Hot water recirculating systems

[M_Six]

Anyone here use a hot water recirculating system? We've been thinking about having one installed on both water heaters. It's always been a pain waiting for hot water to work its way through our Byzantine piping system, but it's gotten much worse since we had a new faucet installed in the kitchen. The faucet is pathetically at slow 1.5gpm and it takes a good 3 or 4 minutes to get warm water and another 1 or 2 for it to get really hot. The hot water circulating pumps are inexpensive enough, but I'm wondering about downsides.

[2000cs]

We had one and turned it off. Pump ran over $10/month and with just two in the house it wasn’t worth the cost. Instead, when we remodeled we “cleaned up” our Byzantine piping and insulated much of the hot lines with the foam pipe tubes.

A recirc pump basically turns your hot water piping into radiant heating unless you insulate all of it. It is ok for high demand uses (hotels, hospitals, etc) but pretty inefficient for residential use.

[M_Six]

Thanks. That's the kind of feedback I was looking for. I knew there had to be an energy hit larger than what the manufacturers claim.

[Bc2005]

To make it more efficient some folks install a switch in the system. Could be a push button timer switch, or a motion sensor in the kitchen. Runs the circulator for a set time or to a set temp, and then shuts off.

[2000cs]

Originally Posted by Bc2005

To make it more efficient some folks install a switch in the system. Could be a push button timer switch, or a motion sensor in the kitchen. Runs the circulator for a set time or to a set temp, and then shuts off.

We had that, an on-off switch unfortunately located next to the pump in a basement utility area (where the water heater was) - I don’t know if having it off was part of the cause of a scale problem that built up on the impeller, but we replaced the pump twice (easy job, just have to use food-grade lubes). If we had kept the pump operating I would have added a water softener too. Pumps then were over $100 - not the end of the world but still…

[Car-Addicted]

Had Grundfos circulator pump on a propane hot water heater. It cost me a fortune by running all the time. It had a timer on it but my life is not that regular so disconnected.
Under mistakes made when build a house, I plumbed the house with supply and return lines for hot water. Master bath room is on second floor and a long way from heater. Because it has a jacuzzi it is plumbed in 3/4" so there is a massive amount of water to move to get hot water. I think it take about 2 minutes to get hot water to master sink now.

Here is my current answer but I have not had time to implement it is made by Metlund. I have also changed to Bosch tankless water heater with recirculation capabilities just to make things more complicated.

https://www.amazon.com/APCOM-Water-R...71429838&psc=1

[vreihen16]

When I was researching on-demand hot water options to replaced our failed oil boiler two years ago, one feature they had was a "push for hot water" button that you could put near distant faucets. It would fire up the on-demand hot water heater, and start the recirculating pump for a short time to draw hot water to all of the faucets. One manufacturer offered mixing valves to somehow recirculate the "cold" hot water back through the cold water line, instead of needing a third pipe for return water.

I will probably just go with per-fixture on demand electric hot water heaters when we build the Garage Mahal, although a central on-demand with recirculator and pushbutton is still an option on the table.

Right before the oil boiler crapped out, we had all of the hot/cold water lines in our house replaced with a star-wired central manifold with individual PEX runs to each fixture. The manifold has an option for hot water recirculation, but the PEX runs out to the faucets are not part of the loop in this architecture.....

[lakefront]

Using a Grundfoss recirc pump in our house for over 17 yrs now, really like it.Certainly should insulate the pipes, but that's true for any hot water system. This pump has a timer that you can set for certain times of the day (off at night), very simple, very dependable. And $10/month? Worth it.
But if you are having issues at one area in particular, why not a tankless heater just for the kitchen faucet?

[vreihen16]

https://www.navieninc.com/accessories/hotbutton

https://www.navieninc.com/accessories/navicirc

[M_Six]

Thanks for the replies. At $10/month (x2), it might be worth it. But other options like tankless systems under the sinks would get too pricey considering we'd need several. Mostly it's the kitchen and the two bathroom sinks. We have two water heaters, so two pumps and three valves would do it. No way to insulate the pipes at this point. But I have seen that some pumps come with timers. Or I could just stick a smart plug in the mix to set the time that way. If I was really weighing energy costs vs water costs, the energy costs would be higher. Our water bill is usually under $50/month. So running the water for a bit isn't all that costly. It's just a pain waiting for hot water.

[R BMW]

I,m not really that much of a conservation activist but water is a resource just as energy usage and should also be considered.
Steps off soapbox and into one of our 10,000 lakes here in Minnesota.

[M_Six]

Originally Posted by R BMW

I,m not really that much of a conservation activist but water is a resource just as energy usage and should also be considered.
Steps off soapbox and into one of our 10,000 lakes here in Minnesota.

Not that big of an issue here in central IL. We live above a huge aquifer from which we draw water. I have a septic system that returns water to the ground and hence back into the aquifer. In a closed loop system like this, there is very little water waste. Even with the drought conditions this summer, there was never a call to conserve water here. And I'd be willing to bet that my running the faucet a few times a day while waiting for hot water wastes far less water than the houses in the McMansion neighborhood across the way watering their huge lawns all summer. A large portion of that water evaporates and is lost to the closed loop system.

