drain boiler then remove pump and unscrew the valve itself and pull forward to repair. The diaphragm is located at the bottom of the valve held in by about 8 screws.

hope that helps ya

andy, August 2007