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General => Lighting & Load Control => Topic started by: anthonyris on April 30, 2011, 08:44:38 pm

Title: Z-wave relay for hot water heater
Post by: anthonyris on April 30, 2011, 08:44:38 pm
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.
Title: Re: Z-wave relay for hot water heater
Post by: JOD on April 30, 2011, 11:52:01 pm
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.
Title: Re: Z-wave relay for hot water heater
Post by: huogas on May 01, 2011, 12:05:44 pm
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 ?
Title: Re: Z-wave relay for hot water heater
Post by: iflyM3 on May 01, 2011, 12:25:44 pm
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.
Title: Re: Z-wave relay for hot water heater
Post by: oTi@ on May 02, 2011, 09:46:36 am
Evolve LFM-20 is maybe not just enough ?
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).
Title: Re: Z-wave relay for hot water heater
Post by: shady on May 02, 2011, 09:10:40 pm
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.
Title: Re: Z-wave relay for hot water heater
Post by: huogas on May 02, 2011, 09:20:09 pm
A "relay" activating a relay that feed the electric water heater !

Good idea Shady!
Title: Re: Z-wave relay for hot water heater
Post by: oTi@ on May 02, 2011, 09:28:09 pm
A "relay" activating a relay that feed the electric water heater !
Such as the ELK 9200 solution presented by @JOD. Or anything like it, as @shady suggested.
Title: Re: Z-wave relay for hot water heater
Post by: huogas on May 02, 2011, 10:29:37 pm
Right !  :)
Title: Re: Z-wave relay for hot water heater
Post by: FrankHill73 on May 02, 2011, 10:40:33 pm
A "relay" activating a relay that feed the electric water heater !
Such as the ELK 9200 solution presented by @JOD. Or anything like it, as @shady suggested.

I used the 220v contactor over the Elk for my pool pump because of the cost differential. My .02
Title: Re: Z-wave relay for hot water heater
Post by: iflyM3 on May 02, 2011, 11:04:02 pm
That is another brilliant idea!  Please keep them coming!
Title: Re: Z-wave relay for hot water heater
Post by: anthonyris on May 05, 2011, 07:38:06 pm
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.

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.
Title: Re: Z-wave relay for hot water heater
Post by: JimMac on May 06, 2011, 02:53:15 pm
I have two on order from Amazon.com for $64 each. Sold through Surveillent.
http://www.amazon.com/ELK9200-HEAVY-DUTY-RELAY-CONTACTOR/dp/B004HMZOUS/ref=sr_1_1?ie=UTF8&s=electronics&qid=1304707872&sr=8-1
Title: Re: Z-wave relay for hot water heater
Post by: shady on May 06, 2011, 08:36:27 pm
I used the 220v contactor over the Elk for my pool pump because of the cost differential. My .02

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

Quote from: huogas
A "relay" activating a relay that feed the electric water heater !

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

Title: Re: Z-wave relay for hot water heater
Post by: JimMac on May 25, 2011, 10:54:44 pm
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.
Title: Re: Z-wave relay for hot water heater
Post by: anthonyris on May 28, 2011, 09:52:53 pm
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.

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.

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.
Title: Re: Z-wave relay for hot water heater
Post by: SuperflyMD on May 29, 2011, 06:02:24 am
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?
Title: Re: Z-wave relay for hot water heater
Post by: anthonyris on May 30, 2011, 11:32:41 am
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.


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?
Title: Re: Z-wave relay for hot water heater
Post by: JimMac on May 30, 2011, 10:32:05 pm
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. 
Title: Re: Z-wave relay for hot water heater
Post by: mitch672 on May 31, 2011, 11:57:44 am
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...
Title: Re: Z-wave relay for hot water heater
Post by: JimMac on May 31, 2011, 01:09:11 pm
Your savings can depend on allot of factors;
How well insulated is your tank, the insulation is not the same in all tanks.  You get what you pay for.
How long you are away, holidays, vacation, business trips.
My biggest cost saving is in allowing Vera to only turn on the tank only when my electric rates are at the cheapest $ per kwh, (7pm-7am).  These new electric smart meters are being installed throughout Canada and the US.  Are you ready for them?

If your not renting or your electric rates don't fluctuate during the day then your saving may not be worth the expense unless you do the installation yourself.

