Average Labour Cost/Price to Top Up/Re-Pressurise a Boiler/Central Heating

To clarify the following prices it is recommended that you read the article in the INFORMATION box below the PRICES…

(These prices are based on a tradesman’s rate of £150.00 per day and a labourer if required at £100.00 per day. This includes the cost of buying and collecting any materials, dumping any waste if necessary and any incidental materials they will need. The minimum price will usually be for a half day)

How Much Does It Cost To Fill a Central Heating System?

filling loop

These prices are based on a tradesman’s rate of £200 per day and a labourer if required at £100 per day. They include the cost of buying and collecting the materials, dumping the waste as necessary and any
incidental materials they will need.

Job 1

If the plumber is already at your house doing another job: To top up a central heating system due to radiator bleeding/removal:

Job 2

If the plumber is called out solely to top up a central heating system due to radiator bleeding/removal:

For your must-see guide to Tradesmen's Rates please click on the map…


Boiler Re-Pressurising/Topping Up Guide and Information Sheet

Your central heating will either operate as an “open vent” system at atmospheric pressure, or it will be “pressurised”. Back in the good old days, 99% of systems were open vent. There was a supply tank in the loft and if any water ever left the system because of a leak or “bleeding” a radiator etc, the system automatically filled itself again and you were non the wiser.

This was OK if you had a loft, but in a flat, where the
supply tank has to be on the same floor, problems can occur. If the system is pressurised, these problems are removed. Combination boilers then became very popular particularly in said flats and these require the system to be pressurised.

There is a school of thought, which says that pressurised systems are more efficient and nowadays more and more otherwise normal systems are being pressurised. One massive advantage of a pressurised system is the removal of the
loft supply tank. If you have a combination boiler as well, the cold water storage tank in the loft can go and the hot water cylinder in the airing cupboard. More space, less freezing, it makes a bit of sense I suppose!

How is the system pressurised you ask? Simple, it’s filled from the cold water main and a pressure vessel is fitted to take up any fluctuations as the water heats and cools. So “pressurised” actually means about 1½-2 bar. An open vent system operates at 1 bar.

The filling point (filling loop) should be easy to spot, there’s probably be a flexible hose near the
boiler, this has a tap at either end of it and turning them both on, allows mains water into the system. There will be a gauge on the boiler, when the pointer rises to about 1½, both taps are turned off and the jobs done. It takes 30 seconds.

Our (now famous) school of thought, says that the householder can’t be trusted with information like this. That he will try it himself and over pressurise. That’s true but what he can’t do is work out
why the pressure is dropping (unless he’s stood in a pool of water). Ultimately he will call in a plumber, probably the plumber who services the boiler, probably the plumber who left the flexible pipe in situ. which allowed the householder to fiddle about in the first place!

If the system is losing pressure, it is for a reason.

Either you have bled a radiator and not topped up the pressure, or there’s a leak. If there’s a leak it has to be fixed. Call the plumber in to sort out the problem, he will charge you for
that and pressurise the system as part of the process.

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