Those who use tankless water heaters face this constant issue. It takes a few minutes to get hot water from the faucet or shower. If you look up for the reason for this issue, you may find that it is due to the distance of the faucet or other fixtures from the tankless hot water heater that causes this delay. The water that stays in the hot water lines gets cold till the next use. So the next time when you open the faucet or other fixture, this water staying in the hot water line needs to be flushed out before the actual hot water reaches you. As per research, this has resulted in the wastage of about 12,000 gallons of water per year in most households. This is where recirculating pumps can come to your aid. They keep the water in the hot water lines heated as a result of which water wastage is eliminated.
How does a recirculating pump work on a tankless water heater? In this article, we will see how.
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What Are Hot Water Recirculating Pumps?
As said earlier, the significance of hot water recirculating pumps comes when you have to wait for several minutes for hot water to come up from your shower or faucet. Waiting for hot water for a few minutes can cause inconvenience and result in wastage of water unless the unused cold water is collected and used for some other purposes. Let us see why this happens.
When having separate handles for hot and cold water, what you expect is hot water to come out of the faucet when you turn the hot handle and cold water to come out of the faucet when you turn the cold handle. But you never get hot water instantly and what you get is a stream of cold water from your hot tap before the water heats up. This is because the leftover water in the pipes has cooled over time. Actually, as you used the hot water tap last time, by the time you turned the tap off; there was still hot water in transit from the water heater to the faucet. As you turned the faucet off, there was no way for this hot water to go out. This hot water sits within the pipe. It loses the heat over time, resulting in the leftover cold water in the pipes.
Now when the next time you turn on the hot water tap, this cold water that is stuck in the hot water pipes needs to make an exit before the fresh hot water comes in. This is the cold water that you get for a few minutes of turning on the hot water tap. After forcing out all the cold water out, you will receive the hot water from the water heater. As the distance between the faucet and the water heater increases, it will take more time for the hot water to reach you. Also, this will result in more water getting wasted.
How The Problem Gets Solved With Hot Water Recirculating Pump?
With a hot water recirculating pump, you can prevent this situation as cold water sitting in your hot water pipes is re circulated back to the water heater, which brings in new hot water to the faucet so that it is ready whenever you are in need. These instant water pumps are usually installed above the water heater. However, it is easiest to install them at the farthest faucet in the system. In such cases, they are installed under the sink. The system may also include a sensor valve that is installed under the farthest sink from the water heater which “senses” when the temperature drops below around 90 degrees and open a valve that allows more hot water to flow and triggers the hot water pump to pump more hot water. Thus the hot water pump prevents wastage of water and also saves a few minutes of waiting for hot water.
There are tankless water heaters with built-in recirculation pumps. They may cost you in the range $250 to $450. If looking for new tankless water heaters, you can look for those with an built recirculation pump as this can save additional costs later on. In case of tankless water heaters without a recirculation pump, you need to buy a separate recirculation pump which may cost you around $200 to $ 400. This also requires additional installation charges around $150. It is good to look for complete kits that include both the pump as well as the control devices. It is best to have a thorough understanding of the plumbing fittings and get the pump installed or else seek the help of a professional.
Due to the frequent drought conditions and related water restrictions in many US states like California, the state’s Building Energy Efficiency Standards roll out that all new homes must include hot water recirculating pumps with regard to faucets that are farther than 50 feet from the water heater. This prevents water wastage as well as the inconvenience caused to the homeowners as they wait for the hot water. If you own an older home, still it is a good idea to invest in recirculating pumps for your tankless water heaters.
Compatibility Of Recirculating Pump
Now you need to understand that not all water heater recirculation pumps are compatible with tankless water heaters. So it is better if you check the manufacturer’s guidelines and ensure that a particular recirculation pump will work on your tankless water heater. You need to check the flow rate that is required to operate your tankless unit and make sure that the flow rate of the recirculation pump meets or exceeds the flow rate of the tankless water heater. Otherwise, the device may not even turn on. There is also a chance of harmful short cycling of the tankless water heater.
Will Use Of Recirculating Pumps Void The Warranty Of Tankless Water Heaters?
If used in continuous run modes, then there is a chance that the warranty period of most tankless water heaters will get void. However pumps with proper control options like sensors, timers, etc. with necessary auto shut off features may not make the warranty period of the recirculating pump void.
