Correct quantity of Alphi 11 in heating system?

swagman

I have replaced a radiator and when refilling the system with Fernox Alphi 11 antifreeze and inhibitor, about how much should I use for a house with 11 radiators?

I can find advice on the dilution proportions in relation to the total fluid capacity of the system - but I don't know what that capacity is!

Would a 5 litre pack be enough?

Wherryman

What type of heating system do you have?
Why do you need to use the ALPHI-11 combined antifreeze and inhibitor?

swagman

Thanks for your reply.
It is an open vented system, with an oil fired condensing boiler (not a combi). I had seen somewhere a recommendation that alphi 11 was the best stuff to use.

Wherryman

Personally I have never known anyone’s heating system to freeze up but I'm sure that in some circumstances it is possible.
In the past I have used Fernox MB1 and Sentinel X100 and they both seemed to work as I have no doubt all listed below do.

From the Fernox website "average 3 to 4 bedroomed house (100 litres), I would have calculated slightly less, about 80 litres. Take your pick:-

ALPHI-11
The minimum recommended “in-use” concentration of the product is 25%
in order to ensure adequate corrosion protection.
This concentration will protect down to -11°
5Ltr £22.98 x 5 = £114.90 Total cost

MB-1
The recommended ‘in-use’ concentration of the product is 4%.
One 4 litre pack will treat an average 3 to 4 bedroom house.
4Ltr £19.99 Total cost

F1
The recommended ‘in use’ concentration of the product is 0.5%.
One 500 ml pack will treat an average 3 to 4 bedroomed house (100 litres).
500 ml £14.97 Total cost

Or also from Screwfix:-

1Ltr Sentinel X100
1 litre of Sentinel X100 is sufficient to treat a typical domestic system of up to 10 radiators.
Larger systems should be dosed with 2 litres.
1Ltr £14.49 x 2 = £28.98 Total cost

No Nonsense Central Heating Inhibitor
1Ltr bottle treats up to 10 radiators.
1Ltr £7.95 x 2 =£15.90 Total cost

swagman

Brilliant Wherryman. Thanks for all the detail.