Aquanta turns your hot water heater into a smart hot water heater

[apostolakisl]

On 3/18/2019 at 12:00 PM, Jojo-Madman said:

In researching this Aquanta controller, I stumbled across this forum and thread, which I love the information shared, thanks!

I was originally looking for information which validated or disproved that this unit really works as marketed, and came across a field study done by "Minnesota Department of Commerce, Division of Energy Resources" for Field Study of an Intelligent, Networked, Retrofittable Water Heater Controller which was the Aquanta unit.

http://mn.gov/commerce-stat/pdfs/card-water-heater-contoller.pdf

In reviewing the test results, it seems to me that this controller may not really provide energy savings as indicated, and at the very least, appears to possibly result in higher water usage due to irregular water temperatures vs steady state.

While I love the concept idea and was ready to order one to try (my cost is higher as I am not in the USA), between the fact that the results of this report seem in conflict and that the unit is cloud-based, I am somewhat reluctant now.

Does anyone have further insight into this?

If you live in a cold climate and your hot water tank is inside the conditioned space, this won't really save you anything.  Realize that the heated water "wasted" heat is heat that escapes into the air around it.  If you are heating that air anyway, you are simply using your hot water heater to heat the air instead of your furnace.  So your only savings would be the difference in efficiency between your furnace and hot water heater, which could be zero, but in any case it probably isn't a lot.  Now if on the flip side your are in a hot climate and the tank is inside the conditioned space, you would see a double savings of not heating water for nothing and not having to then use your AC to pump out the lost heat.  And finally, if  your in a hot climate and the your tank is not in the conditioned space (attic or garage), then your savings would strictly be how much less time the tank is heating.  But, where I am in Texas, your hot water tank might be sitting in an attic or garage that is 100 or even much hotter.  In that case, the tank heat losses will be virtually nill when sitting.  The heaters would only come on when you draw cold water from the city into the tank upon using hot water.

[larryllix]

Water not kept under a certain temperature in a tank can accumulate Legionnella bacteria and has caused the deaths of many people, in the past.

The first well know known group to die from this were "Legionnaires" thus the name of the newly discovered bacteria "Legionella".  Their sins were taking showers at the conference hotel. It is a bacterium passed by inhalation.
In later research done in Quebec Canada, it was discovered that gas fired hot water heaters do not accumulate live Legionella bacteria, likely  due to the flames heating at the bottom of the tank, eliminating the cooler pockets below the electric strap or immersion heater.

[Skazzy]

2 minutes ago, larryllix said:

Water not kept under a certain temperature in a tank can accumulate Legionnella bacteria and has caused the deaths of many people, in the past.

The first well know known group to die from this were "Legionnaires" thus the name of the newly discovered bacteria "Legionella".  Their sins were taking showers at the conference hotel. It is a bacterium passed by inhalation.
In later research done in Quebec Canada, it was discovered that gas fired hot water heaters do not accumulate live Legionella bacteria, likely  due to the flames heating at the bottom of the tank, eliminating the cooler pockets below the electric strap or immersion heater.

But what about electric water heaters? Is this bacteria issue still a thing? I will email Aquanta about it to see what their take is.

[larryllix]

15 minutes ago, Skazzy said:

But what about electric water heaters? Is this bacteria issue still a thing? I will email Aquanta about it to see what their take is.

Do you mean Tankless? Electric water heaters were covered in my post. They ARE the problem.. Tankless only have a very small pocket of water and it gets heated well enough to kill the bacteria each cycle.

https://www.cdc.gov/legionella/about/index.html

"Each year, 8,000–18,000 people in the United States are hospitalized with Legionnaires’ disease."
Quote from https://www.cdc.gov/healthywater/pdf/swimming/resources/legionella-factsheet.pdf

[Skazzy]

15 minutes ago, Skazzy said:

But what about electric water heaters? Is this bacteria issue still a thing? I will email Aquanta about it to see what their take is.

You only mentioned gas: In later research done in Quebec Canada, it was discovered that gas fired hot water heaters do not accumulate live Legionella bacteria, likely  due to the flames heating at the bottom of the tank, eliminating the cooler pockets below the electric strap or immersion heater.

