Shut OFF water heater during peak power times

[SteveQ]

I finally ordered the "Relay in a box" RIB24P30 from EnergySavingControls.com and installed it yesterday.

This is a really elegant way to control an electric water heater. I mounted the relay directly to the outside of my main electric panel. I used 2 wire nuts to connect the N/C relay outputs to the power feeds to my water heater and connected the common for each side of the relay directly to the 30A breaker.
Easy installation!

I am controlling the relay coil with a standard 24VAC HVAC transformer. It is the same transformer being used to power the contactors that control my electric baseboard heating. The transformer is always ON. I switch the 24VAC transformer output to the relay ON/OFF via a hobby boards 4 channel relay (www.hobby-boards.com 8CIO4-R1-A ) I control the Hobby-Board relay via my XAP one-wire network connected to Homeseer.

I have Homeseer setup to turn the water heater OFF during peak power times (3-7 PM) and overnight (11PM to 7AM).

Everything is working great and I expect to save enough money over the next 10 months to pay for the relay.

Steve Q

 

[10Seconds]

Slightly off topic question. Any way to control a gas water heater for the same purposes?

I would love to know the same thing. Or even to be able to remotely adjust the temp down when its not a time its in use. Anyone?

 

[drozwood90]

Get a tankless.

For how much you will pay to get a controllable device for the tanked unit, you probably won't ever get the return.

My tankless (from the last house) had a box that could actually control the temperature. So, when we were not in the shower, we could have it crank the temperature up for dish washing.

In the new house, the builder put in a tanked unit...didn't really have a choice (for how much he wanted to "upgrade" me to a tankless...I could put in 3 of them in my current house). But my tanked unit has a pilot light...I just wish I could change the setback on it, automatically. As there are LOADS of time where that would benefit us.

I'd just have to ensure that the burn time to come back up to temperature was not wasteful. I.e. the amount of gas that it uses to come back to temperature, as opposed to maintaining temperature...is less. Which means the off period needs to be pretty high. Such as when we go away for the weekend...I turn off the tank. Saves maybe a buck or two...

Probably will get more accuracy when I get my light sensor hooked in, so I can monitor the burn cycles better (assume when it's burning it's burning at it's maximum load).

--Dan

 

[ysualum]

I ended up putting a UPB switch on my recirculating pump. At least I can program and control when the hot water is flowing.

My water heaters actually have a powered vent that has to be plugged in. If the vents aren't functional, the water heater won't function. In theory, if I plug them into a UPB outlet/receptacle, I could control the tank when I want as well. Figured it's not worth the headache and likely will get little payback on that.

I figure there is more heat loss w/ hot water constantly flowing through the entire house, compared to the heat loss from the water heaters.

 

[10Seconds]

I ended up putting a UPB switch on my recirculating pump. At least I can program and control when the hot water is flowing.

My water heaters actually have a powered vent that has to be plugged in. If the vents aren't functional, the water heater won't function. In theory, if I plug them into a UPB outlet/receptacle, I could control the tank when I want as well. Figured it's not worth the headache and likely will get little payback on that.

I figure there is more heat loss w/ hot water constantly flowing through the entire house, compared to the heat loss from the water heaters.

This is actually a great spot to put one of those, the circ pumps are energy hogs (obv. depending on the pump) and shutting it off when you dont need it can save a ton. I am just getting started with UPB, but this is the first place one is going. I used to just unplug the stupid thing.

 

[drozwood90]

Sure! Run it in the morning, 20 min before shower...

Otherwise leave it off...

--Dan

 

[Michael McSharry]

Probably will get more accuracy when I get my light sensor hooked in, so I can monitor the burn cycles better (assume when it's burning it's burning at it's maximum load).

I did a how-to for Cocoontech on the light sensor to monitor the water heater flame. I found over time that the temperature sensor mounted near the chamber was a more reliable way to detect pilot light vs. full ignition. It is a continuous measurement so not dependent on single event. I just established temperature setpoints at the rise and fall to synthesize a switch output.

The chart shows the red temperature measurements and the blue line that is the synthesized switch with the semi-transparent area the cumulative propane consumption. The $ calculation is based upon the BTU input rate of the water heater, the duration of the switch, the BTU/gallon for LPG and the cost of the propane.

 

[Michael McSharry]

I ended up putting a UPB switch on my recirculating pump. At least I can program and control when the hot water is flowing.

I concur that this little pump is a best left off except when needed. For most who are on a fixed time schedule a basic timer will do the job. I do use an UPB applicance module so the weekend vs. weekday schedule can be altered. I also monitor the water flow so when the second shower starts I turn it off early so it is not running after its purpose has been served.

 

[damage]

whenever i see this topic, i'm reminded of this article http://bit.ly/ba2mKH i'm sure it's been debated to death, but thought i'd bring it up

 

[drozwood90]

Probably will get more accuracy when I get my light sensor hooked in, so I can monitor the burn cycles better (assume when it's burning it's burning at it's maximum load).

I did a how-to for Cocoontech on the light sensor to monitor the water heater flame. I found over time that the temperature sensor mounted near the chamber was a more reliable way to detect pilot light vs. full ignition. It is a continuous measurement so not dependent on single event. I just established temperature setpoints at the rise and fall to synthesize a switch output.

The chart shows the red temperature measurements and the blue line that is the synthesized switch with the semi-transparent area the cumulative propane consumption. The $ calculation is based upon the BTU input rate of the water heater, the duration of the switch, the BTU/gallon for LPG and the cost of the propane.

Michael, that's the light sensor that I was referring to!

You were very inspirational in regards to that.

--Dan

 

[SteveQ]

whenever i see this topic, i'm reminded of this article http://bit.ly/ba2mKH i'm sure it's been debated to death, but thought i'd bring it up

This is an interesting issue. I had not seen it before. In my case:

1. The water is from my well and therefore the probability of contamination is minimal.
2. The water is softened before being heated.
3. We do not use soft water for cooking/drinking.

In my opinion the risk of bacterial contamination is extremely small.

Steve Q

 

[mingomtman]

Sorry for reviving this years down the road....  This is the answer I had been looking for ( I think)  
I have a whole house generator (Generac Guardian 14KW) and auto transfer.  However, there are some items that NEVER want to use with the generator (such as hot tub and my second hot water tank).  The load shedding built in is terrible as it keeps trying to energize everything and then shuts down every load shed device and starts a cycle until it overloads again.  Very clumsy.  
I was planning to use the relay N/C to run the appliances and then whenever the generator runs, it will get activated to disconnect the appliances.  
I am not sure how I am going to wire the 24VDC adapter to become energized only when the generator is running, but there should be several ways to do it.  
 
I would really like to take the concept to the next level and incorporate my ELK M1 to sense the generator and switch the control RIB relays.   
How would I build a power sensor?  One for generator and another for utility?
 

 

[RAL]

There was a discussion of how to sense when a generator is running in this thread that you might find helpful.