Z-wave relay for hot water heater

Other Devices & Integrations Lighting & Load Control
1

Anyone using a relay to control an electric hot water heater? If not a relay, how?

I have a Rheem Hybrid Heat Pump in our weekend house, and would like to be able to control it via Vera (have hot water when we arrive is a huge WAF credit…

It’s 240v with a max draw of 22 amps.

.//A.

2

Yep, I’m using ELK 9200’s on my heaters plugged into controlled outlets. Not my first choice, I wanted the Intermatics but they were discontinued at the time.

JOD.

3

Evolve LFM-20 (http://www.smarthome-products.com/showproduct.aspx?ProductID=2975&SEName=evolve-lfm-20-20a-z-wave-relay-fixture-module) is maybe not just enough ?

4

that’s funny, i was just looking over the ELK 9200 last night thinking to myself what else I could use that for besides my hot water heater (central HVAC emergency shut off?)… and I also stumbled upon the Evolve LFM-20 wondering what I could connect that thing to, perhaps make a z wave controlled robotic lawn mower, how about a z wave controlled Roomba? lol.

5

And you’d probably need two, and make sure you always switch them in tandem (which is a given in the mentioned ELK and Intermatic units).

6

You’d want to use an electrical 220VAC contactor purchased at your local electrical supply shop. Then you’d trigger it with a simple 120VAC Z-Wave appliance module. Bring your appliance module with you when you go to buy the contactor and the load info water heater and explain to the electrical supply shop what you are trying to do.

7

A “relay” activating a relay that feed the electric water heater !

Good idea Shady!

8

Such as the ELK 9200 solution presented by @JOD. Or anything like it, as @shady suggested.

9

Right ! :slight_smile:

10

Such as the ELK 9200 solution presented by @JOD. Or anything like it, as @shady suggested.[/quote]

I used the 220v contactor over the Elk for my pool pump because of the cost differential. My .02

11

That is another brilliant idea! Please keep them coming!

12

Thanks. Wanted to check if anyone actually had one in service. Glad its working. Will also allow me to shut it down overnight. I have a good size solar array, net-metered, so I try to isolate electrical usage to daylight hours to make up for the $.20 → $.10 beating I take per kWh selling power back to LIPA.

ordering from AutomatedOutlet this evening… $78.
.//A.

[quote=“JOD, post:2, topic:168243”]Yep, I’m using ELK 9200’s on my heaters plugged into controlled outlets. Not my first choice, I wanted the Intermatics but they were discontinued at the time.

JOD.[/quote]

13

I have two on order from Amazon.com for $64 each. Sold through Surveillent.
Amazon.com

14

You’re right, you can save some money doing it that way, by sizing the contactor for you application. Ebay has this 40A contactor for $40, but $64 for the 60A Elk one is a pretty good deal and you get an alarm enclosure.

http://compare.ebay.com/like/110678587028?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&rvr_id=230306896370&crlp=1_263602_309572&UA=WXI7&GUID=2c1a79f212f0a0269971ea61fff4d3b8&itemid=110678587028&ff4=263602_309572

Thats how I turn my PC on/off with Z-Wave (using a little 120VAC ice cube relay and appliance module).

15

I thought that I would post this for information to others who are also looking to control high current appliances. I received last week two ELK 9200’s. Connected one to my hot water tank and a z-wave plug outlet. Works great, now when I enter my door code not only does my water supply turn on so does my hot water tank. It also turns off with my exit scene, great energy saver. I am installing the second one to control my hot tub. Were I live the cost of electricity will vary up to 50% depending on the time of day/night starting this June. I have programmed my hot water tank and hot tub to only turn on during the least expensive times. I can over-ride either one using a secondary scene controller if I want to. Since this is for my summer home and I’m only there on weekends and holidays saving 50% on electricity with these two appliances makes Vera pay for herself very quickly. I’m ordering two more for my rental cabin, no renters, no wasted power. The only modification I made was to take the relay out of the second box and added it to the first (now two-in-one). Saves space on my wall.

16

Just finished install of the Elk relay, plugged into a GE z-wave outlet. Works great, looks great. full HW control.

Wrangling with 10/3 romex wasn’t fun…

.//A.

[quote=“anthonyris, post:12, topic:168243”]Thanks. Wanted to check if anyone actually had one in service. Glad its working. Will also allow me to shut it down overnight. I have a good size solar array, net-metered, so I try to isolate electrical usage to daylight hours to make up for the $.20 → $.10 beating I take per kWh selling power back to LIPA.

ordering from AutomatedOutlet this evening… $78.
.//A.

[quote=“JOD, post:2, topic:168243”]Yep, I’m using ELK 9200’s on my heaters plugged into controlled outlets. Not my first choice, I wanted the Intermatics but they were discontinued at the time.

JOD.[/quote][/quote]

17

Any hard data on how much money you are saving? I have six condo’s I’d like to install this in, but between parts and labor I’m looking at $100 each. How long would it take to pay that $600 back?

18

100% depends on the hot water heater you are using, and the demand. If you look at the specs of yours, it likely has operating costs listed. If it’s standard electric, pretty easy to do a straight-line analysis of operating costs per hour. If you have the HW heater turned off for 8 hours at night, you should be saving <1/3 of your daily operating cost. I say <1/3 because there is obviously no demand in the overnight hours.

I won’t get into the “heat mass” argument that says, “if you’ve heated something, it’s more efficient to keep it heated”. Modern, well-insulated HW heaters tip that argument a bit, as the insulation tech has greatly evolved.

.//A.

19

I just ordered a few more @ $52 .54 from Security Sellers. @ that price you should save plenty. Wiring is very simple but if you are not comfortable best to have an electrician set you up. I now have these in both my rental units.

20

correct me if I am wrong, but electric hot water heaters have thermostats, which shut them off when they are at operating tempature. If there is no usage, they rarely turn on, because they are pretty well insulated these days. You will loose some heat in the interconnected copper piping due to conduction, but its minimal.

Also, once you turn it back on, it could take several hours to reach the normal operating tempature again…

I don’t think you are saving as much as you think you are.

here is a way to confirm this.

get a wattmeter or CT’s (Current Transformers) that are capable of measuing the current of the water heater, there are several on the market… Run it normally for a week, no on/off control. Now run it again for another week, doing all of the shutting down and restarting that you think is saving you money. compare the 2 weeks (hopefully the operating conditions (outside tempature, which affects the incomming cold water temp) / # of people taking showers is similar). You might have to do it for a month per test for real world results.

I doubt you will see much of a difference. Hey, if it makes you feel good, go for it, but I question if you are saving much. vacation properties are probably where it makes the most sense…