Water Quality Matters
Analogous to plaque buildup in our veins and arteries from ingesting fatty foods which requires our heart to work harder to circulate blood throughout the body, if we fill our hydronic system – often referred to as the load side of a heat pump that distributes heat in the form of warm to hot water throughout the building – with water with significant amounts of dissolved minerals, so-called “hard” water commonly found in water from wells and even in some municipal sources, we’re asking for trouble in the future. Over time, those minerals (commonly calcium and magnesium) will come out of solution and deposit as carbonates and sulfates on the inside of metal piping, narrowing the channel and increasing resistance to water flow causing the circulating pumps to work harder and/or the flow rate to decrease. In the latter case, this will affect the efficiency of the heat pump and may even create more stress on the heat pump which can shorten its life. In severe cases, the pipes become completely clogged and the system fails.
This is preventable by simply filling the hydronic system with clean – mineral- and sediment-free – water in the beginning. Well water is commonly high in mineral content and (if so) unsuitable for hydronic duty. Softening it for potable use is not a solution as softening simply replaces calcium and magnesium ions with more soluble ions like sodium, which will eventually also scale the inside of metal pipes. Deionization, unlike softening, strips the ions from the water using special resins rather than replacing them with “less bad” ions. For some dissolved minerals, most notably iron, even deionization can’t effectively clean the water.
At Lake Country Geothermal, we’re fortunate that our municipal water supply is quite clean with very low dissolved mineral content. Normally, we will deionize a client’s local water before using it to fill their hydronic system. However, if their water contains iron, we will transport clean water to the site instead.
Frequently, we are upgrading an existing hydronic system from boiler to heat pump. It’s not uncommon for the metal pipes, valves, air separators, and circulating pumps of the existing system to be heavily scaled from years of circulating hard water. While we have the system down to install the heat pump is an ideal time to descale the pipes. By circulating an acidic cleaning agent through the system, the scale can be dissolved and removed, reopening those clogged “arteries”. A word of warning, though: this descaling process is not for the DIYer. These are strong acids that can burn skin and, if improperly handled, can explode, thus should only be used by trained professionals. In addition, some materials, e.g. nylon and aluminum, will be damaged by these acidic cleaning agents, so you need to be aware of all the materials that comprise the hydronic system.