[apostolakisl]

My understanding is the the Legionnaire's (the people) at that convention got the bacteria from aerosolized water used to cool the air conditioning condensers outside the hotel which were next to the air intake for the hotel.  From there it was distributed through the air ducts of the entire hotel.  That recycled water was just the perfect temperature to grow the bacteria and as it pours over the fan blown condenser coils it produces a copious amount of fine mist.  But it also is well known to happen when you shower in water with the bacteria.

Don't take this as fact, but it is my understanding that the legionella in a hot water tank are more of an issue for ones that are continuously kept warm but not hot (120 ish).  If you blast it up to 145 a couple times per day you tend to kill stuff.

The bacteria reproduce in a biofilm on the inner surface of the water pipes and tank.  If you cook that surface up periodically it should kill off stuff.  Since gas heaters apply the heat to the surface of the tank, it makes sense that it has a better kill off than electric ones where the walls of the tank are never hotter than the water.  And the tankless ones really blast some serious btu's at a relatively small coil of pipe.  Also, tankless are continuously flushing themselves.

[larryllix]

5 hours ago, apostolakisl said:

My understanding is the the Legionnaire's (the people) at that convention got the bacteria from aerosolized water used to cool the air conditioning condensers outside the hotel which were next to the air intake for the hotel.  From there it was distributed through the air ducts of the entire hotel.  That recycled water was just the perfect temperature to grow the bacteria and as it pours over the fan blown condenser coils it produces a copious amount of fine mist.  But it also is well known to happen when you shower in water with the bacteria.

Don't take this as fact, but it is my understanding that the legionella in a hot water tank are more of an issue for ones that are continuously kept warm but not hot (120 ish).  If you blast it up to 145 a couple times per day you tend to kill stuff.

The bacteria reproduce in a biofilm on the inner surface of the water pipes and tank.  If you cook that surface up periodically it should kill off stuff.  Since gas heaters apply the heat to the surface of the tank, it makes sense that it has a better kill off than electric ones where the walls of the tank are never hotter than the water.  And the tankless ones really blast some serious btu's at a relatively small coil of pipe.  Also, tankless are continuously flushing themselves.

I agree with all the mechanics of that  but the source of the Legionella bacteria in the initial case. IIRC your explanation was one of the theories to explain it that was held for some time when they didn't know the source. I understood the answer was for the management to turn the water temperature from 90 F back to 120 F.

Also it is the pocket under the electrical strap and immersion heaters that never gets up to temperature due to stratification of the water temperature layers. Electric tanks feed in the top and leave from the top and not enough stirring action take place so the bacteria can grow in the lukewarm pocket under the heater. Gas and/or tankless "cook" the bacteria regularly.

I don't believe this ever  happens with chlorine sterilised water sources. More with private water sources where the bacteria is native to the earth soil.

[apostolakisl]

9 hours ago, larryllix said:

I agree with all the mechanics of that  but the source of the Legionella bacteria in the initial case. IIRC your explanation was one of the theories to explain it that was held for some time when they didn't know the source. I understood the answer was for the management to turn the water temperature from 90 F back to 120 F.

Also it is the pocket under the electrical strap and immersion heaters that never gets up to temperature due to stratification of the water temperature layers. Electric tanks feed in the top and leave from the top and not enough stirring action take place so the bacteria can grow in the lukewarm pocket under the heater. Gas and/or tankless "cook" the bacteria regularly.

I don't believe this ever  happens with chlorine sterilised water sources. More with private water sources where the bacteria is native to the earth soil.

