Smart meter

[Galt]

Power co. Has a program daytime hours 22 cents a kWh nights weekends holidays 5 cents a kWh . Customer wants me to install something to automatically turn off four electric heat circuits and his water heater.The four heating circuits are in a separate sub panel next to the main. My idea is to use a 24 volt thermostat that I can program to call for heat at 50 degrees during the 22 cent time periods and say 75 degrees for the 5 cent time. I'm thinking a contactor between main and sub.and another for the water heater. Problem is 24 and 240 in same box. How about a RIB mounted on side with low volts outside? Better ideas are very much appreciated.

 

[fmtjfw]

Does the meter supply a "dry" contact you can use to determine the on-peak/off-peak?

 

[Galt]

Haven't talked to power co. Yet. The way the home owner described it they don't care what you do but from eight o'clock in the mourning till eight o'clock at night you pay the high rate.

 

[cadpoint]

Is this their daily home, I only ask because I think I'd go with an intermatic time for heating water. Of course depending on ones routine they could get away with something but they haven't considered their water usuage!

You should just call Rib's themselves and go forward. In re-reading what they openly offer I had forgotten how they usually control motors, and you also one have pay close attention to the KW controlled by a/each device.
Some out right say no override, so what about the weekends or holidays?

To me (thinking out loud) the old honeywell programable, or any programmable would do all you need per room. You going to have thermostat anywas...

Sounds like a fun job! Bill them two hours for your researching!

 

[Rampage_Rick]

This is the kind of thing they need to get working with Zigbee HAN. The meters we're getting here (Itron OpenWay) are equipped with two radios: 900 Mhz for the mesh network, and 2.4 Ghz Zigbee for communication within the premises using the Smart Energy Protocol.

You can buy Zigbee controlled modules such as the 30A Load Control Module from HAI. However, this unit uses the Home Automation Protocol, so presumably you'd need some kind of Zigbee gateway in between. It's also possible that you could use an SEP compliant thermostat to talk directly with the meter.

The big question revolves around the utility. As far as I know, only Texas and California are enabling the Zigbee radios in their meters. I'm not sure if they're providing load control and pricing data over the connection either.

 

[cadpoint]

Isn't 900 MHz in the Home phone cordless range?

 

[kwired]

Power co. Has a program daytime hours 22 cents a kWh nights weekends holidays 5 cents a kWh . Customer wants me to install something to automatically turn off four electric heat circuits and his water heater.The four heating circuits are in a separate sub panel next to the main. My idea is to use a 24 volt thermostat that I can program to call for heat at 50 degrees during the 22 cent time periods and say 75 degrees for the 5 cent time. I'm thinking a contactor between main and sub.and another for the water heater. Problem is 24 and 240 in same box. How about a RIB mounted on side with low volts outside? Better ideas are very much appreciated.

Your customer probably wants heat before it drops below 50 deg:?

They probably will have times they want hot water as well during the peak period.

But that kind of rate difference is motivation to do something to take at least some advantage of it. Heating is difficult, it is just not all that feasible to somehow store enough heat to ride through the peak period, so alternate heat source for the peak period is probably the best thing here. Water heating may be able to cut some significant cost by having a two water heater system where the tanks are in series, and the incoming cold water enters the tank that has the power shut down during the high price period, but the other one is always on just to make sure there is still hot water for on demand uses. It will not eliminate all usage during high rate period, but will still lower amount of energy used if it is only heating the water say 5-10 degrees instead of 40-50 degrees plus you still need to do high use activity during the lower rate periods or eventually incoming cold water makes it to the second tank.

 

[GoldDigger]

The simple way it was done back in Illinois where POCO provided a second meter with an associated ( sealed) time clock, was to connect the top element of the water heater to the constantly powered feed and the bottom element to the timed feed. The result is very similar to using two tanks. (The single tank was 80 gallons.)

Tapatalk!

 

[gar]

140215-1530 EST

If possible heavily insulate and close leaks. Try to get the thermal time constant of the home to greater than 2 days.

