By Kevin Marois

We have very hard water in Alberta. In fact, most of Canada has hard water and that is a problem if you operate a steam boiler. Recently, some of our customers have had difficulties  caused by hard water. Repairs can be expensive—especially considering that a little maintenance could have eliminated the problem completely.

What is hard water?

Our forests and mountains look beautiful but they make for hard water.

You have seen the white residue in your tea kettle. That is minerals left behind when the water evaporated. Those minerals cause problems in your tea kettle and in your boiler. We have replaced boilers because they were full of scale. The buildup occurs slowly and it is difficult to reverse.

Water flowing through limestone (or other formations) can dissolve calcium carbonate and other minerals. When that water boils off, it leaves the minerals behind.

How a Water Softener Prevents Scale

1. Hard water enters the softener
Hard water contains calcium and magnesium minerals that form scale inside boilers.

2. The softener swaps minerals
Inside the softener are thousands of tiny resin beads charged with sodium. As water passes through, the beads grab the calcium and magnesium and release sodium instead.

3. Softened water enters the boiler
Because the calcium and magnesium have been removed, scale is much less likely to form inside the boiler.

4. The resin eventually fills up
Over time, the resin beads become loaded with calcium and magnesium and can no longer soften water effectively.

5. Salt restores the softener
During regeneration, salty water (brine) flows through the resin bed. The sodium from the salt pushes the calcium and magnesium off the beads and flushes them down the drain.

6. The cycle starts again
The resin is recharged with sodium and ready to soften water once more.

That gets the reader through the process before introducing terms like “ion exchange” and “sodium carbonate-forming minerals.”

This process is called ion exchange. The important thing to remember is that the softener removes the minerals that create boiler scale. No salt in the brine tank means no regeneration, and eventually hard water begins flowing straight into the boiler.

When the sodium ions in the resin bed are used up, the softener will go through a regeneration cycle. Brine (or salty water) is circulated through the resin bed. The sodium in the salt displaces the calcium ions on the resin and they are flushed down the drain. Once the regeneration cycle is finished, the softener is ready to begin softening water again.

You can easily test the hardness of your water. Dip a test strip in a water sample and in a few seconds, you can read the hardness corresponding to the color. The strips are cheap and you will know about the issue before it becomes a problem.

Blowdown

You may have soft water now, but that water still contains minerals. Those minerals are called Total Dissolved Solids. If the concentration of minerals gets too high, your boiler will foam up, and you will have water coming out of your irons.

Those total dissolved solids still need to be flushed out by blowing down the boiler every day.  When you drain that water out of your boiler, you remove some of those minerals. You add fresh clean water and are able to control the total dissolved solids in your boiler.

You Forgot

We always test the water when we do a boiler inspection. Probably 40% of the time the water is hard and there is no salt in the softener brine tank. This isn’t difficult to fix. You buy a heavy bag of salt. You dump it in the brine tank, and you are good for a couple weeks. Then do it again.

We recently had a call for a boiler that would not fill with water. We found that the inlet pipe to the boiler was plugged with scale. We had to drill out the blockage so the water would flow into the boiler again.

Salt

So, to answer the question, boilers are like French Fries because they both need salt. Lots of it.  I haven’t mentioned boiler treatment in this article, but it is essential as well to help control scale deposits and oxygen pitting. One last comment: much of the water in Canada is especially hard from October to March. 

But regardless of the season, proper boiler maintenance is critical year-round. And, despite the ugly photos in this article, it’s fairly easy to achieve if you monitor the equipment, follow a salt and treatment regimen, and value your boiler for the production-driving workhorse it is.

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