Grundfoss pump: Opening the bleed screw

[mike004]

HW is working but CH is not.
I recently had some TRVs fitted and system drained and refilled. Maybe there is air in the system?

The CH pump in the loft is red hot.
I was going to try to bleed the pump, but cannot open the top screw.
Do I need a special screwdriver or tool for this? Its a big screw. Unable to shift it using my biggest screwdriver.

 

[HERTS P&D]

Get a bigger screwdriver!

Are the pipes hot either side of the pump?

Andy

 

[mike004]

Get a bigger screwdriver!

Are the pipes hot either side of the pump?

Andy

It's about 2 inches wide!
Yes, pipes on either side are very hot.
In fact, all the pipes up around seem hot, including the vent pipe to the expansion tank and the main air vent pipe.

 

[seco services]

Sounds more like the heating side is airlocked not the pump if all pipes are hot from pump.

 

[mike004]

Sounds more like the heating side is airlocked not the pump if all pipes are hot from pump.

Is the vent pipe blocked, maybe?

 

[seco services]

Did you open the 3 port valve to manual when you refilled ?
Have you tried the heating only on and the pump on highest speed ?

 

[mike004]

Did you open the 3 port valve to manual when you refilled ?
Have you tried the heating only on and the pump on highest speed ?

The refilling was done by a plumber. He's done jobs for me before and he is experienced. But there was some trapped air after he bled all radiators. The boiler was making a noise, so he banged on the air vent pipe in the loft or something.
How can I release air from the air vent pipe? I guess it bleeds out automatically?

I have settings for HW or HW + CH. Not CH only.

Which way do I turn the pressure adjust to increase speed? Big screw is on top of the pump.

 

[D_Hailsham]

It's about 2 inches wide!

The bleed screw on this pump is the big silver one in the centre of the label, and that's not two inches wide!!

View media item 802

 

[mike004]

Turned pump up from 1 to 2. No joy.
Listening to the pump via a screwdriver, the pump sounds to be turning.
Must be an air block.

No rads at all are working. So this can't be fixed by bleeding a rad, can it?

 

[FiremanT]

The CH pump in the loft is red hot.
I was going to try to bleed the pump, but cannot open the top screw.
Do I need a special screwdriver or tool for this? Its a big screw. Unable to shift it using my biggest screwdriver.[/quote]

If the pump is EXTREMELY hot, I would suggest there is no water there, and you are in danger of ki;ling it. When you listen with a screwdriver, can you hear water movement. Are there any air release valves in the pipework above the pump. Is there water in the header tank?

Did it all work ok after the plumber initially left the job?

 

[mike004]

The CH pump in the loft is red hot.
I was going to try to bleed the pump, but cannot open the top screw.
Do I need a special screwdriver or tool for this? Its a big screw. Unable to shift it using my biggest screwdriver.

If the pump is EXTREMELY hot, I would suggest there is no water there, and you are in danger of ki;ling it. When you listen with a screwdriver, can you hear water movement. Are there any air release valves in the pipework above the pump. Is there water in the header tank?

Did it all work ok after the plumber initially left the job?[/quote]

The CH has been working fine for the 6 months since the plumber drained and refilled the system.
I can't say I can hear water movement from the pump. More a quiet drone...

The vent pipework has what looks to be a brass cylindrical top, with a plastic cap in the top of the cylinder. I unscrewed this plastic cap, but didn't hear any air rushing out.

 

[mike004]

I unscrewed the plastic cap and dropped it. It rolled off into the darkness somewhere.
So no cap on the air vent...I don't suppose this matters?

 

[FiremanT]

I unscrewed the plastic cap and dropped it. It rolled off into the darkness somewhere.
So no cap on the air vent...I don't suppose this matters?

Not really, but did air come out? It is probably connected to the system using a compression fitting. CAREFULLY loosen connection, and see if water exits.

 

[mike004]

I unscrewed the plastic cap and dropped it. It rolled off into the darkness somewhere.
So no cap on the air vent...I don't suppose this matters?

Not really, but did air come out? It is probably connected to the system using a compression fitting. CAREFULLY loosen connection, and see if water exits.

No water, or air exits.
It's a screw-on plastic top. Like for a tooth paste tube, only smaller.