Pressure loss in new loft (unvented cylinder)

[RS_2022]

Hello again. I've now had multiple plumbers as well as Thames Water come in and have a look and it's only confused me more.

The pressure at the water meter is 3.5-4bar with a 20l/min flow rate. The pressure at the outside tap is 3-3.5 bar with a 20l/min flow rate. We couldn't get a pressure gauge to fit on any of the inside taps, but the flow rate in the kitchen is between 8 -10l/min and in the loft it's about 13l/min. I have a new Megaflo in the garage and the plumber who installed it has told me that all the pipes coming from the Megaflo are 22mm ones.

I have new plumbing and new Hansgrohe fittings in both the first floor and second-floor bathrooms and the fitter has assured me that all the pipes he's used are also 22mm ones, that connect to 15mm ones just before they connect into the shower/etc.

It seems like the water pressure & flow are both good at the water meter as well as at the outside tap, but both drop significantly inside the house.

I've had a few people suggest I change the mains pipes to 32mm blue pipes, but I don't see how that would help considering the fact that despite the old pipes, the water pressure at my outside tap is excellent.

I've also had plumbers suggest the break tank/booster pump solution but no one can seem to work out what the issue is and therefore the solutions they suggest feel like guesswork.

Has anyone had anything like this before? Any idea why the water flow and pressure is dropping so much and what I could do to fix it?

@Vee @ShaunCorbs ?

 

[ShaunCorbs]

Outlets / taps could be restricted/ have flow limiters

Have you tested from an open pipe ?

 

[RS_2022]

Outlets / taps could be restricted/ have flow limiters

Have you tested from an open pipe ?

Not from an open pipe, no. How do I do that?

I did check and the Hansgrohe products all seem to have a max flow rate of 15-17l/minute. Have I just spent a fortune on products that reduce flow/pressure?!

hansgrohe Overhead showers: Raindance Select S, 2 spray modes, Item No. 26466000

Overhead shower 240 2jet with shower arm. Click for More!

www.hansgrohe.co.uk

hansgrohe Hand showers: Raindance Select S, 3 spray modes, Item No. 26014000

Hand shower 120 3jet PowderRain. <li>The handshower envelops you in a delicate coat of micro-fine PowderRain - a wonderful feeling.</li>; Click for More!

www.hansgrohe.co.uk

Vivenis Bath mixers: designed to run 2 outlets, Chrome, Item No. 75445000

Single lever bath mixer floor-standing. <li>Mixes air into the water. For a soft, low-splash water jet and full, light drops.</li>; Click for More!

www.hansgrohe.co.uk

 

[ShaunCorbs]

Would suggest getting a plumber in to test from the loft bathroom both hot and cold flow rates from an unregulated source eg straight off a 15mm pipe to a basin etc

 

[RS_2022]

Would suggest getting a plumber in to test from the loft bathroom both hot and cold flow rates from an unregulated source eg straight off a 15mm pipe to a basin etc

Okay, I'll do that and report back. Thanks so much.

What would be a good flow rate and pressure in this situation? The house has 3 bar & 20l/min at the outside tap, the system is an unvented Megaflo installed 6 months ago and I have 2 bathrooms - 1st floor & 2nd floor (loft).

 

[ShaunCorbs]

Ideally you should still have 20lpm upstairs but let’s say 2 bar 15lpm is ok in the loft

 

[RS_2022]

All checked.

Ideally you should still have 20lpm upstairs but let’s say 2 bar 15lpm is ok in the loft

Ok so I've now checked -

Pressure at water meter - 3.5-4bar
Flow rate at water meter - 20lpm

Pressure outside tap - 3-3.5bar
Dynamic pressure outside tap - 2.5-3 bar
Flow rate outside tap - 20lpm

Pressure in 1st floor bathroom - 2.5 bar

Pressure in loft - 2.2bar
Flow rate in loft - 13 lpm (from a shower hose without the showerhead)

The flow rate seems to be dropping quite considerably from the outside tap to the 2nd floor, but I think pressure's probably okay..?

What do you think?

 

[ShaunCorbs]

They look just about there depends how much of a good shower you want

If your happy with first floor bathroom shower then you shouldn’t notice any difference

But if you do like a good shower only way is to control the water pressure yourself eg dab pump in my above link you can set it to 4 bar etc providing the issue is just your incoming mains water

 

[RS_2022]

They look just about there depends how much of a good shower you want

If your happy with first floor bathroom shower then you shouldn’t notice any difference

But if you do like a good shower only way is to control the water pressure yourself eg dab pump in my above link you can set it to 4 bar etc providing the issue is just your incoming mains water

Thank you. I do want a good, strong shower. Do you think installing a pump will be more effective than a mains pipe replacement in this scenario?

 

[ShaunCorbs]

It all depends on what the water supplier can give you, you already have a good supply I doubt your loosing / they can increase it by replacing the mains

 

[Ben-gee]

With a lot of showers being “eco’d” to 9lpm I would have thought 13 acceptable to any planet loving grown-up.

Seriously though, have you tried a proper air incorporating shower head, like Hansgrohe raindance etc? You’ll be surprised at the perceived differences…

 

[Timmy D]

Could be debris in the loft shower inlet filters