Basics of a Hot Water Recirculating System

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A standard hot water heating system only heats water at the tank, and from there it has to travel through your pipes to reach an outlet. This results in a delay between turning on the hot water and getting hot water out of the faucet.

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To reduce waste and increase efficiency, a hot water recirculating system will keep the hot water moving through your pipes (in a loop) so that the water is ready to use as soon as you turn the faucet on. Keep reading to see if this system is right for you.

Where Are Recirculating Pumps Used?

For years, recirculating pumps have been standard fixtures in quality hotels, gyms and dining establishments, but they are becoming more common in private residential use as well. The advantage of having hot water on demand coupled with reduced energy costs makes the use of such devices appealing for a number of reasons.

Where they were once provided as a convenience to clientele, they are now being used as a way to cut costs around the home. Some of today’s best tankless water heater models even include a built-in recirculating pump.



When a hot water valve is opened, hot water is never more than a few seconds away. Instead of hot water having to be pushed all the way through the system from the hot water tank, it only has to be pushed through the line leading from a primary water line to the faucet itself.

The recirculating pump keeps hot water moving through your home’s hot water pipes at all times, on demand, or set for specific hours via a timer (different from a water heater timer). If the hot water is not used, it simply returns back to the tank.

This primary cost savings comes from less water going down the drain before the temperature is suitable for use. Recirculating pumps reduce usage in water sensitive regions, and winter savings has the potential to be substantial.


Initial cost is the primary disadvantage to a hot water recirculating system. A new unit can be equal to many months of water usage bills, and installation increases the cost even further. The good news is that most recirculating pumps can be installed fairly easily, and most home hobbyists will have the tools and skills necessary for the job.

A new pump is crucial to your savings as well, since older models tend to operate continuously rather than on demand. Furthermore, well insulated plumbing pipes can prevent energy loss and increase the efficiency of any water heating system.

Installation Considerations

hot-water-recirculating-pumpInstalling a water recirculating pump will require you to add some piping to allow water to flow continuously through the hot water system. Typically, the pump is installed in close relation to the holding tank, but you can also install recirculating pumps near faucets which are used often to provide instant hot water at that location.

On the other hand, spot-heating water may be more affordable with the use of an inline water system that can be mounted under a cabinet or in a nearby closet.

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A hot water recirculating system may be a big investment for small families, but it can be a great way to save money in a large household where hot water is in greater demand through a larger area.

As a rule, if it take more than 5 seconds for hot water to reach a faucet, installing a recirculating pump could save you money in the long term, but it may also be a good idea to look at other heating methods as well.

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  1. We’re in the stages of finalizing plans for a new construction. Never really considered a recirculating system until I saw this article. Do you think it’s worth it to put in a hot water recirculating system during construction or wait until sometime down the road?

    • If you are even considering a system, I would definitely say YES, have it put in now. This is double important if you have a large floorplan. It’s much cheaper and easier to do without walls and it’ll pay for itself in <5 years. Trust me, you'll love it.

  2. I have a recirc pump w/timer for hot water. As long as pump is running, I get hot water BUT if the pump is not running, hot water will NEVER come to the faucets. WHY? It seems to me, once I turn the faucet on & pump is not running, the hot should come when all the cooled water has run down the drain — NOPE! It never comes.

    I think its plumbed wrong; this is brand new 2019 install.

    • It seems like a check valve problem. It’s either worn out or simply not there. It usually goes between the pump and the tank. Its purpose is to prevent cold water from flowing backwards through the return line when the pump is not running.

  3. Our house was built in 2018 and has a recirculating pump with a timer. The builder set the pump to run continuously, but there were times when the water didn’t get hot, just warm. Can running the pump continuously cause the water to not get as hot because it doesn’t stay in the tank as long? Would it be better to set the timer to recirculate hot water at peak usage times?

    • With a long run (ie: large homes) or with older piping, yes there can be enough heat loss where the water that’s returning to the tank doesn’t allow the water heater to keep up. Yes, if you’re not getting hot enough water and your water heater is set at 125 to 130 degrees, test setting the timer to turn on right before peak usage times.

      Many builders set it to run continuously since in new homes, it doesn’t cause much of an increase in energy usage and they simply don’t know what your household’s peak usage times are.

  4. I have a similar issue as Joe. Its a complete new plumbing system installed on an old home. Tankless heater, copper pipe, recirc pump. I remember it working when we first moved in, the water got hot within seconds. But as time has gone by I have resorted to just unplugging the recirc pump. It would provide luke warm water almost right away but would take five minutes or so for the water to get hot. Once it was hot you would have to turn the handle in the shower all the way back to the cold side to have any effect on the temp. Then it would get cold so you turn it back to hot and it takes the rest of the shower to get back to hot. With the pump unplugged, it takes a bit to get hot but it responds to the temp much better therefore remaining hot the entire shower. I’d like for it to work considering the kitchen could use the help but I don’t think I can justify a plumber visit for basically a luxury.

  5. I am building a new house and have 3 DHW loops, 3/4″ supply piping and 1/2″ return piping (all in PEX A). All outlets have either a TacoGenie Motion Sensor (554-4) or TacoGenie Push Button (554-3) which will be used to initiate the pump. Do I need to have 3 Circulating Pumps (like the 008-CT ) – one for each loop – or can I run all loops with one pump (like the 0011-CF)? If I’m using one to do all 3 loops does anyone have a piping layout you can send me and would I need to have actuators on each loop?
    Also if we have Circulating Pumps do you also need DHW pumps? Thanks.

  6. A recirculating system is a great system. But, there are a number of calculations that must be used to engineer a functional system. I’ve seen a lot of systems that were properly engineered, but poorly maintained and used improper replacement devices.
    Do some research before throwing a system together.
    Fixture units, heat loss due to friction, length of supply and return lines, and plumbing design are all considerations

  7. In terms of the life of the pump, is it better to turn it on/off (we have inside switch) or is it better to let it run continuously? Currently, we turn it off at bedtime and on the next morning and let it run continuously throughout the day. Is this the best practice?

    Thank you

  8. I have installed a Watts recirc. pump, I’m pleased with the immediate hot water, but now I have to run the cold side for a longer period to purge the hot water from that side. I do understand the physics of this. do you have a recomended cure or fix for this?

    • That’s the biggest negative with a “comfort” system which uses the cold line to circulate unused hot water back to the tank instead of a dedicated hot return line. Unfortunately, there’s not much you can do about the issue. Some people simply turn the pump off in the summer.

  9. Both my (tankless) hot water heater and my recirculation pump have temperature settings. Should they be the same, or should one be higher?

    • The recirculation pump temperature setting should be less since it measures the temperature in the return line. It’s usually set to around 90-95 degrees F but many models are non-adjustable. It’s best to check the owner’s manual.

    • If I need to shut off water to my house, is there any danger to my recirculating pump and/or water heater when I turn the water back on? I thought a plumber once told me that that would be a problem.

      • If you were to shut the water off and THEN use up all the water in the tank, you would be more likely to burn out a heating element or the pump. It would be safest to shut off the power to the water heater and pump while the water is off.


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