Flushing Central Heating Radiator

[kofi2003uk]

hi Everyone,
am about to do my first 'serious'(and dont lol) plumbing work. Am planning to flush out one of my radiators in the sitting room as there is no air in it but wont get hot-only just gets warm, sometimes hot at the top with cold spots. am sure its full of sludge. i will use my garden hose on mains to flush the dirt out. hope that works ok. i have a jet wash but not sure if its a good idea to use that one.

my worry is how to put is back without leaks so your advise and tips please will be very welcome.

1.when i put the radiator back, do i have to apply PTFE tape or something like boss white or can i just screw the bits back on and just tighten please?

2.when i undo the nuts to isolate the radiator, will there be an 'Olive' ring already in the pipe each end that i need to look out for and put back? if so do i just insert and tighten bolts?

3.anything i need to be aware of or any tips that will make this job easy.

4.i have a tank in loft so i believe its an open system? once i refill the radiator, is there anything i need to do before starting the heating again please?

thank you

 

[CBW]

Good evening Kofi,

Before doing any of that, have you tried anything else, or looked for anything else? Is it new problem, or has it always been there? We can offer advice on the above for sure, but no point wasting your time if it’s something else.

 

[kofi2003uk]

Hi
Thanks for the quick reply

Yes I think I have checked everything.

Rad used to work ok but now only warm with the top getting hotter. The sides sometimes get a bit hotter too but overall not heating up properly

I thought it was air but water comes out straight away if I bleed it. I turned all the rads downstairs off to increase the pressure but same result. I can’t think of anything else though. Rad is fully turned on with TRV amd other end lock shield also on
Many thanks

 

[CBW]

Hi
Thanks for the quick reply

Yes I think I have checked everything.

Rad used to work ok but now only warm with the top getting hotter. The sides sometimes get a bit hotter too but overall not heating up properly

I thought it was air but water comes out straight away if I bleed it. I turned all the rads downstairs off to increase the pressure but same result. I can’t think of anything else though. Rad is fully turned on with TRV amd other end lock shield also on
Many thanks

Could be a stuck TRV pin, try removing the TRV head, check for pin movement.

 

[kofi2003uk]

thanks for the reply. i checked the TVR and its working ok. pushed it up and down a few times and its not stuck. thank you

 

[CBW]

1.when i put the radiator back, do i have to apply PTFE tape or something like boss white or can i just screw the bits back on and just tighten please?

2.when i undo the nuts to isolate the radiator, will there be an 'Olive' ring already in the pipe each end that i need to look out for and put back? if so do i just insert and tighten bolts?

3.anything i need to be aware of or any tips that will make this job easy.

4.i have a tank in loft so i believe its an open system? once i refill the radiator, is there anything i need to do before starting the heating again please?

thank you

1. Screw back on and tighten is usually ok.
2. Disconnect from rad valve where it joins onto radiator, not at pipe. Yes there will be olives, but already compressed on.
3. Turn both valves off, open bleed vent until water stops, if it doesn’t stop then the valve should are passing, if water stops then proceed to take rad off, I like to use one half of a compression stop end so it’s easier. I would also open valves up into a bucket to ensure flow between the 2 valves is present, before flushing rad.
4. Refill, vent air until water flows and close, all should be good.

 

[kofi2003uk]

thank you so much. i appreciate the help/advice.

 

[alan333]

I'm not a plumber but learned a bit about my gravity system.

To test the pipework without removing the radiator...
Turn the system off.
Turn off both rad valves. Open the bleed screw - you should get virtually no water coming out.
Now open one rad valve and open the bleed screw - you should get a steady stream of water.
Now close that valve and open the other one instead - you should get a steady stream of water.
If there's hardly any flow with one valve open there's a fair chance that pipe is blocked.

 

[kofi2003uk]

hi Chaps,
update. so thanks for the advice. following your the advice above , i found out the TRV side has a very slow flow unlike the lock shield side. seems to be blocked in the TVR connection/shield. the TVR connection is the flow side and gets very hot but the water comes out very very slow/trickle into the radiator. Looking at the flow from the TRV side, am sure the connector there has to be replaced. the micro plastic pipe is also very hot all the way from wall to the TRV.
please see pictures.
Now the question is how do i replace that whole unit/connector on TRV side . Am not sure how to connect the plastic pipe to the TRV unit. is this something i can do with some advice please? am very confident disconnecting and reconnecting the unit to the radiator itself. just have no idea how to connect the plastic pipe to underneath the TRV. any info/ help will be much appreciated.

the Pin is not stuck. that has been checked and it moved freely up and down. however radiator is just warm.

thank you

 

[CBW]

Good evening Kofi,

So what you need to do is isolate the cold feed outlet of your feed and expansion tank (usually a bung) and bung the vent pipe, then drain the leg of water in the trv side, and use a blanking plug on the radiator, once the water ceases to flow, then change the 15mm trv, reconnect to rad, unbung the tank, fill and vent, then test.

 

[kofi2003uk]

thank you 'The Novice'. i will try this.really appreciate your help. one further question if i may please. how does the 15mm push fit stem(the yellow elbow in picture) actually connect to underneath the nut/valve please? is there a ring in the nut. clearly am a complete beginner .

many thanks

 

[kofi2003uk]

i wonder if i need this which is already made up? just tighten? please see link below
https://www.toolstation.com/jg-speedfit-bent-tap-connector/p28769

 

[CBW]

Because it's a stem elbow, it's rigid, and an olive (ring as you're calling it) inside will crimp onto the stem part, so you can just undo the nut ans re-use. It's a bit like a piece of pipe. however the one in that photo looks like it's not full socket.

 

[CBW]

i wonder if i need this which is already made up? just tighten? please see link below
https://www.toolstation.com/jg-speedfit-bent-tap-connector/p28769

No do not get that, it's a tap connector. If you want to purchase a new one, just get like for like.

 

[kofi2003uk]

ah that will be much easier if i can just reuse same nut already sitting on the stem elbow. i will give it a try sometime this week. i will go up to the loft and find and close expansion tank outlet and vent pipe. hopefully not too difficult to do.that will be fun lol. am sure i would have learnt a few things after this. thank you so much. will update.