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

[DerbyDad03]

Thanks, but yeah, you really are late. ;-)

That type of device is exactly what we have been talking about all along. Only difference is the manufacturer:

AMH3K-7 (requires power under sink)

AMH1K-3UV (does not required power under sink)

Another possible solution is to reroute the pipes into the kitchen and then directly into the powder room, boxing the pipes (PEX) in along the short wall.

I'll know more on Tuesday. My daughter closes on the house on Monday and we'll be heading there (3 hours) on Tuesday to clean and fix a few things before moving her in later in the week. The plumbing is the first issue I will be investigating.

re: "The only "downside" that my wife complains of is that when you turn on the cold water, it's actually a bit tepid for the first 20 second before the ambient temp of the cold water is available."

Actually, that's not the only downside.

First, the condition you describe above basically replaces the waste of water and time while waiting for hot water with the waste of water and time while waiting for cold water. It's probably less waste, but there is still some.

However, the other downside is that you are "constantly" using hot water and sending cold water back to the tank. Is that less of a waste of energy than the water cooling off in the pipes after each use and then having to be drawn all the way from the tank to the fixtures? That depends on usage, size of the house, distance from the WH, etc.

Yes, instant hot water is a really nice convenience, but it's not free.

[Unquestionably Confused]

[snip]

Sorry about the delay but I was without my usenet reader for the past two weeks.

Your points are all valid regarding the "downsides" and TANSTAAFL but my purpose in installing the Watts unit was convenience and it is that. As for the tepid water from the cold tap. No biggie. We have instant cold softened water from the refrigerator and cold from an unsoftened tap right at the kitchen sink.

Undoubtedly it costs more to run the recirculating pump in terms of both the pump operation as well as the cooling and reheating of water that's running through the pipes.

That said, the recirculating pumps (watts, et al) that do not require electric at the sink are ideal for any situation where the pipes may be subject to freezing in the winter due to lack of insulation in the area, etc.

[DerbyDad03]

Based on what you know about your installation, how is the toilet affected by your installation?

If the cross-over valve is at the sink, does that mean that the pipe to the toilet is ignored? Perhaps the actual plumbing layout matters?

I'll know more tomorrow about how the bathroom is plumbed , but in this case the sink and toilet are on opposite walls of the powder room. Looking under the sink, the braided supply lines for the sink come straight up through the bottom of the vanity. I suspect that placing the cross-over valve between those 2 supply lines will only circulate water through the sink loop and water in the supply to the toilet will remain stationary and therefore subject to freezing.

It may require a dedicated return line for the toilet in order to create a loop. The pump may not be as plug-and-play a solution as we would like.

[Unquestionably Confused]

As the water is recirculated back via the cold water line, it should provide freeze protection to the toilet in the powder room if that's where you're going with this.

Granted, you're not likely to get warm water running up in the stub to the toilet supply, but there should be enough warmth to keep it from freezing.

In a normal installation Watts says that you only need the one transfer valve at the fixture furthest away from the hot water heater.

Example: If your hot water heater is in the basement and you have a common plumbing core rising vertically to the second floor and all fixtures "feed" off that loop, just put a transfer valve on the sink in the upstairs bath.

OTOH, if your powder room is serviced by a loop that runs by itself to the back of the house (North) and everything else is serviced by a loop rising elsewhere West side?), then you would want to place another transfer valve at the furthest fixture in that run, assuming your install is to ensure "instant" hot water at all fixtures along that run.

As described above, the plumbing layout definitely matters. Ya gotta remember that the purpose of the recirculating pump is not to prevent freezing but to reduce the time waiting for hot water at a distant tap

Never really gave it a thought since it's irrelevant in my installation. The workaround, as I see it, would be to plumb a cold water loop to the toilet and add another transfer valve there. If the toilet was on the same wall as the lavatory, I doubt that it would be necessary as normal convection would probably do the trick. In your case, maybe not so much.

[Clare Snyder]

Which will LIKELY be the toilet - which "generally" does not have a hot water pipe so the valve would need to be plumbed between the basin hot and the toilet - - - -

[Scott Lurndal]

Leaving aside bidets, which do have a hot water connection, the reason for the 'furthest away' rule is to ensure that any intermediate sink also has instant hot water. If you placed the transfer valve at the sink closest to the water heater (as the pipe flies), then the downstream sinks would still need to wait for hot water. So place it at the sink (generic use of the word) at the end of the hot water line. If you have multiple hot water runs, you need a transfer valve at the furthest sink on each run.

There's no need to plumb the transfer valve at a toilet.

[DerbyDad03]

Just checking: Have you read the entire thread?

This thread is not about getting instant hot water at any sinks.

It's about preventing the freezing of supply lines that run through an unheated crawl space. The supply lines feed a sink and a toilet.

