new mixer tap, water pressure now bad

12-07-2019 2:23pm #1

hi all,

I had an incident with an old bathroom tap which suddenly cracked where it connected to the water mains. Thankfully I avoided much damage by emtying the water tank in the attic. I also disconnected the water to the hot tank by turning the wheel in the airing cupboard where the immersion tank is.

The next day I fitted a new mixer tap, only to find that the water pressure is only middling from the cold setting, and down to a trickle on the hot setting. This is the same for all the other taps in the house with the exception of the main kitchen tap, which I know connects straight to the mains supply.

I wonder is there a simple fix for this? I looked up this problem online and there is quite a variation on solutions, some of which seem quite technical.

Thanks in advance

Markcheese · 12-07-2019 2:35pm

Well the kitchen cold tap is off the mains, so seperate...
Are all the hot and cold taps else where really poor pressure,?
Did the storage tank in the attic refill fully?
If it was just the new mixer I'd have thought it was your new tap,
Maybe a partial airlock?

John.G · 12-07-2019 2:40pm

Also ensure that you have fully (re) opened any gate (wheel) valves that you previously closed, there should be ~ 4 to 5 full turns between fully closed & fully open.

Sleeper12 · 12-07-2019 2:51pm

You may have bought a mixer for a pressurised system. This does not explain the difference between the hot & cold but you might not get as good pressure as your old mixer when you fix the air lock or whatever is the problem

22-07-2019 12:37pm

hi all... thanks for getting back to me.

I checked the 2 tanks in the attic (hot and cold) and both have appeared to have filled back up properly.

There are 2 knobs / wheels in the airing cupboard where the emersion tank is and I have turned both of these anti-clockwise as far as they will turn.

The water pressure is still bad upstairs (hot and cold in all taps in both bathrooms), and bad downstairs (hot only). The cold tap in the downstairs bathroom appears to have better pressure than the cold taps upstairs, and the cold tap in the kitchen is fine.

I am wondering is there any chance that some sort of foreign body may have gotten into the tank upstairs and is now partially blocking the water pipe somewhere past where the hot water and cold water pipes join?

corkgsxr · 22-07-2019 9:38pm

Probably airlocked

LIFFY FISHING · 24-07-2019 9:35am

The new fitting you bought is very likley to operate off a pressurised water system as most european systems are, from what you say your plumbing system seems to be a traditional gravity system...hence the low pressure comming from your new fitting.
Check the installation manual for your fitting it will in all likleyness say minimun operating pressure 1 bar.

Markcheese · 24-07-2019 6:40pm

LIFFY FISHING wrote: »

The new fitting you bought is very likley to operate off a pressurised water system as most european systems are, from what you say your plumbing system seems to be a traditional gravity system...hence the low pressure comming from your new fitting.
Check the installation manual for your fitting it will in all likleyness say minimun operating pressure 1 bar.

I thought that originally, (and it still could be that too), but the op said his other tank fed taps are very poor pressure as well..

whizbang · 24-07-2019 9:40pm

Can you temporarily link your Kitchen cold and hot taps, so the mains cold pressure will backfeed into the attic tank.

This will clear any airlock, and may clear any debris also.

Better if 2 people are involved; one to check the tank, and one to turn cold water on and off.

John.G · 24-07-2019 9:52pm

Deleted User wrote: »

hi all... thanks for getting back to me.

I checked the 2 tanks in the attic (hot and cold) and both have appeared to have filled back up properly.

There are 2 knobs / wheels in the airing cupboard where the emersion tank is and I have turned both of these anti-clockwise as far as they will turn.

The water pressure is still bad upstairs (hot and cold in all taps in both bathrooms), and bad downstairs (hot only). The cold tap in the downstairs bathroom appears to have better pressure than the cold taps upstairs, and the cold tap in the kitchen is fine.

I am wondering is there any chance that some sort of foreign body may have gotten into the tank upstairs and is now partially blocking the water pipe somewhere past where the hot water and cold water pipes join?

"There are 2 knobs / wheels in the airing cupboard where the emersion tank is and I have turned both of these anti-clockwise as far as they will turn".

I know I said it in my post #3 but it won't take a minute to do it again, shut both valves fully, they should take 4/5 turns and then again ensure that they open 4/5 turns anticlockwise, there is sometimes nearly a full turn of free play in these valves before anything happens.

15-09-2019 12:54pm

John.G wrote: »

"There are 2 knobs / wheels in the airing cupboard where the emersion tank is and I have turned both of these anti-clockwise as far as they will turn".

I know I said it in my post #3 but it won't take a minute to do it again, shut both valves fully, they should take 4/5 turns and then again ensure that they open 4/5 turns anticlockwise, there is sometimes nearly a full turn of free play in these valves before anything happens.

bingo! thanks, I had meant to post here weeks ago. Not only did this restore normal water pressure to the hot taps in the house, but the upstairs radiators have never been as warm. One of these wheels must only have been half-on for years.

micks_address · 15-09-2019 2:47pm

I was just about to open a similar thread.

