This isn't an automation question...rather a general question / comment for the DIYers on this group and looking for opinions. Good thing i've noticed about the hubitat group is people aren't afraid to tackle their own projects nor afraid to consider non traditional solutions to problems.
Over the last few days we've seen the coldest temperatures Houston has had in decades ( it was below freezing for several days and got down to 10f) . Being from Canada, they have codes, or perhaps best practices, where they build homes with the cold weather in mind and avoid some of the traps that cause freezing pipes like not running pipes in attics or in outside walls. So far i've been very fortunate and haven't had any pipes burst...mainly as i took some precautions and ran heat tape and then insulation on all my hose bibs, kept my water running in a few taps and even put space heaters in my attics...but according to the local news and people i know...many were not so fortunate and i know many people who have had water pipes bust in attics and over garages...etc.
About a month ago i installed a watts water re-circ system and put the thermostatic valve under the farthest run in my house ( under the kitchen sink) It has drastically reduced the time to get hot water to that tap but with the way my house is plumbed..there are a lot of runs to other sinks that are not on the same line...so i dont get a lot of benefit from that one valve in the sink. I had planned on running a few more valves to some other areas that are not on that sink line.
I got to thinking about how they work and wondered if this could also solve the frozen pipe issues that many face. As i understand how these work, when the water recirc pump is running, the valve will open any time the temp on the hot side of the recirc valve drops below a certain temp, which then allows the water in the hot line to flow into the cold line which then recirculates back through the hot water tank. Took me a few minutes to figure out the water flow worked as i failed to see how any water could flow into a pressurized cold line but once i drew out the schematic of the plumbing, it's easy to see that even in a pressurized system, the water has to flow back to the hot water tank..even in a closed system provided the hot line is at a slightly higher pressure ( from the re circuit pump) .
If a person were to put those thermostatic valves under every sink..or perhaps just the sinks on the outside walls) ...when the water gets cold...the valves would open and allow some hot ( or rather warm at that point) to circulate through the much colder cold lines and hopefully that should be enough water transfer and flow to keep all the lines from freezing? Seems to me that if this were the case and this helps stop freezing lines...i'm certain more people would make the small investment to stop the frozen pipe issues many just experienced.
I truly fail to see why builders dont offer home owners an option to winterize when building a home. Fully understand its more cost to route lines away from outside walls. Even in Canada where we lived there were lines on outside walls but they were installed in a double wall. the wall was insulated, drywalled then another set of studs installed and the pipes were installed on the warm side of the insulation. Sadly as that can only be done on a new build .and even then if the home owner asks for it ( assuming builders would do it here) ...its too late once you buy a home pre built. I have 3 sinks and a toilet on outside walls with normal insulation, and 4 hose bibs where neither one of them has an internal shut off valve. I dont expect the water mixing form the re circuit system will help those as there is only 1 cold line to a hose bib and no way to mix the water...but perhaps the solution would cover most of the freezing issues.
oh..and incidentally...ive also figured out that a zen 16 doesnt respond well in the cold. On one of my hose bibs i installed a zen 16 to control my pool filler. As i needed to maintain water to that area i set up a rule to turn on the water for 1 min every 15 mins to maintain flow ( which usually prevents freezing) turns out that the device would receive the command to come on reliability but even after multiple off commands..the device wouldn't shut off the relay. Luckily i have a momentary button on the setup so i'd simply go out frequently and turn it on and off manually. So...seems like anything under 28 degrees would cause it to pooch. Not a complaint...it was more for convenience as my installation wasn't designed for this..rather to make it easier to keep my pool full.
Hope this helps someone. I do think a re circuit system with multiple valves should keep most areas of the house flowing even in the coldest of temperatures.
Thoughts from the interested?