I only find articles stating the 1976 Philly outbreak was from the cooling tower.  Found several other outbreaks that were listed as cooling tower sources.  CDC lists 4 sources.  https://www.cdc.gov/legionella/downloads/fs-legionnaires.pdf

120 degrees as I understand is the problem.  Hot water was turned down to 120 back in the 70's as part of a gov't misguided attempt to save energy.  They still recommend it with a side note to turn it up if you are at risk.  https://www.energy.gov/energysaver/services/do-it-yourself-energy-savings-projects/savings-project-lower-water-heating  140 is the solution.  If I ever stay at a hotel that keeps its "hot" water at 90, I'll be checking out, not because of Legionella, I'd be shivering my but off in a 90 degree shower.  A minimum comfortable shower is going to be more like 105 (I keep my tankless at 120 and when in the mood for a good hot shower, I put it on full hot).   It also depends on how hot the air is in the bathroom as to how hot is hot enough for the water.

Legionella can live in a bio-film on the pipes not just in the tank, but anywhere in the water system.  Especially if you have a recirculator and water that is 120.

[Jojo-Madman]

Thanks for the replies ...

Working in a related industry,  I understand water heater radiate heat losses to living space and how in some cases it becomes a trade-off. For me here in Canada, WH's typically are located in unfinished parts of basements such as utility rooms that are generally kept cooler than the main living space of the home, unless it is small and the furnace is in the same space, which for me it is.

Regarding using a smart plug, I had considered it as a possibility as I already have various other zigbee/zwave/wifi controls in our home for various uses. As part of that, I spent some time searching to see if someone had already research or had data available regarding the rate of heat loss from a typical modern insulated water heater, but haven't found anything yet. Once my electrical main panel has been upgraded to breakers, I am hoping to include a Brultech system, which I could add temperature probes into the data measuring, and may at that point just do the measuring myself.

While I do take the issues around legionella seriously, given how our municipal water supply is treated (chloramines) and our widespread use of natural gas-fired water heaters here, including my own, it's not likely an issue. Besides, I am hoping that there is a way to make sure the WH comes on and the water temperature is >140F at least 30 minutes or so ahead of our typical weekly use schedules.

One of the other energy saving devices for water heating that I have in my home is a drain water heat recovery unit, which acts like a heat exchanger on your main waste stack in the home, so it as well influences the incoming water supply temperature to the water heater, aiding in energy cost savings.

[apostolakisl]

48 minutes ago, Jojo-Madman said:

Thanks for the replies ...

Working in a related industry,  I understand water heater radiate heat losses to living space and how in some cases it becomes a trade-off. For me here in Canada, WH's typically are located in unfinished parts of basements such as utility rooms that are generally kept cooler than the main living space of the home, unless it is small and the furnace is in the same space, which for me it is.

Regarding using a smart plug, I had considered it as a possibility as I already have various other zigbee/zwave/wifi controls in our home for various uses. As part of that, I spent some time searching to see if someone had already research or had data available regarding the rate of heat loss from a typical modern insulated water heater, but haven't found anything yet. Once my electrical main panel has been upgraded to breakers, I am hoping to include a Brultech system, which I could add temperature probes into the data measuring, and may at that point just do the measuring myself.

While I do take the issues around legionella seriously, given how our municipal water supply is treated (chloramines) and our widespread use of natural gas-fired water heaters here, including my own, it's not likely an issue. Besides, I am hoping that there is a way to make sure the WH comes on and the water temperature is >140F at least 30 minutes or so ahead of our typical weekly use schedules.

One of the other energy saving devices for water heating that I have in my home is a drain water heat recovery unit, which acts like a heat exchanger on your main waste stack in the home, so it as well influences the incoming water supply temperature to the water heater, aiding in energy cost savings.

I always wondered if anyone was using a heat exchanger on waste water in cold climates.  When the incoming water is 40 degrees you could easily pick up 20 or 30 degrees.  I also had trouble getting past how that works, though, when your waste water has big hunks of human waste that would plug up a heat exchanger.

I am not sure that it makes any difference that you keep your hot water tank in a cooler room or a room without its own duct work.  If that room is inside the same insulating blanket as the rest of your house then heat is escaping the other parts of your house into that room.  The colder the room, the more heat escapes.  So if your hot water tank is keeping that room a bit warmer, you'll lose less heat from the other portions of your house.

[larryllix]

1 hour ago, apostolakisl said:

I always wondered if anyone was using a heat exchanger on waste water in cold climates.  When the incoming water is 40 degrees you could easily pick up 20 or 30 degrees.  I also had trouble getting past how that works, though, when your waste water has big hunks of human waste that would plug up a heat exchanger.

