Reduced shower pressure, any ideas?

Reduced shower pressure, any ideas?

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boxster9

Original Poster:

466 posts

199 months

Thursday 3rd April 2014
quotequote all
Does anyone know what the problem may be here. Whenever we use the shower and another tap is opened (could be anywhere in the house) , the pressured from the shower is reduced to a mere trickle. It seems we can't have two showers running at the same time, which defeats the object of having two bathrooms in the first place.

The mains pressure is good, so it must be something to do with our plumbing setup.

Any thoughts ?


elanfan

5,516 posts

226 months

Thursday 3rd April 2014
quotequote all
If you live in a modern house it could be your upstairs cold water comes from a tank (similar to the hot water but from the loft)rather than the mains. Probably insufficient pressure from the set up.

yellowtang

1,772 posts

137 months

Thursday 3rd April 2014
quotequote all
Combi system or gravity fed?

jontymo

810 posts

149 months

Thursday 3rd April 2014
quotequote all
Sounds like you have a combi boiler!

jock mcsporran

5,001 posts

272 months

Friday 4th April 2014
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If it's a power shower would having a combi affect it? Surely the cold feed wouldn't be going through the boiler in that case.

We have the same but the upstairs shower is on the second floor. We've just put it down to the height. If anyone turns on a tap or goes to the toilet elsewhere in the house I burn my bum as the pressure drops.

Zoon

6,654 posts

120 months

Friday 4th April 2014
quotequote all
On your boiler or underneath there should be a pressure gauge. It should have markings with a green range between 1-2 bars. If it's below this the pressure will be poor. There is usually a filling loop which you can open which lets pressure into the system.

rossmc88

474 posts

159 months

Friday 4th April 2014
quotequote all
Zoon said:
On your boiler or underneath there should be a pressure gauge. It should have markings with a green range between 1-2 bars. If it's below this the pressure will be poor. There is usually a filling loop which you can open which lets pressure into the system.
Is that not for your heating system pressure? Not your hot water pressure

Pferdestarke

7,179 posts

186 months

Friday 4th April 2014
quotequote all
If the tap is earlier in the pipe network than your shower, which it likely is, then it will vastly reduce the pressure of water travelling to your shower.

Why must a tap be on when someone is in the shower?

Just ask them to not turn it on fully or leave their washing up until you're done in the bathroom.

Failing that, you need to get the water feed to the shower first. But then the problem will be reversed.

Zoon

6,654 posts

120 months

Friday 4th April 2014
quotequote all
rossmc88 said:
Is that not for your heating system pressure? Not your hot water pressure
In my experience it has always resolved problems with hot water pressure, I'm not a plumber however!


The Restorer

841 posts

227 months

Friday 4th April 2014
quotequote all
boxster9 said:
so it must be something to do with our plumbing setup.
Must be. How's your plumbing setup?

Combi, hot water tank, power shower, electric and so forth.

Give is something to go on...

boxster9

Original Poster:

466 posts

199 months

Friday 4th April 2014
quotequote all
The house is approx 10 yrs old. There's no hot water tank in the attic. We have one of those 'Megaflo' type cylinders in the airing cupboard , an 'Oso indirect unvented water system'.

Previous house we lived in we could have three showers running at the same time with no loss in pressure.

fourpointsixgt

513 posts

163 months

Saturday 5th April 2014
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Mega flows should easily run 2 showers, these are pretty much the best providers of hot water there is, they use mains pressure stored in the cylinder, sending it to the hot taps, there's usually a blending valve on the outlet of the cylinder which mixes cold water with the hot. I would first check the cold mains pressure is good at all the taps, then check the tap in the cupboard where the megaflow is, this will be on the cold pipe going into the cylinder, probably 22mm, make sure it's fully open. Any on depth work on these has to carried out by a qualified unvented hot water plumber. Post a pic of the cylinder cupboard if you're not sure.

dirkgently

2,160 posts

230 months

Saturday 5th April 2014
quotequote all
boxster9 said:
The house is approx 10 yrs old. There's no hot water tank in the attic. We have one of those 'Megaflo' type cylinders in the airing cupboard , an 'Oso indirect unvented water system'.

