Hot water heater automation

[jeffreyd321]

I have seen some topics on water heater automation. Some folks believe that the new water heaters are so efficient that they don't loose heat and don't re-fire when not being used. If you check with any water heater manufacturer such a Rheem for example, you will see that they are either developing or have developed automation devices to control their electric water heaters. There is one gas water heater manufacturer, (Bradford White) who makes a timer for its gas water heaters. There is also a gas water heater timer available that fits most gas water heaters. It can be used with any home automated device. Believe me, (a plumber for over 40 years), water heaters can save energy if they are controlled, rather than left sitting while you are away to work or play.

 

[wkearney99]

Yeah, there's the tradeoff between shutting it off during away times versus the cost of burning enough energy to bring it back up during times of potential use (vs just hold it steady).

No way in Hell I'd currently trust any of the home automation schemes to have absolute control over it though.  Few (none?) are genuinely reliable enough to trust with the task.  That and since I do most of my work from home it's not like the house is truly ever unoccupied for long enough stretches to make it worthwhile.   I do use the manual 'away' setting when we're gone for more than 2 days.  It's a Bradford White gas water heater, installed in 2013 (with a powered exhaust vent blower).
 
Still, it's worth looking into what's available.

 

[pete_c]

Welcome to the Cocoontech forum JeffreyD321.
 
I have a Bradford White natural gas water heater (50 Gallon) here and a happy camper.  I never touch it and probably would never automate it.  That said natural gas is still reasonably priced here in the midwest.
 
Someone said to me the other day that Bradford White is the only company these days making their water heaters in the US.
 
Thinking they manufacture their stuff  in Michigan. 

 

[RAL]

I used to have an 80 gallon electric water heater. Since I am on time-of-use electric metering, I used X10 to turn the water heater off during peak hours and allowed the heating elements to run only during non-peak hours.  That saved hundreds of dollars a year on our electric bill.  With 80 gallons of capacity, we rarely ran out of hot water.  The X10 has been 100% reliable for over 25 years.
 
I now have a heat pump water heater.  It's over 2 times as efficient as the old water heater, but I still run it only during off peak hours. 
 
I agree that with a gas fired hot water heater, automation would make less sense. The savings wouldn't be as great, since there is no time-of-use metering for gas anywhere that I know of.  Unfortunately, we don't have natural gas service available in our area, otherwise I'd be using it.  I do have propane, but the heat pump water heater is less expensive to operate vs a propane water heater.
 
GE makes their heat pump water heaters in the USA.  A.O. Smith also makes many of their water heaters in the USA.

 

[Madcodger]

We also use a GE Geospring heat pump water heater. One of the better things we've installed. I try to run it in heat pump only mode, which is amazingly efficient (well over 30% savings). My wife likes the convenience of the hybrid mode, though, as it gives faster recovery times and is still a significant (probably over 20%) savings. I recetly ran it there over the holidays when we had guests, and it worked fine despite extra showers, dishwasher use, etc.

For vacations, it has a setting that allows us to tell it how many days we'll be away, and it automatically brings the water back to full temp by the time we're back. It also has a high demand mode that uses the regular H2O heater elements, but I have not yet found this necessary unless it's a house full of guests AND significant dishwasher and laundry use. But that's a lot of hot water. I think they quote full tank of heated water in under an hour, and high demand mode certainly kept up.

Most of our use of hot water is in the morning, and I don't recall hearing the unit run in the evening unless there is significant demand on it (i.e., shower). Otherwise, it seems to heat, then shut down, and that lasts until the next day. That seems to negate the need for timing things unless you want to have a period of relatively cooler water in the tank before allowing the unit to turn on. That sounds like a potential bacteria breeding ground, so I'll pass. Then again, i suppose that occurs when we go on vacation, now that I thi k about it! Hmmm .... Maybe not such a good idea...

The unit has a port designed for automation and GE started down that path, but I don't believe they still support it. I think there are third party interfaces, but I see no need. Not everything needs to be controllable via our phones and such!

 

[wuench]

Yeah, there's the tradeoff between shutting it off during away times versus the cost of burning enough energy to bring it back up during times of potential use (vs just hold it steady).

