Repressurising boiler

calum · 29-07-2009 9:45am #1

Trying to figure out how to repressurise our gas boiler (which has a faulty valve, replacement on order). Plumber topped it up last week by fiddling around in the hot press, but looks like I'll need to do it myself this time if we're to have any hot water tomorrow, and I can't figure out what he did

Pipework in hot press is per attached photos. I assume the pipe with the pressure gauge on it is the one that leads straight down into the boiler, and that it's the bits around that I need to be fiddling with, but so far none of my fiddling has worked, and I could be wrong anyway of course

Any clues??

Pete67 · 29-07-2009 1:37pm

You're on the right track - the unit with the pressure gauge is a pressure reducing valve, with a build in isolating valve. The installer has also fitted a gate valve above to isolate the water supply which is good practice, and there is a check valve (one-way valve) below it.

So, open red handled gate valve, then slowly open the black valve built into the regulating valve, it is usually the one on the opposite side to the pressure guage. Allow the pressure to increase to approx 1 bar then close both valves. Job done.

If you have to repressurise the system frequently the risk of corrosion to steel radiators is increased due to the continuous influx of oxygen rich water, so get the leaks fixed or you will have more problems!

calum · 29-07-2009 1:51pm

Cheers, will give that a go. Yeah, definitely want it fixed asap-- they were hoping to come back and fix it today in fact, but haven't heard from them so far

calum · 29-07-2009 2:21pm

Hmm, nothing doing, I must still be missing something

Opened both valves, but can't hear any water running into boiler like I could the other day, and pressure isn't increasing.

Pete67 · 29-07-2009 2:52pm

The Pressure regulating valve has two knobs, one is an isolating valve to close off the water supply and the other is the adjustment to set the operating pressure, probably adjustable from 0 to 3 bar. Figure out which one is which and check that the pressure adjustment is set to something sensible - 1.0 to 1.5 bar.

It is also possible that the main water pressure is currently too low to fill the system, or that the check valve is sticking closed.

Stratocaster · 29-07-2009 3:33pm

Pete67 wrote: »

The Pressure regulating valve has two knobs, one is an isolating valve to close off the water supply and the other is the adjustment to set the operating pressure, probably adjustable from 0 to 3 bar. Figure out which one is which and check that the pressure adjustment is set to something sensible - 1.0 to 1.5 bar.

It is also possible that the main water pressure is currently too low to fill the system, or that the check valve is sticking closed.

Pete is correct, the PRV is probably not set to let enough pressure through or the mains pressure its too low at the present time. You can adjust the maximum pressure with the adjustment on the left of the PRV. That looks like a tamper proof cover for obvious reasons. Under the cover you will find in most cases a spindle and a lock nut. To increase pressure in most cases you adjust the spindle clock wise, anti clockwise to reduce. Unless you are experienced enough I wouldn't adjust the PRV.

Call a plumber and ask him to show you how to set it in detail while he sets the pressure. The idea behind a PRV is you should not have to top the system up, it does so by itself.

You will commonly find these installed on heading systems although it is against the regulations as a heating system must not be permanently connected to a fresh water mains supply. Even though a non return valve is part of the assembly which prevents heating water entering entering the mains water, it is still possible for bacteria to pass through the assembly. Due to minimal regulations in Ireland these PRV installations tend to be installed un noticed.

29-07-2009 4:27pm

To add to what Pete wrote about system water, I would flush the system, add a inhibitor (which is a chemical that prevents the build up of sludge/ contamination) and fit a filling loop which is the proper connection between a pressurized system and the mains, i find PRV's tend to be used to hide potential water leaks and system water that has no inhibitor can kill a boiler very quickly, if you get a build up of sludge, Gary.

calum · 29-07-2009 4:44pm

Stratocaster wrote: »

Pete is correct, the PRV is probably not set to let enough pressure through or the mains pressure its too low at the present time. You can adjust the maximum pressure with the adjustment on the left of the PRV. That looks like a tamper proof cover for obvious reasons. Under the cover you will find in most cases a spindle and a lock nut. To increase pressure in most cases you adjust the spindle clock wise, anti clockwise to reduce. Unless you are experienced enough I wouldn't adjust the PRV.

Call a plumber and ask him to show you how to set it in detail while he sets the pressure. The idea behind a PRV is you should not have to top the system up, it does so by itself.

Yeah, looks like the pressure is adjustable with a screwdriver; the cover indeed indicates clockwise turn to increase, anticlockwise to decrease. I'll probably just leave well alone at least until we completely run out of hot water, though (which will likely be Thursday, at this rate...)

We called the plumber last week, if he'd shown up by now we wouldn't be having the problem

Stratocaster · 29-07-2009 4:52pm

gary71 wrote: »

To add to what Pete wrote about system water, I would flush the system, add a inhibitor (which is a chemical that prevents the build up of sludge/ contamination) and fit a filling loop which is the proper connection between a pressurized system and the mains, i find PRV's tend to be used to hide potential water leaks and system water that has no inhibitor can kill a boiler very quickly, if you get a build up of sludge, Gary.

Over the next 5 to 10 years I feel you will see the effects of the building rush and forget about the regulations boom on all heating systems in Ireland.

If you have money now is the time to invest into boiler heat exchanger company's. 3 of them have been replaced on my road and I can think of another 5 not too far away. All down to a small leak and a constant supply of mains water.

I have never seen a system flushed or inhibited on any of the sites in this country after the main plumbing contractor had completed the 2nd fix. It should only add 2 hours work and the costs of a few ltrs of chemicals.

Stratocaster · 29-07-2009 4:57pm

calum wrote: »

Yeah, looks like the pressure is adjustable with a screwdriver; the cover indeed indicates clockwise turn to increase, anticlockwise to decrease. I'll probably just leave well alone at least until we completely run out of hot water, though (which will likely be Thursday, at this rate...)

We called the plumber last week, if he'd shown up by now we wouldn't be having the problem

An immersion should be fitted to your cylinder to provide hot water during boiler down time. If you haven't got one you should ask the plumber to fit one while your systems being topped up.

BostonB · 29-07-2009 4:58pm

Thats for sure. I'm only realising now how badly mine was installed.

29-07-2009 8:09pm

Stratocaster wrote: »

Over the next 5 to 10 years .

Try 5 to 10 months, i going out to single jobs/whole site's and have to explain how there's no warranty on a boiler/site because of contamination in the water thats absolutely knacked the boiler(s) meaning a power flush plus possibly new boiler(s), i can count on one hand how many new installation i come across that have been flushed properly and had inhibitor added, unfortunately without that work being down it voids the warranty and dramatically shortens the working life of the boiler,Gary.

Repressurising boiler

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