Previous house we lived in we could have three showers running at the same time with no loss in pressure.
The usual (but not only) cause of lack of flow from an unvented cylinder is a failure of the pressure reducing valve.

zed4

7,248 posts

221 months

Saturday 5th April 2014
quotequote all
boxster9 said:
The house is approx 10 yrs old. There's no hot water tank in the attic. We have one of those 'Megaflo' type cylinders in the airing cupboard , an 'Oso indirect unvented water system'.

Previous house we lived in we could have three showers running at the same time with no loss in pressure.
My house is also 10 years old, with the same OSO hot water cylinder, and I have the exact same problem. frown

CorradoTDI

1,432 posts

170 months

Saturday 5th April 2014
quotequote all
When was the last time the Megaflo was serviced / drained down?

heliboy

63 posts

197 months

Saturday 5th April 2014
quotequote all
The air gap in the cylinder has been lost
You need to rein state the air gap
Their will be a sticker on the cylinder to show how to reinstate the air gap
This can be done by the home owner
From memory on a mega flow you close the incoming cold water supply pipe by the cylinder
Open the lowest hot tap normally the kitchen until the water stops
keep tap on
Hold open the pressure release valve on the the cylinder this can take 20 mins
And air will be pushed up the release valve and push the water out of the cylinder and out of the lowest tap
When the water stops running from the tap the air gap has been reinstated
Close tap
Turn back on the in coming water supply pipe
This should be done at least once a year

Please remember do not play with these cylinders as they are a potently a bomb as you need to be qualified to install and service these
Google myth busters
Good luck


boxster9

Original Poster:

466 posts

199 months

Saturday 5th April 2014
quotequote all
Thanks all. Although I mentioned Megaflow, it's actually an 'Oso' brand but the cylinder looks identical to a Megaflow.

I'll try to post a picture of the setup.

Rickyy

6,618 posts

218 months

Sunday 6th April 2014
quotequote all
fourpointsixgt said:
Mega flows should easily run 2 showers, these are pretty much the best providers of hot water there is, they use mains pressure stored in the cylinder, sending it to the hot taps, there's usually a blending valve on the outlet of the cylinder which mixes cold water with the hot. I would first check the cold mains pressure is good at all the taps, then check the tap in the cupboard where the megaflow is, this will be on the cold pipe going into the cylinder, probably 22mm, make sure it's fully open. Any on depth work on these has to carried out by a qualified unvented hot water plumber. Post a pic of the cylinder cupboard if you're not sure.
On a thermal store, not usually on an Unvented Cylinder.

Loss of the air gap (if it's that type) won't cause low pressure either.

It is most likely a problem with the pressure reducing valve. It could also be an issue with the non return valve built into the pressure reducing valve assembly.

Has any work been carried out on the mains outside recently? Quite common for debris in the pipework to clog up non return valves. There may also be an NRV after the stop tap, worth checking that too.

brianb

440 posts

135 months

Sunday 6th April 2014
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I agree with Ricky, you really shouldn't have that much of a pressure drop with an unvented setup,

Get a decent plumber round, it sounds like a simple problem

Where you based?

jakef

1 posts

112 months

Thursday 27th November 2014
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Hi - I had the same problem with poor pressure upstairs from my Megaflo. I spent ages draining the pipes looking for air locks and re-airing the tank.

I took out the 3 bar pressure reducer and noticed a white plastic end was missing compared to the pictures online of a new one. I bought a replacement online for £40 and when I fitted it it made matters worse.

After a little more digging and reading this thread I decided to take some more pipes apart and found the white plastic end jammed in the non return valve.

When I took it out the pressure returned. smile