compact water tanks for flats

[Andrew Gabriel]

A friend with a flat has an all-in-one water tank, with a pair of header tanks on the top (heating circuit vented tank, and low pressure water supply), sitting on a large hot water tank. It's one large integrated and insulated unit.

Problem is that the hot water taps will only run for about 10 seconds before the flow reduces to a dribble. There's a power shower which will run a bit longer. The cold taps supplied from the header tank will run indefinitely.

What I suspect has happened is that the feed from the low pressure water supply tank into the hot water tank underneath it has become blocked, with just a tiny trickle getting through. When you run a hot water tap, the static pressure in the hot water tank rapidly drops due to the restricted feed, down to the same trickle which is getting through the blocked pipe. The power shower on the other hand is probably capable of sucking further hot water from the hot water tank once it's started, without any static pressure in it.

The feed pipe from the header tank to the hot water tank must be integral, as it doesn't run external to the integrated tank setup. (I couldn't look in the top of the header tank, due to only about

5" clearance from the ceiling and lack of lights/mirrors at the time.) In another similar (but much older) setup, I saw somthing similar, and the problem was that the feed pipe runs out of the bottom of the header tank and down through the middle on the hot water tank, thus heating the water in the feed pipe before it emerges at the bottom of the hot water tank. The effect is that the feed pipe scales up on the inside and blocks. I think this matches the symptoms my friend is seeing.

If so, any suggestions for clearing this out? The thoughts that have occured to me are:

1. Dissolve a load of Furnox DS-3 and pour it in the header tank. Slowly draw off hot water, which will slowly draw it down the feed pipe.

Flushing the furnox from the system is going to be a nighmare, probably requiring leaving water running through the hot water system for a day or so to get it all out of the tanks by slow dilution.

1. If I can find the pipe outlet from the header tank into the hot water tank, I might be able to get one of those giant clock-spring-type drain cleaners into it, and wiggle it around enough to unblock it. Access is going to be the big problem with that, only having a few inches to reach in at the ceiling (and the whole thing is in a built-in wardrobe with access from only one side anyway.

I'm sure this must be a common occurance in flats with these all-in-one water tanks. How is it normally fixed?

[Bob Minchin]

Back flush with mains pressure cold water up the hot output perhaps with a pressure regulator in line to keep things under control. Excess water should come out via whatever overflow system is fitted. The furnox approach has got to be a very last resort.

[meow2222]

On Sunday, June 9, 2013 9:08:46 PM UTC+1, Andrew Gabriel wrote: re blocked filler tube, hitting it nearby might help some. But odds are you need proper access to clear it all. Might need removing, hole cutting, fixing, and soldering.

NT

[Nthkentman]

A friend with a flat has an all-in-one water tank, with a pair of header tanks on the top (heating circuit vented tank, and low pressure water supply), sitting on a large hot water tank. It's one large integrated and insulated unit.

Problem is that the hot water taps will only run for about 10 seconds before the flow reduces to a dribble. There's a power shower which will run a bit longer. The cold taps supplied from the header tank will run indefinitely.

What I suspect has happened is that the feed from the low pressure water supply tank into the hot water tank underneath it has become blocked, with just a tiny trickle getting through. When you run a hot water tap, the static pressure in the hot water tank rapidly drops due to the restricted feed, down to the same trickle which is getting through the blocked pipe. The power shower on the other hand is probably capable of sucking further hot water from the hot water tank once it's started, without any static pressure in it.

The feed pipe from the header tank to the hot water tank must be integral, as it doesn't run external to the integrated tank setup. (I couldn't look in the top of the header tank, due to only about

5" clearance from the ceiling and lack of lights/mirrors at the time.) In another similar (but much older) setup, I saw somthing similar, and the problem was that the feed pipe runs out of the bottom of the header tank and down through the middle on the hot water tank, thus heating the water in the feed pipe before it emerges at the bottom of the hot water tank. The effect is that the feed pipe scales up on the inside and blocks. I think this matches the symptoms my friend is seeing.

If so, any suggestions for clearing this out? The thoughts that have occured to me are:

1. Dissolve a load of Furnox DS-3 and pour it in the header tank. Slowly draw off hot water, which will slowly draw it down the feed pipe.

Flushing the furnox from the system is going to be a nighmare, probably requiring leaving water running through the hot water system for a day or so to get it all out of the tanks by slow dilution.

1. If I can find the pipe outlet from the header tank into the hot water tank, I might be able to get one of those giant clock-spring-type drain cleaners into it, and wiggle it around enough to unblock it. Access is going to be the big problem with that, only having a few inches to reach in at the ceiling (and the whole thing is in a built-in wardrobe with access from only one side anyway.

I'm sure this must be a common occurance in flats with these all-in-one water tanks. How is it normally fixed?

Personally if it's water used for bathing I'd steer well clear of Fernox ! As a last resort after back flushing I might use Citric acid crystals and allow to work overnight then run the taps for a few hours to flush through.

[Owain]

In my case, I've saving up for a 'megaflo'

Owain