Bleeding radiators

[Chris B]

I have never owned a pressurised heating system.

I am trying talk a relative (100 miles away and not very practical) through bleeding radiators. (He has described to me radiators hot at the bottom and cold at the top).

If he has a pressurised system is it near enough certain that it will have to be re pressurised after bleeding?

I have found videos on YouTube showing how to do both, but whilst there only seems to be one type of radiator bleed device so far I have found 3 different ways of pressurising a system depending on the installation (plumbed in hard, with a normally disconnected filling tube and with some WB key). No doubt his will be a 4th way.

Having watched the videos he is willing to try bleeding but to avoid call out costs intends to live with it as is if it will need to be re-pressurised.

I will not be in the area until Christmas to do it for him.

[Martin Bonner]

If he has a pressurized central heating system that he doesn't know how to repressurize, it is near enough certain that it will need repressurizing *already*. Ours needs it every six months or so.

Every system I have seen, has a flexi-connector from the mains to the CH system, with valves on both ends. You have to open both valves to pressurize the system. Open one, open the other for 5 seconds and close it. See what the pressure is. Open the second valve again for an appropriate length of time and close it. Repeat until the pressure is right (I'm assuming the pressure gauge is not visible from the valves). Close the first valve.

The flexi-connector is because you're not supposed to have a "permanent" connection between the CH and mains. The flexi-connector is "temporary" (but is never removed).

(It's only a month until Christmas...)

[Chris B]

Yes thanks you are preaching to the chior - the YouTube vids show how easy it is - you dont need to convince me. But it does look like there are other possible installations other than the disconnected flexi pipe.

From your other comment Perhaps the fact that he doesn't know how to do it means that he doesn't have a pressurised system. The fact that he isn't willing to learn is the frustrating bit.

(with apologies to Martin for the personal reply - I must disable that "Reply" button in TBird.)

[Tim+]

Make/model of boiler would be a good start. Even then, depending on the installation it might not have an integral expansion vessel or filling loop. My boiler is in the loft and expansion vessel is in my garage.

In general, for most combis it's a question of guddling around underneath until you find a flexible loop and two taps. Opening the taps will pressurise the system (which should be done whilst keeping an eye on the pressure ).

It's certainly not complicated but you do need to know where to look for the taps/connections etc.

Tim

[Syd Rumpo]

Yes, and it may well need to be re-pressurised several times during the bleeding process.

Cheers

[Adam Funk]

The plumber who installed ours told me that in his experience disconnecting the "temporary" connector almost inevitably causes people to lose parts, get debris in the threads, &c., so it's a stupid rule.

[Mike Barnes]

It might be a stupid rule but it has the side-effect of making the filling connector and valves instantly recognisable.

Which is No Bad Thing.

[ARW]

Indeed.

[newshound]

Agree about the flexi connector, but I've only ever had one manual valve with a hand operated tap in mine. I can't recall whether there are non return valves, or whether there might be a screwdriver operated valve which I have never touched.

I think you can usually see the pressure gauge while doing this. I would recommend repressurising a bit carefully the first time you do it. Whilst overpressurising is not unsafe, because there will be a pressure relief valve, in my experience you don't want to lift the relief valve because they never seat reliably once they are removed, the small leakage gradually erodes the valve seat and then you end up having to repressurise every week, if not more frequently.

The presence of a pressure gauge and/or the filling loop should be a give-away as to whether or not it is a pressurised system.

[newshound]

Excellent point.

[Adam Funk]

I had a little trouble interpreting your comment at first, but I think it's my own fault for assuming the "stupid rule" was unambiguous. I do *not* think having easily recognisable connectors & valves is stupid --- that's a good idea. What the plumber & I think is stupid is the rule that he is supposed to disconnect at least one end of the flexi-connector.

[Adam Funk]

...

I've only seen a few combination boilers, but the ones I have seen always have the filling loop very close to the boiler & the pressure gauge integrated into the boiler. I can't imagine why you'd want to install the filling loop elsewhere. *But* I'm aware that there are other kinds of pressurized CH systems --- I haven't seen them but maybe they are set up differently?

[Krankie]

Not stupid! Its primary purpose is to prevent contamination (inadvertently or otherwise) of the mains system which is the supplier of drinking and cooking water to you and to many other people. This could be back siphonage during a mains shut down for repair etc. Your outdoor water tap is (should be) fitted with a non return valve for the same reason. Your wc cistern has a small hole at the top of its ball c*ck silencer pipe to admit air thus preventing back siphonage. Your cold water storage tank - Ditto.

[Mike Barnes]

We could end up going round in circles on this but unless someone stupidly thought that disconnection was essential, I don't think we'd have got distinctive valves. So AFAICS that stupid rule does, entirely by accident, have benefits.

[Chris J Dixon]

AIUI many boilers will lock out when they detect low pressure, so re-pressurising is not optional.

Chris

[John Rumm]

Other than boilers that have an internal filling loop, the braided flexi pipe is common enough that you will very rarely see anything else IME.

[John Rumm]

Its quite common to fit the filling loop remote from the boiler when the boiler is installed in a less accessible place like a loft or garage. Then fitting it (with its own pressure gauge) in the airing cupboard is often more sensible.

[John Rumm]

Its often easier to explain to someone how to do it with the help of a friend...

I.e. one person goes round bleeding rads as required, and someone else man's the tap, with the instruction "every time you see it fall below 1 on the dial, give it a burst until its back up to about 1.5".

[Adam Funk]

OK!

[Adam Funk]

That makes sense; thanks.