Use of Fernox

[Mr-H]

I know that Fernox is a rust inhibitor for Central Heating, but I am now told that the water in the expansion tank should have been 'reFurnoxed' every year or so. My central heating system is by no means new, and was for many years subject to an annual maintainance check by the Gas Board.They never checked the strength of the water, and thge amount of time they took casrrying out their annual check recduced from 3-4 hours to about an hour. I eventually cancelled the contract after they threatened closure of my system unless I complied with new regs etc. My heating system is now not working too well, and I am seeking advice re. Fernox please. Should it be used as I am now advised? Can I use it without flushing my system out first? Should the strength of the water in the system be tested every year? Any other advice would be gratefully received.

[AlBags]

Fernox has a range of products for different uses.
Descalers, inhibitors and general cleaners for different types of system.
If you have an iron boiler with no copper or alloys in exchange system, when system was last refilled, it should have had standard inhibitor added .. maybe MB-1. This .. like antifreeze in a car, lasts for years. $L does about 10-12 rads in average system.
I would drain and refill only after 5 years-ish .. if the system has remained maintenance-free (water system) in this time.
You can test the Ph of the additive if you like .. You need around 7.5
Additive should be around 4" of system total.

[Mr-H]

Thanks - so, how do I test?

[The-HouseHusband]

You get two types of Furnox, an inhibitor and a flushing agent. if you have had the inhibitor in for a number of years it will be due a drain down and flush. Have never heard of water strength being tested, probably yet another con by the gas board to get out of the service contract.
If it is an old system just drain down the system, refill with fresh water and flushing agent, run system as normal for a few days and then drain down the system again. You will then need to flush the system through a number of times with fresh water to clear all the flushing agent.

[Mr-H]

Doesn't sound like something an ordinary joe could do!! Thanks, but I think a professional might be needed!

[AlBags]

Well .. Fernox recommend SG is tested every year .. but that's a bit OTT. They actually do about 8 types of treatment types.

You can use Litmus paper or similar to test.
Just drain and refill system with some SB from Plumbers merchants every 5 years ish .. That's what the most caring of us would do .. at the most!

[Dagebu]

Try the Fernox technical helpline on 0870 870 0362, the people there are very helpful and it's for homeowners as well as heating engineers.