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Air lock in indirect cylinder coil

Postby loadsafranks » Fri Sep 12, 2008 6:06 pm

I have installed a new condensing bolier. Central Heating works fine, but I cannot get any hot water. I think there may be an airlock in the cylinder coil - how do I clear this?
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Simply Build It

Postby nitro23456 » Sat Sep 13, 2008 11:44 am

crack open the nut on the return until water flows. careful not to flood the house.
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Postby htg engineer » Sun Sep 14, 2008 9:27 am

"I have installed a new condensing bolier"

CORGI registered ? if not get it checked by a Registered Gas Installer, if you don't it's an illegal installation and you're boiler warranty is void.

htg engineer
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Postby loadsafranks » Mon Sep 15, 2008 4:53 pm

Thanks Nitro. I loosened the the connection on the return pipe (lost a litre or so onto the floor) but managed to clear the airlock. I now have hot water again.

To htg - it was an oil fired boiler - so no to CORGI

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Postby screech » Tue Sep 16, 2008 9:07 pm

the easiest way would've been to prevent the boiler firing and then starting and stopping the pump a few times until it cleared the air. much less messy.
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Postby psycole » Sat Dec 13, 2008 12:13 pm

Following from loadsafranks problem, I may have similar. Hot water cylinder replaced some weeks ago. Along with valve in flow to cylinder coil (inlet at bottom of tank), held for the moment in open position (I don't want to wire it in until this problem is solved). I CANNOT seem to get water (from the boiler) to flow through the coil - consequently it won't heat water and I'm stuck with the immersion heater (desperately uneconomical!). The cirsulating pump has been replaced to see if the old one (25 years on the run) was knackered, but no difference. A bathroom radiator tapped of the indirect circuit, however, continues to heat fine: its return pipe to the boiler enters the vent pipe (to expansion tank and down to the boiler)) about 40cm below the return from coil. Replacement valve checked out - seems okay: no restriction to flow. Coil "blown through" (when empty!) - again, no apparent restriction. SO it must be a stubborn air lock? Presumably I need pressure to force the air out of the coil into the vent pipe? Could it really be that stubborn? Is it anything to do with horizontal flow and return pipes to coil, and right angle joints to main flow and return (vent) pipes? Please help me get cheaper hot water for Christmas!
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