Depressurising sealed system.

I have one like this in the passage:

passage:

It's on page 4 of the catalogue.

The ideal arrangement for this is to have a lockshield with an integral drain-off point like Screwfix 11074 . If you close off both the rad valves you can use it to (partially) drain the radiator and then introduce the inhibitor to that radiator.

Why worry about it being 'a little'? It will need topping up anyway and even if you're on a meter won't cost much. Certainly cheaper than risking spilling inhibitor.

Problem is I can't really be bothered with all that hose pipe business.

You should have had the job done by this time :-)

popliteus?

My take on this is that it is far better to partially drain a radiator to ensure there is space for the additive. It simply isn't possible to inject additive if there is no space in the radiator - and you need to allow the air to escape as the additive goes in. My radiators are about 22 years old an I use a square key to completely remove the top 'bung' think then pour in Fernox through a funnel and bit of tube.

Drain off enough to depressurise the system - then open a bleed valve on one radiator. Drain off enough to nearly empty that radiator - possibly a bit more than the quantity of additive.

Inject additive - refit bleed valve - run system and then bleed after it has all mixed up

How often should you drain down and add fresh chemicals?

IIRC Fernox say to replace every 5 years. Sentinel only needs to be replaced when the system is drained down. Whatever you use it is a good idea to check concentration levels every year using a test kit and replenish as necessary.

Apologies if this has been stated by others.

I have a pressurised system and encountered a significant problem when adding Fernox from a mastic tube.

My rads are double panel with a tee piece linking each panel and the bleed point in the middle of the Tee. I found that the tip of the Fernox tube didn't want to fit into the hole left by the bleed nipple and the flexible hose supplied wouldn't bend into the Tee after removing the end cap so the Fernox tended to dribble out.

My solution was to get a spare end plug for the rad - one with a hole in the centre for the bleed nipple - and drill out the bleed nipple hole until the hose supplied with the Fernox tube was a pretty tight fit in the hole. After de-pressurising the rad as described above I replaced the end cap with my 'adapted' one and injected the Fernox without spilling a drop. Then replaced the end cap and proceeded as described above.

HTH

Richard

This bloody threads been going for 22 hours :-)

Just drain it somewhere. If necessary crack open a valve at the end of a radiator and let water drain into a baking tray or bowl. it isn't rocket science.

Fairy nuff if you have plenty of time to waste. And the same the next time something like this crops up.

I've done this one approx every 3 years. Usually in conjunction with other work like changing a faulty TRV - or removing rads for decorating, etc. And I've had no problems with rusted out or blocked rads - indeed I've just installed a new boiler so used a cleaner first and the flush afterwards showed pretty clean water.

And get some of that lovely black water all over the carpet? ;-)

It's certainly not to use the proper drain point. Which for some reason most don't want to use.

John

I'm not commenting on or disagreeing about the need for draining to allow space for the Fernox.

It's getting the damm stuff to creep into a horizontal pipe and flow into the rad rather than back out whence it came that I prompted my twopenneth worth.

Richard

That's just down to things that you probably learned at school...If you want something to go in ( in this case inhibitor) then something ( in this case air) has to come out .If the tube won't allow the air to come out then the inhibitor will just spill back out. Simple.

=A0 =A0 London SW

The job has now been completed.