How to drain a central heating system
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- Опубликовано: 4 янв 2020
- For both Combi boilers and F and E systems. A few tips on draining your heating system and refilling.
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Many thanks Al. 
Хобби
Love this guy. Any plumbing stuff I do, I always seek this guy out.
Thanks Dan.
Same here! Never had a problem as long as I follow his advice to the letter
Great video Al. I learn such a lot from your videos - really clearly explained. Thanks
Thank you - you have made it sound so simple and logical to drain down my system whilst I change valves for a new radiator. I am even thinking about moving the pipes into a wall channel to avoid tiling around the pipes that currently project out of the floorboards.
Good luck with it Ian.
Thanks. I will need an assistant on the other end of a phone then. I have 12 rads and the boiler is at the opposite end of the loft hatch.
What a brilliant informative chap. Always watch his videos everytime I have any sort of plumbing issues.
Thanks Chris.
Thanks me old mate, once again your videos are saving me money, I’m most appreciated for this, I need to clean the heating system, Worcester boiler has been with us for 7yrs, but I’ve never done the clean out of the rads. Needs to be done with fresh inhibitor. Trying to stop that crackle sound when someone upstairs having a shower turns off the hot water. Many thanks.
No problem Stuart.
You save me loads of money and keep me out the wife’s road.
She and I thank you loads.
Stay well and stay safe and keep making great videos.
Ash from 🏴
Thanks, you too!
You couldn't explain any better. Great video. Thank you
You're welcome!
Best, simplest explanation I’ve seen so far!
Glad it was helpful!
Love this Guy hes made my plumbing jobs so easy with all the good advice. My next job is to change a radiator and valves. Thankyou!
No problem.
Nice one Al, I did mine (F&E) yesterday but watched your video anyway. Keep up the good work 👍
Thanks bikerchris.
Well done your instructions are so clear. Thank you.
You’re welcome 😊
Thanks governor.
Great explanation great video as usual
thanks adda.
Many thanks I’m learning fast your the best on u tube.
Glad to help
Brilliant explanation - thnx so much for making this process simple and understandable
You are welcome!
Thanks mate you explain stuff very well
No problem.
Thank you so much,your video helped me drain the system and replace a radiator after a teenage darts incident.Mny Thanks Sy
No problem
I love your videos. So knowledgeable.
Glad you like them!
Thanks very much, very helpful and concise.
No problem.
Thanks for this video it's very helpful and well explained 👍
My pleasure 😊
Hey Al, going to execute this next week. Wish me luck👍
Have fun!
Good advice thanks Der ❤
You’re welcome 😊
Most of the time you will have a isolation valve or a gate/lever valve on the inlet to the tank, alittle easier to stop the water entering the tank. Really good video, you have explained it really well as usual 👍
Thanks Craig.
Bloody good well explained vid mate 👌
Thanks 👍 Cheers Tim.
Best explanation cheers 👍
Glad it helped
You sir are a legend !
Ha ha thanks Adam.
Thanks Al. Trying it tomorrow. For those wanting to jump to F&E system 5:20
Good luck with it Mike.
@@dereton33 Thank you Al. Was actually replacing a 3 port valve. Watched your other video on this too. All went well until I discovered I'd re-fitted the old valve! Anyway, with the new valve on, the heating is still not working. This could be because I didn't replace the actuator. Will do that tomorrow. Cheers.
Cheers for the info, it came in use today m8 👍
No problem 👍
Best explained video..thanks
You are welcome
thanks great video very helpful
Glad it was helpful!
Good video Al..
I'm flushing & cleaning my f&e system in the week as it's venting into the tank.
I can use a bungy cord to hold up the ball valve and empty and clean the tank first, so the rust laying in the bottom of the tank doesn't go down through the system, (I think I have enough sludge already in the system causing the problem) I can also turn off the mains stop valve in the loft which feeds both the big main water and f&e tanks, so that's handy..
I'll just have to watch that when I refill with the cleaner that the system doesn't overflow so losing the cleaning strength.. 👍
Good luck with it Dave.
Thank you very helpful.
You're welcome!
Spot on,cheers mate.
No problem
Really useful, thanks!
You're welcome!
Well done, thank you
No problem 👍
Thanks for the video, was very useful. At which point in the re-pressurising my combi boiler should I add inhibitor?
