Would a water recirc system help keep lines from freezing?

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?


I live in Dallas, so I sympathize. Buildings are built to minimum code defined by the City - usually with major inputs from the builders and not the citizens. Winterizing costs, so the buildings are coded based on normal conditions (complex definition).

Slab construction versus a basement / crawl space. There is an extra cost to create a basement or crawl space and the value (in Texas) is limited. Additionally, a basement is at least partially heated - so the cooling load on the total house is increased.

Recirc systems for hot water are a convenience. These require pumps and additional energy consumption - but save water. So there is a cost-benefit trade the consumer decides. As far as for cold-water, the recirc system has little value except for freezing conditions. A retrofit would be relatively expensive on slab construction and the initial cost plus maintenance would still be expensive for relatively rare (every thirty year) events.

However, it would be possible to redesign / recode the slab foundation plumbing to assure that all pipes are internal relative to the walls and all faucets are also originate from internal (vice wall) locations. A minimum of two feet from the edge could then allow plumbing to be behind the cabinet door - but in the insulated space.

I have often imagined a single-story slab foundation with water line conduit (with the lines in the conduit) and access points installed on the slab at junctions. This would cost more on installation but would reduce eventual maintenance costs.

Finally, all items are cost vs benefit trades. This includes the infrastructure for power generation and distribution. The STATE must control those factors to assure a reliable power system based on worst-case conditions over a 50{?) year cycle (i.e., this happened in 1989 and if they used a 50 year cycle we would have been ready). Also, as we go green, strong consideration should be given to reliability and availability of sufficient power to meet daily and annual extreme cycles. Think nuclear fusion, newer (high-tech/modular) traditional nuclear power plants, and low-cost (per watt-hour) battery technologies as the essential enablers of our green future.

I am 72 yo - so the future is yours, not mine. Of course I care, but this must be solved by the current 20 - 65 yo population using common sense, detailed cause-effect analysis, and realistic cost-benefit trades. Haste is both essential and our enemy.



Fully agree with you points.
I'm pretty certain if i build another house, i'd spend the money and winterize it. As you note - there is a cost benefit tradeoff and most people probably wouldn't spend the money regardless...but i tend to look at the extremes. I wired a portable generator into my panel ( by code with a mechanical interlock) and even though we dont use it frequently...it is needed in the extreme ( like a hurricane or this freeze as example...we lost power for 30 hours this week)

I really think for the as built homes however, there might be an unintended benefit of the re circ system in helping keep lines from freezing. Just running it by some others for an opinion before i shame my friends into installing one!

But if power fails and it freezes, you are back to faucet drip to preclude freezing. (PS - I did this and had no problems on my pipes; including, the external wall mounted tankless water heater - I got down to 0 at my house.

I live in one of the colder cities in Canada, earlier this week the temperature hit -38 overnight. (pick Celsius or Fahrenheit at this temperature they would be very close, lol). In the Canadian Building Code an outside wall is an insulated outside wall that also performs a vapor barrier function. Any wall built inside of this, is considered an inside wall, even if it is built right up against an outside wall. So in Canada there is no water lines in outside walls if you understand the building code's definition of an outside wall.

Obviously keeping all your water lines in inside walls and then keeping the house warm is your best defense, but what if the heat in your home goes out for an extended period of time? From the news we are getting it sounds like this was a reality for many people in Texas. We deal with this is Canada by having both an electrical line and a natural gas line connected to most houses. If my electricity goes down, I can still run my natural gas furnace with a small generator, since I just need electricity for the fan. (Natural gas supply is ridiculously reliable, as opposed to electricity).

If I lived in Texas, and was either building a home from scratch or doing serious modifications. I would use a manifold system on both my hot and cold water lines. Basically, as soon as feasible you manifold the cold water line coming into your house, and run individual lines to each fixture, same on the hot. Insulate the lines up to the manifold. In a situation like you are currently having you can easily shut-off and drain any lines that you don't absolutely need, and leave the other ones running enough to prevent freezing. This system has the added bonus of being able to use small diameter line sizes from the manifold to each individual fixture, which usually means you don't require recirculating lines on the hot, since the water arrives fairly quick from the HWT to the fixture.

In the worst case scenario, and you can't keep your lines from freezing with a small flow of water through them, you drain everything down and wait for warmer weather.

Now, how to get HE to automate the whole process..... hmmmm.


You are correct. Ultimately, if no power - we are had. If no power, you could drip all water lines inside the house - getting that hot 36 F water into the house. But that would eventually cause the City water system to fail due to excessive use. And your drains may eventually freeze.

BTW - as we go green, natural gas and oil service to houses will have to be curtailed / eliminated. These are (after) carbon sources. Also, older natural gas infrastructure is in need of replacement and instead of replacing it is more attractive to go electric.

Since I have gas heat, a power bank with sufficient power and fast-recharge capability may be the answer. But that would only handle a 2 - 3 day case with full power out (some have lost for more than that on this event).

I don't doubt that is the reality in warmer climates. But natural gas for building heat, is here to stay in many parts of Canada. In Canada, it is not one type of infrastructure (electrical grid vs natural gas grid) competing with another. We need them both. We have so much surplus electricity (hydro generated) in my province, will sell a significant amount to Minnesota. There is simply no alternatives on the horizon to deal with the space heating when temperatures get as cold as they do. To give you an idea of typical heating costs in my city during a cold winter month:

  1. Heat with resistive electrical heat $500+ (this is at $0.10/kwhour)
  2. Heat with natural gas furnace $150.00
  3. Heat with air to air heat pump and resistive electrical heat $450.00. (The air to air heat pump doesn't work below -20 degrees C. So most of your heating is with resistive) No extra cost for the heat pump since it doubles as an air conditioner in the summer and you need that anyway.
  4. Heat with ground source electric heat pump. $150.00 This sounds like the best option, you have the same cost as natural cost but from a renewable carbon free source, until you realize this option has an additional cost of at minimum $30 000.00 to install. This has not become cheaper over years, but has become more expensive due to increased construction costs. Ground source heat pumps vs Air-to-Air heat pumps are not even in the same ballpark when it comes to installation cost.

