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boiler fill water quality - gerry gill

for the feed to boilers on initial fill. is this something i should do vise using city water? i can see where it would be better than well water. or is this more a necesseity for glycol systems? just curious, always willing to learn.


  • hr
    hr Member Posts: 6,106
    Fill water criteria

    If you are using hydronic system glycols it is VERY important to know "what's in your water" Every glycol manufacture I have talked to or recievied installation information is very adamant about the blend water quality. It protects the integrity of their product as well as your systems and your reputation.

    If you can assure your blend water contains low traces of calcium less than 50 ppm, magnesium less than 50ppm, chloride less tham 25 ppm, sulfate less than 25ppm and total hardness as CaCO3 less than 100ppm then you are safe to mix :)

    I've found for the cost of testing every well, on every job for these it is much easier for me to purchase DI water. Failure to use good quality blend water with glycol will "use up" the inhibitor components in the glycol. You may end up with your brand new glycoled system in a dangerous ph range from day one! Having seen the damage bad glycol can do to boilers, pumps, etc and how quickly the damage occurs, and having had to pay for the fix myself.. it's just not worth the risk for me. DI water is cheap.

    Now, not all filter methods are the same. True distilled water is made by boiling water to steam and collecting the condensate. A pretty involved process. This type of treatment is not all that common anymore and hard to find in large size containers 5 gallons or more.
    More common is DI-deionized, DM-demineralized, or RO reverse osmosis. Real pure water, RO for example, can be very aggressive to copper components. Until a new copper installation has a chance to get a film layer it is very susceptiple to corrosion from aggressive water. Same for zeolite softened water (water softners)

    For my water only systems I use a mix of DI water and Hydronic system treatment products. The treatment products put film providers into the mix, balance the ph, add O2 scavengers and other helpful components. Different manufactures use different chemical to accomplish this.

    So where to draw the line? If your system is comprised of say a inexpensive water heater and pump is it worth the expense to purchase DI water and hydronic system chemicals??

    What if you are using a $3,000.00 or 4,000.00 boiler?? I would say in this case you may want to take a good look at what's circulating inside that system, if you put your name on it :)

    I suspect the new breed of high efficiency, thin walled hx heat sources would be very sensitive to poor, or agressive water quality. Same for thin sheet metal panel radiators. Not a lot of room for error, like the old thick cast iron boilers.

    Chlorine levels are another area of concern.
    I suspect a recent 3 year old CombiCor failure on a city water system may have been linked to this. The people that know, or should know, are suspeciously quiet :)

    Always check with the manufactures of the equipment to get their recommendation, of course.

    hot rod

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  • yo, HR

    what is that pic of??
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