Just before re- pressuring.
LEGEND!
Thanks
Great video as always. Very much appreciated. When draining the heating system do the radiator vavles need to be fully open as the locksheild vavle are balanced?
Yes open them fully
@@dereton33 Thanks very much Al. Always helpful.
Another great video, thank you. Can I just switch of the water in a system by closing the valve on a filling loop?
Yes you can It will already be closed so go ahead and drain.
Good video, what if you have sludge in the system, using an old back boiler?
Flush it through first.
dereton33 thanks, I was told you cannot flush an old Baxi Bermuda boiler though, is that right?
Thanks for the video's I like your no nonsense approach. I have an old heating system in a bungalow fed from an oil fired boiler in the garage. I've been looking at magnetic filters and wondered if they are worth investing in, would be interested to see a video on them and whether you recommend them or not and fitting by your average diyer or a call the plumber type job.
I have a video on them but not installing them. I think they are worth the money.
@@dereton33 thanks, found it.
Came across your video whilst trying to learn how to flush my Combi boiler heating system after introducing a cleaner. Very helpful and easy to understand. Could I ask is it possible to flush the cleaner out of the system by leaving the drain valve open and opening the supply tap on the boiler that would normally repressurise the system?
Yes that would be fine
Hi. Im a big fan of your website and advice on plumbing issues. I have a question for you though as I cant find a vid on your you tube page for this matter. Basically Ive drained down my F&E system to replace the 3 port valve but I also need to change lock shield and TRV valves to some of the rads downstairs. My problem though is that I cant seem to drain down the water to what seems like the whole of the ground floor. Not sure if the only way will be to go to each rad and sit there with a bucket and towels and drain them one by one? Being a professional what would you suggest?
Hi Phil, buy some cheap self cutting drain valves and put them on each drop at the lowest point on each rad as the pipework goes into the valves, either side so long as they are positioned at the lowest points.
Great video, very helpful as usual! My drain cock is under the thermostatic valve of a rad I removed to decorate. Can I drain the system while the rad is off or do I need to put it back on first?
Many Thanks
You can drain it still, rad off or not.
@@dereton33 Brilliant. Thanks for the help.
Best guy
Cheers Ash
@@dereton33 I have replied to your email mate
Thank you uncle Al , your vids are super... Are you based in London?
No I am in Devon, thanks for liking the vid.
Hi Al! Good day! Great videos as always! i had a Potterton Profile 18s boiler with F&E tanks, i wanted to drain them so i can clean the tanks. But when i check there is no drain valve on all the radiators. What im planning to do now is to close the main valve under the sink and close the ball valve in the tank with wood and string then drain the water by opening the water tap on all bathrooms. Will this one work? Hoping for your advice.
Check the pipework for a drain off also. You can get a screw into pipework type drain valve. Opening the taps will not drain the heating system, just the large cold water storage tank.
Hi Al, great video, just a quick question regards draining down, I presume we don’t have to turn off lock shield and TRV’s when draining? And what happens if can’t open a bleed valve on rad when trying to drain down to get air in system? Thanks
The air will get into the rad after a full drain down. If not just loosen off a rad valve .
@dereton33 thanks for the guide. question i have a rad turned off as it is leaking and some turned off as i don't use them upstairs. do i need all my rads on to drain the system properly or can i leave them off at the valves? thanks
If you want to drain the lot, for say a flush out or to add inhibitor, then open all the rad valves and the air cocks on them to let the air in as the water runs out.
Brilliant, thank you. I plan on draining my entire system and then to remove and flush all radiators. What is the best method of cleaning the small f&e tank? I could drain and clean it by hand, but is there a chemical I could use to dissolve the sludge and then siphon it out? Thank you!
Good old washing up liquid is best to clean the tank. Anyway good luck with the job.
Thanks Al, this is really helpful. We're following your instructions just now, but having a wee issue. Some radiators are fine and we hear the air going entering when we bleed them. Others are draining through the bleed valve with a fine spray of water coming out of the bleed valve. What are we doing wrong?
Make sure the drain valve is completely open, bleed valves open on the upstairs rads first then move to the downstairs ones. They should soon start sucking air unless they are on a drop system.
