Minimum flow rate required for unvented domestic hot water system

You'll probably be alright. 2.8 bar is plenty strong enough to push through a restriction. If your flow rate relied on wide bore pipes under low pressure, the effect would be much greater than your high pressure system.

In any case, I suspect your supply might be capable of more than 25lpm. The water company is only interested in there being more than 7lpm or 9lpm or whatever their standards are. If they get 25lpm out of a thin bore mains pressure only kitchen tap, they're going to say "that's fine" and not investigate further.

Christian.

Reply to
Christian McArdle
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replying to IMM, Peter Clarke wrote: interesting, I have a similar issue. But I would add that my concern is people downstairs at breakfast time flushing loos and using mains cold at the kitchen sink; this will reduce pressure and flow to the showers if everything depends on incoming mains. In my case I am going to be using 2 tanks in the loft to supply the 2 ensuites only. The main drawback will be the heat loss from the existing combi , on its long journey to the new DHW cyclinder that I am installing for the ensuites, and that in summer some of my central heating flow/return will be running hot just to get heat to the DHW cylinder.

Reply to
Peter Clarke

Peter, please read this.

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Reply to
Graham.

Shouldn't do.

Not if you spilt 24mm cold from right after the stopcock to geed everything but the hot water tank. Roof mounted tanks are always less pressure than mains is. So as long as you have adequately sized pipework you will always do better with mains pressure than a header tank.

Reply to
The Natural Philosopher

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