From softened water to raw water in a steam boiler

Steve Fessette

Another water treatment question. I stopped putting softened water into the make up and piped in raw water to bring down the PH level. If our raw water runs about 25 grains hardness will there be any effect from doing this?

fredy

boiler water

I’m no expert but when they installed my boiler and hydronic heat system in my home I want to put in distilled water rather than well water (hard water).  The installer said they would not warranty the system if distilled water was used because it was slightly acidic and would ruin the tubes.  I believe the distilled water PH is normally just below 6.  I offered to neutralize the distilled water but the plumber did not want to deal with the concept.  Ground water ph varies and has minerals in it that cause it to be “hard”.  Messing with the ph of the ground water may cause the minerals to form solid elements (salts) which can accumulate and if large enough quantity my collect in the system and cause a restriction(s) of flow.  Perhaps if you installed a fluid injector and only injected clean ph balanced water this may be an option.  

Jamie Hall

The short answer is...

no.  Provided -- and this is important -- you have very little leakage and very little makeup water.  Very little being defined as whatever the boiler manual says is acceptable.



While there will be scale precipitation from the hard water, it will be minor, and should be taken care of with normal maintenance.



Note that this is very different from a domestic water heater!  There you have an open loop, and are constantly adding new water.  As a result, scale can build up remarkably fast in a water heater.  But a boiler is closed loop, and once what scale is going to build from the initial fill, that's pretty will it.



I totally agree with the manufacturer or installer who said not to use distilled (or deionized) water.  We rarely think about it, but both distilled and deionized water are incredibly aggressive -- that is they will corrode almost anything, fast (water is as close to a universal solvent as we have, particularly for metals).  It's not a matter of pH (although that makes a difference), but of ionic balances in the water.

NJSteam

Distilled water

"Pure" water, by definition, has a pH of 7, or neutral.  But when water is exposed to air, it absorbs carbon dioxide which lowers the pH and makes it acidic.