I am not sure that it makes any difference that you keep your hot water tank in a cooler room or a room without its own duct work.  If that room is inside the same insulating blanket as the rest of your house then heat is escaping the other parts of your house into that room.  The colder the room, the more heat escapes.  So if your hot water tank is keeping that room a bit warmer, you'll lose less heat from the other portions of your house.

There was a big push to sell these when they first came out. Here is one model that was created locally to me.
https://www.homedepot.ca/en/home/search..html?autoSuggest=prodcat&q=power-pipe:relevance#!q=power-pipe:relevance

Trouble with this idea  is it  only works while the intake of the water is simultaneous with the output of the warm (grey) water.  Dishwashing machines, bath tubs, and clothes washing machines do not benefit from these devices, as they do not intake hot water at the same time they are dumping it. Therefore there is no heat exchange.

However, running hot water for showers,  washing face,  hands or other objects can benefit.  Plugging and filling up the sink first, nullifies the workings of the heat exchanger.

At their huge price tags I doubt they would ever pay for themselves in most people's life times. No calculations have been done by me.

[apostolakisl]

I suppose if you had septic, you could run your inbound water through submerged coils.  But I'm not sure anybody who lives somewhere that cold has a septic tank.  And I'm also not sure if the cold would suppress your aerobic bacteria.  My aerobic tank sucks in outside air to aerate the water, I can't imagine that working if the air outside was below zero.  It would have to ice up for sure.  Maybe people in the super cold have old fashioned anaerobic septic tanks.  I just don't know.  Aerobic bacteria must also make some heat themselves.  Probably not much, though.

[Jojo-Madman]

 

 

 

 

 

 

 

6

56 minutes ago, larryllix said:

There was a big push to sell these when they first came out. Here is one model that was created locally to me.
https://www.homedepot.ca/en/home/search..html?autoSuggest=prodcat&q=power-pipe:relevance#!q=power-pipe:relevance

Trouble with this idea  is it  only works while the intake of the water is simultaneous with the output of the warm (grey) water.  Dishwashing machines, bath tubs, and clothes washing machines do not benefit from these devices, as they do not intake hot water at the same time they are dumping it. Therefore there is no heat exchange.

However, running hot water for showers,  washing face,  hands or other objects can benefit.  Plugging and filling up the sink first, nullifies the workings of the heat exchanger.

At their huge price tags I doubt they would ever pay for themselves in most people's life times. No calculations have been done by me.

Well, now that you brought that particular product up, I just might happen to know a little more than most people .. ?

While it is true that not all hot water uses can benefit from DWHR, such as batch dishwashing like we use in our homes, a majority of it does. In the past decade or so, cold water washing has become the norm with continual development of advanced detergents, as environmental conservation of energy is a concern, especially now with the time of use electric billing here.

If you look at the percentage of hot water usage in the home, generally bathing makes up a majority of it, and in new home construction, there is even now a push to have homes with showers only, tubs being viewed as obsolete by some. I know even in our 50 year old home, if I ever redo the upstairs bathroom again, the combo shower/tub is coming out and it will be just a large shower with a bench in it.

Energy savings and payback is a function of a number of variables such as, number of people in the home, shower time lengths, shower water temperature, length of the DWHR installed, incoming cold water temperature (the larger the temperature delta, the more heat is recovered), how many showers/bathrooms are feeding that drain stack, gas vs electric water heating, etc. Depending on the factors, it can be as short as 4-5 years for young families, and as long as 10-12 years for singles or seniors. There are also a number of energy rebate programs that also help reduce the cost of retrofitting them into existing homes

One thing often overlooked, is that by simply installing one, it greatly impacts the recovery time of the water heater, and in some cases eliminates ever running out of hot water.

So, yes they do work and can pay for themselves ...

