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ice blockage
Friday, January 24 2025
Gretchen wanted to take a shower early this afternoon, but, to her surprise, no water came out of the shower head. I thought maybe the well pump pressure valve was stuck again and needed a knock, but that wasn't the problem. Water was flowing perfectly fine from the cold water taps but not from the hot water taps in several places in the southern half of the house. There was no hot water at all in the master guestroom bathroom, in the upstairs shower, and in the Roman bathroom bathtub. This indicated a blockage in the hot water pipe somewhere upstream from those locations. These pipes are supplied by a massive inch-thick copper pipe running through the ceiling joists in the basement within three feet of the top of the house's west foundation wall. To block such a pipe would take a substantial mass, and if it were to grow gradually, there would've been indications of its restricting effects. So the best candidate for a blockage was one that materialized quickly, and that could only be ice. It was probably no coincidence that the blockage happened after weeks of unusually cold peak-winter weather during which, for the first time, we weren't running the boiler (due to the installation last winter of the first floor minisplit). Obviously, it's never good when a water freezes in a plumbing pipe, particularly a copper one. But inch-diameter copper pipe can probably stretch better to accommodate expanding ice than thinner copper, and it's also possible that the ice could've formed in a way that pressed the expanding volume axially instead of radially (though making this assumption is how I ended up splitting my Van Gogh coffee cup). To see if freezing or near-freezing conditions exist in the inter-joist voids in the basement ceiling, I put a couple thermometers in them, one being rubber-banded to a long plastic pipe so I could place it as far west as possible. (It helped that there are still large rectangular holes cut periodically in the drywall ceiling down the entire length of the basement hallway, a legacy of numerous utility installations.) After an hour or so, I measured temperatures as low as 38 degrees, so it seemed plausible that they could've dipped below freezing on some particularly cold night, especially if a wind had been blowing and the pipe passed near one of the two ducts that vent the two basement bathrooms. And once frozen, due to thermal inertia, they would stay that way until there had been a fairly long period of warmer weather. The easiest way to thaw such an ice blockage would be to position an electric space heater to blow into the inter-joist voids, but all the electric space heaters are at the cabin. Gretchen suggested running the boiler to at least indirectly heat the basement hallway, and once that was going I realized a good way place heat in all the inter-joist spaces near the ice blockage would be to turn up the heat on the living room hydronic zone, which is supplied by pipes running parallel to the potable water pipes in the suspect area. After nearly an hour of running the heat, I got a regular dripping from the hot water bathtub tap in the upstairs bathroom, which was beyond the blockage. This suggested the blockage had become imperfect. A few minutes later, the dripping had turned into a trickle, and a few minutes after that, the tap was running normally, indicating the blockage (which must've been ice) had melted away entirely. Fortunately there were no signs of leaking in the basement ceiling, suggesting that the pipe had survived this near-brush with death.
To keep this from happening in the future, the plan is to improve the insulation around the vent ducts connecting the outdoors to the basement bathrooms. I also would like to completely bypass the inch-thick hot water line supplying these bathrooms and use one or more half-inch PEX lines instead. With the existing system, it takes a very long time for hot water to make it from the source of hot water in the boiler room to the far-flung bathrooms through the absurdly-thick one-inch pipe. When running new PEX (taking advantage, yet again, of the six or seven holes in the basement ceiling), I can route it closer to the center of the house, away from sources of cold.
Meanwhile Gretchen was in New Paltz at the opening of the new brick & mortar location of the Little Loaf Bakery with her erstwhile erstwhile friend Carrie (of Carrie and Michæ). Neville came with me and Charlotte on our walk this afternoon, which was just up the Farm Road and then back home east of the wetlands along its east side.
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