New kitchen sink = no hot water

[whistler]

I replaced my kitchen sink and tap today, a fairly problem free plumbing job ...... However after checking for leaks I ran the hot water and it seems to cycle between luke warm and cold but never gets hot.

I have opened all the taps to make sure there is no air in the system but still not hot water.

The only difference is that previously I had seperate hot and cold taps and have replaced with a mixer. I have isolated hot and cold supplies to the new kitchen tap but still no hot water to the bathroom.

Could the mixer tap somehow have damaged my Vaillant combi boiler?

 

[whistler]

An update on my problem ...

After a while it is possible to get hot water. i.e the shower was working fine this morning. However when the hot water has been turned off and then on again, the water is only lukewarm. I seems we have to leave it a while before we can get hot water again.

I'm baffled as to how just changing a tap could have caused this. Any ideas?

 

[Paul Barker]

The mixer tap can send cold mains back up to the combi through the hot pipework and completely screw it up.

Put a check valve on the hot pipe to the mixer tap and see what that does.

 

[whistler]

Thanks Paul,

I have closed off the cold supply to the tap so no cold water can be getting back to the boiler now. It seems that the damage whatever it is has now been done. I'm guessing that the divertor valve in the boiler has been damaged.

However it seems to work ok the first time hot water is drawn, but try it again later and it doesn't work. Maybe the valve is sticking?

 

[Gasguru]

What Vaillant boiler model is it?

 

[whistler]

What Vaillant boiler model is it?

Turbomax Plus 824/2E

 

[Gasguru]

These boilers have problems with the diverter valves. Open the hot tap fully and check the left hand 22mm pipe under the boiler doesn't get hot.

 

[whistler]

Replaced the diverter valve today and now have loads of hot water.
Thanks for all the replies.

My only concern is why replacing the kitchen tap caused this or maybe it was just co-incidence?