[Jojo-Madman]

9 minutes ago, apostolakisl said:

I suppose if you had septic, you could run your inbound water through submerged coils.  But I'm not sure anybody who lives somewhere that cold has a septic tank.  And I'm also not sure if the cold would suppress your aerobic bacteria.  My aerobic tank sucks in outside air to aerate the water, I can't imagine that working if the air outside was below zero.  It would have to ice up for sure.  Maybe people in the super cold have old fashioned anaerobic septic tanks.  I just don't know.  Aerobic bacteria must also make some heat themselves.  Probably not much, though.

You would need to eliminate any risk of cross-contamination in the event of a breach in the coils, one of the main reason DWHR is double wall vented in its design within North America

[apostolakisl]

47 minutes ago, Jojo-Madman said:

You would need to eliminate any risk of cross-contamination in the event of a breach in the coils, one of the main reason DWHR is double wall vented in its design within North America

Well, yes, but it would be quite a difficult thing.  It is kind of like being "safe", there is no such thing, just various levels of safety, but I think you would be well closer to the "safe" end of the spectrum here.  Since the fluid in the tank is going to be downhill from the house by necessity, and the water in the water lines is pressurized, there is no way for the septic water to get "pumped up" into the house  And if your septic ever did pressurize, you'd have your drains shooting out sewage, so you might get clued in there.  If you had a small hole in the water line, and for some period of time the water line was not pressurized, there could be some mixing that then would be pumped into the house when water pressure is restored.  But that would require a number of very unlikely events including 1) unpressurized water lines for a reasonable length of time, 2) a hole in the water line of reasonable size and, 3) failing to notice the water loss and septic overload of a hole in the water line.  I'd say my chances of accidentally ingesting water from my septic during my routine inspections is higher (like I got splashed in the mouth or something).  And trust me, I don't let that happen.

[Jojo-Madman]

51 minutes ago, apostolakisl said:

Well, yes, but it would be quite a difficult thing.  It is kind of like being "safe", there is no such thing, just various levels of safety, but I think you would be well closer to the "safe" end of the spectrum here.  Since the fluid in the tank is going to be downhill from the house by necessity, and the water in the water lines is pressurized, there is no way for the septic water to get "pumped up" into the house  And if your septic ever did pressurize, you'd have your drains shooting out sewage, so you might get clued in there.  If you had a small hole in the water line, and for some period of time the water line was not pressurized, there could be some mixing that then would be pumped into the house when water pressure is restored.  But that would require a number of very unlikely events including 1) unpressurized water lines for a reasonable length of time, 2) a hole in the water line of reasonable size and, 3) failing to notice the water loss and septic overload of a hole in the water line.  I'd say my chances of accidentally ingesting water from my septic during my routine inspections is higher (like I got splashed in the mouth or something).  And trust me, I don't let that happen.

You would be better off circulating some form of glycol thru a closed loop system and extract the heat off it thru a heat exchange of some fashion. The loop could be cast into cement at the bottom of the holding tank to take advantage of a thermal mass.

While cross-contamination appears unlikely, it's a health risk not worth taking ...especially if you ever have gone thru the UL, CSA, NSF, etc certification process

 

[mwester]

The septic tank itself is usually at ground temperature in the winter -- while it does warm up slightly during heavy hot-water use (laundry for example), in general there's just not enough hot water or even warm water involved.  Consider: a septic tank is often holding many hundreds of gallons of water in the holding/settling portion -- given that, even emptying a typical 40-gallon DHW tank down the drain won't raise the temperature enough to matter in terms of warming incoming water (which, like the tank, is at ground temperature).

Further, up here in the frozen tundra, we rely on the relative warmth of the water in the tank to keep the septic field itself from freezing during the coldest parts of the winter, 'cause if that were to happen, well, then let's just say things get very very unpleasant indeed.

(I have both a septic tank and a well -- plus cold temperatures... we pay close attention to the entire water system all winter!  )

[larryllix]

37 minutes ago, mwester said:

The septic tank itself is usually at ground temperature in the winter -- while it does warm up slightly during heavy hot-water use (laundry for example), in general there's just not enough hot water or even warm water involved.  Consider: a septic tank is often holding many hundreds of gallons of water in the holding/settling portion -- given that, even emptying a typical 40-gallon DHW tank down the drain won't raise the temperature enough to matter in terms of warming incoming water (which, like the tank, is at ground temperature).

