Using Central heating WITHOUT fernox inhibitor

[Ed Sirett]

Also the pipes were wider?

Generally from what I see most systems without inhibitor (or not topped up) seem to survive (not flourish just survive) provided they are either the sealed type or the conventional type in good order.

Then really horrendous corrosion happens with open systems which faulty layouts which pump over or suck air in.

Occasionally systems can get into anaerobic corrosion. This is where the oxygen is supplied by breaking down the water into hydrogen and oxygen. The hydrogen gas then collects in a favourite radiator. If I meet this I flush the system twice with water - draining it as far as possible each time. The put in a double dose of inhibitor. The causes of anaerobic corrosion seam to be:

1) trying to treat a noisy boiler with acid and then failing to flush a neutralize it. 2) New systems which were not treated with a "new" system cleanser to neutralize the flux.

[Andrew Gabriel]

A week should be more than enough.

If you have a second similar jar, do a control experiment. Airate some water: 1/4 fill an old plastic drink bottle with tap water, and shake vigourously to dissolve the air in the water. You might notice the bottle collapse slightly as the air is sucked into the water (the effect is more noticable if you 1/2 or 3/4 fill the bottle, but this might not airate the water so well). Now pour this into a second jar with a nail, and close the lid. This nail should rust, so when it has, if the other one hasn't, you can conclude that the inhibitor is still working.

[Ed Sirett]

My view on power flushing is that sometimes it might be necessary to deal with SYMPTOMS that must be dealt with separately.

Often other approaches to flushing are as effective such as using the mains feed to flush each radiator in turn.

I'd prefer not to have one of the gadgets lest I'm considered in the same league as a "Power Flushing fixes all problems I don't have a clue about" member.

[Aidan]

Don't think so, I had conventional pumped systems in mind, not microbore.

True, a serial killer of radiators & clogger of pipes. Obvious and avoidable. A lot of people complain about repeatedly replacing radiators, but Mr. Plumber hasn't tackled, or mentioned the cause. He regularly sells them new rads and a powerflush too.

I think this is what I know as galvanic/bi-mettalic corrosion. Caused by acidic water, hydrogen in rads is a symptom. It is anerobic, in that there is no need for air to enter the system.

Treating a boiler with acid descaler would only be necessary if the boiler was scaled-up, but scaling would only occur if there was a leak (leak in DHW cylinder coil, F&E tank incorrectly set-up & overflowing when hot) and fresh water was coming in.

I once looked at a LTHW district heating system on a school site in which the F&E tank (as big as a Transit) had been set up in the 60s so that it was full when cold. I identified the cause in the 80s, when the estimated repair costs were into 6 figures. Some of the cast-iron rads had 40 sections, of which only 5 got hot; the other 35 were blocked with sludge & scale. Descaling was recommended, but I left before they did anything.