Best additives for gas-fired hotwater central heating system?

I think it's time I replenished the additives in my system since I haven't added anything for three or four years, and have added quite a lot of freshwater during that time, to keep the pessure correct.

What is a good and economical additive to use, and how much for a smallish 3-bed house?

The crud that I'd most like to eliminate are those hard little black bits (iron oxide?). I did a desludge job on it about 3 or 4 years ago, but the black bits are back! - I found some the other day when I looked inside the secondary heat exchanger..

Thanks

Dave L

Reply to
Dave£
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In message , Dave£ writes

Inhibitor.

Fernox is good and reliable and I usually use that. Or Sentinel.

If it's bad enouhg I'd add some of the cleaner stuff first, leave it for a couple of weeks , drain down and refill with inhibitor. When I installed my system I connected up the mains to the heating circuit and flushed it through, seemed to remove most of the crud.

Reply to
chris French

The first point is that most corrosion inhibitors tend to lose their properties after about three years, so it's time to deal with it anyway.

Second point, is that it is a good idea to put an in-line strainer on the return to the boiler to prevent particles of crud reaching the heat exchanger,

There are a few options with inhibitors and dosing techniques:

1) Use a gel cartridge like Fernox Superconcentrate which you inject via a radiator vent using a mastic gun. Easy, but the most expensive

2) Plumb in a pipe with a service valve to use as a dosing point, then

a) Liquid inhibitor such as Fernox MB-1 can be pumped in against the pressure using a modified garden sprayer.

b) As a) but release the system pressure and put in inhibitor using a funnel

.andy

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Reply to
Andy Hall

I introduce Sentinel X100 into the system using an additive filling point near the boiler (which is at the top of the system).

Christian.

Reply to
Christian McArdle

Thanks to Andy, Chris and Christian for answering this one.

That sounds like a brilliant idea. I can't imagine why they don't fit one as standard! Can you (anyone) recommend such an item and advise where I can buy one? One that is compact, small and easy to clean out would be ideal.

Dave L

Reply to
Dave£

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