One other big bonus for me... I have kids who like to take very long showers.  Now when the hot water runs out they get out real fast, saves on my water bill.  :o
Title: Re: Z-wave relay for hot water heater
Post by: JOD on May 31, 2011, 01:46:47 pm
Your savings can depend on allot of factors; .
I agree.  My savings wont be but pennies if any as my hot water heater is turned off most of the year except for a few weeks in winter. I have heat recovery units on my A/C's that make the hot water whenever the A/C's are running.
But now Vera monitors the outdoor temperature and if it drops below 70F & We Are Home & it is not between 11:00pm - 5:00am will turn the hot water heaters on.
It's still a work in progress as there are days above 70F with low humidity to where we have the windows open and the A/C wont be running.....But that's another topic.

JOD.

Title: Re: Z-wave relay for hot water heater
Post by: Sonnyzav on September 29, 2011, 06:32:26 am
I have a domestic hot water tank that is connected to my forced hot water heating system. I would like to be able to turn the hot water on/off using Vera. My thought is to wire some kind of on/off switch in the thermostat circuit. Any ideas on how to do this?
Title: Re: Z-wave relay for hot water heater
Post by: JimMac on September 29, 2011, 11:45:01 am
Is that tank used to heat the water or is it used just for storage?  I have one domestic hot water tank that is used by my Geo-thermal heating but the tanks is for hot water storage for the radiant floor heating, it is not wired to power.  If yours is connected to power then the ELK9200 should work fine as long as you don't exceed the rated 60 amps.  This relay switch will cut the main power to the tank using Vera, I don't know of any high current z-wave relay you can use in the tanks thermostat and still close the access panel.
Title: Re: Z-wave relay for hot water heater
Post by: Sonnyzav on September 29, 2011, 06:20:44 pm
There is no power to the water heater. Its set up as a seperate zone on my forced hot water furnace. The only wiring is for the thermostat. I simply want a z wave device that will open and close the thermostat circuit.
Title: Re: Z-wave relay for hot water heater
Post by: grybrd on September 29, 2011, 06:51:59 pm
@Sonnyzav ... the LFM20 mentioned above is what I use to interrupt the low voltage line between the water tank and boiler.  Very easy to install.
Title: Re: Z-wave relay for hot water heater
Post by: Sonnyzav on September 30, 2011, 07:02:32 am
Thanks so much. I will give it a try
Title: Re: Z-wave relay for hot water heater
Post by: kaldoon on October 01, 2011, 08:20:07 am
Now that the CA3750 Contactor Module  (http://www.smarthome-products.com/p-331-intermatic-intouch-ca3750-contactor-module.aspx) has resurfaced  - I used it in a great number of installations to control hot water heaters, pool pumps and other large devices
Title: Re: Z-wave relay for hot water heater
Post by: grybrd on October 03, 2011, 11:21:35 am
@kaldoon ... It appears that Sonnyzav need is for a low voltage run to the heat source and the CA3750 would be more applicable to high voltage pump circuits.
Title: Re: Z-wave relay for hot water heater
Post by: JT on April 27, 2013, 02:05:31 am
Anyone try this Intermatic CA3750 product?

http://store.homeseer.com/store/Intermatic-CA3750-Z-Wave-Contactor-Module-P407.aspx (http://store.homeseer.com/store/Intermatic-CA3750-Z-Wave-Contactor-Module-P407.aspx)
Title: Re: Z-wave relay for hot water heater
Post by: FireBird on April 27, 2013, 07:57:24 am
I'm using the CA3750 for my 240v pool pump, should be the same wiring for a 240v water heater.
Title: Re: Z-wave relay for hot water heater
Post by: Z-Waver on April 27, 2013, 04:10:20 pm
Does this contactor make any noise at all, buzz or hum, when the contactor is engaged? I'm fine with a click or clack at the moment that it engages or disengages, but does it hum during operation.
Title: Re: Z-wave relay for hot water heater
Post by: FireBird on April 27, 2013, 05:09:35 pm
It does make a very slight hum, but you would only hear it from 3 feet away or less. It's harder to tell in my case because the pool pump is running, I doubt you would ever hear it installed in a basement.

For anybody interested, here is a modified wiring diagram for the CA3750.