Water softener

Shemp

Is it ok to fill my steam boiler (1 pipe system, over a 100 years old) with water that has gone through a water softener?

Roger_at_SorbOx

I'm not a steam guy, but in general it's better to fill with water that has been demineralized. A water softener will usually exchange so-called 'hard ions' such as Ca2+ and Mg2+, which cause scaling, with softer ions such as Na+ or K+, which do not. So water softeners lower hardness, but not conductivity, since they leave you with just as many mineral ions as you started out with. And high conductivity always facilitates the process of corrosion, while low conductivity inhibits the process. Demineralization actually removes both hard and soft ions, both preventing scaling and lowering corrosion potential.

nicholas bonham-carter

I think that there is the further danger of introducing the trace amounts of salt left in the softened water, which would be very damaging to the cast iron sections of the boiler (see "graphitic corrosion").
If your system as a whole is tight with no leaks, then the amount of fresh water added every year will be very small.
Valving off the auto-feeder is a good idea, so that you will be aware of any excessive water-loss.--NBC

gerry gill

I prefer not to have softened water go into steam boilers. The trace amounts of salt that somehow get in the water can't be good..sounds like Roger knows the chemistry of it, I am just going on gut instinct.

Bio

I do water treatment in health care, a water softener uses "softening resins" to continuously absorb calcium & magnesium (hard water) from water supply, the salt mention above is only use to regenerate the softening resin (resin releases Ca & Mg to the drain) which is usually done 3 times a week, all is then rinsed to drain and ready to continue to soften more water

Jamie Hall

Unless your water is very hard (not just hard) it is much better to use the straight water than softened water. As Bio noted, most water softeners use a resin which exchanges... note EXCHANGES... the Calcium and Magnesium ions which are responsible for hardness for Sodium ions, which are not hardness causing (they stay in solution). Unhappily, the Sodium ions actually increase the corrosive tendency of the water, and you do not want that.

If your system is reasonably tight, the amount of scale caused by the routine feedwater won't be a problem. Of course, it it's leaky...

So, bottom line. Do not use softened water as boiler feed. If the system uses a lot of boiler feed, you are going to need deionized water, not softened, and you may need to use corrosion inhibitors (deionized water by itself is pretty aggressive) but that shouldn't be a problem except in open systems.

Shemp

Is there something that I can put along the water feed line between the softener and the boiler? Reverse osmosis or some kind of filter system ?

nicholas bonham-carter

Just feed from the cold line, as any R-O filter will not like the hot water.--NBC