Lime in hydronic system
Our low-temperature 9-year-old hydronic heating system, which uses city water in a closed loop with panel radiators, has been accumulating some kind of minerals in a sand-like form. They particularly collect inside the mini flow-meters built into a recently-installed Viega manifold, sometimes clogging them. Possible solutions I’ve considered include:
1. Flushing the system thoroughly.
2. Using some of the magic chemicals sold for hydronic systems, including cleaning solutions and lime-scale/corrosion prevention solutions.
3. Adding a dirt trap before the manifold to collect the debris without clogging the meters.
4. Refilling the system after flushing with trucked-in conditioned water instead of city water.
Does anyone have suggestions as to which of those are the best options, or which brand of chemical treatments is trustworthy? I’m guessing flushing plus chemicals is probably adequate, but I’m not sure how to tell the snake oil apart from the effective treatments. And I might want to install a dirt trap while the system is drained just to be sure.
It’s a water-water ground-coupled heat pump system, and the water exiting the heat pump is usually 100 F or lower, so it shouldn’t be a worst case scenario for lime deposition. It might be adequate to just flush it, but I don’t want to get into a cycle of flushing it, refilling it with fresh city water, and then having all the minerals in that water collect in those meters, prompting a need to flush it again. In retrospect, having the flow meters sticking up off the manifold rather than down would have been better, but that’s hard to change that now.
Thanks for any advice even though this isn’t really a green building question per se. My plumbers and my local water testing company had no suggestions to offer.
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