@@dereton33 Thanks for the advice. Drain valve was completely open (could there be 2 drain valves?) Did upstairs first...had to drain one radiator through bleed valve. When we moved downstairs we had to drain one radiator through bleed valve completely and then others were empty. My worry was that there might be water in pipes somewhere still...though the radiators now all seem to be empty. I'll go and educate myself on drop systems!
Thanks
No problem
Superb video. I have an F&E system that needs draining due to venting to the tank causing water to run out of the overflow pipe. Also, some of the radiators do not heat up fully due to sludge build up. System hasn’t been drained or cleaned in 20+ years. 1. Is it best to remove these radiators and flush them out with a hose? 2.when done, should I add the rust inhibitor into a radiator or into the small tank when refilling the system. Thank you
Yes remove and clean out each radiator. Put the inhibitor into the small tank.
Thank you!
A great video but could you please advise on the best way to cut in to radiator pipes so I can fit a new radiator whilst removing the old. It's an Feed and Expansion system so would bunging the feed and vent to create a vacuum work or do I need to drain down the whole system. Thanks
Yes, that will work fine.
@@dereton33 thank you, that's a relief although I suspect I'll be needing to remove each radiator thereafter to flush individually as I don't think the system has been flushed since 1965 when it was installed. Thank you again. I love your videos, they inspire me hugely.
Thank you very much for these very informative videos. I would like to ask a question. In my son's attic room there is a radiator which I would like to change as well as the valves. It is a combi boiler. The pipes are 8mm. Unfortunately, there is no drain off. I have found that by opening the bleed valve in this rad, I can release the water pressure. (This radiator is by itself in the attic). Am I right in thinking that I would be able to change the radiator and valves and only need to drain the radiator. And when I take off the valves there will be no water pressure, which will allow me to replace them without any disastrous floods occurring? All the Best from County Durham!
Yes up there the pressure will soon drop off. So replacement will be easy.
Great video! I need to drain, clean and put inhibitor in my combi system but none of my radiators have the drain. There is something that looks like the drain, but on the outside wall, almost at ground level, under the boiler... could that be it? Is it normal to have it outside?
Yes that is more than likely it and yes it is quite common to have them outside.
Hi Al! I have a new greenstar life combi, how would i refill the system without turning the boiler on? As the pressure indicator is digitial i cannot see how much pressure is in the system. Many thanks for your videos
it will have to be powered on. Manual gauges are the best where you do not have to have the boiler powered but like everything, is being discontinued in favour of digital crap.
@@dereton33 thanks! Do i risk damaging boiler of i switch it on with insufficient pressure? Many thanks
Subscribed recently as I’m finding some great tips on the channel.
I can’t find a drain cock on the ground floor rads although they do have a removal plug on some on the lock shield valve, but there is one on the return side of the combi which is wall mounted on the ground floor. I only need to drain it to extend some heating pipes upstairs so can I just drain off from the combi as it doesn’t matter about the ground floor rads being emptied?
Cheers
Simon
Yes just drain from the combi as you are working on upstairs rads, it also will save emptying all the downstairs ones as well.
@@dereton33 smashing, thanks. (It’s next to the back door as well so that’s handy).
@@dereton33 It drained no bother from the combi, a bit of fettling to get the last bit out the upstairs pipes and soldered on some new sections.
Thanks again for the reply 👍🏼
Would be reallty grateful of a quick reply as I have my central heating system currently drained off. Im attempting to refill with X400 but I can't push my hose far enough into the radiator, and the X45 keeps spilling out onto the floor!?.
Open the cap the other end of the radiator to allow air in.
Good evening sir I wonder could you advise me, I have to drain my heating system on the weekend to replace a lockshield valve I sheared off closing the other day. My question is , I had a plumber add a new radiator in my downstairs living room 3 years ago, which is fed ( it seems from pipe work going up into (or down from🤷🏼♂️) the ceiling directly below my front bedroom, could this mean it is a ‘spur’ off my bedroom rad, and will this in effect make it the rad furthest from my combi boiler. Thank you for all your previous helpful videos and tips. P.S. my boiler is situated just inside my back door at the rear of the house.
Yes, it will a dropped spur, from the heating pipes leading from that radiator. It will make it the last rad on system and furthest from your combi.
@@dereton33 Thank you so much, you are a true gentleman.
top vid mate.
after filling you said check rads. if de not fully hot, it means air needs to be let out. you said turn boiler off to let air out? is that correct or did i misunderstand.
thanks
You are correct. Good luck with it.
