basin & hot water cylinder

[izzy eckerslike]

I am thinking of adding a wash basin in our dormer bedroom, the hot water cylinder is behind the wall in the loft area, as the dormer floor is about 10" higher than the loft floor it means that when I fit the basin it will likely be about level with the top of the cylinder.

Will I get hot water to flow to the basin? the cylinder top up tank is quite a bit higher so will it help to add more pressure or will I likely just get a dribble ?

 

[seco services]

long as the cws is higher than the tap on the basin it will work.
how much higher is it than the tap ? that will tell you how good the pressure will be ?

 

[dextrous]

I am thinking of adding a wash basin in our dormer bedroom, the hot water cylinder is behind the wall in the loft area, as the dormer floor is about 10" higher than the loft floor it means that when I fit the basin it will likely be about level with the top of the cylinder.

Will I get hot water to flow to the basin? the cylinder top up tank is quite a bit higher so will it help to add more pressure or will I likely just get a dribble ?

The emboldened bit is the important part. The higher this "top up tank", the greater the pressure. The position of the cylinder is of no relevance (eg it could be on the ground floor, but the pressure would be the same)

 

[izzy eckerslike]

Maybe all right then as when I am stood in the loft the bottom of the tank is level with my head & I am 6ft !

thanks for the info

 

[seco services]

you may just about stuggle to get 0.1 bar.

 

[TicklyT]

Make sure your basin taps are OK for a gravity system. Many are designed for higher pressures from combis and unvented systems, and won't work on pressures below about 1 Bar. That's about ten times the pressure you will have available.

Taps for gravity systems are designed to work in situations like yours.

 

[izzy eckerslike]

Thanks TicklyT,
I wasn't aware of that so I now know what to look for

 

[kirkgas]

i would also suggest you get taps with 15mm outlets so you can connect 15mm pipe straight to the tap, as opposed to 10/12mm that some monobloc taps have, the height of the water in the top up tank is critical but so is the horizontal distance from the tank to the tap, especially on lower height of tank, if the tank is above the tap it will work, but if it has to run a fair amount horizontally to the tap it will decrease the pressure as well.

 

[TicklyT]

That's one reason for measuring the head from the base of the cold storage cistern. The true head, of course, is proportional to the water level in the cistern, which varies a bit as water is drawn off. Measuring from the base allows for the absolute worst case, and a bit for friction losses in the pipework.

I may be wrong, but I don't think I've ever seen any taps suitable for gravity feeds with anything smaller than 15mm connections. I think the 10 or 12mm tailed taps usually state a minimum WP of 0.5 Bar, but sometimes they will just about get away with running at about 0.3 Bar.

OP - Try to avoid using the small bore flexible tails and service valves often fitted to 15mm pipework. You can get full bore isolating valves and flexis, but IMO they start to look a little clumsy if they are on display.