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Watch my video! 😅

Yes, at the start of the experiment, I only added water that I had boiled on the stovetop. Then toward the end of the heating season I started collecting condensate from my heat pump water heater and dehumidifier and I used that.

We tend to focus of pH (and, by the way, 7.5 is basic, not acid) as it's easy to measure and not all that difficult to buffer to pretty much any number you care to name.

It's not the only factor in boiler water chemistry, however, and if you are serious about controlling your boiler water chemistry you need to pay attention to — and be prepared to correct, if necessary — all cations and anions and oxidation/reduction potential, at the very least. Further, different uses require different (sometimes dramatidally different) treatment. Once through process steam boilers, for instance, often can only have the chemistry controlled through frequent blowdowns — while closed cycle power boilers run on distilled water and may require not only water chemistry treatment, but also volatiles to protect the steam side (particularly superheaters).

Residential and small commercial heating boilers should be closed cycle, but often aren't.

Thank, @ethicalpaul — and to clarify my somewhat incoherent ramblings, I agree that for most residential systems — and, for that matter, many smaller commercial systems — simply doing two things… well, three! — is quite sufficient: making sure the pH is in a reasonable range — somewhat basic, if possible, but don't get carried away with the chemicals — and keeping dissolved oxygen as low as possible — which means adding as little water as possible, which in turn means no leaks and keeping vents in good working order — and bringing the system to a good boil if water does need to be added.

All that's required.

Thanks for that detail, Angelo!

One of the issues of the site here (particularly this Strictly Steam forum that we appreciate so much) is that there are a lot of residential systems being discussed, but there are also some commercial and process systems. And speaking for myself at least, sometimes we talk past each other.

So my respected, dare I say friend, Brother @Jamie Hall even though he lives with a fantastic old residential system, he has a lot of knowledge about all kinds of commercial stuff.

And my good frenemy (😉) @Mad Dog_2 works with large multi-unit systems I think and probably some commercial stuff too and seems to be quite good at it.

I don't really know @ARobertson13 but he seems to be talking about some commercial and steel boilers as opposed to our residential cast iron simple stuff.

So for us residential cast iron folks, yes, there are lots of chemical treatments out there, and lots of variables, but for us I think the biggest two issues by far are oxygen content (affected mostly by fresh water introduction) and PH level (which when high enough will greatly reduce corrosion of iron).

My video about this didn't get much attention here on the forum when I announced it, but I'm going to link it here again because it shocked me so much. Based on what I saw in my one year old and continuing experiment, you can, for all practical purposes, eliminate corrosion in a residential boiler simply by keeping the PH up around 11, and by removing oxygen from the water before you add it (the PH is much easier to deal with and manage than messing with manually adding water, and gives a great result by itself).

This isn't new information by a long shot, but homeowners are being kept in the dark about the very simple things they could do to make their boilers last way way longer. Please watch my video @ARobertson13 @Mad Dog_2 and then tell me it's not a little bit about how clean the water looks, or that PH-boosting additives don't matter—I know you've seen mud generated by even "tight" steam boilers. I agree it's not about surging, or shouldn't be.

I second what @ethicalpaul says about pH! Out of habit….I always drained my boiler at the beginning of the season. There would be a bunch of mud and gunk at the bottom and the float type LWCO would drain a bunch of rusty, crusty liquid too.

I've been using Rectorseal 8-way for about 5 years now, just enough to get the pH to about 10-ish. At the beginning of this season I cracked the boiler drain and the LWCO drain to see if any dirty water would come out….crystal clear!

Keeping the pH to 10-ish on my boiler slows corrosion dramatically and keeps the water super clean.