DIY Doctor

Refilling unidentified boiler

Postby alexw » Fri Nov 25, 2011 12:24 pm

Hi everyone,

We've recently started using the central heating in our new house, and found that the radiators in the loft bedroom were mostly full of air - no heat apart from the bottom of them, and lots of gurgling noises as the water sloshes around. Bleeding the radiators has helped a little, but the pressure now seems to be so low that no more air comes out of them.

At the moment, the pressure gauge on the boiler is around 0.7 bar when not in use, and just under 1 bar when it's on. From what I understand, this is a little low, so might it help to top the system up?

Unfortunately, the people who installed the boiler took off the front panel, so I don't know what model it is. There's what appears to be a filling loop underneath, although this looks different to what I've seen elsewhere: it's a piece of solid pipe, with a red dial (secured by a screw) that's currently pointing to the number 2.

If anyone had any tips on whether the system needs refilling (and how to do it), that'd be really appreciated. I've attached a couple of pics of the boiler and the filling loop.

filling loop_sm.jpg
filling loop_sm.jpg (21.21 KiB) Viewed 483 times
boiler_sm.jpg (20.89 KiB) Viewed 483 times
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Simply Build It

Postby plumbbob » Fri Nov 25, 2011 8:36 pm

It is normal to keep the system pressure to at least one bar. Where is the boiler in relation to the loft bedroom? If it is on the ground floor and the loft room is on a second story, it may be necessary to increase the pressure to 1.5 bar just to ensure there is sufficient pressure to expel the trapped air.

Open the filling loop until the level is achieved. Bleed the air, then refill as necessary. Repeat until water is expelled from the radiator bleed valves.
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Postby alexw » Sat Nov 26, 2011 11:06 am


Thanks, that's what I'd thought (the boiler's on the ground floor and the bedroom is on the second floor).

However, I'm not entirely sure how to open the filling loop with this setup. I'm guessing that the large red dial at the bottom should allow you to set the pressure of the water in the loop, and that I'll then need to open one of the three valves below the boiler, but any idea which one?
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