White Powder Under Boiler

[Mike Lamb]

What is the reason for all of this white powder beneath a 55-year-old boiler and what would you say about it?

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[Marc]

I'm aware of a white residue that is sometimes seen on flue caps and is a result of the action of the acids within the flue condensate upon the galvanized coating of the cap.

I'm not sure this explains what Mike L has seen.

Marc

[Mike Lamb]

This is just above the burners so I think it is a combustion issue.

[John Dirks Jr]

Some expanded explanation might be found here.

https://www.inspectorsjournal.com/forum ... IC_ID=5166

[John Kogel]

That much ash tells me it is an old boiler that has maybe not given much trouble but might be near the end of its life.

[Brandon Whitmore]

It seems to be quite common on old natural draft furnace, pool heater, and boiler burners/ heater exchangers that haven't been cleaned in quite some time. The stuff just needs to be cleaned up. I've never paid attention to the actual reason.

[Mike Lamb]

HVAC-Talk forum says it is from condensing. Sustained return water temps below 130 degrees. Clean it and it shouldn't be something to worry about.

[dennispalmer]

Boiling hard water (with high mineral such as calcium, magnesium etc) in a boiler will soften it by precipitating the calcium carbonate, as its solubility decreases with increasing temperature cause the white powder in the boiler or heating system.