There is a lot of talk these days about heat pump water heaters being the most environmentally friendly and efficient water heaters available. However, owners have reported issues when using heat pump water heaters in conjunction with a dedicated recirculation loop. The issue being that the heat pump water heater requires a certain temperature differential between the water coming into the water heater and the water temperature in the water heater. With a continuously running recirculation pump the differential is never met so a heating cycle is not initiated and the water in the heater cools down leaving the home owner with mildly warm water. You can read about this in the Rheem technical bulletin. Rheem recommends only using the unit in High Demand mode or Electric only mode and says that Energy Saver mode won't work well.

Fortunately the Smart Recirculation Control 32 solves this problem for heat pump water heater owners as our control turns the pump off when the loop it up to temperature preventing the heat pump water heater from cooling off thus restoring peak efficiency of your water heater investment while still providing you with the convenience of hot water at your fixtures.

When we first introduced the Smart Recirculation Control tankless water heaters were not nearly as popular as they are today. Installing the flow meter on a tank water heater simply entailed disconnecting the flexible cold water hookup line, threading the flow meter onto the tank and reconnecting the flexible hookup line. 

But tankless water heaters are many times installed with hard copper piping right up to the water heater not allowing any way to easily disconnect the cold water feed and install the flow meter. In these installations we recommend that the flow meter be installed in the copper piping with union fittings on each end to facilitate easy removal and replacement rather than threading it onto a NPT fitting and soldering it into place. Not that we have had failures of the flow meter, the failure rate is exceedingly low, but they are a mechanical device with a spinning magnet if there is an issue with debris getting stuck in the flow meter and it needs to be removed from the line, you will be very happy that there are union fittings to facilitate the easy removal.

When installing the Smart Thermostatic Control in a home without a dedicated recirculation loop there is always the question, "how many AquaMotion AMK-ODR valves do I need and where should they be installed?"  The simple answer is you need one AMK-ODR valve at the end of each dead end hot water line. However, if you don't have a plumbing schematic for your home this may not be a simple answer. The way to figure out how many dead end hot water lines you have is to wait for the hot water lines to cool off. Then go to the sink in your home that takes the longest time to heat up. Run the hot water at this location until the water is hot. Now go to all the other sinks in your home and see if they have hot water at them. If the water is hot within seconds, then it is on the same line. If it doesn't heat up quickly then it is probably on a separate line and will need a second AMK-ODR valve. Many homes have a line that services the bathrooms in one direction and a second line that services the kitchen, but that is just a generalization. And depending on the location of the water heater relative to the hot water fixtures, an AMK-ODR valve may not be necessary on some hot water lines. For example if the water heater is located in the garage adjacent to the kitchen or laundry room then a valve at that location is probably not needed because it will have hot water quickly already. It can take a few cycles to get an understanding of your plumbing layout especially if your home has had an addition, but this method should give you a good understanding of how hot water flows in your home.

To access this feature open the smart phone app and go to the menu.  Select "Firmware" (if you don't see firmware then you don't have the Smart Recirculation Control 32, contact us if you would like to upgrade and will will send you a link with a special upgrade price).  By default the firmware family that you purchased with your device will be selected and if the latest firmware is currently installed then it will be grayed out and not able to be selected.  However, since the hardware for all our devices is the same, if you select "Show All Firmware Version" at the bottom of the screen it will allow you to select and install any firmware from the entire family of products that we make.  You obviously need to understand the implications of doing this as each of our products has unique features that are tailored to a specific solution.  Some are for dedicated recirculation loops and others are for using a thermostatic crossover valve that connects the hot water to the cold water at the furthest sink.  Some use 2 temperature sensors and the difference between them to know when to turn the pump off and others use a single temperature sensor and an absolute value to turn the pump off.  Before changing your firmware family I suggest you read about the different product to understand how it functions.   If you have any questions please contact us. 

