swapping new rad for old...but differnt size!!

[bigdeano]

hi, just logged on need some help, just took the old rad off in the bedroom and want to replace with a new one with new valves etc, but its a different size so got to move both pipes about 6 inches, its in the bedroom and is the furthest rad away from the boiler,question is ;
do i need to empty the system?
if not,is there a way to cut into the pipes without flooding the bedroom?
my plumbing skills are basic but ive plumbed in baths and sinks etc but done nothing to central heating systems, so any reply treat it like your dealing with a right thicko , and i might have a chance,
thanx

 

[WabbitPoo]

do i need to empty the system?

No, but you do need to drain it enough to empty the system to below where you are going to work.

I am no plumber so I'll leave those that are to give more details if you need them.

 

[kevplumb]

whats the system ??

 

[bigdeano]

its NOT a combi boiler and its that old theres no name or numbers on it , the stat says honeywell on it if that helps

 

[kevplumb]

well based on the info supplied

either drain the system or bung the header tank

raid the veg rack

 

[bigdeano]

sounds quite simple enuff, (famous last words!!!), part draining the system sounds good to me but how do i know how much to drain off?, got 3 more rads upstairs all 1.2m, time wise or quantity or how to check will do, thanx

 

[DoctorNick]

Sounds like you'll have a head tank to keep the system topped up with water? This sounds like it is *not* a sealed (newer) type system.

You'll need to turn off the mains supply to the header tank. I would let it drain down when you partially drain the system rather than try to stop it draining.

Open your drain valve (at the lowest point in your system) and keep an eye on the header tank. Once it is empty, the level will quickly go down to the upstairs rads. Open a bleed screw on one and once you hear air being pulled in, fully unscrew that valve and open bleed screws on the others upstairs (if you have TRVs or shut-off valves on your rads, you could try closing those on all rads except the one you need to remove. Trouble is that if these don't cloe fully, you get a slow leak back into the system and out the pipes you are working on. Hence, might be best to leave valves open and drain all upstairs rads).

You can tap the rads and you'll notice the noise change and you can usually tell when they are empty. When you think they are, shut off your drain valve downstairs and slowly loosen the connector at on end of your rad. You'll probably get a few drips, but if you get a good stream of water, you need to drain the system a bit more.

Eventually, you'll have an empty upstairs system (or just that rad if you decided to close TRVs etc on the others). You can then do the work.

When refilling, double check all connections you have disturbed and close all bleed screws. Re-establish supply to the head tank and once it is full, go around all the rads and open the TRVs then bleed the rads.

Once your happy that you think you have all the air out, make sure all TRVs and valves are open and fire up the boiler. Once at operating temp, you should bleed the rads again.

Check for leaks at all stages!

Job done.

Good luck!

 

[bigdeano]

now thats a reply!, thanx for that doctor nick, i feel a bit more confident in tackling the job, cheers for that