How to fill inhibitor where no valve on top of radiators and magnaflow filter cannot be opened. Sealed unvented central heating system

[Mottie]

Thank you all for the useful replies.
I'll use the Rapid dose after draining the radiator a bit to allow enough inhibitor in. It's slightly more expensive but given only to be done once in a while, it's less fiddly than other useful methods like syringe and tube etc.

Suggestion 2:

 

[DP]

Any reason why would there be pressure in the rad if both valves are closed and some water is taken out of rad by temporarily loosening the valve nut to drain a litre of water?

When you press the syringe against the hole after removing the bleed pin, press the plunger to the bottom expelling the liquid, what is left in the hole will blow back due to pressure increased by the plunger ( be it minuscule). For positive results a needle needs to go past the hole so that liquid going into the radiator will also let the air out past the gap between the needle and the annular gap in the bleed hole.

 

[Mottie]

When you press the syringe against the hole after removing the bleed pin, press the plunger to the bottom expelling the liquid, what is left in the hole will blow back due to pressure increased by the plunger ( be it minuscule). For positive results a needle needs to go past the hole so that liquid going into the radiator will also let the air out past the gap between the needle and the annular gap in the bleed hole.

Surely that will only happen if you have water in the rad up to the bleed screw? If the rad has been drained of fluid and only contains air, surely the liquid from the syringe will fall to the bottom of the rad leaving just air to be expelled when you remove the syringe? Will 100ml of fluid at a time cause much pressure when forced into an empty rad - how much fluid does the average rad hold?

 

[Burnerman]

This one every time for me:

Fernox F1 Express Central Heating Protector 400ml - Screwfix

Order online at Screwfix.com. Provides long term protection of domestic central heating systems against internal corrosion and limescale formation. Prevents corrosion of all metals found in these systems. Quick and convenient, doses in only 30 seconds. Maintains system efficiency and extends...

www.screwfix.com

Straight into a radiator blanking plug or through a bleed valve hole, even into the filling loop direct.
John

 

[Bod ...]

Have you not got a Towel Rail?

 

[gas112]

ignore the syringe suggestions and use the rapid dose .
As for the seals your local plumbcentre will have them on the shelf or next day

Adey MagnaClean Professional O ring service kit | Wolseley

Looking for a Adey O-Ring Service Kit SEAPKPRO? Order from Wolseley today - free delivery or click and collect available nationwide.

www.wolseley.co.uk

or city plumbing

Adey MagnaClean Pro2 Seal Pack PK2-02-00829-01

7 x O rings for the MagnaClean Pro2

www.cityplumbing.co.uk

 

[Samsg30]

How much inhibitor will be needed for 3br bungalow when whole pipe work is drained 3 times meaning not much inhibitor left in the system?
The sentinel 100 rapid dose is costing £25 for 300ml whereas a standard 1L bottle is just for £15.
So if I need at least a litre in it, I'd be looking £75 just for inhibitor.

Can I not drain the water (around 2L) so the pressure in red expansion vessel is zero and then take the flexible end out and use funnel to pour down whole 1L tub?

 

[gas112]

the rapid dose will be more concentrated so will be equivalent

 

[Burnerman]

How much inhibitor will be needed for 3br bungalow when whole pipe work is drained 3 times meaning not much inhibitor left in the system?
The sentinel 100 rapid dose is costing £25 for 300ml whereas a standard 1L bottle is just for £15.
So if I need at least a litre in it, I'd be looking £75 just for inhibitor.

Can I not drain the water (around 2L) so the pressure in red expansion vessel is zero and then take the flexible end out and use funnel to pour down whole 1L tub?

I think pouring the inhibitor down the expansion vessel hose is a no -go.....there will be continuous airlocks.
The injected stuff is so much more convenient, straight into a radiator via one of the plug blanks, leaving a bleed nipple loose so the water can displace.
If you have a dry radiator, then you could pour the inhibitor in, if there is a blanking plug big enough.
The Fernox stuff I mentioned has an adapter that screws directly onto the filling loop - dead easy! Expensive a bit maybe, but you don't do it too often.
John

 

[Harry Bloomfield]

The sentinel 100 rapid dose is costing £25 for 300ml whereas a standard 1L bottle is just for £15.

https://www.ebay.co.uk/itm/29583665...bRkxdbW+mtHWkFWeBo+mxnOQ==|tkp:Bk9SR5jTo7O7Yg £14.49 for 300ml

 

[DP]

I think pouring the inhibitor down the expansion vessel hose is a no -go.....there will be continuous airlocks.
The injected stuff is so much more convenient, straight into a radiator via one of the plug blanks, leaving a bleed nipple loose so the water can displace.
If you have a dry radiator, then you could pour the inhibitor in, if there is a blanking plug big enough.
The Fernox stuff I mentioned has an adapter that screws directly onto the filling loop - dead easy! Expensive a bit maybe, but you don't do it too often.
John

Round top with just the bleed nipple. No blank plug

 

[Burnerman]

Maybe he could open the bleed on an adjacent rad?
John

 

[DP]

If all this is a pain, I would isolate all the upper floor rads, remove the bath room rad complete with the valve and fill the rad with chemicals, close valve and reconnect the rad.

 

[gas112]

Maybe he could open the bleed on an adjacent rad?
John

i hope that isnt a serious suggestion

 

[Burnerman]

I'm not trying to be an arse here, but if the system pressure is at zero, injecting say a litre of inhibitor into one rad, would displace a litre of liquid from an adjacent one through an open bleed.....would this not work?
John