Leridian Dynamics Inc. is proud to announce the release of a LEED for Homes v4 compliant version of the Smart Aquastat Control. The control comes configured by default to perform to their current exact specifications but the parameters can be modified via the smart phone app if the specification happens to change or the performance of the system does not provide adequate comfort. The following is the section of the LEED for Homes v4 specification that regulates recirculation pump controls.

Paths 1 and 2, Pumps and Controls for Hot Water Circulation Loops
Circulating systems must meet the following requirements.

1. Circulating pump may not operate continuously, on a timer control, or on a water temperature (aquastat) sensors. Gravity and thermo-syphon circulation systems are prohibited.
2. Circulating pump must be demand activated by a momentary contact switch, motion sensor, flow switch, door switch or voice command.
3. After the pump starts, the controls shall allow the pump to operate until the water temperature in the return pipe rises not more than 10ºF (6 ºC) above the initial temperature of the water in the pipe. Controls shall further limit the water temperature to a maximum of 105ºF (40 ºC). Controls shall limit pump operation to not more than 5 minutes per activation in the event that both means of shutting off the pump have failed.
4. Circulating hot water systems must be provided with an automatic or readily accessible manual switch to turn off the hot water circulating pump when not in use.
   

There are many different recirculation pumps on the market and it can be quite confusing to know which one to choose for your recirculation system or even if the pump that you currently have installed is adequate.  Because our controller is designed to run the pump only when you demand hot water, having a high flow pump is important to provide adequate responsiveness and comfort.  It is for this reason that we recommend a pump that will flow 15 - 20 GPM.  These are generally 1/12 HP pumps.  We sell a pump that meets this criteria called the AquaMotion AM5-SF1L.  This pump is rated at 18 GPM and 1/12HP and is adequate for most homes.  For larger homes or homes that have a 1" recirculation loop installed or for people who just want the best on demand performance we recommend the AquaMotion AM10-SF1L.  This pump is rated at 31 GPM and 1/8 HP.  All AquaMotion pumps are designed and manufactured in the USA and come with a 3 year warranty.  These pumps require a flange kit which is included in the price (specify 3/4" or 1" when placing your order) and they come with a 10 ft. electrical cord. 

If you already have a pump installed and are wondering if it is adequate, look on the pump for the rated wattage.  If it is less than 50 watts then it will probably not provide adequate on demand performance.  Specifically we have come across some very small 1/40 HP (20 watt) pumps that only provide 3 - 5 GPM flow and they really don't work well in an on demand environment.  A simple test you can perform would be to unplug the pump at night before you go to bed.  Then, first thing in the morning before anyone uses hot water, get a timer with a second hand and plug the pump in.  Hold the return line and time how long it takes for the pipe to start getting warm.  Anything longer than 60 - 90 seconds will probably not provide adequate performance. 

Homes that do not have a dedicated recirculation loop can be retrofitted with the Smart Thermostatic Control Complete System that consists of a Smart Controller, an AquaMotion AM5-SF1L recirculation pump and one or more AquaMotion AMK-ODR thermostatic valves. These valves connect the hot water line to the cold water line under the furthest sinks in the house allowing water to be pumped from the hot water line into the cold water line until hot water reaches the valve causing it to close. The controller senses when the flow stops and turns the pump off rather than allowing the pump to dead head against a closed valves like all other systems. You can see a video of the installation on YouTube.

The question always comes up, how many AMK-ODR valves do I need? Depending on how the plumbing is run in your home you may get better performance with multiple AMK-ODR valves under multiple sinks. To know how many valves you would want you can perform the following test. Allow the plumbing to go cold, so doing this first thing in the morning is good, and go to the furthest bathroom in the house and run the water until it gets hot. This will simulate one valve installed under that particular sink. Once you have hot water at that bathroom, go to the other bathrooms, kitchen and laundry room and run the hot water timing how long it takes for the water to get hot at that location. If you have to run quite a bit of water down the sink while waiting for hot water, it may be beneficial to install another valve at that sink location. 

