PROBLEM:[/B
Last year we had our hot water cylinder moved up into the loft. Some time later (I don't know how long), When filling the bath with hot water, the water suddenly slows to a trickle. I usually get exactly the same amount of water before this happens. Give it about 30 minutes and we're good to go again. The water is heating up properly.

Once water runs slowly. I turn the hot tap off, you can then hear bubbling in the pipes. If you try the hot water a few minutes after this, you get a lot of spluttering and the water very quickly runs slow again. You need to give it about 30 minutes or so before trying again.

[B]ATTEMPTED FIX
Tried bridging hot and cold with a hose (on all taps) I've even let it run for a few minutes so that water is spilling out of the overflow.

I've tried turning off the cold water supply, then turning on all the hot taps to try and empty the tank, but the same thing happens.

SYSTEM INFO
We a have a gas boiler in the kitchen (not combi). The cylinder isn't pressurised, and is fed directly from the cold water supply (the header tank was removed by the council when the new system went in). I know bugger all about plumbing so


ADDITIONAL INFO
There's a 15-20ft run of horizontal pipework running from the cylinder, across the loft As the cylinder is over a supporting wall.

When our plumber moved the cylinder into the loft, he said there was a pretty bad coming from the bottom of the tank. But I don't know if he did anything about that. Maybe sediment?

I know bugger all about plumbing, and would be appreciative of any help whatsoever! I'll try to answer any questions about my system if further info is required. Thanks Folks!

The hot line to the bath tub may be partially blocked. When you turn on the water the pressure is released from the faucet faster than the water line can fill because of the partial blockage. Once the faucet is shut off the pipe will come back up to full pressure.

You need to find where this blockage is and repair it, then I think you will be okay.

OK Waldo,
A few questions. You're in thee UK, correct? This hot water cylinder, is it hot water heater or a storage tank? Are your fixtures gravity fed from a storage tank in the attic or are you under pressure?

We a have a gas boiler in the kitchen (not combi). The cylinder isn't pressurised, and is fed directly from the cold water supply (the header tank was removed by the council when the new system went in).
Please explain the difference between the old system and the new.
Was your old gravity system replaced by a pressurized one? I need to understand exactly what you have before I can help. Ssnlw's answer work work for me if I knew more about what you have. Regards, Tom

Hi Speedball, thanks you taking the time to answer this. First to answer your questions.

1 - Yes, I'm in the UK
2 - The hot water cylinder is storage, there's a heating coil that is heated by the boiler in the kitchen
3 - There is a pump that heats both water and radiators.
4 - It's not a pressurised system (if that's what you're asking)

Think I may know what's going on
I think I may have located the problem. Thanks to sslnw who pointed out there may be a blockage. I recently had to remove the ball valve in the toilet cistern as the valve was blocked, and the water was running into the cistern very slowly

The blockage was caused when the council changed the main supply pipe a while ago. When I removed the ball valve, it was full of grit and crap. I cleaned it out and hey presto, water running into cistern fine.

So, with this in mind, I went into the loft the other day. I ran some hot water off for a few minutes. When I got up into the loft, I could hear and see cold water running into the storage tank, albeit very slowly. There's a cold water storage tank built into the top of my cylinder (The cylinder is quite tall.)

My problem is there an access port in the top of the cylinder to get access to the valve, but it's tricky to get in there. I'm going to wait until Monday before attempting this so I'm not stuck all over the bank holiday weekend without hot water if I can't get the valve back on!.

But in the meantime, please keep feeding back more info if you have the time. Maybe you guys can help on the best method of getting the valve out (and back in!):)

Can you take a picture of all this? Tom

Hi Tom.

Here are some pictures. When I run off hot water, the cold water tank fills up very slowly. It looks like the tank at the top is split into two sections. I'm not sure what happens on the other side of the tank, but there is another ball valve in it. It's a bit tight up in my loft as it's only a small house. So the pictures where taken at an akward angle.

Like I said before, it's quite a small access hole, and very fiddly to get at the valve fitting to unscrew it.

Waldo,
Your pictures failed to make it. Tom

Sorry about that Tom. I'll try them one at a time. Here's the first

And the second

And the final one...

And here's a final one inside the tank.

Could a spring be a blockage? I just replaced a few washers and stoppers and noticed an extra spring where the water comes in. I tried to pull it out with needlenose pliers but it fell down the pipe. Could that be what is causing my slowdown?

My slowdown appears to be happening for all hot water faucets.

I had turned the Main Water on and off a bunch today and thought that might have something to do with it? I just turned the main off without doing anything for the water heater.

Q