radiators

[bcafg1]

Need to swap a large radiator for a smaller one in a downstairs bathroom on a combi boiler system. Would I need to drain down the system to do this?

 

[bab]

Do u own wellies or waders. the system should be under min 1 bar pressure when u take off the big rad u will hav to drain that first. after isolating it of course. you now need to alter pipes to new rad size. how do u plan to do that. soldering? comp joints very long tail extensions?

 

[bcafg1]

wont need wellies if i drain system at drain off cock will i? plan to solder the joints. It iis a downstairs bathroom so wont i have to drain the whole system? So i can solder joints. Also are the hot and cold distribution affected by removing the radiator. Do i need to turn the combi off and also the water supply into the house or is it ok with the filling loop closed off

 

[bab]

Best to turn lecky off but i feel you might be a litte out of ya depth mate. Dont meen that in a nasty way. Got any mates who hav a bita know how.

 

[bcafg1]

Understand what your saying. But cant i just isolate boiler,close all valves on the other rads,drain system down and take the rad off and install smaller rad with extra pipework. Then fill system back up to 1 bar with filling loop and make sure all rads are balanced

 

[Slugbabydotcom]

the system should be under min 1 bar pressure when u take off the big rad

Pressure should be zero.

Then close off both valve and work on just one end at a time. That way the drinking straw effect will stop you losing all the water from your system. BUT remember that you cannot solder pipes which have water in them so use compression or push fit fittings or sometimes you can figure out a way of getting the water out of the pipe where you want to solder

 

[bcafg1]

Thought the 1 bar pressure was wrong. Was told not good practice putting compressions on ch(not sure though). wouldnt it be better to turn off the valves on other rads so not to lose all the water in the system and then drain down what water is left in the pipework. Iwould then be able to solder the extra pipework and fit new rad. Really just want to know the correct procedure for doing this thanks for any advice

 

[bab]

isolating al rads instead of draining can cause major air locks but give it a go worst case is yu will hav a crash course in purging air from systems .DONT FORGET TO ADD MORE INHIBITER>

 

[bcafg1]

Thanks for your help

 

[Roddders]

There is nothing wrong using compression joints on a system. You really only have one option in my view and that is to drain system. Remove the old radiator, then replace using either pushfit fittings or alternatively solder if you are sure there is no water left in pipes. The hassle of getting rid of air locks is I feel more hassle than its worth

 

[Slugbabydotcom]

Was told not good practice putting compressions on ch(not sure though).

Nothing wrong with using compression fittings on CH. They just dont look as pretty.
Getting rid of an airlock on a pressurised system like yours is a breeze compared to open vented. A full system drain off would leave you more liable to airlocks as the drained off system would then be full of air!
Just remember the drinking straw principle relies on only having one pipe open to the air at any one time so make sure that you keep the all the valves closed until you have finished.
If you have little faith in the drinking straw principle once you have reduced the pressure to zero and closed off the valves, rather than cut into the pipe first, just undo the nut on the bottom of the rad valve. That way you can just tighten it up again if you hit the panic button. You can expect maybe a mugful of water so get a towel round it.
Shutting the other rads off at both ends is a belt and braces approach and understandably if it was my first time I would do the same, but I dont need to now because I'm a believer

 

[bcafg1]

Thanks for last replies . Ended up draining the system and replacing radiator by soldering extra pipework. Fitted rad valves with no trouble filled system back up to 1 bar. Turned heating on and bled rads making sure pressure was around 1 bar mark and everything has worked a treat. Bit of balancing but now all rads are red hot thanks again