central heating is working, but no hot water

[Newby2]

Hi

I have a 20 year old conventional glowworm central heating system (2 water tanks in loft, a hot water cylinder in airing cupboard). The central heating works okay: boiler is working and radiators are hot. However, there is no hot water. To be more precise, the water from the hot water tap is initially hot/warm, but the flow is very small, and after a while the water just completely stops.
What could be the problem? Any advice would be appreciated!

 

[Jajodu]

check the cold water cistern in the loft. i bet it's empty.

 

[Newby2]

Hi
If the cold water cistern is empty, what is the cause and how to fix it? thanks.

 

[terryplumb]

Are all hot water taps like this or just one tap ? If loft tank is not filling the ball valve is suspect ,replacements are around ten quid.

 

[Jajodu]

check it first. there are probably two, one large one that feeds the hot water tank, the other for the boiler. the fill valve is probably stuck , or the feed pipe is frozen

 

[Newby2]

all the hot taps are like this. could it be the motorised valve faulty? It's a Drayton 3 port valve and I saw the black indicator is at "H".

 

[Jajodu]

just check the tank in the loft.

 

[Jajodu]

it feeds the hot water cylinder and if it's empty you get no hot water.

 

[dilalio]

all the hot taps are like this. could it be the motorised valve faulty? It's a Drayton 3 port valve and I saw the black indicator is at "H".

Motorised valve has nothing to do with flow to hot taps - water to hot taps comes from tank in loft via cylinder, (where it gets heated by exchange from the coil) and then to each outlet.

 

[dilalio]

Have you manipulated any ballofix/gate/lever/stopcock valves recently?

But as said... just go check the tank... how hard can that be?

 

[Newby2]

thanks for all your suggestions. I checked the loft tank and there is water. The ball valve seems open as I can hear water dripping in from the inlet. I then checked all the hot water taps. It seems the kitchen hot tap downstairs is much better than the upstairs taps where the water flow is a trickle. The water is warm/hot though. I haven't touched any valves lately. Any ideas? many thanks,

 

[dilalio]

Airlock

 

[dilalio]

https://www.google.co.uk/search?q=remove+hot+water+airlock&ie=UTF-8&oe=UTF-8&hl=en-gb&client=safari

 

[terryplumb]

The large tank in loft should be around two thirds full ,not just a few inches .Is it ?