UKC

Must admit I've not done this before but I'm fed up trying to get a plumber! How simple is it?

The valve/radiator arrangement is similar to this:

https://cdn.shopify.com/s/files/1/0187/1602/products/BlueCaps.jpg?v=1354033...

I assume that, having turned off the valves at both ends it's a simple matter of slackening off the nut between the valve and the radiator, and allow the radiator to drain with no need to turn off the mains supply.

Can anyone confirm please?

Thanks

In principle. But..   does the new one fit on the brackets? Is it exactly the same length? Will the nuts be water tight again.?Radiator water is filthy. 

If you are lucky.... yes.  It really depends on how good those valves are - you will always get some leakage though, but if they don't shut off properly your entire heating system will drain into the room the radiator is in (and keep going if you haven't turned off the supply)

It is a much safer idea and really not that much of a ball ache to turn off the supply, drain the system, change the rad and refill (remembering to add inhibitor into the system as required)

(I am assuming you have a gravity fed system)

If you've got light coloured carpets, I strongly suggest you drain the CH system, open the bleed screw on the one you're changing.

Yes, it's straightforward, just close the valves and unscrew - slowly, in case the valve leaks.

It is absolutely guaranteed to dribble rusty water on the floor however careful you are and however thoroughly you drain it. This water will stain absolutely anything. Make sure you fully protect any carpet with a taped down waterproof cover. 

It depends how new your radiator valves are. If they're new modern ones then it's possible. If not you may have to fit new valves which will require the system to be drained

To fit the new rad you'll probably have to fit the new brackets as well, so you need to work out the correct fixing heights so the valves line up with the radiator.

These will help you adjust for slight changes in length of the radiator compared to the space left between the valves without having to modify the pipework https://www.google.co.uk/search?q=radiator+valve+extension&oq=radiator+...

HTH Davey 

Turn the valves off.

undo the valve but with a spanner- but you need to grip the valve with another spanner or grips so that you don’t apply twist to where the copper pipe joins the bottom of the valve.  If you accidentally loosen that you’ll have a problem.

get a mate / mrs / child and hold one side each with the valve nut loosened but still finger right.  Then quickly undo the bolt to release the rad from the valve. 

At this point quickly put your thumb over the now exposed hole in the bottom of the rad to stop the water coming out.

lift the rad off the bracket and flip it 180 degrees so the hole is at the top.  Thus keeping the black water inside until you’re outside.

if you have trv valves (thermostat), they can open on their own if temp drops so best to get new rad straight on.

do up nuts assuming they fit, remember not to twist the valve / pipe connection, bleed of air.

you may need to top up the heating system pressure if you have a combi boiler - via the filling loop... 

Thanks for comments and advice.

FIn reply to mypyrex:

Plus one for draining the system, assuming you know where the drain point is , and what system you have. If it's a combi , make sure the hose connecting the combi  system to the water main is fully locked off at both ends then disconnect the hose so that there is no risk of the system refilling, then it's just a case of loosening the square drain nut outside with a pair of pliers. ( after shutting down the boiler system of course) 

This will give you the comfort of not rushing and risking staining carpets etc, or even damaging pipes.  

Even when drained , dirty water may escape so ,if possible,  pull back the carpets from the radiator, and have something  handy to plug the radiator ends , a trimmed cork to a cone shape should work, and, as suggested,  flip the radiator upside down to carry it outside. 

Nb if the draining point not already over an outside drain, push a hose onto it and lead the hose end to the nearest drain (IF the water draining is a problem where it is currently located. ) 

I have drained my combi system ( and that of my daughters) a few times, and it's easy  enough to do and refill, try You Tube for. refil procedures bleeding etc. 

Good luck. 

I wouldn't drain the system. The valves either end of the rad are there so you don't have to, isolating valves.

As others have said, have something to catch the water, isolate the two valves, open the bleed valve slowly to release some pressure in the rad, slacken the nut on the rad side slowly and catch the water.

When the water in the rad has stopped coming out, remove both nuts, remove the rad trying to keep it a level as possible. Replace with new rad, put PTFE tape once around the rads new valve thread, tighten and open both valves. Open bleed valve and bleed the air out of the rad.