Install a 1000 to 2000 gallon tank of water. At night heat the water with electricity to get tank to 180 F by the start of high cost electricity. A change in temperature of 1000 gallons of water from 180 to 130 F will provide about 50 * 8 * 1000 BTU or 400,000 BTU. During the day heat the water from a solar thermal array. Probably can have a comfortable temperature at minimal electrical cost. But there is substantial capital cost.

This link http://www.spookydistance.com/solarhome/Thermal Mass.html provides a calculation to compare cement with water.

.

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[kwired]

140215-1530 EST

If possible heavily insulate and close leaks. Try to get the thermal time constant of the home to greater than 2 days.

Install a 1000 to 2000 gallon tank of water. At night heat the water with electricity to get tank to 180 F by the start of high cost electricity. A change in temperature of 1000 gallons of water from 180 to 130 F will provide about 50 * 8 * 1000 BTU or 400,000 BTU. During the day heat the water from a solar thermal array. Probably can have a comfortable temperature at minimal electrical cost. But there is substantial capital cost.

This link http://www.spookydistance.com/solarhome/Thermal Mass.html provides a calculation to compare cement with water.

.

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I had that kind of thought but wasn't sure just how much water one would need to store to be able to heat the home for 8-12 hours, plus you would need a heating system that will use the hot water if you don't currently have one that will. You will also either want some kind of backup or override should you not have enough stored heat for the demand.

 

[gar]

140216-1427 EST

kwired:

My home built in 65-66 has full fiberglass insulation in 2x4 studs, and 10" in the second floor ceiling, and a furnace with possibly 70% efficiency. During the summer I did a thermal time constant estimate, and it seemed to be a little less than 24 hours.

During the summer my gas consumption is about 1 CCF or 100,000 BTU per day, hot water heating and some range top cooking.

Last month gas consumption per day was:
1-7-2014, ........ -5 F outside, ...... 70 F inside, ...... in-out diff 75 F, ..... 25 CCF ..... 0.3 CCF/F
1-13-2014, ...... 40 F outside, ...... 70 F inside, ...... in-out diff 30 F, ....... 9 CCF ..... 0.3 CCF/F
1-21-23-2014, ... 0 F outside, ..... 70 F inside, ...... in-out diff 70 F, ...... 20 CCF ..... 0.29 CCF/F

If I could reduce this heat loss by a factor of 5, then it might be possible to increase the thermal time constant toward 4 days. In my case not possible without rebuilding the house.

There are architects in town that are pushing very thermally efficient home designs. Usually 6" walls with staggered 2x4 studs with foamed in place foam insulation, and staggered 2x4 studs. Basements with insulated walls and floors. Ventilation heat exchangers. And ground based heat pumps. But at our present natural gas prices I think a high efficiency gas furnace is operationally competitive with ground based heat pumps, and a lot lower capital cost.

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[Fulthrotl]

Power co. Has a program daytime hours 22 cents a kWh nights weekends holidays 5 cents a kWh . Customer wants me to install something to automatically turn off four electric heat circuits and his water heater.The four heating circuits are in a separate sub panel next to the main. My idea is to use a 24 volt thermostat that I can program to call for heat at 50 degrees during the 22 cent time periods and say 75 degrees for the 5 cent time. I'm thinking a contactor between main and sub.and another for the water heater. Problem is 24 and 240 in same box. How about a RIB mounted on side with low volts outside? Better ideas are very much appreciated.

RIB is a simple solution. i like simple, mostly.... unless i get
bored, or am designing a pid controller for my smoker...
then i end up going full space shuttle. :dunce:

are the 4 heaters being controlled from one t stat?

simple. get a nest programmable controller, and
set it up any way you want. set it to turn on at 40
degrees during expensive time, if all you want to do
is keep stuff from freezing.

separate t stats? you could use 4 nests....

the good thing about nest's is you give the owner
a iphone app set up, and they can do anything with
the nest they want to remotely, including turning on
the heat if they need it on the way there.

the water heater, use a intermatic 7 day timer to turn
the heat off on peak times. use it to drive a relay if the
contacts in the intermatic aren't big enough.

