Bleeding pump and replacing bleed screws

[Mmcgar]

Hi all, 2 quick questions about bleeding CH systems. I have an open vented system and have been having to bleed it a fair bit recently.
On my cylinder and 1 radiator the screw that you loosen to bleed has become a bit mangled and I'm struggling to both loosen and re tighten them. I'd like to buy some spares in case I end up not being able to get 1 tightened back up , what exactly are these called? I take it I can buy them from screwfix or B&Q?

Also, should the system pump be bled? I see there's a screw on the front which looks like it is for this purpose

Thanks in advance

 

[stem]

They are called Radiator Bleed Valve Screws and they are readily available. A quick internet search found an example here.

The pump screw does allow the pump to be bled, but they don't normally need bleeding.

You shouldn't have to bleed the radiators frequently, if you do there is a problem somewhere that should be investigated. Nothing to do with it being an open vented system, I haven't needed to bleed mine for over 10 years.

 

[JohnD]

Give the system a chemical clean, rinse, and refill using inhibitor. Old open vented systems are usually dirty with corrosion sediment, drowned and rotted spiders etc.

You will have to find the drain cock, once you've done that, it's pretty simple.

Start by baling out all the mud from the feed and expansion tank and sponging it clean so it doesn't get washed down into the radiators. Sit by the f&e while someone turns the heating on and off to see if it is pumping over through the vent pipe.

Sentinel X400 is a mild and simple sludge cleaner (non acidic, won't do any harm) and you leave it circulating during normal operation for up to 4 weeks before draining and rinsing.

A typical system needs a litre costing about £15

Use X100 or similar inhibitor on final fill.

If you find fungus or bacterial slime in the F&E, wipe it out with bleach, get a tight-fitting lid to keep dirt out, and order some Fernox biocide.

 

[Mmcgar]

Hi thanks for the replies.
Are these bleed screws normally a standard size or does it generally vary?

Yeah I know I shouldn't need to bleed so much but I keep getting air trapped particularly in my cylinder coil I think, it's been ever since I had the system drained down , it's a separate issue which I need to suss out and fix or replace the system (its old and done in microbore)
Cheers

 

[stem]

Are these bleed screws normally a standard size or does it generally vary?

Unfortunately they do vary, but you can often identify them by the manufacturer of the radiator. See here.