It might sound a silly question, but -
If I connect a pressure gauge to the cold water tap in the kitchen sink and
turn the tap on full, will that give me a measure of the mains water
The kitchen is on the ground floor and fed directly from the mains.
(I don't want to spend £2000) on a combi boiler only to find it won't work!
It will, but that does not actually tell you much of use (other than you
have enough static pressure to exceed the minimum required by the boiler
(often 1 bar).
You need to measure the flow rate, by timing how long it takes to fill a
container of known size from the fastest flowing tap in the house.
Under 10 lpm - no hope.
10 - 15 - too low unless you are fitting a low power combi (i.e. under
30kW) and will only even need one tap at a time
15-20 is better - but still not great. Over 20 is usually adequate.
A reasonable combi (say 35kW) will be able to manage about 15 lpm of
water at a usable temperature. So if the supply can manage 25 lpm that
should prevent the shower stopping when someone flushes the loo, or the
dishwasher decides to fill.
Don't think it makes much difference does it? The static pressure seen
by the boiler may be less by about 0.3 bar or so. The total length of
pipe from mains to tap is much the same and the sizes of pipe also the
Well I assume you will have much the same pipe layout wherever you place
the combi, be it near to the start in the kitchen, or near the tap in
the bathroom. The total quantity of piping, bends etc will be about the
same, so the total flow resistance ought to be the same.
If the flow is marginal then it is worth using swept bends and bigger pipe.
In theory; yes! The pressure gauge should be connected directly to the tap.
Most kitchen taps do not have the external thread for connecting a hose
though - unlike external garden-hose taps. FWIW; manufacturers seem to cite
3 Bar as the optimum pressure , Please be aware that pressure and flow,
albeit interconnected, are different aspects you'll still need the flow of
12 lts per minute.(?)
Sorry, it's 2000 euros - I'm in Ireland - about 1250 sterling.
It'll be an exteral combi (Grant) located on the ground floor just outside
When I connected a gauge to the tap it reads about 2 bar.
I haven't checked the flow rate yet but I will at the weekend.
What about booster pumps? Would one of these help?
I'm thinking if I install a cold water storage tank(fed from the mains)
alongside the boiler, and connect it to the boiler via a booster pump, would
that work? Obviously there wouldn't be much pressure coming out of the tank
since it's on the ground floor, but would a booster pump suck enough water
out of the tank to feed the boiler?
That's alot of cash - is there alot of re-plumbing involved?
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