Draining problem

[Loofah]

Hi, I'm trying to drain the HW system from a baxi 105e combi but seem to have hit a problem - it's not draining!

Have attached a hose pipe with jubilee clip to the lowest drainoff point, put towels in place, opened all valves, then opened the drain valve and opened the bleed valves upstairs. I got some hissing and figured water should be pouring out the hose but I got was a small dribble (OK maybe a couple of points worth). The hissing (air being sucked in) upstairs stopped pretty quick but since then (about 2 hours now) nothing much at all. I've also tried opening some bleed valves downstairs but just get underpressured dripping.

Have I forgotten a vital step?

 

[Loofah]

Have looked about and found another drain point which appears to be working. Guess I have a faulty drain off!

 

[Loofah]

So the water stopped... but not all rads had drained so I go back to 1st drain point and make a mess with a screwdriver yanking out bit of washer. Hose back on and more draining later all but one rad has drained, naturally one of the ones I want to change valves on. I finally found a 3rd drain off specifically for this rad, tucked underneath the boiler cupboard and nigh on inaccessible.
Acts of contorsion and some blue air later I hope to heck its all out!

 

[Loofah]

Right, fed up to back teeth of this, will return to it tomorrow!

Am I OK using hot water function on boiler without causing any damage?

Should be as on separate circuits but always nice to check

 

[Armo74]

If your changing the lockshield it might be a good idea to get one with a built in draincock.

 

[Loofah]

Not a bad idea at all!

 

[Loofah]

Hmm, new valves are a tad shorter than the old so hoping the olives fit snuggly as there wasn't too much pipe going in as I'd hoped.

Also, if anyone else is doing the same thing, you can use the boiler for just hot water while CH is empty!

 

[McCombi]

If you have released the system pressure then thehot water will not work as there wont be enough water in the boiler/system.

Why dont you fill it up again to just over a bar pressure with filling loop so you can use the hot water.
When you're ready to drain the system again, why not

- Isolate the electric to boiler
- remove 2 screws on front of boiler and remove outer casing panel
_ DO NOT REMOVE ANY SCREWS ON THE SILVER FRONT PANEL INSIDE

- To the rhs of boiler (to the right of pump) you will see a drain point (white I think), attach a hose and unscrew knob to drain the water, this will take the pressure off the system.

- If it's rad valves you're changing, simply place a tray/container under a valve at radiator and empty the contents of the rad that way, as you have released the pressure already, it shouldnt be messy.

- Do the same for all rads you're replacing the valves on.

_ When complete, simply close the drain point again on boiler, put outer cover back on, and refill via filling loop. You may have to vent the rads also if they aren't heating at the top.

 

[Loofah]

Thanks Brassedoff. I managed to drain all sections of the central heating so still had pressure in the boiler (whether that's correct or it just worked for me i don't know). If I hadn't managed it through the numerous drain off points I probably would have just called in the professionals.

Anyway, valves all replaced and I'm about to refill the water...

EDIT: All has gone to plan. Am quite happy there was only a teensy leak, sorted by a bit of tightening of the nuts which is ironic as thats what happened when I turned on the filling loop too lol