Slow running hot water

[BernardW]

I have recently installed a new dual tap in the kitchen of my bungalow. The previous tap had 15mm pipes soldered into the tap so the flow was acceptable, but the new tap has flexible pipes which reduce the flow.
At the present time it takes 25 seconds to fill a 1 litre jug which is obviously not accepable.
The system has a 25 gallon header tank about 0.5 metre above the cylinder.
Would raising the header tank by 200 to 250mm have any significant affect on the flow?
If the answer is that it would make little difference, could I install a pump between the header tank and the cylinder? preferably vertically mounted on a 22mm pipe.

 

[COG]

Raising the tank would have no noticable deference not by 250mm, if your tap was ok before then check out your new tap even with 8mm tails you should be getting more than 2lt per min i would say something around 6 to 9 at least.

 

[BernardW]

Thank you for reply, but the pressure has always been low and only allows a trickle to the washing machine when warm water is required.
The kitchen sink tap is a considerable way from the boiler but the washing machine is quite close.
If raising the tank will not make much difference, then a pump would seem the only solution, but what pump would be required?

 

[ChrisR]

What diameter is the pipe from the CW cistern in the loft to the HW cylinder?
It could be that you have scale blocking your pipes, though restrictive taps are most likely to be the culprit. Try connecting your mains CW to your hot for half a minute - perhaps at the washing machine. You may blast crud back up into the tank. Run some CW first so it doesn't overflow.

 

[BernardW]

The tank is not in the loft of my bungalow because the pitch of my roof is only 12.5 degrees so there is no room. The bottom of header tank is approx 18" above the cylinder and has 22mm pipes.
I will try your back flush idea though.

 

[oilman]

Your new tap is probably a high pressure tap on both cold and hot. With your water supply, you should have a low pressure tap for the hot side. This may be a problem for you now without buying another tap which is low pressure both sides, and then fit a restrictor in the cold side. You may find there is a restrictor that can be removed from the hot side.

 

[BernardW]

I didn't realise you could get high pressure taps prior to your answer, but when I installed the tap I removed the restrictor in the hot tap connector which gave the current flow of 1 Litre in 25 seconds.
I still think I will have to resort to a pump, yet no one has suggested this as an alternative.

 

[oilman]

We try to not suggest expensive solutions before establishing there is no alternative. (Probably why we can't get featured on ******** From Hell programs )

If you have removed the restrictor, you could take the tap off the sink and try a test with a hosepipe to supply the water and see what happens, it may reveal something.

 

[BernardW]

The tap would appear to be fine because the cold water flow is fantastic.
This new tap is taller than the previous tap as well as having a smaller bore in the flexible pipe. from the bottom of the header tank to the top of the tap is approx 11". Is this enough to give a reasonable flow, I suspect not.

 

[BernardW]

Surely someone somewhere has a solution oe am I left ttotally on my own

 

[ChrisR]

Grundfos do a pump for just this sort of application. iirc it gives about 7metres head , for about £70 + vat. I asked about the hw cylinder feed pipe. This has to big enough that there's no appreciable resistance in it. If there is it would mean a slight pressure drop . This in turn would mean that air would be drawn down the vent pipe. I bet your feed pipe is 3/4 or 22mm. It would have to be at least 28mm if not 35

Stooge around the Grundfos site or call them.

Later - had a look. I' was thinking of the UPA 15-90

see here

 

[galwag]

some taps have a removeable filter at the end of the spout. It is mainly the hot side that blocks due to small bits of limescale

 

[BernardW]

Thank's Chris for news about the pump, I phoned Grundfos but they wanted £1,00 per minute to tell me which pump. (ROBBERS).
Does the pump fit 22mm pipe and what part number do I require?