A couple of my Danfoss radiator valves have stopped working and are not letting the warm water through. The British gas engineer who normally services our system said that there is a "Slug" that sticks in the valve preventing it from opening. It only takes him a couple of minutes with no draining of the system. We have cancelled our service agreement due to moveing house but now need to get these working. Does anyone know how to do this?

Evets, October 2008

do I need to bleed the cold water out of the radiator afterwards?? doesn't seem to be heating up yet???

marion, November 2013

Thanks for the advice here. Had 1 rad not working in hallway and it always felt like a fridge as you walked through it. The hall is central within the house so its a constant walk through. Nice warm rad now! And saved getting the plumber out!

Mike, October 2013

Further to "Lucy, Nov. '08": There is indeed limited water leakage, but not negligible - plan for half a coffee mug.
The grippy washer on the pin doesn't slide easily. It can hold the pin too far in - so before reinstalling the pin-&-domed-hex assembly, make sure there's at least 1/4"/6mm of pin standing out.

Apart from the above - thanks, folks: brilliant!

Bri, October 2012

If your Danfoss is like mine it's easy. Get a screwdriver, pliers and WD40. Unscrew the metal band holding the controller to the pipework. When loose enough, grip the thermostat and twist/pull it off. If your system is very old you may break off a couple of plastic grippers but this doesn't matter. The pipework has a 'no leak' pin protruding which should be free to move in and out. It will be stuck. Spray with WD40 and use the pliers to pull/push it in/out. There is no chance of water escaping. When free replace the thermostat and all will work until next year when you may have to repeat the process.

Colin, October 2012

Some of the older Danfoss models, need a small allen key into a small hole in the top. When this is unscrewed, you can take off the rest, revealing the small pin.

Kristofer, January 2012

Inhave the same problem and went through the same steps but the black valve doesn t pop out after i have removed the pin. Does that mean the whole thing needs to be replaced?
Al

Al, October 2011

All the above info has been extremely useful. So thanks to all the contributions.

I have removed the head of my pegler belmont thermostatic valve and the 'guard' nut to expose the pin. I have tried to gently push it in and out but this doesn't seem to have freed up the valve.

I just want to check can i remove the pin whilst still on radiator or will this then start to release the water in the system all over the place?

If I can remove the pin what do i do to try to repair the pin and or free the blocked valve and then replace it back again and refit?

Any help greatly appreciated so i can get the radiator working again in my young sons bedroom...

Many thanks in advance for any help and advice

Ian.

Ian, January 2011

Thanks to all who posted here

it took me 3 goes and about 5 re reads of this post but Its all systems(radiators) go at our house.

I now have a Nice warm rad in my living room

Merry xmas all

Cycle2worker, December 2010

brilliant advice in this post. I had two rads that would not heat up and was planning to buy new valves. Now following the tips here I have two nice hot rooms again - thanks all

Jim, December 2010

Turn the valve to its warmest setting. Remove the clamping band round the neck of the sensor head (Either an allan screw or a philips screw), and twist the head off , then you will see a pin protruding from a hexagon nut. Unscrew this nut - this is safe, at most only a very small amount of water will escape, so have something available to catch this. The unit you have withdrawn has a capsule through which the pin passes. you can free off the pin, clean it thoroughly, and replace it in the capsule. if it moves freely, problem solved, replace and tighten up . However, if the unit is old and pitted or otherwise worn, it may not free permanently. If it sticks again, it can be replaced with a new capsule which can be obtained from the Danfoss suppliers for about £4, after which the valve should be as good as new.

Douglas Watt, December 2010

Thanks Tim (Nov 2010) to whose answer I would add that before I could turn the inner black collar nearest the rad (on mine anyway) I had to remove a tiny plastic plug which was preventing the turn needed. Then easy peasy to remove the whole thermostat casing and jiggle the needle.
Heat on - marvellous!
Granny Dec 2010

Granny Dec 2010, December 2010

Thanks to Tim (Nov 2010) but when jiggling the needle valve don't pull upwards too hard or the needle will come out followed by a jet of water! Luckily I just put my thumb over the hole until I could put the needle back in. Works a treat now!! Thanks again.

David (Norwich), November 2010

Thank you for the info - now have a lovely hot rad in the bathroom! Easy peasy!

Chris, November 2010

Many thanks to all you posted answers here, I had the same problem with three radiators not getting hot. Removing the Thermostat housing was easy on mine just unscrewed the hand tight nut that attached the housing to the valve exposing the pin and then using a 10mm socket unscrewed the nut that contains the pin and removed. I found this nut to be very tight but it will come free. The issue I found is not with the pin but the valve itself (which the pin fits into) which was stuck down but gentling wiggling this released it and it sprung up. I then pushed it up and down with a screwdriver until it was free and sprung back every time I pushed it in. You will get a little water come out of the valve doing this so ensure you have a bowl underneath the the valve to collect it. But I figured this would flush through any scale etc that caused the valve to stick in the first place. So after cleaning the pin of any scale I screwed it back in and checked that the pin was pressing against the spring loaded valve, refitted the housing and now the radiators get hot. Took no time at all.