 

[kwired]

140216-1427 EST

kwired:

My home built in 65-66 has full fiberglass insulation in 2x4 studs, and 10" in the second floor ceiling, and a furnace with possibly 70% efficiency. During the summer I did a thermal time constant estimate, and it seemed to be a little less than 24 hours.

During the summer my gas consumption is about 1 CCF or 100,000 BTU per day, hot water heating and some range top cooking.

Last month gas consumption per day was:
1-7-2014, ........ -5 F outside, ...... 70 F inside, ...... in-out diff 75 F, ..... 25 CCF ..... 0.3 CCF/F
1-13-2014, ...... 40 F outside, ...... 70 F inside, ...... in-out diff 30 F, ....... 9 CCF ..... 0.3 CCF/F
1-21-23-2014, ... 0 F outside, ..... 70 F inside, ...... in-out diff 70 F, ...... 20 CCF ..... 0.29 CCF/F

If I could reduce this heat loss by a factor of 5, then it might be possible to increase the thermal time constant toward 4 days. In my case not possible without rebuilding the house.

There are architects in town that are pushing very thermally efficient home designs. Usually 6" walls with staggered 2x4 studs with foamed in place foam insulation, and staggered 2x4 studs. Basements with insulated walls and floors. Ventilation heat exchangers. And ground based heat pumps. But at our present natural gas prices I think a high efficiency gas furnace is operationally competitive with ground based heat pumps, and a lot lower capital cost.

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I understand it takes some time to recover capital cost of most ground source heat pump systems, but outside of that what is your electric rate? Last I knew a geothermal still had significant less operation cost than natural gas in these parts.

I don't know current electric rates, but information on 2012 rates from my POCO for my home's rate and class would have been 9.8 cents per kWH for the first 500 kWH, 6.9 cents for the next 500 kWH, 6 cents for the next 4000 kWH, and 6.9 cents for anything beyond that - per month. There is also a $19 charge no matter how much energy is used plus sales tax. Rates did not go up this year, not sure if they changed in 2013. During coldest winter months I probably average 3000 to 4500 kWH depending on conditions, and of course that is for all electric usage not just my heat pump. So the first 1/4 to 1/3 of the consumption is at a little higher rate and after that is at a pretty cheap rate compared to most of the country. AFAIK propane or NG would cost me more to heat my home.

My electric bill from January was only $312.00, used 4048 kWH. That was running all of my general lighting in the house and shop - no heat in shop except some electric heat in a small room of about 100 square feet, a hot tub that didn't get much use but still had to maintain temp so it wouldn't freeze, hot water and clothes drying. And Jan was fairly cold, seems like we had more sub zero temps than usual this year, and a lot of strong winds as well.

We are supposed to have one of the lowest electric rates in the country though, and electric heating is pretty common here because of that. The power suppliers in this area have a lot of capacity to run not only air conditioning in the summer months, but also irrigation loads for farmers in summer months is a pretty significant load in much of the rural area here. That infrastructure that supplies that is not loaded in the winter to anywhere near what it is loaded in the summer, and by giving special rates for electric heating customers does serve the power suppliers interest just to put some additional usage on that infrastructure during this off peak time. Electric rates do go up for nearly all class of customers during the summer months.

 

[ActionDave]

the good thing about nest's is you give the owner
a iphone app set up, and they can do anything with
the nest they want to remotely, including turning on
the heat if they need it on the way there..

Interesting thing about the nest..??they were just bought out by google ...

not happy with knowing everything you do on the web, they want to know how you like you like to live.

 

[gar]

140217-1302 EST

kwired:

My DTE rate averaged over a full year is about $ 0.16/kWh. One rate structure for electric heat is 0.074/kWh for the first 20 kWh per day plus 0.06/kWh for that over 20 kWh. This is just for energy, rhen add to this distribution of 0.043/kWh. Further add sales tax and other charges. Thus, average is not below $ 0.08/kWh.

In 1 CCF there is an energy content of about 29.3 kWh. At $ 0.16/kWh the equivalent of 1 CCF would cost $ 4.69, at $ 0.08/kWh cost is $2.35 . My cost of natural gas is $ 0.793/CCF . Thus, the ratios are about 6 or 3 to 1.

