Radiator - refitting
Open vented systems
For sealed systems, seek the services of a professional heating engineer
The connection between the valves and the radiator is of the compression type. It is, however, possible that with age the fitting may be a little worn. In this case you can render it watertight using one of the following methods.
Preparing the connections
Wrap a short length of PTFE tape around the thread in a clockwise direction before assembly. Or -
Smear a little jointing compound around the thread before assembly.
Both of these will take up any small gaps in the threaded section helping to seal the connection.
Lift the radiator up onto its brackets.
Manoeuvre the valve assembly at both ends so that they sit squarely onto the radiator connections.
Hand tighten the nut onto each valve, taking care not to cross thread them.
Tightening the valves
Holding the valve assembly with a pipe wrench so that it cannot be pulled off the pipe, use a second wrench to do up the connecting nut. This should be just tight enough to render the connection watertight. Excessive tightening may damage the fitting. Remember, you can tighten a joint if it leaks, but if it has been overtightened, you will need to dismantle it and start again.
Filling the radiator
Having tightened both connections, open the bleed valve at the top of the radiator.
Now open only the flow valve at the bottom of the radiator. This will be the valve used for turning the radiator on and off. This will allow the water to flow in, and air to be pushed out at the top.
When the water starts to splutter from the bleed valve, close it.
Now open the return valve at the bottom of the radiator by the same number of turns used to close it originally allowing water to circulate through the system once more whilst maintaining the origanal balance of flow.
Having left the return valve closed until the radiator is full, you will have prevented air from being pushed round into the rest of the system.
Check both connections for leaks before allowing the heating to be turned on again.
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The thread is the means of tightening and retaining the fitting only, and does not seal it. If the thread is contaminated in this way, it could prevent the fitting being fully tightened, and will make future removal difficult. A lttle compound on the olive only could be used, but nothing on the thread.
Over many years I have had to repair many leaks caused by this simple fault.
It is only the tail of the valve that goes into the radiator that should be wrapped with PTFE.
Tape or for that matter any other sealing compound is only used with tapered threads and the instructions seem rather bad in explaining the different sealing methods used.
On the radiator you have olives, ball and socket, and tapered joints so hard to say instructions are wrong yet since it talks about compression joints clearly they do not want PTFE tape. I often cheat are run electricians solder (softer than plumbers) onto the olive where they have been over tightened. wrapping PTFE tape around the olive may work but rather hit and miss. Where soldering is not an option then I would be looking as some paint on sealant rather than PTFE.
However I was asked to write instructions for this site and I considered carefully to ensure the instructions as far as I could covered every eventuality. However in doing this I made them over complicated and they were as a result rejected.
All trades need around 4 years to learn and it is near impossible to write simple instructions for what is really a complex operation. With Electrics it seems to be health and safety which is missed out by the DIY guy. When I do some thing as simple as fitting a 13A socket I use a £750 test set to ensure it is safe. Clearly the DIY guy is not going to buy a test set and even to hire costs £75.
So safety in the main goes to the wind.
I am sure the same is true of nearly every other trade? But in general I do think the forum Sysops should remove posts over one year old to ensure outdated information is not left in place.
I'd be happy if we could still use hemp and Boss White!!
On new compression fittings thre's no need for anything at all, but those of us that are a bit old fasioned like to use a little smear of jointing compound, but only on the olive. (WRAS approved compound with pottable water)
Old fittings being reused, I would always use a bit of something, again, only on the olive. If the fitting has been overtightened, or has been strained, there are tools to remove the olive without damage to the copper.
The main point I was making is keep it off the thread, the only thing I ever put on the theads is a little grease, anti seize copper grease is ideal, for those joints that may need to be undone in the future.
Another mostly unknown little tip (in DIY circles) is, with a lot of tap tails, and tank ball valves,
if you look at the end of the tail, there is often a slight internal bevel making it a very poor joint with a standard tap connector. Just use the nut and olive from a compression fitting, most fittings use a BSP thread.
With plastic all those sounds of expanding and contracting have gone. No olives all push fit stuff.
Of course 13 years ago it would have been still all copper. There are still a few who refuse to change likely they have tried installing it like copper straight runs and no spare so it will have pulled out but instead of blaming the way they fitted it they blame the plastic.
Plastic certainly has it's uses now, especially as it can be threaded though in much the same way as cable, a point not missed by SuperRod, I see.
One of the problems though, with domestic plumbing is the wall thickness of the tube, so a tube of the size of 15mm copper has a smaller bore.
