Rain Water for the heating system

Walter_3

Just a stupid question. Is distilled water, such as rain water good for the hydronic heating system?

Thank you.

Don Walsh

Rain water is not distilled water. It is simply atmospheric liquid. It (rain water) is full of contaminants that are both naturally occuring in the atmosphere and from the source of handling after it has fallen. Distilled water is water that has been boiled and condensed by contact with a cooler surface.

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scrook_2

in particular...

it may be acidic primarily form pollutants from burning fossil fuels. The water picks up the acid gasses out of the air. Worst in industrialized regions and regions downwind (even *far* downwind) of the prevailing winds.

Mike T., Swampeast MO

Neither would be good for a hydronic system

Distilled water is more corrosive than most tap water. Sounds strange I know, but water "wants" to have some dissolved minerals--and if it can't find the typical
"hardness" minerals (calcium and magnesium) it will start grabbing iron, copper, etc. from the system.

Rain water is both naturally soft and naturally slightly acid. This is likely the worst combination to put in a closed heating system.

Rudy

Distilled

While we are on the subject. Is AC condensate distilled? It seems it should be since it's condensed from indoor water vapor. Of course there's all that crud in the bottom of the drain pan.....

hr

Distilled is overkill

and would actually need to be blended to buffer the ph back up. Some glycols are blended with distilled water, DOW premixed, for example, but the inhibitor package brings the ph back to the operating range needed. Usually 9-10 for glycols.

What you really want for a hydronic system, if the on site water is bad, is de-mineralized water. This comes from a filtration process.

Most water treatment companies sell it in gallon or 5 gallon containers. Locally I pay around 10 cents a gallon. They actually fill a 55 gallon plastic drum for me right from the filter process.

True distilled water is condensended from steam vapor. A fairly slow and expensive process for large quantities.

hot rod

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jim_31

Distilled water is very much like "Reverse Osmosis" water.
Water that has had the mineral removed from it which in turn can be aggressive on pipes. When you remove certain propeties from water such as "calcium & magnesium" the now purifed water will want to take it back on. thus pulling it from the pipes.
As for rainwater. Rainwater is somewhat acidic. Thus the term "acid rain". I'm sure you could use it but not without checking the PH level first. 7.2Ph is neutral.
Good luck

George_10

Adding treatment

If you are forced to use other waters due to the on-site water being unusable, then our treatment product, would protect the system in many ways. It would raise the pH and inhibit corrosion. It also contains an oxygen scavenger.
I would strongly advise that the system be thoroughly cleaned first so as to remove all of the installation contaminants. These include solder flux, cutting oils, grease, dirt and other construction site debris. Our cleaner removes these as well as passivating the metals so the initial fill water's oxygen is prevented from beginning the corrosion process.

A properly cleaned and treated system should remain free of chemical problems for at least a year or more. On going service will maintain this friendly environment.