Further, up here in the frozen tundra, we rely on the relative warmth of the water in the tank to keep the septic field itself from freezing during the coldest parts of the winter, 'cause if that were to happen, well, then let's just say things get very very unpleasant indeed.

(I have both a septic tank and a well -- plus cold temperatures... we pay close attention to the entire water system all winter!  )

Yes. It was mentioned there is some heat generated by the degeneration of the sludge by enzyme action and that helps to keep the contents slightly warmer. I wouldn't want to remove any of that heat as it would stop the break-down and then you have problems. I understand  more northern folks insulate their septic fields in the winter when cold snaps happen, using straw and other materials. Here we get a lot of snow and the ground never freezes at Lat. 44.3 degrees.. I had to open my up to clean the affluent filter a few weeks ago. Thank you Insteon Leak Detectors for saving my basement again.!!!

My septic tank is 1000 gallons (Imp or US?) and considered about average for a 3-4 bedroom home.

[apostolakisl]

43 minutes ago, mwester said:

The septic tank itself is usually at ground temperature in the winter -- while it does warm up slightly during heavy hot-water use (laundry for example), in general there's just not enough hot water or even warm water involved.  Consider: a septic tank is often holding many hundreds of gallons of water in the holding/settling portion -- given that, even emptying a typical 40-gallon DHW tank down the drain won't raise the temperature enough to matter in terms of warming incoming water (which, like the tank, is at ground temperature).

Further, up here in the frozen tundra, we rely on the relative warmth of the water in the tank to keep the septic field itself from freezing during the coldest parts of the winter, 'cause if that were to happen, well, then let's just say things get very very unpleasant indeed.

(I have both a septic tank and a well -- plus cold temperatures... we pay close attention to the entire water system all winter!  )

I assume you have true septic, not aerobic?  I can't imagine pumping 0 degree or colder air into the tank without freezing it very quickly.  In my neck of the woods, aerobic is required as it supposedly results in much cleaner water exiting the system.  And the drain field is not passive, you have a 3 chamber aerobic system and then a holding tank from which it pumps to the drain field.  Some will pump to sprinkler heads if the soil doesn't pass the "perc test".  Those folks definitely want the water clean or it would stink it up big time.  They will also treat the holding tank with chlorine just to get rid of that last little tiny bit of odor.  The water that makes it to the holding tank is clear and very close to odorless.

Where I live, cold water isn't really cold, even in the winter.  I would say our water never gets out of the 60's.  My well water is about 75 year round and it is an 800 foot well.  On demand heaters work great with this sort of "cold" water since you don't need much temp rise so the gpm's can be quite high and still deliver 120 degree water.

[larryllix]

2 hours ago, apostolakisl said:

<snipped>

Where I live, cold water isn't really cold, even in the winter.  I would say our water never gets out of the 60's.  My well water is about 75 year round and it is an 800 foot well.  On demand heaters work great with this sort of "cold" water since you don't need much temp rise so the gpm's can be quite high and still deliver 120 degree water.

Then you can actually use "cold water detergents" too. Check out a box of "cold water detergent" and find their definition of "cold water" is really luke warm. Detergents don't work in "cold water" My well puts out about 45-50 F water. My tankless works for it's money and also heats my house. Unfortunately the tankless units I have owned, do not have burners that go low enough BTU to feather the slab heat in mild weather. The mixer feathers the supply  by down mixing but then the gas Tankless units shut down due to lack of volume.

[Jojo-Madman]

Well at this point, I think I am putting the Aquanta controller system on the back burner for a while. Looking at what its going to cost me to get here, and some of the questions I have regarding it's overall accuracy, I am opting to put the monies towards a Brultech system, which I can expand to measuring inputs from the WH. Remote switch OFF/ON can be done thru Z-Wave automated receptacle for now.

[Skazzy]

Here’s Aquanta’s perspective on the issue. They also commented on the study that the OP posted. 

