Head of water

Does one measure head of water from the bottom of the tank or the top? I'd assume bottom.

Working in a place last week, old building converted into bedsits a few years ago. Water tank in a cupboard on a metal stand with the hot water cylinder underneath.

Bottom of the tank was 4' from the floor. Bathroom on the same floor a few feet away.

Water pressure was terrible, toilet cistern took around 10 mins to fill.

ISTR that to get 1 bar pressure you need a 10 metre head? From the bottom of the tank was roughly a 1 metre head.

Are there no regs about this sort of thing?

Reply to
The Medway Handyman
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The top. The clue's in the name. Head of water.

Reply to
Dave Baker

Basically agreed. On the other hand, if something has to cope with the available pressure/flow when the tank is nearly empty, the bottom would be the 'worst case'.

Reply to
Rod

The top.

Not ideal.

For good flow at low pressure you need careful design - and appropriate fittings. The cistern might have a valve designed for high pressure. And or a service valve also designed for high pressure. Perhaps most taps are also these days - and will severely restrict flow at low pressure.

The art of plumbing for low pressure systems seems to have disappeared. The principle often gets blamed for that. And pressure and flow confused.

A decent enough example is tipping water out of a bucket. All the water will flow out of it very quickly. Not so from a watering can - even although the pressure is the same.

Reply to
Dave Plowman (News)

In designing I'd use bottom or middle rather than top. You do need to select your fittings to be suitable for low pressure, this is in the specification of decent stuff. Probably not on unbranded from a shed though. Also you might have to use 22mm instead of 15mm tube.

And yes 1bar = 10m head.

Reply to
Dave Liquorice

..of the water..which may well be near te top of te *tank* if supply exceeds demand. Or not, if the reverse..

My neighbour had the same. We had fitted a mains pressure tank, to his existing system and scrapped the crappo tank. An theh electric shower too..

I cantell you having lived with a similar system, that 10 minutes to fill a bog is par for the course. Even if you take the end off a 16mm pipe :-)

yeah, its so archaic these days that bucket diameter pipework isn't even available..and if it is, it empties the tank faster than it can be refilled, leading to even worse problems like heating coils burning out..

Which is why we use mains pressure, if the mains has any,or pumps, if it hasn't, or stick a tank up as high as possible, where its guaranteed to do the most damage when it overflows or bursts, and needs the most insulation to stop it...;-)

I looked at all sitatins when doing my systems here, and mains pressure solved every problem. It ws just a shade more expensive.. but

- it doesn't need electricity to run..

- it can be put anywhere at all, consistent with the ability to dump the safety valve stuff somewhere safe, and ve reasonable pipe runs..

- it never overflows, bursts, or has a sticking ballcock.

Frankly unless you are subject to frequent and lengthy loss of mains water, gravity fed is a load of ballcocks.

You CAN spend a fortune making it work, but then its only other advantage - the tanks are cheap - is lost.

Reply to
The Natural Philosopher

Has the ball valve (or equivalent) got the right reducers/parts for low pressure?

Reply to
<me9

When we had that arrangement (minimal head), one WC took forever to fill. (Certainly over five minutes, I think nearer 10!)

Upon complete replacement inspected the float valve, OK - ball valve. Found the inlet was chock full of limescale. It was quite a large bore of metal - but the end result was tiny, probably around 3mm.

So, though the poor head might have been an obvious culprit, it was instead our good friend calcium carbonate. (An interim arrangement with new cistern but old pipes proved this beyond doubt.)

Reply to
Rod

I wondered about that. Called the supplier to ask if there was a low/high option - like you get with the two nozzles supplied with a basic ball valve - there wasn't.

The Torbek I used in the end had a high pressure reducer option, which I didn't use obviously. Didn't fill much faster though.

Reply to
The Medway Handyman

Torbeck have a HP and LP flow restrictors but can be used without one at all. The ones I've fitted here have no reducer as the cold head is only about 2m (loft tank to floor below). Loo cistern takes maybe two or three minutes to refill from empty.

Reply to
Dave Liquorice

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