OT: What Do You Know About Recirculating Pumps? (Prevent Frozen Pipes)

Does anyone here know anything about using recirculating pumps to prevent frozen pipes in a house? I have a general idea of how they work but I've got specific situation I'm interested in.
I've just looked at a house that a family member is thinking about buying. The current owner disclosed that they always shut off the water to the first floor powder room when the temperatures won't get above the teens (°F). Here's why:
1920's house. The back porch was enclosed and turned into a powder room. The powder room is over an unheated crawl space. As shown in the link below, the pipes to the powder room originate in the basement laundry room, go through the rim joist into the crawl space and then up into the powder room. The pipes in the crawl space are sealed in insulation, but I guess not enough.
I know that heat tape is an option, but that would require working in the tiny crawl space, removing the existing insulation, etc. I'm wondering if a recirculating pump could be placed in the powder room loop to keep the water moving and warm. If that would work, I could put it in the laundry room where there is room to work, power is available, etc.
Here's the layout. Any ideas would be greatly appreciated.
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Reply to
DerbyDad03
On Fri, 13 Nov 2020 17:11:19 -0800 (PST), DerbyDad03
Recirculating pumps would need two pipes for each feed - one to the cold space and one from the cold space and ideally with the pump at the end of the line (adjacent to the fixture). Probably less work - and less power needed - to add thermostat-controlled heat tape.
Reply to
invalid unparseable
sealed in insulation, but I guess not enough.
power is available, etc.
How big is the crawl space? Might be enough to put a light or two down there (incandescent, not "high efficiency"--you want it for the heat, not the illumination).
Reply to
J. Clarke
I'm not sure that that is correct. There are under the sink units that tie the hot and cold lines together at the unit to create the loop.
One example...
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Thermostat-controlled heat tape may require maintenance. At a minimum, inspection is required. This is a very small crawl space and the perspective buyer is not the type to be crawling under the house to inspect the tape as required.
Reply to
DerbyDad03
It's a consideration, but risky. Knowing the perspective buyer as I do, any kind of "rig" wouldn't be ideal. The buyer is not the type to be crawling under a house to change a light bulb or even open the access panel to check it.
While not somebody's 90 YO grandmother, imagine if it was yours. Would you prefer to use a light bulb to keep Granny's pipes from bursting or would you install something a bit more robust? ;-)
Reply to
DerbyDad03
in news: snipped-for-privacy@googlegroups.com:
I don't know much, but I do know a few things. The "little red" recirculating pumps common on boilers need oil once a year or so. It doesn't take much, a tablespoon or two, but they need it. (Here's your reminder to go check your boiler--if it's got an oil hole put some in it!)
Recirculating pumps don't want to be run dry. I think our Geothermal system was low on water from day 1. We've had several new pumps installed as the bearings keep going out, but if the water level is right the pumps should have been ok. (Not happy with the installers, I think they were hacks.)
It DOES work extremely well to open the tap to a thin stream. I've used that method for years to keep an outbuilding pipe from freezing over. If possible, remove the faucet aerator so it doesn't get clogged with calcium.
When it gets cold enough, moving water will freeze. (I left a garden hose on trickle for a few hours on a 0F night and it froze. (I was building an ice rink!)) I know you'd rather not waste the water, but where are you going to find a source of ready heat to keep it warm enough? How much pipe run in a heated space are you going to need?
Puckdropper
Reply to
Puckdropper
On Fri, 13 Nov 2020 17:11:19 -0800 (PST), DerbyDad03
It would require adding return lines through the crawl space for both the hot and cold, with 2 pumps, returning the water back far enough into the heated envelope of the house to absorb enough heat to counteract the cooling in the crawlspace. Since you have to work in the crawlspace anyway it might be just as easy to install a pipe heater tape (or simply blast heated air into the crawlspace at the pipes when the temp drops)
Reply to
Clare Snyder
On Fri, 13 Nov 2020 20:09:47 -0800 (PST), DerbyDad03
the return lines for a "short loop" recirc system could be just 1/4 inch poly line like is used to feed the icemaker in a refrigerator. It takes a lot less heat to keep water from freezing than it does to melt it after it has frozen!!! (at 144BTU/LB latent heat of fusion - about as much heat as it takes to heat that lb of water from freezing to 144 degrees - - - - -
Reply to
Clare Snyder
On Sat, 14 Nov 2020 03:15:55 -0500, Clare Snyder snipped-for-privacy@snyder.on.ca> wrote:
are sealed in insulation, but I guess not enough.
power is available, etc.