Another reason to install a second or third valve is if you have a large house. The AMD-ODR valves have the highest flow of any thermostatic valve on the market, but they still restrict the pump flow. So if you have two bathrooms that are near each other but far from the water heater, installing one at each location will allow twice the water flow thus speeding up your on demand hot water performance. 

A third, but advanced trick for getting better on demand performance would be to plumb the AMK-ODR valve in behind the stop valves underneath the sink. The water is delivered to the sink through a ½” pipe, but the stop valves neck that down to 3/8” which significantly restricts the hot water flow. Installing a ½” T behind the valve directly to the ½” pipe and then plumbing the AMD-ODR valve directly to this T instead of to the valve outlet will allow greater flow through the valve. This technique requires turning off the water to the whole house and a little bit of advanced plumbing to remove the T that comes on the end of the AMD-ODR valve so it can be connected directly to the ½” T, but you may find it beneficial. The AMK-ODR valves do not have tapered thread so they must be connected with an o-ring or washer to keep them from leaking.

Leridian Dynamics, Inc. announces the release of the Smart Aquastat Control.  The Smart Aquastat Control is an on demand pump control for use with a dedicated recirculation loop.  It differs from the Smart Recirculation Control in that it has only a single temperature sensor and turns the pump off when the single sensor reaches the configured temperature rather than run the pump until the temperature difference between the water heater outflow and the return line are within the defined tolerance. This system is designed to be used on tankless and combination domestic hot water heaters that have strict temperature input requirements.  It can also be used on a tank water heater if you want to turn the pump off based on an absolute temperature rather than the differential.  

I recently learned of an incentive rebate program by the Marina Coast Water District (UPDATE: Marina Coast Water District no longer offers this rebate) to encourage home owners to install a recirculation pump. If your house is already plumbed for a recirculation loop then you simply need to install a recirculation pump to qualify for the rebate, but I would also recommend installing our Smart Recirculation Control 3 when you do so you so you don't have to live your life on a strict hot water schedule.

I have discovered that many homes built in Monterey County within the last 30 years had a recirculation loop installed due to building code requirements, but there was no code requirement to actually install the pump! Check your utility closet near your water heater for a capped off copper pipe sticking out of the wall and that is your recirculation line. 

If you don't have a dedicated hot water recirculation loop you can still take advantage of the rebate offer by installing a thermostatic hot water recirculation system. These systems use a thermostatic crossover valve that allows a pump to push hot water through the valve into the cold water line until the water heats up, then the pump closes. There are a few manufacturers of these types of retrofit systems, but they all run their pump on a timer and when the valve heats up and closes they simply allow the pump to "dead head" against the closed valve wasting energy and heating up the pump. Our Smart Thermostatic Control solves this problem by monitoring the system for water flow and when the thermostatic valve heats up and closes and the flow stops, the controller senses this and turns the pump off. Our controller also will run the pump on demand so you don't have to live your life on a strict hot water schedule.  We also use the AquaMotion AMK-ODR crossover valve that has 4 - 5 times the flow of the plastic valves from our competitors so you get much more responsive on demand performance.  It is recommended that you install one valve at the end of each dead end hot water line so that all your fixtures in your house have the benefit of on demand hot water. Save money when buying the full system. 

If you don't live within the Marina Coast Water District, check with your local water district and see if they offer any rebates for installing a hot water recirculation system.  If the do, please let me know, I'll be sure to add it to my blog. 

Starting with Firmware Version 2.0.5 the timers in the Smart Recirculation Control will automatically disable themselves if a hot water draw is not detected within the last 24 hours.  As soon as a hot water draw is detected or the controller is connected to with the smart phone app the timers will automatically be re-enabled. 

This does not impact the ability to manually disable the timers from the settings menu in the smart phone app.  This is intended simply as a fail safe if you do go on vacation and forget to manually disable the timers, not to worry, they will automatically disable themselves!

Leridian Dynamics, always looking for ways to save you worry :-)