Combi boiler drain...........

[ste b]

Morning everyone,i get straight to the point,when i studied @ college one of the things they didnt tell us was how to drain c/h combi boiler,having just changed a rad for a friend i have the problem of the pipework not matching up exactly to the new rad,which was allready bought before i could measure up,i am going to have to remove rad stats etc and alter the pipework to suit,my question is which is the best way to drain and alter pipework to suit new upstairs bathroom rad,is it just as simple as draining the system,i am a little confused of exactly what to do but am confident i can do the procedure once i know it lol,do i have to drain all the system? is it possible to just drain upstairs? do i have to open all air vents upsatirs? a simple step by step guide would be greatly appreciated form turning boiler off to turning boiler back on, i know its a pretty simple procedure but i never done it lol,done lots of jobs for friends since finishing my level 2 but never had to drian a system yet,will get some pics posted now i have reset and remebered my password lol..............thanks hope i not asking too much.........

 

[SimonG]

How much shorter is the rad, tool station do some nice little extensions that if you are only 20 or 30mm out work a treat. They start at 10mm long and go upto 100mm, the bigger ones may look a bit numb but the smaller ones should be ok.

 

[stevetheplumber]

drain as normal hose on open rad vents job done hook the hose up above ground floor rads and you only have to vent upstairs

 

[ste b]

Cheers for the quick reply,s not to bothered about extensions but i will check um out for future reference for sure,cheers simon g.
When you say drain as normal,is it just as simple as switching boiler off,close flow and return to boiler,fit hose to drain on rad,open drain and open air vent on rad to drain system,like i said i never done this before and want to be sure i dont wreck my mates combi lol.To re-fill do i just do opposite to above?

 

[Hybrid]

Leave flow and return isolators on boiler alone, they frequently leak,
Knock boiler off, attach hose to downstairs drain-off and open rad vents upstairs. When it's drained down below where you want to work you can close the drain-off. Do as steve suggests and hang the hose up.

 

[GrahamM]

Good advise from Hybrid regarding the boiler iso valves.
Do not touch these. Especially if boiler is a good few years old. They usually start leaking, then your 1-2 hour job runs into a day as you have to go source some new iso valves to replace as well. Been there. Learned the hard way.:yesnod:

 

[Ian10261]

More often than not i get away with draining a tiny ammount from seealed systems when altering rad pipes. Close rad valves, use wet vac to drain rad, then hold wet vac nozzle over either valve and turn it on, there will be an initial rush as the system de-pressurises and the flow will in most cases slow down gradually until it stops. This works on the principle that water cant get out if air cant get in so you must only work on one open end at a time. I always have a push fit stop end handy for if anything goes wrong once the pipe is cut. Dont get me wrong though, this doesnt always work, C/H systems are real individuals and whilst ive had some where i can leave the pipe open for ages, others simply wont hold or drip constantly etc. I always try this first as its can be a real time saver, it will even work on open vented systems, you can buy special cone shaped rubber bungs to block the cold feed and vent pipes at the F &E tank.

 

[ste b]

Great advice,it is a pretty simple procedure then if you know what your doing,cheers for advice on iso valves,i wont touch them,doing the job next weekend so i will let you know how i get on,just to add,when i re-fill the system will all the rads need bleedingorjust the upstairs,thanks a lot.........

 

[wheeto]

There's no harm bleeding them all. Don't forget the inhibitor. On a sealed system, pour inhibitor into a radiator by removing one of the blanking plugs before re-pressurizing the system.

 

[ste b]

Cheers wheeto,allready got the inhibitor ready,cheers every1

 

[stevetheplumber]

best way to get inhibitor in is ladder towel rail failing thatand if youve drained down pick smallest rad shut valves remove complete with valves put it on its side remove vent open valve to release air and pour in through vent tapping shut valve replace vent drop rad back on to pipe work fill system and check for leaks but dont release the inhibitor till your sure everythings ok then open valves saves either filling twice or losing hinhibitor cos you have a leak

 

[ste b]

Cheers steve,the ree-placement rad is a towel rail,the trouble is its wider then the old one,thats why i gotta drain the system to fit the new rad and pipework,and its got 15mm valves and the pipework is 10mm...............cheers for info,its on-board....

 

[ste b]

Hi everyone............Just drained my system,if i gona break one it may as well be mine lol,i did have a small drip from under my boiler so i decided to drain and try some c/h sealer for small leaks,not sure if its stopped the leak yet it does take a few days for pressure to go down,but i will let you know.I did everything i was advised to do and all seems well up to now,i only drained about 3 quarters of a standard size bucket from system and then added the inhibitor and sealer to the system,i added into different rads upstairs,did feel a little bit of pressure with girlfriend saying have you done yet every 2 mins lol,so i threw her out and all seems well and the system is back up to pressure with all rads working well........cheers,may post a few pics of the real job and red removal and fit next week.........cheers