A few questions

Questions about central heating and boiler questions in here please.

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mishy
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A few questions

Post by mishy »

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I'm replacing 3 radiators (of 5) and have a few questions

Firstly, is the attached picture my drain off valve? If so, what device do I use to operate it? and if not, what is it?
Would there be any issues in draining just 3 of the radiators, or does it have to be all 5?
I've made a start with one of the radiators and have forgotten how many turns the lockshield valve was - is that a major issue? How does that work exactly? Would it cause my system to become unbalanced - and if so, what does that mean?
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mishy
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A few questions

Post by mishy »

a follow up question, if i am looking to drain the central heating system, if i remove the final radiator, can i drain the system by opening the trv of this radiator?
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Someone-Else
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A few questions

Post by Someone-Else »

Only if you want to flood the place should you open the TRV with no radiator.

You should look for Image something like this. You will only see the square end and the "barbed" bit
You push a hose onto the barbed bit, and turn the square bit. It's a tap to drain your heating. You may find a few of them, but you want the one lowest down.
We have a radiator on the first floor that has two of them, and we have two more under the floor of the ground floor. I think there is one near the boiler too.

I am NOT a plumber or heating engineer.

Regarding your picture, it may be a different version of what you are looking for, can you post a picture (right way up) looking at your "thing" that is looking at it, NOT looking down on it.

For help with pictures, see my signature.
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mishy (Sun Sep 13, 2020 9:09 am)
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A few questions

Post by stevei »

It does look like a drain valve.
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mishy (Sun Sep 13, 2020 9:09 am)
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A few questions

Post by mishy »

thanks guys, i guess it is a drain valve but with a different design.
i think ill just fit a new one as couldn't get this to work in any case....

regarding draining via the trv, i was watching this video (11 mins) and the suggestion was made to attach a copper pipe to the trv of the final radiator and this would also drain the system:
https://youtu.be/2bjqSULzmUQ?t=661
is this advice wrong?

thanks
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A few questions

Post by Someone-Else »

No, nothing wrong with draining from the lowest TRV, except that the pipes will still be full of water, and ordinary garden hoses like you and I have don't slide onto 15mm copper pipe. They do however slide easily onto the drain cock "barbed bit" (Try it with your hose and see)
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mishy (Sun Sep 13, 2020 8:18 pm)
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A few questions

Post by mishy »

so i've had a go installing the drain cock, does this look right?
i cant tighten the nut with the bit with ptfe tape on, is that going to be enough or do i need to adjust it in some way?

thanks
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A few questions

Post by Someone-Else »

To me, it looks like the threaded part with the PTFE tape is too long, as it looks like the copper pipe from the floor is being bent to the left. But like I said, I am NOT a plumber
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mishy (Wed Sep 16, 2020 9:34 am)
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mishy
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A few questions

Post by mishy »

thanks, i can probably trim the part with the ptfe down to get the pipe to straighten, i was thinking more in terms of the nut not being fully engaged on the thread, i cant get it to turn anymore, just wondering if that is right
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A few questions

Post by wine~o »

Undo the lower nut on the valve that's on the copper pipe, then undo the larger nut. You should now find you have enough wiggle room to straighten the valve and get the larger nut to engage fully (you might need to use less ptfe) once the larger nut is fully engaged and tightened then re make the lower join. You'll probably find that this will also take the bend out of the copper pipe.
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mishy
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A few questions

Post by mishy »

wine~o wrote:
Wed Sep 16, 2020 9:59 am
Undo the lower nut on the valve that's on the copper pipe, then undo the larger nut. You should now find you have enough wiggle room to straighten the valve and get the larger nut to engage fully (you might need to use less ptfe) once the larger nut is fully engaged and tightened then re make the lower join. You'll probably find that this will also take the bend out of the copper pipe.
the larger nut is already fully engaged - it is being engaged leftwards(ie away from the ptfe bit of pipe). i am actually replacing the laminate so im probaby just going to make a cut in laminate/floorboard to straighten the pipe so that is not a major issue, its more the nut on the right, it just looks odd having that entire threaded section of pipe(covered in ptfe) not being used. in any case, if thats the way its designed im fined, i just wanted to check there was no obvious mistakes!
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A few questions

Post by aeromech3 »

You have the wrong combination; the ptfe thread is supposed to go into the radiator; it does Not have the bevel face to make a good fit with the olive washer, if indeed you fitted one under the other nut? inside the ptfe piece there should be a hexagon shape hole for a large allen key tool to be inserted to tighten it into the rad (broad screwdriver blade could be used) the larger nut end which has its own moulded cone shape tightens onto the 3 threads of the radiator valve, just as you have done.
There are two types of radiator valve to radiator fitting: the one you bought and the one that uses a compression olive, same as what you removed, these are more adaptable because you can get different length 'tails' to make up the distance between radiator and valve which you needed, due the removal of the original drain fitting. I have not been able to find a valve with a drain that has the compression olive fitting. You might be lucky and not get a leak but it is not right.
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A few questions

Post by aeromech3 »

If you wish to keep the new valve and have access to Toolstation catalogue page 121, second row first items on left Radiator valve extension, you will need to work out what length you need and with at least 10 wraps of ptfe screw that into the radiator base, then with 10x ptfe screw the bit with the large nut onto it and then tighten the large nut onto the valves 3 threads. Will look like the picture which was, if I remember, only a 25mm extension part 65625.
Don't buy the second and third from left items on that page, they are for the compression/compression fitting type valve.
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A few questions

Post by mishy »

thanks aeromech3, that makes sense, that whole ptfe threaded bit being exposed seemed a bit dodgy but im a novice at this stuff so wasn't sure if it was just me!

will get that extension piece and see how that works

on a side note, i bought some new trvs and they came with the following piece:
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i attached them as follows:
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these felt right at the time but now that you've mentioned compression fitting, i'm not sure.....is that right or should i change them for the extension piece mentioned above?
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A few questions

Post by aeromech3 »

That looks fine provided you fitted the brass (copper) olive inside the nut and tightened the nut whilst firmly forcing the TRV to bottom and stay on the chrome extension.
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