Cold Water Tank connections

[Mike S]

Hi all,

Wonder whether anyone can help with the following question. I need to connect up a downstairs bathroom to the cold water cistern in the loft so that I can use balanced pressure mixer valves (at present bathroom cold water is high pressure mains fed whilst hot water is low pressure gravity fed).

Can I do this by drawing water from a new branch running off the top of the 22mm pipe that feeds cold water from the cistern to the hot water tank? Or do I need to insert a separate outlet from the cistern?

In the case of the former option the branch would lie about a foot below the cistern, but high enough above the inlet into the hot water tank, I think, to prevent heat from the hot water tank affecting the new cold water supply.

Any suggestions or advice would be much appreciated.

Thanks

Mike

 

[Agile]

You can do either. A new cistern connection is best.

There should be no heat going up the cold feed to the cylinder.

Depending on the flow rate to be taken you might have a problem with sharing the outlet for the cylinder but that would not usually apply to a shower.

Its better NOT to take a pipe up above that pipe but rather horizontally.

Tony

 

[Mike S]

Its better NOT to take a pipe up above that pipe but rather horizontally.

Tony

Thanks for the prompt reply Tony! Do you mean I should insert a T in the horizontal section of the existing cistern outlet pipe?

I was planning to insert a T in the vertical section of the existing outlet just below the ceiling (in airing cupboard where hot water tank is located) with the new 15mm leading horizontally away from that... or is that best avoided?

Thanks again for your help.

Mike

 

[Agile]

You were not clear.

I thought you meant it was going up and then down.

That would cause air to collect there.

As long as its all down or horizontal there should be no problem.

Tony

 

[mysteryman]

It would be preferable to take a separate cold feed from the tank. It should be slightly lower than the supply to the cylinder, so that if the cold tank runs dry, the hot water stops before the cold.

If you do branch it off the cold feed to the cylinder, the branch should be above the top of the cyl, so that the cyl will not drain through the cold to the shower.

 

[Mike S]

It would be preferable to take a separate cold feed from the tank. It should be slightly lower than the supply to the cylinder, so that if the cold tank runs dry, the hot water stops before the cold.

If you do branch it off the cold feed to the cylinder, the branch should be above the top of the cyl, so that the cyl will not drain through the cold to the shower.

Thanks! Yes, I was intending to branch off well above the cylinder. Your tip about the location of an additional outlet on the cold water tank is also helpful, as I wouldn't have thought of that.

So I'm I right in summarising: ideally a new outlet from cold water tank would be the thing to do, but I shouldn't have any major problems if I branch off from the cold water feed to the hot water tank providing I follow the advice already given. I intend to feed one mixer tap, one shower mixer, and one washing machine in this way. Are there any potential downsides to not having an independent outlet?

 

[mysteryman]

A combined cold tank outlet would be more restrictive, so you would get better flow rates with separate supplies, particularly when several mixers are in use.

 

[picasso]

check you w/machine before you start work

http://www.whitegoodshelp.co.uk/wordpress/low-water-pressure-and-washing-machines/

 

[Mike S]

check you w/machine before you start work

http://www.whitegoodshelp.co.uk/wordpress/low-water-pressure-and-washing-machines/[/QUOTE]

Thank you! Glad you pointed this out to me.. I would never have thought of that. Since the bottom of the water tank won't be more than about 12 feet (if that) above the washing machine then I guess low pressure could be a problem for future washing machines if not the current one.

Back to the drawing board! Does anyone know how well pressure equalising valves work.. maybe I should connect the shower and basin mixers to one of those... however, the suppliers of the mixers that I'm thinking of buying imply that the products are not guaranteed if used with pressure equalising valves.

Otherwise I need to keep a separate mains supply for washing machine plus new gravity fed pipework for mixers, which will make things a bit crowded in the bathroom pipewise, as well as the making the job much more time-consuming.

 

[Mike S]

I've discovered that there are also pressure reducing valves that just work on the high pressure supply... is there any merit in these as opposed to an equalising valve? Are there any that can they reduce pressure down to about 0.2 bars which I suspect will be the pressure produced by my cold water tank in the loft?