If you're going to use heat tape, get the Raychem stuff. No thermostat--the tape construction regulates the temperature without one. It's a patented technology that I've personally had occasion to test using Air Force money, so I know that it actually does what it says it does. It's actually a really clever piece of engineering.
Reply to
J. Clarke
Unless I'm misunderstanding how the following devices work, no dedicated return lines are required.
The bottom part of this chart lists the models that are spec'd for "no dedicated return" line:
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Since the house has a hot water tank, the two models shown here seem like they are what I am looking for:
AMH3K-7 (requires power under sink)
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AMH1K-3UV (does not required power under sink)
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Is there a reason either one of these wouldn't work?
Reply to
DerbyDad03
Since the new prospective property owner is someone incapable of maintenance, the solution has to be one with little or none required. So, since you're going to be in the crawl space, repipe (perhaps using PEX) away from the rim joist - maybe one joist in from the rim. Box the plumbing in between the joists. Put a floor grille in the powder room floor so air can circulate in the box. Or, tell your friends the house is unsuitable for them.
No good deed goes unpunished.
Steve
Reply to
shiggins
On Fri, 13 Nov 2020 20:17:12 -0800 (PST), DerbyDad03
More robust than a light bulb? How about two light bulbs? ;-)
Reply to
krw
On Sat, 14 Nov 2020 05:43:54 -0800 (PST), DerbyDad03
Those seem to be huge overkill for this application. At least it appears that these are intended to keep the hot water in the loop hot (instant use), rather than cold, but still liquid.
Reply to
krw
On Sat, 14 Nov 2020 08:22:39 -0600, shiggins snipped-for-privacy@cox.net wrote:
are sealed in insulation, but I guess not enough.
power is available, etc.
I would agree that PEX should have a part in this--for those not aware, it is resistant to freezing. Not freeze proof, enough freeze/thaw cycles can break it down down, but much more resistant than copper or steel.
It's also _very_ easy to replace. No soldering, no threading, no glue, cut it with what amounts to scissors, secure it with a crimper, and it's flexible. You can't _quite_ fish it like electrical wire but it comes close. > >Steve
Reply to
J. Clarke
Replumbing with PEX is also something that I'm keeping in my back pocket.
I'm hoping to be able to re-route the plumbing to keep it inside the house, but I didn't have enough time to really look at it since I was following the inspector around and taking notes.
I have all the stuff I need to install PEX except for red tubing. I have a bunch of blue PEX, crimps, tools, etc. from when I ran air from my garage compressor down to my basement shop.
SharkBites work great also, especially for transitioning from copper to PEX, shut-offs, etc. Easy, but you pay for the convenience.
The expandability of PEX also helps to keep the overall system pressure down if the section does freeze. Frozen pipes may not split at the frozen spot if there is a weaker spot downstream of the frozen section. That PITA "weakest link" thing. ;-)
Reply to
DerbyDad03
in news: snipped-for-privacy@4ax.com:
Something like this?
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It's a low-wattage heater that screws in to a light socket.
Puckdropper
Reply to
Puckdropper
On Sat, 14 Nov 2020 21:24:21 GMT, Puckdropper snipped-for-privacy@yahoo.com wrote:
in
Any decent pet store should have those in stock.
Reply to
J. Clarke
Overkill for the specific situation perhaps, but if it solves the crawl space issue *and* provides instant hot water throughout the system, where's the downside?
Sure, there's more upfront cost, but sticking light bulbs in a crawl space just seems like such a klugey solution. There's obviously no power or a light fixture in the crawl space so there's more to it than just "use a light bulb or two." To be done correctly, the crawl space would need to be wired per code, an exterior fixture would need to be properly installed and in the proper location to provide the required heat, etc.
Then there's the issue of critters. I'd bet they would just love all that warmth.
Reply to
DerbyDad03
in
You mean the light socket that doesn't exist in the crawl space? ;-)
I'll bet the critters would love that kind of heat even more than the kind that comes from those bright light bulbs. Much easier on the eyes. ;-)
Reply to
DerbyDad03
J. Clarke snipped-for-privacy@gmail.com writes:
My folks have PEX in their summer cabin in Wisconsin. Last winter they didn't turn the water off, but rather left the furnace set to 50.
Unfortunately, they ran out of propane mid-winter. The PEX froze and broken in several places causing significant water damage.
Reply to
Scott Lurndal

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