But as a general point of fact, you're correct. Water waste should be as much of a concern as energy waste.

[Bc2005]

If you have a main hot water line running over to the kitchen, and somewhere available to access it, you can try adding a 5 gal electric water heater inline just before the kitchen. It will give you immediate hot water to bridge the gap, although you might also then get a slug of colder water if you run it long enough.

[2heeldrive]

Originally Posted by 2000cs

We had one and turned it off. Pump ran over $10/month and with just two in the house it wasn’t worth the cost. Instead, when we remodeled we “cleaned up” our Byzantine piping and insulated much of the hot lines with the foam pipe tubes.

A recirc pump basically turns your hot water piping into radiant heating unless you insulate all of it. It is ok for high demand uses (hotels, hospitals, etc) but pretty inefficient for residential use.

$10.00 to run the pump, but how much to keep water hot in all the pipes? Isn't it essentially increasing the amount of water that needs to be heated 24/7? That could be a lot of water in a large home.

[OtoPA]

Have one, in line from the hot water line. We have it on a timer so 6am to 1030p. works well. instant hot water from the tap. don't waste (well) water waiting. We've been here 6 yrs. not sure when installed before we bought.

[2000cs]

Originally Posted by 2heeldrive

$10.00 to run the pump, but how much to keep water hot in all the pipes? Isn't it essentially increasing the amount of water that needs to be heated 24/7? That could be a lot of water in a large home.

I had two geothermal heat pumps and the larger one of those put excess heat into hot water heaters (2 50 gal Marathons). The electric heat rarely came on for the water heaters. But with conventional systems, the added water heating would have been significant for us. This of course depends on the length of pipe runs and whether they are insulated, primarily. I don’t know if PEX vs copper or iron pipe matters.

I like the idea of a small electric instant if the need is just to have tea, or a small tank (5 gal or less) under the sink or near it in line for dishes or whatever. It should be rare to need 5 gal of water in one use at a kitchen sink. Recovery time for the tank likely would be under 30 minutes (should be available from the mfgr’s website).

So much depends on the layout of the house, where you have access to water and electric and space for whatever you want to try.

[kscarrol]

I have a tankless with recirculating and like it. System was in the house we bought here. To give an idea of expenses, our last gas bill (tankless is nat gas) was $49 and change and our water bill was $67 but a significant portion of that is from the irrigation system on our 3/4 acre lot.

[M_Six]

I thought about small, tankless systems. But I'd need at least two and they're not cheap. There might be space for a small electric heater under the kitchen sink, but not in either bathroom. I'm pretty sure the only insulation on the hot water pipes is the stuff the plumbers put on when they replaced the two water heaters. And that insulation only runs from the top of the water heater to the wall. I doubt the pipes behind the walls are insulated. The hot water feed to our washing machine is exposed below the normal opening due to some repair work and that isn't insulated, although there is normal wall insulation around it. The builders probably figured the wall insulation was good enough.

[cooolone2]

Well, the real question if coat is how much water and energy is wanted when running a faucet for 5 mins to get hot water every time it's not used for a few hours or so ... As compared to the coat of running an instant HW system?

There are many ways to heat that water or some of the water in the line until the actual heated water reaches the faucet. One way is to install a high wattage heat Trace cable on the line, say for 10' or so, self regulating 30W per foot say... Lol, or of course a small HW heater under the sink. But the least efficient is going to be just opening a faucet and waiting. The recirculating loops and tankless HW heaters seem to be the best of the new tech to go with... Just sayin', so if possible, I'd go that route. And the newer controllers have multi time period programming as well. You don't need to circulate heated water when it's not going to be used...

Good Luck

[vreihen16]

I've been debating in my mind the benefits of single-pipe cold water only plumbing and on-demand water heaters at each fixture for two decades now in a new construction scenario. I don't have the 200A electrical service needed to run electric hot water heaters in our current house, otherwise I would have made the switch here to see how it works out.....

[Chick Webb]

We have a loop & pump because our master... er, primary bath is about 100 ft from the water heater. It's on a Z-wave switch and integrated with our home automation. So when the alarm goes off and "morning mode" starts, so does the pump, but only on weekdays. At other times, all we have to do is say, "Alexa, turn on the hot water pump" and it fires right up. There's a watchdog program that turns it off after an hour, or you can turn it off using the girl. Works a treat.

[M_Six]

Originally Posted by Chick Webb

We have a loop & pump because our master... er, primary bath is about 100 ft from the water heater. It's on a Z-wave switch and integrated with our home automation. So when the alarm goes off and "morning mode" starts, so does the pump, but only on weekdays. At other times, all we have to do is say, "Alexa, turn on the hot water pump" and it fires right up. There's a watchdog program that turns it off after an hour, or you can turn it off using the girl. Works a treat.

I've been thinking about using a smart plug for a pump for the same reason. I don't use Siri, but I can set it up in HomeKit to turn on at 6AM and off at 9AM, then back on around dinner time for an hour or two. So it would only be running a few hours a day.

How long do you have to wait once the pump turns on before you have hot water?