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View the thread, titled "Cold water storage tank setup" which is posted in UK Plumbers Forums on UK Plumbers Forums.

Hi all,

My mates recently bought a new old house and has had extensive work done including new bathrooms etc. We've got a few questions about the hot and cold water distribution. The house is supplied by cold water at around 3 bar, so decent enough pressure. The way it's set up at the moment is the cold for the kitchen sink and outdoor tap are fed off mains pressure, but everything else is fed from a cold water storage tank in the attic, so it's a vented gravity fed hot water cylinder. A pump is installed after the hot water cylinder which pumps the hot water and the gravity fed cold water to most of the house. Cylinder is heated by an oil fired system boiler.

First question is, would it theoretically be possible in the future (years) to have a high pressure hot water cylinder so therefore mains pressure hot and cold water throughout with an apparent mains pressure of 3 bar? Not sure what the flow rate is but definitely doesn't seem too weedy based on the kitchen and outdoor tap, anyway could always have a whole house pump fitted.

Secondly, when I say there is a cold water storage tank in the attic, there's actually 3 of them, and the way they're set up is only one of them has a mains cold supply into it, and the 3 are just linked by the feed pipes at the bottom if that makes sense. Now this seems very unhygienic to me as only one tank would really have the water regularly replenished and the other 2 would be fairly stagnant, thoughts on this?

Would a short term solution be to just do away with the extra 2 tanks and have just the one? And how hygienic would the water be from just one tank? Its not clear why its been done like this, perhaps the original tank wasn't big enough so two extras have been bodged on over time with more bathrooms or whatever, and I can't remember what the size of the tanks are but they're not small. I believe that a single tank would need to be 200-250l, is that correct?

Thanks for any replies!
 
Iirc they have to be designed, so as not to stagnate, so they could be ok. With regards the unvented cylinder, it seems plausible.
 
Multiple tanks is usually because a) mains is slow to fill, or b) powerful pumps empty it quickly, or c) can’t physically get a large tank into loft (through hatch).

It is normal to feed only one tank and link the others as slaves, however it is then normal to distribute water from the furthest tank so that all tanks have their water changed.

Yes if flow is sufficient you could change to unvented, but I’d probably keep what you have if it were me.
 
Multiple tanks is usually because a) mains is slow to fill, or b) powerful pumps empty it quickly, or c) can’t physically get a large tank into loft (through hatch).

It is normal to feed only one tank and link the others as slaves, however it is then normal to distribute water from the furthest tank so that all tanks have their water changed.

Yes if flow is sufficient you could change to unvented, but I’d probably keep what you have if it were me.
The 3 tanks are all different styles and ages so I don't think it was originally designed like that, I guess they're additions throughout the years. The mains is supplied to effectively the first in line so the other 2 don't really seem to have much, if any, flow through them. Can tell this as well as there's a lot more debris in those 2 and a sort of line around the edge suggesting the water has been sat for a good while. Next time we're there we could turn on one or even both showers to see how quickly they do empty and how quickly they're filled back up.
 
If someone has added the extra 2 tanks, it's been done for a reason, most likely because of the pump.
As others, the outlet(s) should be the opposite end of the 3 tanks to the inlet.
If it isn't then the easiet way to correct it is to move the inlet / ball valve to the opposite end, but clean all the tanks out first.
 

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Cold water storage tank setup
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