Re: bleeding a radiator (gas boiler heater)
I always bleed my hydronic rads until water comes out is a steady stream (it will spit air and water for a while). You want all the air to be replaced with water, or you're airlocked with no water flowing through the rads.
Start with the highest bleed valve in the house and work down to the lowest.
If the system has been drained down or any reason, the bleeding will have to be repeated a few times to ban all the air.
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