drained off water to fit new sink, now no hot water

[Frankod]

Apologies in advance, I am posting on behalf of my partner who did a little plumbing job yesterday, he's only really a novice at these things and now clueless as to what to do.!
He drained off the water to fit a new sink, including emptying the full hot water tank. He reconnected the water having fit the new sink and a new mixer tap and water run through taps ok. We have an immersion heater off a gravity fed system and this comes on a timer through the night. Everything was working fine prior to draining off the water. This morning, the water was flowing from the overflow and we had no hot water. We put the boost on to try heating up the water..it flows just barely warm but despite adjusting the ball cock on the header tank (it seems ok) , the water comes out of the overflow. Any advice for us please..thanks in advance.

 

[snowhead]

He reconnected the water having fit the new sink and a new mixer tap and water run through taps ok. We have an immersion heater off a gravity fed system and this comes on a timer through the night. Everything was working fine prior to draining off the water.

Did you have a mixer tap before?

What mixer do you have now?

Was the immersion heater turned off when the cylinder was drained?

 

[smudgie56]

It sounds like you have the wrong type of mixer tap to me. If the hot and cold water mix in the body of the tap you can get a problem with the pressure. The cold water comes in at mains pressure, and if you have gravity fed hot water, the cold water flows into the hot water tank via the tap and forces the 'hot water' back through the tank and causes it to overflow.

 

[Frankod]

Did you have a mixer tap before?
Yes, one that had like a bar across the bottom with a single spout!
What mixer do you have now?
The new mixer is just fitted into a single hole with the hoses underneath to the hot/cold pipes.
Was the immersion heater turned off when the cylinder was drained?

We swithced the immersion off before draining off all the water! It was only turned on again once the water tank had filled up fully but because it is on a timer set to come on from 12 until 7am. The water is not even warm!!

 

[Frankod]

"It sounds like you have the wrong type of mixer tap to me"
Ah, ok thanks. We didn't realise there was a right or wrong type of mixer tap. Is there a certain type you have to fit?

 

[Riley]

As above wrong tap. Maybe post a link to the tap you bought

 

[PlumbBobBob]

do you know if your partner fitted iso valves to the tap feeds under the sink? if he did, turn the cold one off and see how what the hot flow is like. an easy fix is to fit a non return valve on the hot feed but it may cut down the flow somewhat.

 

[Frankod]

Thank you all for your help. It would appear it is the taps. There is a swishing noise from the tap..when it's wiggled, you can hear the water. He didn't fit any valves but thank you steveb, he is now going to diy shop to purchase some. I'll come back and let you know the outcome. Thanks again for the benefit of your knowledge.

 

[dancinplumba]

If no iso turn off at main stopcock. Should also have non return valve on cold supply to stop cross contamination