Putting the transfer valve between the H&C supply lines for the sink may not - depending on how the bathroom is plumbed - prevent the supply line to the *toilet* from freezing.

Just FYI...We have already discussed more insulation around the supply lines, boxing them in and running heated air through the box, heat tape, rerouting the supply lines through conditioned space, etc.

My daughter closed on the house today and SWMBO and I will be heading there (3 hours away) first thing in the morning. My #1 goal is to get into the crawl space and determine the best method for rectifying the situation. I don't want my daughter to have to do what the previous owner did: He shut off the water to the powder room when temperatures got below 20°F.

Personally, I hope that rerouting the pipes up through the kitchen cabinet that backs up to the powder room wall is a viable option. That would be a no maintenance solution. Fix it and forget it.

[Clare Snyder]

There sure is if, as in this case, the purpose is to keep water pipes in a non-heated area from freezing and bursting. You need to keep up with the thread before making statements like that!

[DerbyDad03]

Update:

I spent the week at the house that my daughter recently bought. The house was built in 1935 and at some point the back porch was converted to a pantry and powder room. There is no heat in the space and it sits over an enclosed, but unheated, crawl space. There is spray foam insulation under the floor as seen from within the crawl space. How much insulation is in the interior walls is unknown.

The following diagram and pictures show the exact layout of the supply lines to the vanity. I had originally thought that the supplies lines were in the crawl space and I was hoping that I could bring them inside the room. As it turns out, they are already inside the room, exactly how I planned to run them. The problem is that they are still exposed to some very cold temperatures.

Temperatures during the week ranged from the high 20's F to the low 40's F. The location of the pipes inside that box was consistently ~10°F warmer than the outside temperatures. That would explain the previous owners habit/suggestion that the water be turned off and pipes drained when temps hit the teens. 15°F outside means 25°F at the pipes, getting too close to that dreaded 20°F freeze point.

At this point I seriously leaning towards the under-the-sink, thermostat controlled recirculating pump from HVACQuick. That is the vendor that I spoke too a few weeks ago. He said that the AquaMotion AMH3K-7 with the built-In Aquastat would work fine in this situation. I will need to install a receptacle under the sink but that shouldn't be too hard. There is power in the crawl space for the light above the vanity. I should be able to tap into that.

Other suggestions are certainly welcome.

[DerbyDad03]

Update:

The pump is installed and working fine.

Installed in vanity:

Closed-up, just like before:

The installation of the AquaMotion AMH3K-7 recirculating pump was extremely easy. All of the required fittings were supplied and the instructions were perfectly clear.

The folks at both AquaMotion (the manufacturer) and HVACQUICK (the distributor) were extremely nice and knowledgeable.

The unit comes with a built in timer, which when set to "On" means that the system is operational 24 hours a day. The unit will monitor the hot water at the inlet and when it drops to 84°F it will pull hot water into the pipes and push the cold water back to the water heater. When the inlet temperature reaches 104°F, the pump turns off. The pump is very quiet and unless you are listening for it, you probably wouldn't even notice it.

So far, with the outside temperatures in the low 30's°F, the pump comes on a couple of times an hour and runs for about 20 seconds. The pipes are warm to the touch

100% of the time. That is more than sufficient to prevent the pipes from freezing.

Obviously, a power outage or a pump failure could result in frozen pipes, but that's a risk we're willing to live with.

[Kristjan Robam]

DerbyDad03 kirjutas laupäev, 14. november 2020 kl 03:11:23 UTC+2:

What does the OT mean ?

Robam Kristjan

[J. Clarke]

are sealed in insulation, but I guess not enough.

power is available, etc.

Off Topic

[Kristjan Robam]

J. Clarke kirjutas teisipäev, 22. detsember 2020 kl 17:03:31 UTC+2:

Please, don't do it then . . . . . . . . . . . . . . .

Kristjan Robam

[J. Clarke]

If someone who has been posting to this group for 20 years has an off-topic question, nobody has any issue with their posting it.

However since you have decided that you are going to be a stickler for rules, your "New Talking Place" and "????? ??????? ??????? ???????? ???? (Mini MBA) ??????? ????? ??????? ?????? ?????? ???????? ?? ????? ?????? ? ???????? ??????? ????????? ???? ???????? : ?? 3?12?????2021 ???? ???????? : ??????? ? ??????? ? ??? ?? ?????? ?????????? ?????? ?? ??? ?" are both off-topic for this newsgroup.

[Leon]

Hang around a few years before making any suggestions for the group and how to act. Most of us have been here 10+ years. We were doing just fine before you got here.

[DerbyDad03]

J.Clarke, Leon, et al...

Thanks for the support guys!

[Unquestionably Confused]

Just so you know, Robam, Leon is only talking about MAKING suggestions. You may feel perfectly free to STFU right now! ;)

[gray_wolf]

ROFLMAO ! Good advice !