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Plumberpro, Plumber
Category: Plumbing
Satisfied Customers: 634
Experience:  Heating and plumbing answers. 20 years experience
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When we moved into our home

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When we moved into our home [300 yrs old] the previous owners had renovated the ensuite but had fitted an electric pump as the water pressure was almost non existant yet not too bad elsewhere. We didn't like the noise as it had to be on all the time so we changed to an unvented system which did improve the situation but we did notice that if the bath was running the pressure in the basin taps was reduced considerably. We have since renovated the family bathroom consisting of a bath, separate shower, basin and wc. When the bath taps are fully turned no water will come from any other item. If the bath taps are slightly running then other items can be used with a reduced pressure. Is this normal? We understood the unvented system would give us good pressure under any situation. Look forward to your reply. Thank you Keith XXXXXX

Plumberpro : Hi . I will try to help . When the unvented system was put in , do you know if the mains water pipe into the property was changed?

Unvented system put in 2 months ago. No change made to mains water pipe.


Unvented system put in 2 months ago. No change made to mains water pipe

Plumberpro : The unvented systems are great but rely on a good flow rate and pressure from the incoming mains supply.
Plumberpro : It may be that your mains supply pipe needs to be upgraded. Can you tell me what your mains cold to the kitchen tap is like ?
Plumberpro : The pressure and flow rate should have been tested before installation to determine if a new supply pipe was needed.

Generally the pressure is good. The kitchen tap has excellent pressure direct from mains. It is only the bathrooms that are the problem.

Plumberpro : Hi.. Can I just check that you have an unvented cylinder installed
Plumberpro : Ok. The thing to realise is that pressure and flow rate are very different. If you can imagine having two pipe sizes, one a metre wide the other a hairs width. These could both have the same pressure , but completely different flow rates, in volume terms.
Plumberpro : If your mains supply is too small , you won't be able to get the volume in that you need to run the whole house at the same time .
Plumberpro : Does that make sense?
Plumberpro : Also , do you know if your mains pipe is lead?
Plumberpro : I am sorry to inform you that whoever said an unvented system would give good pressure under any situation was wrong. It needs a good incoming mains supply.
Plumberpro : There are two ways to go about this

Looks like inlet pipe is lead- all other pipes are copper. i understand your point about flow and pressure. only other thing suggested by a friend was that header tank could be pressured more


looks like inlet pipe is lead- all other pipes are copper. Not getting much help from installer of unvented system

Plumberpro : With an unvented system , tanks are not used or needed. In your previous system you would have had cold water storage tanks that could have trickle filled up , ready for when the water was required and then pumped..
Plumberpro : With the unvented , your mains comes in and feeds off to all the cold outlets then branches to your unvented cylinder which is heated by electric or a boiler then on to hot taps.
Plumberpro : The fact the it is a lead mains pipe shows it is quite old and only sized for a tank fed system.

inlet pipe looks like lead- all other pipes are copper. Not getting much help from installer but friend suggested header tank could be pressured more. is that a possibilty?

Plumberpro : An installer has to be qualified to install these systems and should have known this. I would check he is qualified .if not you will have to get someone who is to check it's been installed right.
Plumberpro : Your only options now are to get a new mains pipe put in ( get a few quotes) or to put a booster in

Thanks for your advice. Will do both , get system checked and have new mains pipe put in

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