Can anyone tell me how I drain and refill my central heating with a combination bolier as I need to change bathroom radiator to towel rad.
Turn off power. Find external drain valve (hope you have one) open it and allow water out. Open bleed valves on rads to allow air in so that system can drain. Do your plumbing work. Close all bleed valves and pour inhibiter into an upstairs radiator via a bleed valve cap. Refil system via filling loop underneath boiler to approx 1.5 bar. Bleed all rads until no air comes out. Ensure pressure at 1.5 bar. Done
Hello, New to forum so please bear with me... Have been trawling the internet to find advice on draining my combi boiler then we can shuffle a radiator along the wall a bit, when i came across pretty much my exact question on your forum! yipee! My only question is everywhere else i've seen the info to open external drain valve (no idea where mine is or what it looks like - any advice?) and bleed the radiators, it says 'only for an open vented system - for sealed systems seek services of a plumber' - how do i know if mine is an open or sealed system? I have a protherm combi boiler and no hot water tank. Does that help? Sorry if this is a silly question! Am still learning! Thanks all
If you are running a combi, then you should have no problems. Drain point is likely to be located near the boiler. Locate the central heating pipes entering the boiler. Look for either a drain cock, built into the valve, or a protuding uncapped pipe somewhere, which will have a valve on it. Tango
Draining Combi boilers is easy - look around at the pipe work you will find a ribbed fitting usually close to the radiator which stick out on the end of this is a square which you can using a universal spanner undo . you will have to attach a hose pipe and ensure it is firmly fixed {i use a jubilee clip} open the valve slowly untill you get a flow through the hose pipe dont open it too far about 4-5 turn should do but be careful if the collar comes off you could get wet. open up all vents one by one ensuring the system is empty and the pressure guage on the combi is Zero'd then carry out the work. REfilling is easy - close bleed screws - close drain off - find filling loop on combi and fill up until pressure is about 2 bar - vent rads and check pressure repressurise to 1.5 bar and run sysytem heat test and re-vent, repressurise if req'd. Contact me here if needed
Hi Gas Technician, I am planning to drain my combi system in the next few days, is there any kind of additive i can add beforehand to get rid of some of the sludge/scale that has undoubtedly built up? And is there anything I should add afterwards as well as inhibitor? Cheers B_K
Yes - I recommend Sentinal X300 to flush the system out leave it in for about 2 days then flush it out fill up heat test and reflush with fresh water, run system for about 1 hrs drain system - add Sentinal X100 Inhibitor to protect the system , another good idea is when you have drained the system after the X300 treatment remove all your rads and reverse flush them outside with a hose pipe its easy to do you just need a spare rad valve and a short length of 15mm pipe to connect you hose to.
Can you over treat a system as all i intend to do is change 1 Radiator is it required to retreat system and if so with how much
Hi all, re-kindling an 11 year old thread to just ask a couple of questions as I have to do this to perminantly remove a rad from a system. As well as turning off the power to the boiler do I need to turn off the CW feed as well? Someone mentioned putting in inhibitor when refilling through a bleed valve, how much would you need for a two story flat with 5 radiators (remaining) in it?
This, it's enough for a 8-10 radiator system. http://www.screwfix.com/p/sentinel-...r-1ltr/79683?dclid=CMuDzqX22NUCFYizUQodZYQBOQ
you do not need to isolate the cold water feed to the combi boiler ,when draining radiators. you can not use the boiler for domestic hot water whilst system is drained down. isolate electric supply to boiler before draining .
Cool, thanks guys. I've never tried anything like this before but it seems straight forward enough. Got some compression end caps for the pipes and plenty of towels and containers to catch excess. Wish me luck!
Hello again, so I managed to drain the system just fine, no issues there. Then I lifted the floorboards next to the radiator expecting to see the main feed running somewhere near by. But no, the radiator actually splits off about 4.5 meters away out in the hallway! All the videos I've watched and stuff I've read says to cap the pipe off about 3" from the main line (or as close to as you can) which is doable, but my problem is this: The drain point is higher than all of the pipes in the floor, I guess most times radiators are removed they are close to the main feed and the caps are placed on a vertical bit of pipe just under the floor. If I cut my pipes where I want to there must be about 10L of water still in them and there's no way to get a bucket under there, any suggestions?
That's quite usual - if the only draincocks are above floor level where they can be easily got at, then there will be pipe at a lower level which will hold some water. First thing - if you close off all the valves to all the rads (first noting how far open the lockshields are so you can return them to that exact position), then that will help stop that annoying constant trickle of water when you cut a pipe. Having said that, most water will remain in the rads anyway since air needs to get in to let the water out, so I personally leave the bleed screws shut - unless the whole point is to fully empty the system (eg for a clean). As for the water that will come out that low pipe, you have two options - one is to find a couple of shallow trays to go under it - and keep swapping them - and the other is to simply allow the water to land on the ground under your house where it'll soak in and/or evaporate. There won't be much water. If you are concerned, mop it up with old towels. Something you may wish to consider since you are under there - instead of capping off these two pipes, instead continue them out the house wall and terminate them in a couple drain cocks immediately outside the wall - you have now sorted yer future draining issues
If it's a problem to fit a tray or bucket under the pipe use a heavy duty bin bag or rubble bag preferably one without holes in
I like the idea to continue the pipes out of the wall however my flat is on the first floor above a shop so there are a few logistical issues with that one! Thanks to everyone for the advice, I will be making my cuts this evening and hope that my tray swapping slight-of-hand is quick enough to save the ceiling of the shop downstairs...
Forums
Facebook
Twitter
You Tube
Instagram
Shop