How to drain down a central heating system - Combi boiler 

Good explanation Nick on drain down and refilling the c/h pipe work system. However, in your process you’ve not put any inhibitor back into the pipe work when filling? How would you do that when filling back? Thanks

Thanks very much for this Nick. Drained down, changed two TRVs, and refilled without any issues. Much obliged to you for taking the time to post this.

Hi Nick. I managed to move my radiator to another wall thanks to you. I was so scared to do it but after following your video carefully, I managed by myself. Roofer by trade but slowly getting the hang of plumbing. Legend mate, thank you for the brief and spot on video.

Cheers for that no frills straight to the point no giggles. Spoken like your talking to another willing DIY adult. Thank-you. You made it look so simple

Awesome video! Straight to the point, allowed me to fix my radiators easily, Was nervous about going near the boiler but after watching this it made it so simple to drain and refill!

Good video, do you need to purge the boiler as well after filling?

...and don't forget also to put some jollup in the system while or before you fill the system. One of the Fernox type products (X100 or similar).

Ahh man you are a star. Do you think that draining my system would be a good idea if I'm getting gurgling/bubbling noises from my boiler? Sounds like theres an air bubble in there.

Hi is it possible to close down all the rads except the rad being worked on & just drain from that rad , saving time emptying part of the system & refilling .

Great video, I have a glow worm Ultimate 30c combi boiler, but need to remove 2 radiators so I can plaster the walls. Can i still use my hot water for showers and such(radiators will be removed for a week or so), or would i need to isolate something first? Dave

Half a bar Americans don’t no that

ive got a radiater that has come away from the wall, being propped up by a stool, might have to get the council to do it.

What if I don’t have the said valve on any of my rads ?

Well explained. So if i have 3 floors, would i have to bleed both, the second and third floor rads or just second floor? My drain valve is on the ground floor

Before draining open all the valves on both sides of all the rads, that way all crap will hopefully be flush from the rads. you can buy cleaning solution that you add to the cental heating follow steps on product and how to use you mzy need to flush system after using the cleaning solution Important you will need to add an inhibitor to the system to stop crap buildup if you have belp it may be an idea once you've drained system is to take each radiator off and flush it in the garden with a hose

Hi Nick, great video. Quick question, do you not need to close the internal stop tap in your property before doing the work?. Or will the boiler not replenish if its turned off?

you never included the addition of an inhibitor??

Cheers buddy 👍

You've been a massive help, very informative. I had to install new TRVs and had no clue it was this easy to drain down a system

How can I drain my combi boiler heat system when I don't have a drain valve?

Great video that. More straightforward than others ive watched. Thanks

What if the second half of the house doesn’t have a drain off valve? How can you get the remaining water out?

so, nobody use a jubilee ring in UK?😃 Just keep an eye on that hose..😅

Really clear video. One question though, for those of us on single-level flats/apartments i.e. when the boiler is the highest point in the system: how do you let air into the system when draining? Is there a risk of damaging the boiler by pulling a vacuum if you drain it without opening any bleeds? My towel rail is the highest bleed, but it still floods water everywhere because it's a foot below my boiler!

You have saved my ceilings from being flooded. Thank you

What psi

Jubilee clip on the hose

Thanks Nick your video was clear, concise, extremely informative and a pleasure to watch. I wish that are utube DIY manuals were as good as yours!

I have no filling loop on my boiler or any black valves 😔

Can I do this to drain off all my radiators and remove them all to paint the house, on my Grant oil boiler system? I still want to have hot water though.

Great video but why do you need to drain the whole system if its a combi boiler? Whenever I change a radiator valve on a combi system i always drop the pressure down with the pressure release valve and isolate the flow pipe valve. I get about half a litre of water coming out the pipes when i undo the rad valves but thats it. Change the rad valves, open the flow valve back up, re-pressurise the boiler, bleed the radiator and job done.

What about anti corrosion additive. Guess u pore in radiator b4 refilling.

What do you do if the other drain off radiator was removed?

Could you close all the upstairs rads except one drain downstairs so to saves time filling back up because all the upstairs rads are full except the one you use let air in upstairs

Thanks 😊 Nick very useful video, I feel confident do a little job tomorrow. AA Slough Berkshire.

Thanks so much for this! Moved my radiator with no problems at all. 👏👏

Legend

Great video thanks. Does anyone know if leaving water out of a system for an extended period of time can damage a combi boiler? I am taking most of the central heating pipes out and wanted to check first. By extended period of time I mean a couple of months

Thank you for the video. Good explanation re. multiple drain cocks in the house. Very helpful.

Hi, do you have to turn the water off

Fill go upstairs bleed

Nice job and video and explanation for the residential tech .

I have a leaking 90degree plastic elbow in the ceiling immediately beneath my combi boiler. Found due to staining of ceiling. Strangely system had been good for 8 years, and the leak only appeared after the boiler was serviced. I wonder if the heating water temperature setting was higher after the service and just enough to cause the leak? I saw the service engineer "waggle" the temperate dials which I think is part of putting the boiler into service mode. I have no idea of the original temperature setting, but I never changed it in all those years. Currently it drips. If I refill the system it is good for a few hours until the pressure drops and the boiler shuts itself down. According to a friend I should find a drain point on one of the ground floor radiators (he says it a legal requirement) but there isn't any drain point on any radiator. According to the same friend he suggested for him it would be a DIY job. He lives too far away to help 😞 He also suggested that freezer spray could be used to isolate the pipes around the elbow, although on the upper side of the elbow is the pipe that comes straight from the boiler and I assume(!) that there is an isolation valve on the output of the heating feed which will take care of that side of the elbow? I have used Checkatrade to find interested parties. I emailed one company all details (including lack of drain point). They have said that the job will take 2 to 3 hours. Since in my layman's head swapping the elbow should be pretty quick, what is it about the job that means it could take 2 possibly 3 hours? I just want to make sure that I'm not being taken for a ride.

