Basin Tap Pressure problems Help

[Maxx470]

I have fitted a bathroom suite in our loft conversion, previously it only had an electric shower, WC & small basin.
I have fitted a bath, WC and new basin.
Because it's a bungalow and the cylinder is downstairs and cylinder feed tank is in loft I had great problems in getting the hot to flow to the new upstairs bathroom. So I have fitted a Warwick flange and a Grundfos electric demand pump. This works great on the bath tap ( which is piped in 22mm all the way ). But the basin wont flow Unless I momentarily turn the bath hot tap on, this obviously creates a big enough pressure drop to switch the pump on, where as the basin tap doesn't because it's ultimately piped in 22 to 15 to 10mm.
Any ideas to fix this ?

 

[seco services]

is it a pos or neg head pump ?

 

[kevplumb]

where as the basin tap doesn't because it's ultimately piped in 22 to 15 to 10mm.

and you wonder why it must be on a 3 ft head if your lucky

which is why i would think

 

[Maxx470]

I think it's a positive head pump, the pump is fitted below the cylinder. Like I said it pumps HW the bath no problem but not to the basin which is feet away from the bath, it will work the sink tap if I momentarily turn the bath hot tap on and straight off.

 

[kevplumb]

I think it's a positive head pump, the pump is fitted below the cylinder. Like I said it pumps HW the bath no problem but not to the basin which is feet away from the bath, it will work the sink tap if I momentarily turn the bath hot tap on and straight off.

its not getting the flow to operate the flow switch and dropping into 10mm ain't gonna help

and i'm not being sarky

 

[seco services]

yes but how much higher is the cws tank than the basin ?

i would of used a neg pump then don't get that problem.

 

[Maxx470]

The tank is probably only a foot or so higher than the basin. I don't think I can do much about the 10mm pipe sizes to the tap as it's the type that comes with two short lengths of copper pipe 10mm screws into tap and it's swaged out to 15mm to fit pipework onto.[/img]

 

[seco services]

ft is not normally enough useally abot 600mm (2 ft)
not sure on the grundfos pump what does the mi say ?

i useally opt for neg pumps in loft conversions etc.

 

[Maxx470]

it's

http://www.plumb-warehouse.co.uk/ishop/968/shopscr1495.html

 

[seco services]

i see the pump can't find any instructions on it.

 

[Maxx470]

Does this help ?

//www.diynot.com/network/Maxx470/albums/2911/11268

There "must" be some way to make this work.

 

[seco services]

not really any good its only basic info.
has the mi got no drawings ?

most pumps like salamander will state that it needs a min flow of 1 ltr/min flow to activate the flow switch.

600mm min head between base of cws and example showerhead.


can't see how your going to get the flow to kick the pump in.
only by raising the tank or some pump you can convert to neg head.

or see if they will change it for a neg head pump then it will supply the appliance even if it was above the cws.

 

[Maxx470]

Well Iv'e got it working !.
The water level in the header tank was a bit too low so I increased it & now it works .

 

[seco services]

that was abit of luck.

 

[Maxx470]

Thanks for your input Seco.
Now I have to fine something to replace the screw in sprinkler on the basin tap as it splashes unless I turn it down. Something with a bit of a spout, do you know if these things are available ?.