No way in Hell I'd currently trust any of the home automation schemes to have absolute control over it though.  Few (none?) are genuinely reliable enough to trust with the task.  That and since I do most of my work from home it's not like the house is truly ever unoccupied for long enough stretches to make it worthwhile.   I do use the manual 'away' setting when we're gone for more than 2 days.  It's a Bradford White gas water heater, installed in 2013 (with a powered exhaust vent blower).
 
Still, it's worth looking into what's available.

 
I had concerns about this as well.  The Rheem automation interface is limited by manual valve limits so you can only adjust within a fixed range or activate vacation mode.  But I really do not like the fact that it is 1.) cloud based, and 2.) not using https.    Not using https is not 100% a deal breaker but if they aren't smart enough to take the easy step of switching their servers over to https it makes me wonders what other security gaps exist in their cloud setup.  They obviously don't have someone from a platform, network, or security team providing some checks and balances to the developers....
 
On the plus side it does have a built in leak detector and will send you an alert.

 

[wkearney99]

But I really do not like the fact that it is 1.) cloud based, and 2.) not using https.    
 
They obviously don't have someone from a platform, network, or security team providing some checks and balances to the developers....

 
Agreed, too many gizmos show signs of "just make it work" and "we'll worry about security later".

 

[mikefamig]

I used to have an 80 gallon electric water heater. Since I am on time-of-use electric metering, I used X10 to turn the water heater off during peak hours and allowed the heating elements to run only during non-peak hours.  That saved hundreds of dollars a year on our electric bill.  With 80 gallons of capacity, we rarely ran out of hot water.  The X10 has been 100% reliable for over 25 years.
 
I now have a heat pump water heater.  It's over 2 times as efficient as the old water heater, but I still run it only during off peak hours. 
 
I agree that with a gas fired hot water heater, automation would make less sense. The savings wouldn't be as great, since there is no time-of-use metering for gas anywhere that I know of.  Unfortunately, we don't have natural gas service available in our area, otherwise I'd be using it.  I do have propane, but the heat pump water heater is less expensive to operate vs a propane water heater.
 
GE makes their heat pump water heaters in the USA.  A.O. Smith also makes many of their water heaters in the USA.

 
What brand heat pump did you choose and how many people are in the house using it?
 
Mike.

 

[ano]

I have seen some topics on water heater automation. Some folks believe that the new water heaters are so efficient that they don't loose heat and don't re-fire when not being used. If you check with any water heater manufacturer such a Rheem for example, you will see that they are either developing or have developed automation devices to control their electric water heaters. There is one gas water heater manufacturer, (Bradford White) who makes a timer for its gas water heaters. There is also a gas water heater timer available that fits most gas water heaters. It can be used with any home automated device. Believe me, (a plumber for over 40 years), water heaters can save energy if they are controlled, rather than left sitting while you are away to work or play.

Hello jeffreyd321:
 
Wow we don't have many plumbers on this board. You wouldn't be promoting a gas water heater control, would you?  My guess is that you won't post again.
 
If you are a plumber, you should know what happens to a water heater tank when you heat it and cool it and heat it and cool it and heat it day after day. Expansion and compression, expansion and compression.  If you don't have an expansion tank, then what happens? 
 
Second, you are not going to save a whole lot in energy. The EnergyGuide on my 50 gallon Bradford White Gas hot water heater says the yearly cost is $235.  That includes heating the water which uses the most gas. 
 
A few years ago i tried an experiment. I turned off my water heater and wanted to see how much the water would cool over the course of 8 hours if i turned it off.  I normally have mine set to 130 degrees, so the normal heat loss is between the 130 degree water and say 70 degree water heater temp, a difference of 60 degrees.  After turning off the water heater for 8 hours and not using any water, the temp I measured was 112 degrees.  So at the end of 8 hours, the heat loss differential was 42 degrees. 
 
If you average the 60 degree and 42 degree heat loss over the 8 hours, the average is 51 degrees during the turn-off phase.
 
