Water Header Tanks

[Nevin]

What is the actual benefit of a water header tank? I live in a top floor flat and apart from the cold in the kitchen, all of the other water goes via the header tank in the loft first, so pressure isn't great as its only about 3m above the taps if that.

So is there any good reason you couldn't just disconnect the mains inflow to the header tank and reconnect it directly to the header tank outflo, taking the header tank out of the loop completely?

Other than somewhere to store water which just gets dirty and has sediment lying in the bottom, I can't really see the point of it.

Old flat in London didn't have one and it managed fine, but both my and my sister's flat in Edinburgh have small header tanks with not a lot of drop to the taps.

[rash_decision]

I'm guessing that you could be setting yourself up for some leaks on older pipework due to the higher mains pressure if you do this. My mate did the same and encountered a few leaks, not good if you're top floor!!! Lol.

[Deva Link]

Its purpose is to work in conjunction with the hot water cylinder which needs a connected, but open, water supply to allow for expansion and contraction.

If you connect mains to an ordinary hot water cylinder you would have to cap the vent and the cylinder may well split as it gets hot. They're not designed for mains pressure anyway.

If you've got a combi boiler and no hot water cylinder than the cold water tank in the loft is pointless and should be taken away. Indeed that should be done as part of the installation otherwise mixer taps and showers etc won't be balanced.

[Ferg]

It's an expansion tank.
When you heat water it has to go somewhere, so it rises up the vent.

Unvented hot cylinders have three tiers of safety on every heating source by law, so connecting mains to a vented cylinder isn't an option.

[jagracer]

Is the OP getting a little confused between a header tank and a supply tank or am I being pedantic....again?

Edited by jagracer on Saturday 10th April 19:07

[Ferg]

jagracer said:

Is the OP getting a little confused between a header tank and a supply tank or am I being pedantic....again?

Pedantic?
Do you mean a cold water cistern?

[jagracer]

Ferg said:

jagracer said:

Is the OP getting a little confused between a header tank and a supply tank or am I being pedantic....again?

Pedantic?
Do you mean a cold water cistern?

A cistern to me is a tank for storing water for a toilet or hot water for taps. I mean the big tank in the loft, I suppose storage tank would be more apt.

Edited by jagracer on Saturday 10th April 20:22

[Ricky_M]

Main reason for cold water to be provided via a cistern, is to equalise pressures on the hot and cold supplies for things like showers and mixer taps, the higher pressure cold can force its way through the lower pressure hot pipework. Seen a few bathrooms with mixer taps on baths that have been fitted with a mains pressure cold and a cistern fed hot, one resulted in the cistern back filling and overflowing, made hell of a mess.

How high is the flat block? Mains pressure reduces with height. You'd have very little flow from the mains at the top of a tall block of flats at peak times. With a header tank, as long as it has been spec'd properly will maintain a decent flow rate at peak times.

[Nevin]

Okay, fair enough that answers my question so thanks all for your input. I shall leave it there. Its a big tank in the loft that has a mains feed to it. It then feeds the crappy old hot water tank no gas so no combi) and the cold taps in the bathroom. The pressure isn't great but its bearable so I'll leave it.

Block of flats is only three stories high and mains water pressure is always pretty epic in the kitchen to be honest.

[Ferg]

jagracer said:

Ferg said:

jagracer said:

Is the OP getting a little confused between a header tank and a supply tank or am I being pedantic....again?

Pedantic?
Do you mean a cold water cistern?

A cistern to me is a tank for storing water for a toilet or hot water for taps. I mean the big tank in the loft, I suppose storage tank would be more apt.

Edited by jagracer on Saturday 10th April 20:22

It IS a cistern.