@@dereton33 so just to be sure, when in refilling the system, i turn on the boiler andi close all the valves, increase the pressure to about 1.5.
then turn off the boiler to let air out. then turn on again to increase pressure, then off again to let air out?
Hi AL,
I have my lounge rad been feed with pipes from the furthest upstairs bedroom. I have drain plugs on all the ground floor radiator. I wanted to use the one in the kitchen to drain my system. Would that drain all my rads including the lounge one feed from upstairs or should I use the lounge one only to drain the system. Thanks in advance for all the help . God bless.
The kitchen one will leave the lounge drop feed still full, best to drain from both.
@@dereton33 thank you so much .
If only working on one radiator downstairs, wouldn't an option be to isolate the boiler/ header tank as explained here, then turn off both valves on every radiator apart from the one you intend working on and one upstairs to allow air in, drain the system as explained here, do the work on the downstairs radiator and refill as explained here too? Then turn on the lockshield valves by the number of turns you did to turn them off to ensure they are still balanced? Inhibitor would still be in the system and would save a lot of hanging around to drain and fill?
That is true but we are talking about a complete system drain in order to add system cleaner or inhibitor.
In my bungalow, all the rads are at the same level. Should I try to work out which is the furthest? Not as easy as it sounds when all the pipework is concealed. How about repressurising the system when refilling each rad when the boiler is in the loft?
No need to work out the futhest rad it does not matter. You will have to keep going into the loft to repressurise the system as each rad you vent will drop the pressure.
Bungalow combi boiler central heating flush/draining advice
Need some help with this!
System recently has added sentinel x400 which now needs to be drained out.
So my goal is to essentially flush the system rather than drain it.
But draining the combi boiler system is a problem. Its a bungalow, rads are drop fed.
Drain cock on boiler is 3 foot off ground. one rad has a pegler type drain valve, will that rad valve drain off the whole system?
Will continuously repressuring the boiler help force the water though until it runs clear and not damage the boiler? should i have the heating on when doing this?
cheers!
Drain it all out first. Each rad on a dropped pipe system needs to be emptied, via a drain cock on each leg. One valve will not drain the whole system.
@@dereton33 Thanks for the reply!
I was hoping you wouldn't say that though, as only 2 rads have drain off valves!
Hi deletion, I have a slight issue but not sure if I'm exaggerating this or not.... I don't remember it happening any other winter. But my radiator in my bedroom is making this whistling noise from the water I assume going around but it's really grating after a while. Is there any tip you could recommend, other than turning the thing off?! Many thanks, like I say, it's not overly loud but the whistling type noise is really grating to me!
Check for air first. Make sure the lockshield valve is fully open , if this dies not cure it then the rad needs cleaning out , as it has some sludge build up inside it.
@@dereton33 Many thanks mate!
If I just want to change two valves on one radiator upstairs can I turn all the other radiators off then drain my combo system then I don’t need to fill the complete system after changing the valves. Or would this cause me any problems thanks
Worth a try, I prefer to empty everything.
My radiators don’t have a drain valve on any of them (old house) can I drain by turning on every sink and shower and wait for the water to run out of the system? I only need to change a valve for a heat pump in the hot press don’t need to touch the radiators
No that will not work. I have a self tapping drain valve that you screw into the pipe work in my Amazon shop. You can then use that to drain down. www.amazon.co.uk/shop/dereton33
@@dereton33 ah that’s great I will have a look on the online store!
Also, quick question if you have the time, it’s that the circulating pump seems to be gone in my hot press because it pours out water when I open the center screw (also it makes no sound or vibration, it’s an old grundfos) but I seem to have a combi boiler in my house, yet the tank in the hot press always heats up with hot water when the boiler is on. Does this mean I need to replace the circulating pump?
Will having a circulating pump running damage the combi boiler? Or was the circulating pump purposely cut off for the combi boiler? I can’t get through to a single plumber!
Hi Alan I have a f and e system on the bottom rads there is a bleed of valve on all the downstairs radiators do I put a pipe on each of these thanks Brian
Yes you do, that will empty every dropped pipe rad.