But wait, your only turning it off for 8 hours a day, but its 130 degrees for 16 hours.  So 60 difference for 16 hours and 51 degrees difference for 8. This overall averages out to 57 degrees vs. 60 degree differential over 24 hours.  So if water heater loss/cost is proportional to the temp difference the water heater maintains, your cost to maintain hot water over 24 hours with shutdown = 57/60 or 5% less. In other-words you save 5% of the energy to maintain water temp by turning it off 8 hours a day.  You do nothing, of course, to save on heating the water you use.  
 
So the $235 = energy to heat water you use + energy to maintain water temp.
 
I don't have any idea how much energy it takes to heat the water you use vs. maintain the water temp, but lets say it takes 66.6% to heat the water, and 33.3% to maintain the temp. This means your yearly cost is $156.6 to heat the water, and $78.3 to maintain it.  So taking 5% of the maintaining part, turning off your water heater for 8 hours a day saves.....about $4 a year.  With an electric water heater maybe you save a whooping $10 - $15 a year.  

 

[wkearney99]

Well, ok then!  Thanks for bringing the smack-down math to the game.  
 
With older systems that lacked anything resembling energy efficiency I'd imagine there was a lot of upside to standing down the heat during off-usage time periods.  I know my folks ancient oil-fired furnace with it's attached hot water tank was horrendously wasteful in that regard.  First one up every morning had to fire it back up again.  That and older refrigerators were so often wasteful enough for it to make sense to replace them outright rather than keeping them running all the time. 

I've got geothermal for HVAC now and it's clever to see how the thermostats understand how to ramp the temp back up again for scheduled changes.  As in, the system kicks back in about 12 minutes before my scheduled intervals because it's learned what kind of recovery it needs to get to my setpoint by that scheduled time.
 
I'm all for squeezing energy savings out where practical.  Even if it doesn't result in immediate economic returns.  But some gains aren't always worth the added cost, complexity and impact on convenience.

 

[RAL]

What brand heat pump did you choose and how many people are in the house using it?

 
I have an A.O. Smith Voltex PHPT-60 water heater.  This model has been replaced by newer models that have even higher efficiency.
 
Just 2 of us in the house most of the time.
 
At the time I purchased this 18 months ago, it was one of the few hybrids with a 60 gallon tank. Also, Smith used a powered anode, while other brands did not. Unfortunately, the current Smith models went back to an unpowered anode rod.
 
Most others, like the GE, were just 50 gallons and I wanted more capacity than that to get through the peak electric rate period without having to heat the water.
 
Rheem and Smith both offered 80 gallon units, but they were physically too tall to get down my basement steps. They just stuck the compressor on top of a traditional 6 foot tall tank, making it a monster.
 
Today, the newer models are shorter and slightly wider and would fit. Also, the 60 gallon models have been increased to 66 gallons.  

 

[Desert_AIP]

The only automation for ours is to shut it down in Vacation mode (when we will be gone for a long enough period of time) and to shut it down in case there is a water leak.
When we return from Vacation, it automatically turns back on when we turn the system off or I can run a button remotely to bring it back up to temperature so it is ready when we arrive home.

If the water leak detectors trip, the main water to the house gets shut down.
If the leak is in a hot water pipe I don't want the tank running dry and exposing the elements while they're energized (which will burn them out).

The energy used turning it off for the work day and then bringing it back up to temp is more than the energy to maintain the tank temperature.

 

[LarrylLix]

Google this... "Legionella"
 
Don't keep your water warm in a hot water tank. Can be dangerous. keep it cold or hot. There is a dangerous range.

 

[sash]

curious -- why worry and just use an instant water heater, on normal usage there generally +25% savings, which will compensate for any  tier energy usage  program. I have used one for over 12 years now with out problems. and it works as well as it did  the day I bought it.. and with a normal tank type I was going through a bottom  elements every 1.5 year and top element every 3rd because my water so hard. heck the saving on element alone  probably paid for my  instant water heater in that time period

 

[johnboy70_99]

One other thought - in the winter a lot of the "lost" energy is heat lost into your house which ends up adding to the heat generated by your heating system. Some of it goes up the chimney, but the vast majority of it is likely kept inside the house. So the above calculation of 5% savings is more like 2.5-3% savings as you are really only saving anything in the summertime when you have to remove the heat via AC.