bleading radiator

when i bleed my radiators with the pump running the radiators actually suck air in. I have been told that it may be my pump running to fast so have just checked the speed and yes it was on set to 3 I have set it to 1 but I still cant bleed them but it does not sound like the air is getting sucked in. any ideas the pump is a myson sd53 and the boiler is a baxi back boiler type. i can bleed them ok with the pump off.

Reply to
geoff
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If you can bleed them with the pump off then do you have a problem, or are you just asking out of interest?

Rob Graham

Reply to
robgraham

Why not bleed the radiators with the heating switched off?

PoP

Reply to
PoP

on a similar note, and its probably on par with how long is a piece of string, how often do people bleed their radiators?

Kerry

Reply to
Kerry Hoskin

I sometimes, randomly, feel the top of radiators in our household as I'm passing by. It's kind of a natural action born from experience of these things rather than a predefined maintenance check.

If I get a cold radiator top I will then check the valve ends of the radiator. If they are hot then I bleed the radiator. That action will usually involve checking the other radiators in the vicinity.

PoP

Reply to
PoP

I bleed mine if I have disturbed the system or if a radiator obviously has air in it as witnessed by being hot at the bottom and cold at the top. Otherwise, never.

Reply to
Set Square

I only ask because I have one radiator that I seem to have to bleed every week or so, its the highest radiator in the system so I think air is getting in somewhere.

Kerry

Reply to
Kerry Hoskin

Presumably it's a vented system? Have you checked that it isn't pumping over?

Does it have inhibitor in it? If not, the "air" may be hydrogen resulting from corrosion. Next time you bleed, hold a lighted match by the bleed hole and see whether the gas coming out is flammable.

Reply to
Set Square

Its oil central heating and it was only installed a couple of months back

Kerry

Reply to
Kerry Hoskin

Well yes, but . . .none of this answers my questions!

  • Is it a sealed pressurised system (with filling loop and pressure vessel) or is it vented with a small header tank for the primary circuit in addition to the large header for the hot water system?

  • If vented, is it pumping over? In other words, when it is running, is water constantly flowing out of the vent pipe into the small header tank?

  • What is the gas which you are bleeding out of your radiator - is it flammable?
Reply to
Set Square

Check the inhibitor. The gas in the CH system most probably comes from some chemical reaction within the system, rather than being allowed in from outside the system. Inhibitor ought to stop that taking place.

If you've ever brewed your own beer you will know that yeast forms bubbles by chewing on the nutrients in the beer mix - those bubbles aren't formed because they come from outside the system! Your CH system isn't a beer brewery in disguise, but it's a broadly similar chemical still.

PoP

Reply to
PoP

If it's a fairly new rad you can take the fitting out of the top corner, put in a reducing bush from BES half inch X quarter product 6621, then screw in an Auto air vent- BES product 7498. Make a careful adjustment of the srew on the AAV and air will come out and water will stay in. All for just over a pound!

Jon

Reply to
Jonathan Curtis

"Kerry Hoskin" wrote in news:brij3i$9i1$ snipped-for-privacy@newsg2.svr.pol.co.uk:

By you? If not how do you know if it's got inhibitor in? Did the installers claim to do it - they should have of course, but perhaps they want to install a new system in a few years.

I don't know if there's a definitive test, the water will have a straw colour or (perhaps something else - someone may enlighten us) or you may be able to taste it.

One things for sure, if it's a new system make sure ther IS inhibitor in before it gets much older.

mike r

Reply to
mike ring

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