@@dereton33 thanks Alan thought as much and happy Christmas to you and your family 🎅🎅👋👋
Hi there, great video. I've just drained my system after running X800 through it for a few days but now I can't seem to get the system to refill and the boiler won't fire up! Any ideas? Thanks.
You have air in the system, try venting all the rads again and any air valves on stalks in the airing cupboard or loft.
@@dereton33 thanks Derek, I got there in the end. Had to manually open the electronic valves to help get the water moving and bleed and bleed and bleed and bleed some more! The boiler eventually kicked in. My CH pump is making a squeeking noise now so I think there may be a bit of air locked in that too so I'm going to look at bleeding that. Thanks for your reply and help, your videos are incredibly helpful.
If you drain an f and e system, is it ok to add your inhibitor straight into the f and e tank before refilling, so it goes straight down into the system? Also, does it matter in what order the radiator valves are opened and closed, i.e do you have to work out the order of the radiators on the system to get the best results?
Pour it straight into the header tank before refilling, it does not matter which order the rad valves are opened or closed.
@@dereton33 Ok thanks, much appreciated.
Oh I forgot to ask, i have 9 Rads how much inhibitor do I pour into the system I’m guessing about half a ltr, is that enough. Thanks.
With 9 rads put in at least that much, maybe a tad more.
I seem to have a drain valve on the lock shield on every radiator is it ok to drain down from one of these?
Yes fine.
If I don’t have a drain valve and I want to drain all radiators separately, should I start with radiators upstairs or downstairs? I know for bleeding of the radiators I have to start downstairs. Instead of draining all radiators and just want to drain one upstairs to add new inhibitor, you think this will this cause any issues?
Just shut off the rad valves to that rad and slacken off one of the rad valves, empty the water into a container until it stops running, then add your inhibitor and retighten the rad valve, turn both valves back on and bleed the rad.
@@dereton33 many thanks. It worked like a treat 😃 Thanks again for sharing all your knowledge here. We would be lost without you for Central heating DIY which may cost us a fortune.
can I use the cold water tap after the system has been drained to hose down the rads
Yes . That`s fine.
I have a Vaillant combi boiler. How can the system be entirely drained when the drain valve is on a radiator connection and there is pipe work under the ground floor?
It wont, it will only drain to the level of the valve. You will need to fir one to the pipework under the floor.
@@dereton33
Well surely building regs should require draining of the CH at its lowest point. Not much point in draining, flushing and refilling if you're going to have old contaminated water left in the system.
What if the lowest rad is on the same level as all the other ones on the ground floor. I just have one drain valve to the rad fitted in the hallway.
That will still be ok.
Does this apply to gaz mains comby and oil comby?
Yes.
Is it definitely the case you don't have to turn off the water to a combi boiler before draining a system and if so why? Everything I read online says to isolate water to the boiler or turn off at the stop clock. Want to safely drain system before having new rads installed. Please help!
You do not need to turn the water off. Do not believe all you read, sometimes there is just too much misinformation.
@@dereton33Thanks for reply. Love the vids. I guess the logic as a closed system once pressurised and so long as I don't open refill loop no problem?
Hello mate.
I 've got two drain cocks one by front door and second one by the back door, the one by the back door keeps dripping water, can I replace it with an compression Elbow because I already have drain cock by the front door?
Thanks
If you want to, but they are usually fitted on dropped radiators in order to drain them. Changing that drain valve for an elbow means you will not be able to drain that radiator drop.
Thanks for your reply, that's very hopeful
Weirdest place you have found a DOC?
I've found one sticking out thru the the outside brickwork, directly behind a patch of stinging nettles. Ouch!
Worst is where there's one under the groundfloor floorboards.... and the customers have laminated or tiled over it. Isolate smallest ground floor rad and whip it off. Towels usefull.
I found one under some raised decking.
I had to remove a section of decking to get to a back inlet gulley that was blocked. Found a dead rat inside. Ate it for my tea. Already marinated. Why, oh why do they do that? Same with inspection chambers.Beggars belief.
Oh dear a D. O. C. fitted out side
Is the most effective way of draining
A system if you follow the rest
Of the video
@@timmclean-inglis9371 I must have missed that bit, no doubt the missus was nagging me after doing a ten hour day. Have you teken't bin out? Boots off. I've just bloody well mopped that floor. I'm ovulating.... ten..... shun! etc etc. Ugh! ---> Smiley face, btw. ;-)
👍👍
No problem.