My province has an abundance of cheap electricity from renewable (hydro) resources, so much so we sell a large amount of it to Minnesota. Even with this reality, we still predominately use natural gas for our space heating, due to our temperatures.


That's a good idea. I'm building another house in Alabama, and might do exactly that on that one. Not a huge extra cost (some labor, a couple dozen valves, and extra line) if you do it during construction, and I really like the idea of individual lines per source.


I am not sure how natural gas supply in the US works, but in Canada it is very reliable. Each natural gas pumping station on the gas grid has backup generators than run on the natural gas inside the pipe. Canada's entire electrical grid could fail for weeks on end and the gas to your house will keep flowing. In the past, parts of Canada have had severe ice storms that have knocked out power for a significant amount of time, the natural gas just keeps flowing, due to the inherent design of not requiring a functional electrical grid to continue operation in severe circumstances.

Due to this reality, many Canadians (myself included) have a small (2000-3000) watt generator to provide the home with back-up power for things like the furnace fan, sump pump, fridge/freezer, control board for a instantaneous gas fired hot water heater. etc...

The best part about this, is you just install a natural gas conversion kit on the generator and you are good to go. When my power goes out, I simply throw the generator on the back deck, plug my generator into the same type of gas outlet my BBQ is plugged into, and fire the generator up, it never runs out of fuel. My furnace, hot water heater, sump pump, fridge/freezer, cell phone charger, all stay functional in perpetuity.

Keeping your house warm in extreme temperatures, even when the electrical grid fails, is something many Canadians strive for. Just thought I would share some popular strategies we employ.


I was in a friends house here recently and his builder used a pex manifold that went to every separate tap. Might cost a little more but if I were to build again that would be the absolutely minimum I’d do.
The one improvement I’d make to it would be a way to drain the manifold so the lowest valves on the hot and cold for me would be running out of the house to a drain!
Would love to get a do over on this place but not practical now.

Agree. Separate issues.
I also advocate people in houston installing portable generators too. Though more for AC when the power goes out after a hurricane vs power outages from cold !

Definitely would want a low drain point. I looked at maybe 30 different PEX manifold designs this morning - including pro/con. I almost know enough to be dangerous at this point.


The natural gas flowed all through this storm BUT there were risks that there would be interruptions. Much like the home building standards being different for homes, the infrastructure at the well head is different in warmer l than i Canada so while there was less supply from some wells going offline, there was enough to meet the demand.

i wish i grabbed a pic of that manifold. It was very clean and was large enough for a 4000 sq foot house with 4 baths

That's me on several subjects ...


I agree to the recirculation pump helping to prevent freezing in the pipes. I mean think of it this way, which freezes faster a lake or a stream? Well the lake does because the water is sitting still. This is why the drip method works. Keeping the water moving prevents it from freezing. This would certainly help if the water in the lines was always moving, let alone pumping some hot (or warm) water down the cold line.

I have one of these setup in my home, and absolutely love it. Best $200 I ever spent. I was pretty lucky in the way my house was plumbed. From my basement, the water lines split off once and go to the kitchen. The second set of lines goes straight up and connects to the half bath on the main floor and the rest of the 2nd floor. I added the temp valve to one of the bathrooms upstairs, and that means I have hot water upstairs under a minute (usually 30 seconds) to the farthest bathroom upstairs. Its nice keeping the pipe going from the basement to the upstairs ready to go, as now we no longer freeze our hands when washing them upstairs. I have even had guests comment on the rapid hot water, without even knowing it was there.

Although, going back to would it help with pipes freezing. I doubt it would be a end all solution. As you have a hose leading to your sink after the valve, that could still freeze. And you still need power to keep the pump running. Though, I think it would help at least prolong the inevitable. It would probably still eventually freeze (at some location), but this may help make it take longer to freeze. And, if you are regularly using the water, then you may not see an issue.


I have a different understanding of moving water not freezing.

At atmospheric pressure water freezes at ~0°C. There is a phenomena of dead still water becoming super cooled but that is not the case here.

The only way to significantly depress the freezing point is to increase the pressure which also is not the case here. At least not to the degree needed for a significant temperature depression.

The dripping water actually moves relatively warm water from underground, keep it moving through the pipes and increasing the amount of heat that must be lost for the pipes to freeze. At some point if the heat loss is great enough dripping water will still freeze.

If one were to recirculate water in a closed loop, the freezing point will not be depressed and the water will freeze. This is of course assuming part of the loop is not being heated by some means.

Well - recirculation should increase entropy (by causing turbulence). And, I think an increase in entropy should reduce the probability of freezing.

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I agree but I can't imagine the effect would be significant enough at any reasonable flow rate.

I designed an ice detector for aircraft use and had to deal with the adiabatic rise from the supercooled water impinging on our probe at 350 knots. While not the same I suspect the change in temperatures are not that far apart.

The ice detector is the product I am most proud of. It was my first patent and more importantly I designed it 30 Years ago and its still in production. It is of course for military aircraft.


As long as the water in to the house is not freezing it should work with recirc.

I live in sweden and we are used and prepared for long cold winters. All of our incoming water pipes are at 180 cm (70inch) under ground. after that well isolated and in some cases with heated intelligent cable close to water pipe if necessary.
A simple smart thing is to let all water taps dripping abit. then likely it won't freeze.
There are systems that you put a small pipe inte the big pipe and circulate inside.