On 16 Jan 2005 17:03:06 -0800, wrote:

In order to add an Inhibitor to my houses central heating system, I've
attempted to drain the rads using a drain off cock near to the boiler
on the ground floor, opening radiator vents on the first floor. That
worked OK ( air being sucked into the vents ) so I tried the ground
floor rads but they continued to have +ve pressure with water dribbling
out of the vents.

This was still the case even though the water stopped flowing from the
drain off cock - but the radiator vents are about a foot above it.

I'm probably making a beginers mistake but can't understand why these
rads didn't also at least partially empty through the drain off cock.

I had stopped water refilling the header tank using it's input stop
cock in the loft.

Eventually I gave up and finished the job without draining the ground
floor radiators which I hope was OK given I was just trying to get the
inhibitor into the system. But I would like to be able to drain the
whole system for future maintenance jobs.
Thanks in advance for suggestions.

Phil


If the pipes drop down from the first floor to each ground floor
radiator (which is quite common) then the drain cock will empty the
first floor radiators but the ground floor ones will not be emptied.
You will get water out of the ground floor radiators equivalent to the
water in the pipes above them.

If you are only filling with inhibitor and the water was fairly clean
and there was no apparent sign of sludging (e.g. cold spots at the
lower centre of radiators) then what you did is OK.

For future maintenance, you could add drain cocks at each ground floor
radiator, or a better solution is to replace the lockshield valves
with ones with a drain cock in the tails. This will also allow you
to drain radiators individually in a mess free way for decorating.
I used Pegler Terrier valves for this and can recommend them.




--

..andy

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