Ray, November 2010

cand dau drumul la robinet acesta nu ii da voie apei calde sa circule in calorifer si nu stiu care ar fi problema.pute-ti sa ma ajutati?

martac, November 2010

I had serious prob removing the outer plastic adjustment housing to get at the needle valve. With the type I have, you have to turn the inner black plastic collar (nearest the rad ) through a small amount (approx 1/10th. of a rotation). This retracts a set of jaws internally & should enable you to pull off the whole of this housing.Once I got to the needle valve itself, a gentle amount of jiggling in & out of the needle using narrow jawed pliers solved the problem. good luck out there, & not to heavy with the pliers!!!!

Tim, November 2010

Open the radiator thermostat to high, this makes it easier to put back on later

Chaz, October 2010

Well THANK YOU Liam, Derry & Evets & everyone else! I was just about to give up trying to fix my Mum's sticking valve when I re-read the bits about the screw and the collar - YES! It was just as you decribed and much to my 8-year-old son's amazement - I fixed it! Oh, what faith he has in his Mum's ability!
Thank you,

Becs, April 2010

There are many types of Danfoss thermostatic valves.Mine ,you have to lift a little tag(small screwdriver) open to max. then rotate inner ring(black) holding the main (white body) Wringing a chicken's neck comes to mind. The main body will spring out.

Tom, February 2010

Similar but different problem I have several Drayton TRVs that I cannot turn off? If I take the TRV control head off I can see a pin extending out of the valve by about 3mm and can push it down but when I set the Valve to frost the rad stays hot?

Rob, January 2010

Great!! I was told it should work like that, I first tried it, but was unsure if I was doing the right thing. Then I found this website and I gave it another try.

Now my dining room is nice and warm again!! Just in time for some guests that are comming tonight :)

Eric, January 2010

This is absolutelyfab advice and my broken radiator of 3 months is now working well!!!!!
Saving on the cost of a plumber too!!

Andrew, January 2010

Great advice. You do need a small alan key to undo the casing. The casing still need a firm yank for it to come away but this doesn't break it and no water is released. You then see the pin and the nut which is unscrewed. Only a little water is released.

Brosnana, December 2009

Found the information very useful but had trouble getting the casing off. My valves are horizontal. I found that a tiny allen key grub screw was holding it all together. Once I had found a suitable allen key it was easier. Once the grub screw is removed it is possible to jiggle (very technical term) the casing off to reveal the offending pin. Mine was held in with a 10mm hex headed screw. A yogurt pot caught the little drips of water when I unscrewed it (needs a lot of faith). Once this was out I eased the little pin until it came out then cleaned it up with my fingernail and a squirt of ptfe. After a very few minutes it was moving well.It went back together easily and the radiator was hot before I had put the tools away. I hope this helps.

Wurdsmiff, November 2009

How do I release the collar? there doesn't appear to be a screw or anything!

Lucy, November 2008

Remove the thermostatic control device to expose the pin. With a 12 ml spanner, remove the fitting containing the pin. Only a little water contained within this will escape. Pull the pin out of the fitting to discover a build up scale on the pin. Scrape it all off and clean the pin. Moving the little washer along the pin helps remove the scale. Soak the fitting and the pin in a washing up liquid and hot water for a while. Clean out the fitting thoroughly. Insert the pin into the fitting and work it in and out several times. Don't wory about the position of the washer as it sorts itself out when you refited. Refit the fitting and test the movement of the pin, you will see a significant improvement. This type of maintenance returns the valve to its original performance.

Liam, Derry, November 2008

Well, That all worked well!! :-)

It took me all of 5 mins for each sticking valve.

Once the pinch screw on the collar was slackened off I was able to ease the plastic thermostatic valve housing off to expose the pin. I tapped the end of the pin a couple of times with a small tack hammer and the pin popped out, just as you explained. Fitting the plastic thermostatic valve cover back on was just a matter of easing it back onto the valve and tightening the collar. Sooo easy.

Would it help to put a bit of WD40 on the pin or does it need to be left alone?

Thanks to everyone for the help and advice! :-)

Evets, November 2008

You may need to remove the collar (about 7/16") and gently prise the valve open - it pops up with a satisfying 'click' and may let a small amount of water pass. Replace the collar with the pin in place and then the thermostatic valve.

Markie, November 2008

Yes

a, October 2008

How does the casing come off? The valve is the horizontal type ( I think TRV2000) and has a small black collar with a pinch screw, does this have to be removed to take the valve cover off?

Evets, October 2008

I use the same method, gently tap the pin and you should see it rise, if you have difficulty removing the TRV head then a firm tap on the side of the valve sometimes does the trick.

Martin, October 2008

Remove stat head to expose pin, gently tap the pin with hammer works most of the time

a, October 2008