We got this fitted in our downstairs toilet and the hot pressure is very low..

https://www.homebase.co.uk/estilo-ikon-mono-basin-mixer-tap_p390288

The cold is fine as are the other hot taps.. is it a tap that needs higher pressure?

We have a hot water cylinder and large tank in attic but no small tank in attic..

John.G · 15-09-2019 3:12pm

The attachment says min pressure 0.2 bar, max pressure 16 bar, flowrate 21.1 lpm. If one takes this literally to mean that it will flow 21.1 LPM @ 16 bar then one would expect it to flow ~ 4 LPM from the hot gravity flow and ~ 7.5 LPM from the cold mains @ 2 bar. My mixer (with two separate taps) flows ~ 5 LPM from hot tap only (gravity fed) and 10 LPM from the cold tap only at a mains pressure of 2 bar.

micks_address · 15-09-2019 3:25pm

John.G wrote: »

The attachment says min pressure 0.2 bar, max pressure 16 bar, flowrate 21.1 lpm. If one takes this literally to mean that it will flow 21.1 LPM @ 16 bar then one would expect it to flow ~ 4 LPM from the hot gravity flow and ~ 7.5 LPM from the cold mains @ 2 bar. My mixer (with two separate taps) flows ~ 5 LPM from hot tap only (gravity fed) and 10 LPM from the cold tap only at a mains pressure of 2 bar.

Not sure what you are saying? I should expect it to be low? It's fine but not great... Especially for a 80 euro tap...anyway to increase the flow rate? The cold is obviously way stronger

John.G · 15-09-2019 4:02pm

Yes, because the gravity fed hot water will only have a pressure (head) of 0.5 bar, then you can only expect ~ 1/2 the flowrate of hot water supplied at say 2 bar. I am assuming that the cold supply to this mixer is from the mains. Some houses have fully pumped hot&cold systems which will give this 2 bar pressure to both hot and cold supplies. You could fit this pump (still not cheap though) to the hot water supply to that mixer, https://showerpowerbooster.co.uk/

micks_address · 15-09-2019 4:25pm

John.G wrote: »

Yes, because the gravity fed hot water will only have a pressure (head) of 0.5 bar, then you can only expect ~ 1/2 the flowrate of hot water supplied at say 2 bar. I am assuming that the cold supply to this mixer is from the mains. Some houses have fully pumped hot&cold systems which will give this 2 bar pressure to both hot and cold supplies. You could fit this pump (still not cheap though) to the hot water supply to that mixer, https://showerpowerbooster.co.uk/

Thanks,
Looks like a tap change be best way to go? It do for now.. are there mixer taps that will flow better? Similar style?

John.G · 15-09-2019 5:35pm

That would seem to be the obvious way to go but while I've often seen them advertised as suitable for pressures down to 0.2 bar, I have not seen any stated flow rate at these low heads
Some reader on here might have sourced one and be able to give some info.

micks_address · 15-09-2019 5:48pm

John.G wrote: »

That would seem to be the obvious way to go but while I've often seen them advertised as suitable for pressures down to 0.2 bar, I have not seen any stated flow rate at these low heads
Some reader on here might have sourced one and be able to give some info.

Could anyone link to a tap which might work better? I'm not going to rush into changing it but probably will have to eventually

John.G · 15-09-2019 6:41pm

micks_address wrote: »

Could anyone link to a tap which might work better? I'm not going to rush into changing it but probably will have to eventually

Just found this on a "Franke" website and it states that it should give at least 4 LPM at 0.3 bar so this ties up with mine (downstairs) Franke which flows 5 LPM with a gravity head of 0.45/0.5bar.
https://www.franke.com/gb/en/ks/expertise/select-kitchen-sink/tap-features-flow-rates.html

I would measure the flow rate from your existing hot tap with a 1 litre milk bottle or such like and if its not less than say 3.5 LPM I'd say you won't get much improvement with any other.

micks_address · 15-09-2019 8:23pm

John.G wrote: »

micks_address wrote: »

Could anyone link to a tap which might work better? I'm not going to rush into changing it but probably will have to eventually

Just found this on a "Franke" website and it states that it should give at least 4 LPM at 0.3 bar so this ties up with mine (downstairs) Franke which flows 5 LPM with a gravity head of 0.45/0.5bar.
https://www.franke.com/gb/en/ks/expertise/select-kitchen-sink/tap-features-flow-rates.html

I would measure the flow rate from your existing hot tap with a 1 litre milk bottle or such like and if its not less than say 3.5 LPM I'd say you won't get much improvement with any other.

Actually all sorted... A good plumber told me to check the flexi pipe to see if it was kinked... It sure was..happy days

new mixer tap, water pressure now bad

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