How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Andrew Smith Your Own Question
Andrew Smith
Andrew Smith, Plumber
Category: Plumbing
Satisfied Customers: 3767
Experience:  City and Guilds qualified plumber
Type Your Plumbing Question Here...
Andrew Smith is online now

Our central heating system had become quite inefficient, with

This answer was rated:

Our central heating system had become quite inefficient, with lots of rads only warm in the centre.
Our plumber advised us to pressurise the system, to push the water round, to avoid a powerflush in case sludge etc in the system was causing the problem.
We did that, and we have a few problems:
1) the system loses pressure from 1 bar to 0 bar in about 24 hours!
I have to recharge it every day.
— where is the pressure going??
2) the system is much much noisier than before, especially if I forget to recharge the pressure
3) so it looks like we might have to do a power flush anyway, and it turns out to be about the same price!
Anyway, the question I have is why is the system losing all that pressure?
I guess that must mean it isn't airtight? Does that mean it also isn't watertight? Is there a pipe somewhere leaking under a floorboard?
You need to get the system to hold pressure first.
Can you check the copper discharge outside (about 3ft below the flue) and see if the water is leaking from there when you re-pressurise.
Try a balloon or a plastic bag
Customer: replied 2 years ago.

Yes, it leaks from there when we re-pressurise. Also there is a brown streak down the paintwork from the discharge pipe, so it must have been leaking for some time. The system has been losing pressure like this for a few months.

If you get the valve replaced then your system will hold pressure again.
You may find this will cure everything and should only costs you about £80.
Ring a couple of local plumbers and tell them you need a new PRV, tell them the make and model and go for the best price.
Customer: replied 2 years ago.

What is the advantage of a pressurised system over an unpressurised system? It feels lots more elements that can break and need maintaining. We had a gravity feed with a couple of pumps before and it worked perfectly. The only reason for pressurising the system was to avoid the cost and hassle of a power flush. Was that a false economy?

A pressurised system removes the need for a tank if the roofspace.
Pressurising your system lets you know if there is a leak by the pressure dropping - whereas a tank will continue to fill.
You may still need a powerflush, a pressurised system does not remove the need. If your system slowly rots then the sludge produced will still block pipework and radiators.
There is nothing wrong with a well maintained standard tank fed system.
Andrew Smith and other Plumbing Specialists are ready to help you