D I got my tanks moved in the attic and since it got done when I put my oil central heating on the water is travelling to my back boiler system and heating my stove and starting the back boiler pump , plumber does not know were he went wrong when moving the tanks , before the oil heating had no bearing on my back boiler system can you help
Need to see what he has done. Get a decent plumber in any case.
@@dereton33 thanks I think he cut out a non-return valve when moving the tanks , any guess where a non- return would be placed on a system like this, to prevent hot water travelling to the stove when the oil is on
How do I do this is the if your drain tap drains where you turn it?
Can you explain what you mean.
Is it any different if the boiler is in the loft?
No Gary.
Can I not connect the hose on the drain of valve on the combi boiler?
It will only drain to the level of the boiler and not empty all the rads.
If i was just putting in inhibitor on a combi system i would just depressurise the boiler and go to the highest radiator and undo either the flow or return and have a catch pan under the connection. Drain out about a litre or two of water and using the syringe type inhibitor remove the vent valve and inject the inhibitor into the rad. Then close the vent valve and close of the return valve and finally pressurise the system and vent the rad
Thanks for never giving up, ever.
@@dereton33 never give up doing the videos ever
I don’t have the drain off ones and can’t drain down the system to change the valves and the radiator
Buy your self a self cutting one then use that.
I would flush it through by opening the filling tap (with the bleeders closed of course).
If the combi is the highest point on the system, doesn't it get an airlock inside it after draining the central heating?
No it has an automatic air valve fitted inside it.
@@dereton33 - Ah, that makes sense! Thanks.
What about a megaflow system?
A different job. Mains off first then drain.
English - tiketty-boo. ( Hindi)
American - okay
Iv no drain off on any rads or pipework downstairs ?? How can i get round that al
Well make sure the water is off to the combi or tank in the loft. Either crack a nut on the bottom radiator to let the water out which takes a while or you could hire a pipe freezing kit, freeze the pipework, then put a drain valve on the pipework then freeze it again. Hope this helps. Steve
Sorry unfreeze
Find smallest rad on ground floor. Close both valves. Test valves are closed by venting off at nipple. If water stops after a few second, Success. CLOSE NIPPLE. Loosen rad valves to rad union nuts and whip it off turning it upside down real quick. Old towels are a good idea.
You can then use a small section of 15mm copper tube wedged into your hose, using a nut n olive attach to hose/copper to TRV. Open TRV.
Then put the kettle on. ;-)
@@loafersheffield good idea
loafer sheffield
Cheers for reply so to clarify iv got a radiator missing where some comedian who was due back post xmas isnt so iv got the pipe work with the nuts capped off where he was gonna be cuttin my copper and moving it a foot or so along the wall what do i attach the hose to the part where he has capped is like a 15 mm locknut where the trv and other end would normally go
I don’t have a drain pipe on any of my radiators to fasten hose to
Check the pipework it must be on there.
@@dereton33 it must be under the floorboards
What if the system hasn't got one? The system I want to drain don't have one
Use a radiator I have a video on how to do it. Or use a self cutting drain valve.
@@dereton33 Yes, sorry I did watch that video before you replied, that video is amazingly helpful. I love the adapter you made to screw onto the lock shield, thats brilliant. I'll like and subscribe 👍
How to depressurise a baxi 836
I have a video on it.
Don’t forget to purge the boiler!
Definitely 👍
I have a 4 years old Comb boiler system. With all respect, you were not very clear in your instruction as to how to do after water is drained. When we want to refill it, minute 3:21. How do you pressurize combi boiler? How do you refill after you drained the water and turned off the drain valve? minute 3:35 Not step by step instruction for us to follow!! Please spend some extra time to explain comb system in detail since many people may have new system now.
Question: How do you stop hot water running? Since there is three stop tap near my hot water cylinder. Which one I need to turn off? Since I want to change hot water tub.
The cold feed one to the cylinder.
There's usually a cold water loop. You insert a special key and turn a knob and then look at the pressure gauge.
I have an F&E system that I would like to drain to clean with x400 and then a few weeks later inhibit with x100, is it nessesary to turn the gas off when draining an F&E boiler?
No you can leave it on.
@@dereton33 Thats great thank you for your advice and for your hard work on this channel.