Low flow rate from new bath taps

[Wartavia]

I've had work done on my bathroom, with a new mixer tap installed on the bath and the hot and cold water flow from the bath tap is pitiful. The hot is coming out at 2.5 litres/minute

I have a older central heating system, with a hot water cylinder in the loft and my bathroom's on the first floor, so it would seem to be a low pressure system. My first thought was that I have bought taps which are unsuitable for low pressure, but I checked and they are supposed to be suitable for both high and low pressure.

The water pipes come into the bathroom as 22mm pipes and the plumber has run two 15mm spurs off it, with flexipipe going up to the taps. This would be the obvious explanation for the low flow.

If I turn the cold water on full, when the hot water is already on full, there is no increase in flow from the mixer spout, so I also wondered whether the taps themselves might also be to blame.

Is there anything else that could be causing this?

Thanks

 

[Deleted member 267285]

Depends if your cold pipes in the bathroom are cistern fed or mains fed. What is the minimum low pressure that the taps are suited to? You’re not going to get much pressure if the cylinder is in the loft, probably less than 0.2bar.

 

[JonathanM]

What was the flow like before? What is the flow from the basin tap?

I have low pressure hot water fed from a cold tank in the loft. I've just checked my bath tap and it's giving 12 litres per minute.

 

[Wartavia]

The bath flow was fine before (1970s taps and 22mm pipe)

The basin hot flow is 3.5l/minute. The basin has also been replaced and a new mono tap installed, using 15mm pipe and flexipipe.

The minimum pressure required for the new taps isn't stated, it just claims to be suitable for low pressure, but I'm going to check with the manufacturer on Monday

There is a large cistern in the loft, so I'm guessing cistern fed, but I'm not entirely sure

 

[JonathanM]

The basin hot flow is 3.5l/minute. The basin has also been replaced and a new mono tap installed, using 15mm pipe and flexipipe.

I have a normal two handle mixer tap on my bathroom basin and that gives 8 litres per minute of hot water with the low pressure/fed by cold tank arrangement.

 

[just pumps]

I've had work done on my bathroom, with a new mixer tap installed on the bath and the hot and cold water flow from the bath tap is pitiful

The water pipes come into the bathroom as 22mm pipes and the plumber has run two 15mm spurs off it, with flexipipe going up to the taps. This would be the obvious explanation for the low flow.



Thanks

Changing pipes from 22 down to 15 and adding braided flexis with a bore of 10mm will make a difference.

 

[danfre]

Are your taps high or low pressure

 

[JonathanM]

Are any isolation valves fully open

 

[Wartavia]

The taps are supposed to be suitable for high and low pressure. The isolation valves are fully open. I suspect it's the pipework

 

[just pumps]

I've had work done on my bathroom, with a new mixer tap installed on the bath and the hot and cold water flow from the bath tap is pitiful. The hot is coming out at Thanks

By plumber or handyman? If the later then easy to fit valves which are not full bore and also to kink the flexis.

 

[oldbutnotdead]

Are there any restrictors fitted to the taps? (Some advertised as suitable for both have internal reducers fitted as standard, they have to be removed for low pressure operation).
The 15mm and flexi tails will be reducing flow/pressure but not by much.
EDIT Can you get to the flexis? If yes, disconnect them and run them into a bucket, compare what you get per minute. 2.5l/min is pathetic.

 

[terryplumb]

I assume the previous bath had two seperate taps ,rather than one mixer ,which would give a better flow connected directly to 22mm pipes. As already said, changing pipe diameters to smaller and using flexible hoses to connect taps will inevitably result in dramatically less flow through mixer taps.

 

[Madrab]

The gravity fed system is designed to use single hi flow taps, it's still low pressure but as they're hi flow it make no difference. Modern mixer taps are designed to use supplies that are ~ 1bar anything less then flow can be significantly reduced, as you are finding.

Your plumber should have known that and told you and if he was anywhere near half experienced he should have at least hard piped it to the tap in 22mm presuming it's a deck/pillar mixer with 3/4" tails? Certainly not, reduced to 145mm then used flexi's, that's just a lazy install.

edited for the wrong number

 

[Wartavia]

Thanks to everyone for their replies. Sounds like it's a combination of pipework and unsuitable taps. Disconnecting the flexis and testing the flow rate sounds like a plan, so I'll try that and take it from there.