If the new rad is slightly smaller than the old one, you can get these to help bridge the gap.

http://www.wickes.co.uk/Wickes-Radiator-Valve-Extension-Piece---40mm/p/4249...

I wouldn't drain the system. The valves either end of the rad are there so you don't have to, isolating valves.

As others have said, have something to catch the water, isolate the two valves, open the bleed valve slowly to release some pressure in the rad, slacken the nut on the rad side of the valve slowly and catch the water.

When the water in the rad has stopped coming out, remove valve both nuts, remove the rad trying to keep it a level as possible. Replace with new rad, put PTFE tape once around the rads valve thread, tighten and open both valves. Open bleed valve and bleed the air out of the rad.

If the new rad is slightly smaller than the old one, you can get these to help bridge the gap.

http://www.wickes.co.uk/Wickes-Radiator-Valve-Extension-Piece---40mm/p/4249...

Or these.

https://www.westradiators.co.uk/radiator-valves/radiator-tail-extensions.ht...

If you drain the system, you only need to drain it to a point lower than the radiator - handy if you're talking about an upstairs radiator. Don't forget to turn off the stop cock by the header tank, or you'll be draining it for a long time!

If you're going to change the radiator, then it may be a good time to install TRVs while you're at it.

Another way to get the radiator off with minimum splillage is to slacken off the nuts, then lift the radiator off the brackets and lie it down, so the top edge ends up lower than the bottom edge, then disconnect it fully and stand it up upside-down. This depends on whether you have a couple of inches of movement in the pipes to allow the lift and be very careful not to bend the pipes while doing it - remember that rotating the radiator may tighten the nut at one end and loosen the other. You'll need assistance, especially if it's a big radiator, as it'll be heavy, but you can then carry it outside, with thumb over the holes and empty it there. Technique as used by ex-plumber mate of mine.

Once the radiator is off, you can control any leakage from the pipes or the radiator with a couple of knocked up stop ends - my Dad has a set of these in the plumbing tool box.

If you're fitting a new radiator, you'll need a specific spanner for screwing the new ends into it: https://www.screwfix.com/p/radiator-spanner/11467

Reassemble with PTFE tape or LSX: https://www.screwfix.com/p/fernox-ls-x-leak-sealer-50ml/23614#_=p

Even if you drain the system fully there'll probably still be liters of filthy jet black water/sludge in the rad you remove which will come sloshing out as you tilt it to get it off the wall, this will stain anything and everything it comes near. I cut the pipes under my floor (a couple of feet under the rad I was removing) to drain mine (they needed cutting out anyway and the underfloor is already flooded so it was convenient), then opened bleed screws all over the place to release airlocks before removing the rad. I still spilled black water all over my thankfully uncarpeted building-site lounge. If you're going to do it lay down plastic sheet and lots of absorbant rags then cap/bung the radiator holes or flip it upside down before you carry it out through the house. Also expect the valves to leak continually while you're working and be prepared for the joints to be weepy when re-made. Jointing paste seems more reliable than ptfe tape for thread-sealed joints (a horrible design) if you have any to make, both seem like a horrible hit and miss bodge!

Start in the morning on a day the plumber's merchant is open all day. Lay down more rags than you think you'll need.

jk

Agree with all the precautions of rags, sheets etc.

In spite of this I managed to get some black gunge on the carpet when replacing a hot water cylinder.

Could not shift it. 

A few months later, was mopping up something else ( dont ask ) and used some baby wipes on the old stain, came straight off, amazing.

Possibly worth mentioning that, if you want, you can change valves without draining the system in many cases.

I did this some time ago. Used a 'kit' from a plumbers merchant which was essentially just a couple of bungs. Header tank mustn't be too high up eg not above a 2nd floor (ours is in loft in a ground + 1st floor house). As far as I remember bungs go in outflow from header tank (one might have a service valve for this) and in end of expansion pipe over this tank. Close valve at other end of relevant rad. Release pressure in system by opening then closing bleed valves. The vacuum formed should (actually did!) prevent mass loss of water. Best undo nuts gently ready to retighten if any problem. Further details must be on internet somewhere.