 

We’ve looked at the Legionella issue closely as we get asked about it periodically.  There is a push and pull between scalding risk (some advocates argue that a set point above 120F is a risk) and Legionella risk (the bacteria apparently grows best in the 110-120F range).  It seems like the scalding risk is the greater issue, and the number of incidents a year is much higher + even the main Legionnaire’s advocacy group says that domestic water heating is an “extremely low" Legionella risk:

"We have found that the risk of acquiring Legionnaires' disease from your home water system is quite low. Generally, those who have contracted the disease from their home water systems are usually smokers. 
Legionella can be isolated from a small percentage of residential water systems. If the bacteria is present, the risk of disease to the average person (with no serious underlying illness) is extremely low. It is also likely to be found in water faucets as well as showers. The role of showers in the transmission of Legionella is overemphasized. Elevated hot water temperature (about 130°F or 55°C) can minimize the chance that Legionella will grow in a water system. Consideration should be given to the risk of scalding to small children and impaired adults if the water temperature is set at this high temperature.” http://legionella.org/faqs/general-public/disease-sources/

Plus the public water system is chlorinated so that is a Legionella suppressant.  There is a study out there about scalding incidence and risk that looked at avg set points: over half are >125F.   http://www.ncbi.nlm.nih.gov/pubmed/23514986  I should point out that Aquanta - when in “Aquanta Intelligence,” or autonomous control, mode - does not typically permanently lower the set point below 120F, but rather keeps the heating off during predicted periods of non-use.

Re: the study, that was indeed about Aquanta.  I would note that it was conducted in early days for Aquanta, so our Aquanta Intelligence control algorithms have improved since then. Additionally, the study was from too small a sample size to draw statistically significant conclusions, and the users involved were already energy-conscious consumers (as evidenced by their very low average hot water usage). So while it was an interesting and useful study, it told an incomplete picture, which the authors acknowledge.

Hope the above helps and thanks for your continued engagement!
Aquanta Support

[larryllix]

Possibly of interest to some. Wikipedia of major legionaries outbreaks. Very common in countries where solar hot water heaters are popular.

https://en.wikipedia.org/wiki/List_of_Legionnaires'_disease_outbreaks

[Jojo-Madman]

I have a better understanding now why Aquanta field trial result savings were also so dismal for NG water heaters.

In talking with WH manufacturers, I have found out that a natural gas 50G "power-vent" water heater which most utilize flue dampers and heat traps, and have approx 2" of foam insulation will take 96hrs under test conditions to react room temperature. My understanding of the testing conditions are that the room temperature is 70F and the water heater is at 140F. Given that 70F is within the normal room temperature, this energy isn't even really lost in colder climates such as mine, as it is only lost to into the living space.

This being the case, shutting off the burner control for 8~12 hrs a day via their smart controller as far as I can figure out is never going to yield a 10% savings for NG water heater. The idling conditions are not consuming much energy in order to do so.

I have simply rigged up a z-wave appliance plug to the 110v AC power cord for the controller and exhaust fan and it up so that I can shut it off when not home for long periods of time.

[apostolakisl]

1 hour ago, Jojo-Madman said:

I have a better understanding now why Aquanta field trial result savings were also so dismal for NG water heaters.

In talking with WH manufacturers, I have found out that a natural gas 50G "power-vent" water heater which most utilize flue dampers and heat traps, and have approx 2" of foam insulation will take 96hrs under test conditions to react room temperature. My understanding of the testing conditions are that the room temperature is 70F and the water heater is at 140F. Given that 70F is within the normal room temperature, this energy isn't even really lost in colder climates such as mine, as it is only lost to into the living space.

This being the case, shutting off the burner control for 8~12 hrs a day via their smart controller as far as I can figure out is never going to yield a 10% savings for NG water heater. The idling conditions are not consuming much energy in order to do so.

I have simply rigged up a z-wave appliance plug to the 110v AC power cord for the controller and exhaust fan and it up so that I can shut it off when not home for long periods of time.

I agree.  The vast majority of hot water energy literally goes down the drain, not out the insulation.