Drain cock for pipework vent? (System refill gone wrong...)

[bpowell555]

Three questions:-

The two pipes each coming out of the top of the boiler - sealed system, not combi - go up to form an inverse u-shaped air trap and each has a drain cock in it. Am I right to use this to bleed any air that might be there?

Also, can I just bleed the pump in the same manner as a rad via its brass screw (above pump)?

Should I have set the three way valve to man when refilling? (Would it be best to start over?)

Cheers!

 

[ChrisR]

Yessa yessa yessa

But "brass screw (above pump)? " ?
Pump shaft should be horizontal

 

[bpowell555]

Yessa yessa yessa

But "brass screw (above pump)? " ?
Pump shaft should be horizontal

Cheers for the quick reply ChrisR! I take it I can wait on the result of these to see if I need to redo it all

Pump has a vertical pipe going through it - is this wrong?

 

[bpowell555]

Think we have crossed wires...

There are usually isolating valves either side (or above and below) the pump to allow you to remove it without draining down the system.

http://www.friendly-help.co.uk/centralheating.html

 

[bpowell555]

Hi chaps, the drain cocks above the boiler - sorry can't orientate the photo properly - did naff all when I opened them! I was expecting a pressurised system to gush and hiss but nada... hmmm

The other photo is of the pump. How do I bleed it? There is a valve above and below the pump but shouldn't they be to isolate the pump rather than to bleed it? Again the photo should be oriented vertically...

 

[ratonnastick]

it wont work that way round! Try flipping the house on its side.
or maybe check the pump valves are open.

 

[bpowell555]

I posted it from a mac and couldn't get the photo orientation correct. Should be portrait style.

Do you mean try opening the valves in order to bleed it? I tried that and there was no air. Tempted to replace both .. these ones are made in Italy and look a bit rubbish.

Any idea whether the drain cocks should have drained some water or not?

Cheers.

 

[ChrisR]

You won't need to bleed the pump as it's on a vertical pipe.

The drain cocks on the inverted U's will probably let air out if you undo them enough, although they probably won't work as intended. As they're in such a hot position the rubber washers will have stuck to the seat inside.
So when you undo, keep going and normally the brass "jumper" part pulls out of the middle of the washer, leaving a hoile in the middle for water to come out. There's quite a good chance unfortunately that it won't seal again when you do it up.

Or sometimes the jumper sticks to the washer and the part you're turning comes out dry. Then you poke a screwdriver in and it hits the ceiling followed by a lot of boiling water......

I'd put the pump on max speed and hope no air was trapped in the pipes, if the dc's don't want to work - the loops are short enough I would have thought.
Sometimes if you loosen the plug screw a bit and work wth a torch and small screwdriver through the spout you can get it to work properly.

 

[bpowell555]

Thanks that's very helpful! I'll try the warmth comparison test each side of the drain cocks and also the pump again.

Because the system is pressurised, that should force out any airlocks, right? So if it still doesn't run then there could be a blockage?

What you were saying about the drain valves rings a bell about the valves either side of the pump: once I opened and closed them they don't seem to be closing properly - one is dripping, and I'm no longer sure they're fully open - anyone still use these?. Maybe broke the washer there One more reason to replace them with ball valves...

Since it gets a little warm I may be able to bleed some more air out and slowly eke the system back on. Otherwise I'll drain the whole thing at the weekend, fernox it and replace the pump valves. (Then cross fingers)..

One question, the drain valve I used to drain the system is above ground level by an inch or so, yet the ground floor rad pipework is laid in concrete - or else the pipework drops down the wall and then up again through the floor - how then would these rads ever be drained?

Cheers.