Any inhibitor chemicals added?

Many thanks for your instructive and simple explanation, that was good tutorial

Great thanks, I have a rad to add and need to cut into the 22mm so i can do this now as i was worried about air getting into the boiler :)

Great video easy to follow. Saved me £600 so very happy 💃🏾💃🏾💃🏾💃🏾💃🏾 and I’m warm 😀

Yea gotta clear out traps better to hook up a pump

Hi, first time I watched your videos and very informative thank you. I hope you don’t mind me asking but are you basically saying if you switch off your boiler then no more water, other than what is already there, will go to the radiators. TIA

No Inhibitor added to the system when you fill it with fresh water?

Is there a way to drain the radiators ( to move them) while keeping the hot water on?

Amazing video, you have a new subscriber Sir. I do not have drain valve anywhere in a system. All there is, is just valves with TRVs and valves for rebalncing the system. Can I just unscrew one of these valves entirelly from the radiator and drain the system that way? If so does it matter which radiator I use for draining the water? I have 5 radiators in a system all on the same floor. Water is basically black when I am bleeding radiators so I need to get rid of that water and get new fresh water into the system so my radiators are not as cold at the bottom from all the sludge gathered.

I have seen some systems where the installer has failed to install any drain offs whatsoever

Great vid

Hi, great video and thank you. Is it safe to dump glycols/biocide/molybdate etc straight out onto the ground? Wont this leach into the surrounding soils and eventually into the water course?

Please help someone! None of the radiators in my house have a drain off valve. How do I drain the system?

Thank you very much for making this video

Great video nick. When draining the water down should your be opening up all the lock shields / TRV's . I want to drain my system to add a cleaner in it?

if i folow your instructions and then turned water back on would it flush sytem round and back out of hose to flush it well and clean.all valves reclosed exept drain pipe valve.. is this right?????

thanks!

Didn't show how to add the additive back into the system.

Mine are bit old radiator and don't have them drain valves.. but can you use on to drain out top floor radiators on boiler?? They should have drain valve should they?? Thanks for educative video

Nice video. At what point do you put inhibitor in the system?

Good explanation 👍🏼

I love your explanation so much better than the others

Thank you for this video mate 💪

Nick i cant thank you enough for this easy straight forward video. I did everthing you said and i had no issues. Keep rockn nick.🤘👋

I usually switch off all the radiators so they don't need to drain. Some water still in the pipe but it doesn't waste all the inhibitor.

What happens then if your in bungalow all rads on one floor turn boiler off. Do you still open all the bleed valves and there are more drain offs.would you have to still drain if from all drain offs or just the one your working on

didnt realise John Terry was also a plumber

Thank you, very helpful.

Thanks great video 👍👍👍

Great video, easy to follow thank you 👍🏻👍🏻

Good. I’m subscribed

Great video Nick. Very informative!

after doing this i can hear the water flowing thru my radiators when the heating is turned on , does this mean there is still air trapped?

Great vid, quick question... If I’m switching an upstairs rad to a towel rail do I need to drain the whole system, or just enough so that the top floor is drained?

Best video iv seen explained bang on ..thanks

Gingle's I ment not giggles. I don't mind giggles lol

Thank you for an excellent tutorial. I will try it out tomorrow.

Stephen jones Love video but how you water to boiler

Thanks for the video.

Are you not suppose to turn off the main water supply that comes into the house first? Otherwise wouldnt it just keep fiiling up the roads and boiler! Just an observation.

very enlightening made it look easy thanks to the plumber

Straight to the point, thanks Nick

A great and simply explained video Nick. I'm a Trader so not much to do with plumbing, but you teach well and I was quite successful changing the rad! Cheers man

Hi, i need to repair a bit of copper pipe i have slightly gouged with a drill bit, its not leaking yet but dont want it to in the future. I need to cut a bit of the pipe away and im planning on fitting a compression fitting. I need to drain the hot water that is in that pipe, is there a way to do this without draining all the radiators and everything? The tap its connected to is the kitchen sink, could i turn off the stopcock to the house and run the hot kitchen tap until it stops?

Thanks for the video, do you have to add some form of cleaning solution to the central Heating system when draining and filling back Up again?

Good vid, Cheers Nick!

No inhibitor before the refill !?

Excellent video!

Great explanation mate!!

Thank you this was very helpful

best vid iv seen straight to the point

Thanks for the clear instructions Nick as I need to do this, I am wondering at what point should chemicals bs added to the system as I live in a very hard water area? Thanks again.

Got a question for ya, over the summer my boiler kept losing pressure and I could see this via the gauge when it kept falling below the green zone, checked all the rads, no leaks and bled too with all being full but it still kept happening and it took absolutely ages for the pressure gauge to reach the green area. Now we've passed summer I've noticed that it's constantly in the green area and pressure isn't dropping and heating and the boiler is working fine...would you recommend changing the boiler or is this just a small case with nothing to worry about? Great video too by the way, I've been wanting to empty the system for ages to add more radiators in new position so thanks 👍

So the radiator water is independent to the mains water, so no need to turn of stopcock as its just the heating side?

Helpful. Thank you

Very well explained, top man!

Should I turn off my water supply first.