Many properties suffer from low pressure. This blog is inspired after my visit to a home in Blowfield Heath. Low Pressure can often be with service pipes blocked with corrosion products or limescale. Checking with you Water Company is a good first step as you may find that its an old lead pipe which you might get replaced free or it might be the stop tap at the meter which is needs replacement. Replacing your own stop tap in your property is also something to be considered as this is often a reason for low pressure.
In my own home in Norwich I am at the end of a long private drive so my service pipe is 90 metres long. Thanks to Wilcon Builders who put in the smallest service pipe they could get away with, I cannot get enough pressure to consistently run a combination boiler. Fortunately I do not have a combination boiler but this did not stop a plumber recommending I should fit one without checking flows and pressures.
Assuming you do not want to replace your service pipe (and the stop tap and meter taps are not the problem), it might be assumed that putting a pump on the incoming service pipe is the solution. If the free discharge from the pipe feeding your pipe is not sufficient you will not be able to.
I will now describe the cycle of pain experienced by a potential customer in Blowfield Heath, Norfolk.
1.0 Bungalow on Gravity System with tank in Loft.
2.0 Plumber advises that she replaces tank and fits a Combination Boiler
2.1 Low Pressure stops boiler working
3.0 Plumber fits Megaflow
3.1 Not enough water flow to fill bath
4.0 Plumber fits mains pressure storage vessel.
4.1 Still not enough water.
5.0 Plumber sucks air though his teeth and walks away with £5K
6.0 Customer contacts Shower Power Booster.
Option 7.1 Go back to the gravity system as it fills slowly and delivers water on demand and fit a SPB to give you the pressure needed for a shower (£140)
Option 7.2 Replace the service pipe.
It is sad when this sort of thing happens and very sad when the plumber walks away with his money whilst leaving the customer with problems.