Low water pressure

G

Grem

Member
I’m hoping someone can help.
Earlier in the year we had our bathroom revamped. Water pressure to the bath was always low but to the basin it was good (we didn’t turn the cold tap on fully as it would splash everywhere if we did). Since having a new basin, and tap, the water trickles out, even from the hot tap which comes through the shower pump. The cold did go through the shower pump but the pump manufacturer told me it was wrong, so I had it changed. It made no difference.
The toilet fills quite slowly too, but I don’t hang around waiting for that.
Is the tap the problem? It’s a Wickes basin mixer tap.IMG_5003.jpeg
The pipe work from the cold water tank? Comes from the tank as 22mm and changes to 15mm for the bathroom. I removed the anti-splash bit in the hopes it would make the flow better, but it didn’t.
The picture above is the tap on full. The isolation valves are fully open too.
Please help.
Mains pressure is fantastic.
 
1. The eighth bullet point states "the minimum operating pressure is shown on the packaging".
2. The nearest looking (but chrome) tap I could find on Wickes web site showed a minimum operating pressure of 0.3 bar. However, it doesn't state what the flow rate at that pressure would be.
3. If you have a cold water storage cistern (CWSC) in the loft and and a hot water cylinder (HWC) in a first floor airing cupboard your pressure for tank fed outlets will be the vertical distance from the outlet to the base of the CWSC in metres divided by 10, so roughly 0.2 bar.
4. I suspect your taps are mis-matched with your water pressure. Possible remedies include:
4.1 Change the taps.
4.2 Install a universal shower pump to feed all outlets.
4.3 Replace the CWSC and HWC with an unvented HWC
 
andy48 said:
1. The eighth bullet point states "the minimum operating pressure is shown on the packaging".
2. The nearest looking (but chrome) tap I could find on Wickes web site showed a minimum operating pressure of 0.3 bar. However, it doesn't state what the flow rate at that pressure would be.
3. If you have a cold water storage cistern (CWSC) in the loft and and a hot water cylinder (HWC) in a first floor airing cupboard your pressure for tank fed outlets will be the vertical distance from the outlet to the base of the CWSC in metres divided by 10, so roughly 0.2 bar.
4. I suspect your taps are mis-matched with your water pressure. Possible remedies include:
4.1 Change the taps.
4.2 Install a universal shower pump to feed all outlets.
4.3 Replace the CWSC and HWC with an unvented HWC
Click to expand...
Thank you. I think I may have to change the tap. Unfortunately I didn’t keep the packaging. I’ll try to find a converter from litres per minute (or may be hours in my case) to bar.
 
Hi,
I’ve just discovered the tap is from B&Q and in the main blurb says it’s suitable for high and low water pressure. Then in the small print it says minimum pressure is 0.5 bar. Mine works out to be 0.22bar. The only thing is that the water pressure was greater pre changing the tap.
Is changing the tap the best solution?
Thank you for all your answers so far.
 
Grem said:
Hi,
I’ve just discovered the tap is from B&Q and in the main blurb says it’s suitable for high and low water pressure. Then in the small print it says minimum pressure is 0.5 bar. Mine works out to be 0.22bar. The only thing is that the water pressure was greater pre changing the tap.
Is changing the tap the best solution?
Thank you for all your answers so far.
Click to expand...
The water pressure was the same before, the flow rate was higher. that tap, like so many modern ones are just NOT suitable for a lot of houses. Changing it for one suitable for 0.1 bar should improve things.
 
Thank you. I’ve just been looking online and they are so expensive, especially when we’ve only just paid out for that one.
Is it permissible to take a feed off the mains that fills the cold water tank? I can adjust the pressure from downstairs as there’s a separate stopcock for upstairs.
 
Yes you could but a pressure reduction valve may be needed and your hot and cold will be out of balance so unless there is a non return on the hot you could end up backfilling the hot tank.
 
If I left the cold tank pipe work as it is, for the shower (no bath and shower has a pump), but only took for the basin and toilet could it still backfill the hot water tank? Where would the non-return be on the hw tank? We had to have a weird thing put on the top of the hw tank when we fitted the shower pump.
 
Tank in the loft serves shower pump, toilet and washbasin and HW tank.
HW from the HW tank serves shower pump and basin
 
1. That tap is a monobloc, so almost certainly mixes hot and cold in the body of the tap. As such, cold water at mains pressure could easily overcome the hot and back flow through the HWC into the CWSC.
2. Backflow could be prevented with a non-return valve in the hot line to the tap from the HWC. However, such a valve would further reduce the hot water pressure and hence the hot flow rate. Such valves are not terribly robust and it could fail in time.
3. The "weird thing" fitted to the HWC at pump installation was likely a special flange to stop air getting into the pump feed.
4. What pump do you have fitted - make and model?
 
It’s a
Grundfos STR2-1.5 CN Twin Impeller Universal Regenerative Shower Booster Pump (x4 Hoses Inc.)

SKU: 98950219-PM1001-98381636-NRV From Anchor pumps
I think the thing on top is a Surrey valve - would that make sense?
 
I'd check again with Grundfos. I'm surprised your pump can't cope with pumping hot and cold to a basin tap if it is universal.
 
When I questioned them about the reduced flow rate, at the tap, the person I spoke to told me it was a shower only pump and the plumber shouldn’t have plumbed the other water off it. That would make sense if I was trying to use the basin and the shower at the same time. The weird thing is that the shower has quite a lot of pressure.
As much as it grieves me, I think I’ll change the tap as a first port of call.
Update - tap for sale
 
Hi All,
I’ve now changed the basin tap and the water flow is better although still not as it was with the ancient taps.

If anyone knows someone who needs an almost new black basin tap, I now have my original one for sale for £50 ono, on Facebook Marketplace
Thank you all for your help.
 
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