"Set Square" wrote in message ...
In an earlier thread, I described a device which I had made to enable a
radiator to be drained prior to removal by pumping air in through the bleed
hole - thus pushing the contents up into the F&E tank (in a vented system
only, of course) rather than spilling it all over the carpet.

The device consisted of a Schrader valve from a car tyre, soldered into a
1/8" BSP fitting which could be screwed into the radiator in place of the
bleed assembly.

However, not all radiators have a a removeable bleed assembly. Some
rolled-top rads, such as http://www.mills37.plus.com/rolled_top.JPG have the
bleed housing integral with the rad, with only the central pin being
removeable. My devise couldn't be used with such rads.
[The rad in the picture has been outside in the weather for a couple of
years - it isn't one of my best ones!]

I have done a bit more research on bleed pins, and all of mine - regardless
of whether the bleed housing is removeable or integral - seem to have a 2BA
thread. I have now modified my gizmo so that it has a 2BA end to screw into
a radiator in place of the pin rather than in place of the assembly. To do
this, I found a 2BA bolt about 1" long and drilled a 1/16" hole through the
centre of its long axis (pillar drill essential for this!), and then cut the
head off. The bottom end of the Schrader valve, below the works had enough
length, and was just big enough in diameter to allow me to tap a 2BA thread
in it, enabling my drilled headless 2BA bolt to the screwed in. The revised
gizmo now looks like this (with the larger 1/8" BSP fitting surrounding it
now being redundant) http://www.mills37.plus.com/Inflation_tool.jpg

Ideally, the bit which screws into the radiator should have a shaped end -
like the original bleed pin - to fit the conical seat in the housing. In the
absence of a model-maker's lathe, I couldn't do this, but it seals well
enough - albeit not perfectly - on the threads with the use of a bit of PTFE
tape. Here it is when fitted to a radiator.
http://www.mills37.plus.com/fitted_to_rad%20.JPG

If anyone thinks that such a device would be useful, feel free to copy or
improve on the idea.

[I still have *one* rad on which I can't use it. It has the bleed screw on
the *back* rather than the end!]

I didn't see the earlier thread which no doubt had much the same
comment of how do you get the gizmo in place without getting water all
over the place from the bleed hole, but then realised that if the
radiator is isolated first then of course there's no pressure !!

Having watched with some amusement my daughter's partner struggle with
a CH system refill after changing a radiator (it's quite good when you
are older and have seen much of it and watch the next generation going
up the same learning curve!), I can well appreciate that this device
could be worth making. I do have the tools - a lathe will be even
better for drilling the 2BA rod - but do wonder whether the time
making the device might exceed the time doing a quick drain down and
refill. One thing that it would be a boon for is removing radiators
when re-decorating though and for that alone I think I will look at
making one.

Thanks

Rob