No hot water flow - all outlets at a dribble

[3max]

Hi folks - I was hoping that someone may be able to explain what has happened to the hot water system at my Dads house. He had a new hot water cylinder installed about 2 weeks ago and everything was fine for a week. Then the hot water 'flow' just stopped. Went to use the hot tap in the kitchen and it ran dry, checked all other hot taps and the shower - all the same. The cold water tank in the loft was full and the cold water system from the tank to hand-basins, loo etc all working fine. Dad has a Saga emergency call out option on his house insurance so asked for a plumber to visit. The plumber was quite honest in as much as he admitted he didn't know exactly what was wrong but he thought he had solved it by using mains water pressure to fill the pipes back up to the tank and assumed it was an air lock.
The system worked fine for 3 or 4 days and then stopped again. This time he called out the plumber who installed the new cylinder and I went to meet him ( my dads quite old at 95, a bit deaf and knows loads but nothing about plumbing!) Evidently there was no sign of any significant scale build up in the pipes - when he fitted the cylinder - so he discounted a blockage, he thought the tank fill was slower than normal but as water had not been drawn off in any large amounts he discounted any possibility that the loft tank had run dry - so he came to the same conclusion that it was an air lock. I watched as he put a hose onto the kitchen tap, he left all hot taps open then, starting downstairs, closed each tap one by one as each ran with water. He disconnected the hose pipe, ran each tap until they were running hot and left, job done.
This was at 3 pm this afternoon, my dad has just phoned at 8 pm to say the hot water taps have run dry again! Can anyone help or offer some advice?.
Many thanks 3 Max

 

[stevetheplumber]

most likley either a valve broken or someting floating around in the cylinder assuming theres nothing in the tank being drawn into the outlet

 

[dancinplumba]

Could be something floating in cylinder, ie: a piece of the insulation that's round your cylinder. This could block outlet when taps are run

 

[plumben]

I'd go with something blocking the cylinder outlet, and when its back filled its pushed around the cylinder until its sucked back into the outlet

 

[Best]

Bit of foam insulation was my first thought also. Probably new foam has got into cylinder, or something similar from cold water tank and now hanging about inside the new hot cylinder

 

[dancinplumba]

It's unanimous then

 

[Unregistered]

Thanks everyone, I don't think anyone's even considered something being 'in the cylinder' - seems like a sound idea and unanimous! - the fitter put a new ball valve on the cold water inlet and the loft tank seems to be clear of any debris - I don't think there are any other valves involved.
Some water does get into the pipes after a time but it soon runs dry on demand - all fits the diagnosis
I think maybe we should flush the cold water feed pipework to make sure nothing's got into that and if that's not it - then it's going be the cylinder out!
Thanks for taking the time, goodnight.
3max

 

[plumben]

Thanks everyone, I don't think anyone's even considered something being 'in the cylinder' - seems like a sound idea and unanimous! - the fitter put a new ball valve on the cold water inlet and the loft tank seems to be clear of any debris - I don't think there are any other valves involved.
Some water does get into the pipes after a time but it soon runs dry on demand - all fits the diagnosis
I think maybe we should flush the cold water feed pipework to make sure nothing's got into that and if that's not it - then it's going be the cylinder out!
Thanks for taking the time, goodnight.
3max

If/once you get it fixed if you could let us know that would be great

 

[3max]

will do. 3max

 

[3max]

Problem solved ~ The plumber removed the new cylinder and as you all rightly predicted - the restricted flow of the hot water was caused by a ball of insulation ( about the size of a small orange !) inside the cylinder.
Lesson learned I would have thought?
Many thanks to all for the sound and friendly advice : -)
Very best regards 3max

 

[plumben]

Thanks for updating us,
It's good to know we diagnosed it correctly