I have never lost gas service for any reason including storms. And I have not lost electric service very often.

For Dec 2013, not as cold as Jan 2014, my bills were:
954 kWh $ 145.08
426 CCF $ 337.86, equivalent to 12,482 kWh.

DTE provides a comparison of my bill with approximately 100 comparable homes. I am am about average on total, high on electric, and low on gas. In my opinion comparable is not really comparable. They do not distinguish between homes that are dog houses, and those that are not, nor between homes used as a business, and not.

.

 

[meternerd]

What about a tankless water heater? Seems like at 22 cents, it would pay for itself before too long. No need to keep water hot when you don't need it.

 

[gar]

140219-1346 EST

meternerd:

A tankless would make no sense. Do an analysis of how much energy is used to keep a well insulated hot water tank at temperature for 24 hours with no water drawn. My guess is about 0.5 kWh three times per day, or 1.5 kWh. I do not have one to test, because I have gas. So if my guess is about correct then at $ 0.22/kWh the keep warm cost is about $ 0.33 .

My hot water usage is about 100,000 BTU per day, or about 20 kWh. Most of this is between 7 AM and 8 PM.

Use of a large hot water tank, possibly 200 gallons, and heated at night would be far less costly than an instant on heater. A tank of this size will have a greater keep warm requirement than a smaller tank, but probably could be insulated well enough to equal a smaller tank.

.

 

[kwired]

140219-1346 EST

meternerd:

A tankless would make no sense. Do an analysis of how much energy is used to keep a well insulated hot water tank at temperature for 24 hours with no water drawn. My guess is about 0.5 kWh three times per day, or 1.5 kWh. I do not have one to test, because I have gas. So if my guess is about correct then at $ 0.22/kWh the keep warm cost is about $ 0.33 .

My hot water usage is about 100,000 BTU per day, or about 20 kWh. Most of this is between 7 AM and 8 PM.

Use of a large hot water tank, possibly 200 gallons, and heated at night would be far less costly than an instant on heater. A tank of this size will have a greater keep warm requirement than a smaller tank, but probably could be insulated well enough to equal a smaller tank.

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Then consider the upfront cost of larger service, larger branch circuit(s), likely higher maintenance costs (typical tank heaters are simple, what few parts there are are relatively inexpensive, and they usually go 5-10 years with little or no maintenance required).

Plus in northern climates the heat they lose is not exactly a total loss during heating season, it just lessens the load for your heating system a little. If you still claim that electric rates are too high for this loss, then maybe you should have a gas water heater in the first place, but same applies to tankless vs tank style water heaters, the tankless may have enough upfront cost and maintenance cost to make one reconsider just how much money they are truly saving. I will not disagree they will use less energy, but bottom line to many is not energy used but rather dollars out of the pocket, with consideration of how many leave the pocket over a time period.

If your overall cost to own and use is less over 5 years maybe up to 10 years, it is worth the investment. If you won't see savings in that time, you are likely better off with the older technology, and one big economic killer is maintenance and repair costs.

 

[gar]

130220-1042 EST

My present 60000 BTU/hr gas 48 gallon tank type water heater was installed in Dec of 1995. That is 18 years of service with no maintenance and moderately hard water.

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[kwired]

130220-1042 EST

My present 60000 BTU/hr gas 48 gallon tank type water heater was installed in Dec of 1995. That is 18 years of service with no maintenance and moderately hard water.

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Probably a pilot light type burner system?

Throw in the higher efficiency technology with combustion air blower and electronic ignition and you are bound to have at least a couple service call situations in that time, and throw away all the money saved by it being higher efficiency Sometimes we go too far with energy efficiency when overall out of pocket expense is what most are concerned with.

Take new cars, they generally use less fuel than the good old cars built before 1980. They also cost more to own and maintain making that old classic not quite as expensive to own as some may think. Now the fact that a 30+ year old car has some other values that are not all that easy to put a price on, is a different matter, but operation cost alone, I would rather have the older car, insurance is also a big factor in the cost of owning a car. A new car generally costs a lot more to insure than some older car that you maybe only have minimal liability insurance on.