Types Of Hot Water Recirculating Pumps And How They Work
Now as seen, recirculating pumps are used to return the unused hot water to the water heater which maintains the temperature of the water and also sends in fresh hot water to your faucets. This ensures that you need not have to wait for the water to heat up. There are mainly two types of hot water recirculating pumps.
Full Recirculating Pump System
Full Recirculating Pump System is also known as Dedicated Loops. In such systems, the hot water flows through a continuous loop throughout the system, which ensures a steady hot water supply, thereby minimizing water wastage as well as the need to wait for some time. Such type of recirculating system requires the installation of additional hot water pipes in your home which return the unused hot water to the water heater, wherein the new hot water can take its place. Thus the dedicated return line creates a loop in the hot water system through which water is circulated from water heater to the faucet/shower and back to the water heater. The recirculating pump draws the remaining hot water back through the loop making hot water available to you when tapping the hot water. Thus your household will have three pipes: hot, cold and recirculation pipe. As water is not left to cool in the pipes, you get instant hot water whenever you need it. The full recirculating pump system is well suited for new constructions or in the case of single-storey homes with crawlspaces which let you easily add a return loop.
Such recirculating systems can run continuously, but in most cases, they use sensors or timers to regulate their operation. If the system involves sensors, then they monitor the temperature of the hot water in the hot water pipe and run the recirculation pump only when the temperature drops below a specified level. This ensures that water is not recirculated when it is already warm. So you need not have to worry about the energy costs associated with such recirculation systems. With timers, you can opt for much better control over the recirculating system. This allows you to schedule when the recirculating system should work or shut off. You can program the system in such a way that the system is turned off when you go out for work or vacation. You can also program it to turn off in the night when you are sleeping. Smart plugs are another means to control recirculating pumps. Using these intelligent plugs, homeowners can control the pump through their phone or tablet, letting you use the phone to turn it on or off. This will also let you schedule the time when the pump needs to be activated. In combination with voice activated smart home system, you can take the experience to the next level by using your voice to run the pump even before you use the shower or faucet.
Now if the full recirculation pump system that you choose doesn’t come with a sensor, timer, or smart plugs, you can get one installed at your own will. With the incorporation of these controls, you can have more control over the full recirculation system
Disadvantages of Full Recirculating Pump System
Full Recirculating Pump Systems require the installation of additional piping throughout the home which carries the unused hot water back to the water heater. This can make the system complex. As a result, the installation cost increases considerably. This cost can further increase if the pipe system in your home is difficult to access.
Recirculating Pump Comfort System
A much easier to install and more cost effective option is the recirculating pump comfort system. In this case, there is no need to install new pipes. There is no need for a separate pipe system, but still you can enjoy hot water whenever needed. Here the unused hot water is sent back to the water heater through the cold water pipes. So there is no dedicated return line and the pump is installed at the water heater, with a bridge valve under the farthest faucet. You can eliminate the need of the bridge valve by installing an under sink pump.
For control, these recirculation pumps may include a built-in timer or an aquastat. With the timer you have the choice of turning the recirculation any now and then. With a thermostat or aquastat, the pump is turned on, while maintaining the desired temperature of water in the line. If not included, the plumber can get these installed for you. Or else you can also go for smart plugs and voice activated smart plug systems.
Disadvantages of Recirculating Pump Comfort System
The major drawback associated with recirculation pump comfort systems is that as the hot water flows back to the water heater through the cold water pipes; you will receive lukewarm water through the cold tap at first. It may take some time for the water to get truly cold. However, this is not quite a big issue as you may not find it inconvenient to use this lukewarm water for household applications. Or else, you can prevent this issue by turning off the pump temporarily when you get to know that you need cold water. This can be beneficial especially during summers when there is no frequent need of hot water and water stays warmer for prolonged times in these pipes.
Pros and Cons associated with Hot Water Recirculating Pumps
We have listed the pros and cons of recirculating pumps for your quick reference.
| Pros |
| Hot water recirculating systems can save minutes and you do not have to wait for hot water. |
| Hot water recirculating systems save water from getting wasted. |
| Hot water recirculating pumps save money over the long term. |
| Cons |
| Hot water recirculating pumps require some initial investment in the form of cost of pump and installation charges. |
| Hot water recirculating pumps without dedicated return loop may result in lukewarm cold water. |
| Hot water recirculating pumps when incorporated have resulted in frequent replacement of sensor valve. |
| Hot water recirculating pumps need an outlet to be plugged into and this may require extra wiring. |