Hot water won't come out of one tap

ben3290485 · 20 Dec 2020

I have a water tank in the attic and a gas boiler and an immersion tank. Yesterday I drained the system (including the water tank in the roof) because I wanted to fit some isolation valves which I didn't actually fit. Now one of the taps in the upstairs ensuite won't put out hot water. Nothing has changed in the system other than me draining it. In hindsight I didn't realise that I didn't need to drain the water tank as I could have just turned off the outflow from it.

Is the hot tape in the ensuite not putting out water because of an air pocket or could it be because of rubbish going from the tank which might have blocked this pipe? Cold water comes out of the tap fine. Or is it something else? Wife is loosing her marbles over it, so any help much appreciated!

terryplumb · 20 Dec 2020

Air lock would be first suspect. Are all other hot taps in the property giving hot water as normally ? If so a blockage on the tap in question would also be likely.

ben3290485 · 20 Dec 2020

All the other taps are putting out hot water. When I feel the pipes behind the sink though it's not hot.

terryplumb · 20 Dec 2020

Is there an isolation valve on the hot supply pipe to the tap in question ?
Can you show pic of the actual tap ?
And is the problem no water coming out at all ,or is it coming out but just not hot ?

ben3290485 · 20 Dec 2020

WhatsApp Image 2020-12-20 at 2.05.58 PM (1).jpeg

WhatsApp Image 2020-12-20 at 2.05.58 PM (2).jpeg

ben3290485 · 20 Dec 2020

There's no isolation valve.
Water will come out of the tap, but just not on hot side.

Madrab · 20 Dec 2020

Is the cold side of that mains fed or from the tank too? Put your finger over the tap and open the tap to the hot side and then bring it into the middle to open the cold side, if you're lucky and it's mains cold then it should back feed up the hot line and clear the airlock.

terryplumb · 20 Dec 2020

Is the cold supply to that tap from the mains ,or is it gravity fed from the tank ? If it's from the mains you may be able to force cold water into the hot side ,to help shift trapped air.
Fialing that ,then disassembly required to check blockages at tap valve.

terryplumb · 20 Dec 2020

Madrab said:
Is the cold side of that mains fed or from the tank too? Put your finger over the tap and open the tap to the hot side and then bring it into the middle to open the cold side, if you're lucky and it's mains cold then it should back feed up the hot line and clear the airlock.

There are seperate levers for hot and cold Madrab

Madrab · 20 Dec 2020

terryplumb said:
There are seperate levers for hot and cold Madrab

Yup, for some reason I looked and didn't see the other lever, jeesh!! Think I'm still asleep

With any luck though it's a single flow tap so OP, finger over the spout, open hot then cold and you may be lucky and it'll back flow and clear the air.

ben3290485 · 20 Dec 2020

Ok. So from my understanding upstairs cold comes from the water tank and it's only the downstairs that comes from the tank. I tried your technique and it seems to have done something as I now have a trickle of hot water coming out of the hot water side and I can feel the hot water pipe is now hot. How do I turn the trickle into a flow?

Harry Bloomfield · 20 Dec 2020

ben3290485 said:
Ok. So from my understanding upstairs cold comes from the water tank and it's only the downstairs that comes from the tank. I tried your technique and it seems to have done something as I now have a trickle of hot water coming out of the hot water side and I can feel the hot water pipe is now hot. How do I turn the trickle into a flow?

Some more of the same process you used, to get the trickle. You still have a partial air-lock in the pipe.

Madrab · 20 Dec 2020

As suggested keep trying and it may clear. If it doesn't and if you have an outside tap and hose then get that and open up the hot and press the hose over the spout and run the cold water. Not full on but just enough just to slowly back flow the hot supply to the HW cylinder and that should clear it.

If you don't have anything like that to hand then you will have to implement something that will allow the pipe to get some mains pressure into it. The current cold supply, if from the CWSC will equalise with the hot water in the pipe and if it still doesn't clear then there isn't enough head of water to clear the pipe out.

Another way would be to tee off the mains feed to the cold water storage cistern (CWSC)actually in the attic and then run a pipe into the HW cylinder feed in the bottom of the CWSC, open up the offending tap and then run the mains gently into the feed, there should be enough pressure to blow the HW pipe clear.

This is a good reason why most professionals will choose to bung the CWSC rather than empty it.

ben3290485 · 20 Dec 2020

Madrab, Terry Plumb. Thank you so much. Tried the hose and then tried the hand underneath to force water back into the hot water and after doing it for the last couple of hours it's finally sorted!!! How do I buy you both a pint as thanks?

terryplumb · 20 Dec 2020

Glad your sorted mate. Pity you can't email beer

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Hot water won't come out of one tap

Similar threads