off peak electric

cgutha

Now that the cost of propane is climbing, I wonder if electric off peak heating is viable. the guy who had this place before me installed a 300 kva 3 phase delta transformer outside my back door. Last year I brought the three phase inside the Hotel Berry, feeding a 225 amp service. (52 slot)
I have learned the cost comparison between electric and LP is to take the KW cost and multiply it by 27 to get the LP per gallon cost.
Because the Hotel was originally one pipe steam heat, I intend to keep it one pipe. Nevertheless, heating the first floor with multiple space heaters at the equivalent of $0.40 per gallon would help any economic situation.
I have contacted my electrician who is out of the office, and the electric company's district rep, Bing and google. But finding the information to wire and control off peak seems to be a well kept secret to the point where I realize I am guessing.
After three months and a couple of calls, I was finally contacted by the rep, it sounds as if his device controls the 24 volt thermostats. this sounds easy in a central heating house where the electric plenum is part of the backup heater.
but one pipe does not have a plenum. I do not have duct work and I am not putting duct work in and I found only one electric boiler so far.
I have seven 30 amp 240v circuits run to where I want them and 3-50 gal. electric water heaters connected to my 240v three phase distribution box. (I figure three 50 gal water heaters connected in parallel is cheaper to buy, install and maintain than one commercial water heater. replacement parts are cheap, plentiful and off the shelf)
My questions concern control and metering of the off peak portion of the system. If I sound confused, there is a reason. I need information.
I have ten devices each with their built in t-stats scattered throughout the house, i wired these into the panel expecting the panel to be controlled as it is on the second meter.

i fear I do not have enough information to ask an intelligent question. Asking google how off peak electric works is time consuming as it gives several commercials and no info.

Do I control and meter each circuit? does the meter record total usage and the off peak device subtract the off peak usage? how does this work? I need details.

ug!
ceg

JUGHNE

Years ago, the old school method of WH off peak was a time clock that would put you on the upper elements (heat top of tank only with use) during day time hours and then switch to lower element at night. (heating the entire tank).

Like I said this was years ago and just for heating DHW.

Some have installed WH elements in the lower portion of stand alone CI radiators that were not piped into the system.
That would give you some heated mass to coast thru part of the day.

Hot_water_fan

I have learned the cost comparison between electric and LP is to take the KW cost and multiply it by 27 to get the LP per gallon cost.

That's step 1. Step 2 is accounting for the efficiency of the LP and electric appliances. LP is less efficient, so electricity is even cheaper.

Larry Weingarten

Hi @cgutha , Water heater manufacturers are going through this same question right now as they try to standardize controlling heat pump water heaters for managing grid power usage. How about contacting the heater manufacturers and your local utility to see if they are all working towards the same standard and equipment? Smart meter / AMI system, SCADA system, and HEMS/Hub/Gateway are three protocols that are being considered.

Yours, Larry

cgutha

interesting. My solution is to set up ten 30 amp contractors controlled by his radio device, run the leads through three current transformers and metering that. But this is only if I understand what they are doing.
ceg

GroundUp

Your 27x theory is not exactly accurate. One kWh yields 3412 BTU as it is 100% efficient. A gallon of LP holds 91,500 BTU per gallon, but is not 100% efficient when exchanged into usable heat. Given the nature of a gravity system, we'll assume an 80% efficient boiler for math's sake. 91,500 X .8 = 73,200 BTU output which is equivalent to 21.45 kWh, not 27. If LP is $3/gal, power would have to be under $.14/kWh to be cheaper. Of course this is all hypothetical and your particular scenario will vary, but in my neck of the woods the off-peak rate of $.07 is considerably cheaper than the current $2.69 LP. A year ago when LP was $.89, even off-peak was expensive in comparison.

Jamie Hall

I suspect that part of your confusion -- which is quite natural; magicians don't want you to learn the secrets -- is that you are really dealing with two separate problems. One is how to control the devices on the interruptible or off peak load, and the other is how to measure the usage. To add to the confusion, an off peak supply is not quite the same as an interruptible supply, as the former is always connected, but billed differently at different times of day, while the latter may be shed at will, remotely, by the power supplier.

In either case, so far as any systems which I have seen or heard of, the items to be on off-peak or interruptible must be on their own meter . You need to supply the wiring from the meter to the load -- in the usual manner -- building switchgear and wiring (breaker panels or whatever)-- and the power company will supply the meter.

cgutha

Hi Jamie, so far the magicians are not talking.
Ground up: your calculations and examples are correct, This is why I did not look at off peak until now.
Jugne: I have seen those timers. but those will not apply here.
hot water: efficiency does matter. figure 80%
Larry: are you saying this is cutting edge?
time for work. the electrician at work does not know either
ceg

jumper

Not a good idea in my opinion. How to store off peak? Better to install those ceiling height electric radiant in each room. Unoccupied can be kept colder. Two circuits & two heaters in each room. During peak hours one circuit is off except for very cold weather. Radiant heat allows comfort at lower temperatures.

Radiant can also be undersized and steam can be fired up for coldest days. I once managed an apartment building with intentionally undersized hydronic heat and supplementary electric running from each tenant's meter. Some tenants left windows open with electric on max when they weren't home. Shows how much people cared about energy bills?

cgutha

Jumper, I have undersized the electrical. I figure if the electric can handle everything down to zero degrees, that will take care of three fourths of the heating year.
No, I cannot have electric on another circuit as backup. that would defeat the purpose of off peak.
I talked with the distributor again.
It sounds like one controller to disrupt the entire panel is the correct way. This panel has its own meter which I already have.
still waiting for the electrison to respond,
will keep you posted
I can travel south to flee from winter, but the politicians are everywhere

ceg

jumper

>>No, I cannot have electric on another circuit as backup. that would defeat the purpose of off peak. <<

Not for backup. Idea is you can run both during off peak and only one during peak. Hopefully demand is minimal during daytime when you pay peak hours prices.

cgutha

Hi, everyone, I have been busy.
As soon as I entered my last comment, the power company called.
The interrupt device goes between the meter and distribution box.
My panel is 3-phase 225 amp so you can look up the controller price.
After two attempts of purchasing one, I found one at 85% off it has arrived.
I then thought placing a switch between the meter and controller would be good. that way when the controller goes bad, I do not need to call the electrician to turn off the power and fix the controller.
I learned that these switch boxes come in standard sizes. Because I am over 200 amps, I need to go with the 400-amp box. you can look up those prices also. Fortunately, the electrician had a used one on hand. he even supplied the fuses.
It turns out that 225 amps on three-phase will be enough power to heat the entire house. That is 40 kva on each leg, including the hot water heaters. I am running 240 volts.
Meanwhile, the right section for my Weir-McLain EGH-80 is on its way. I hope to begin putting it back together in a few months.
The whole house project is nearing its exhausting end. The third floor is nearly rocked and taped with only the baths and fire escape to complete. My wife says she will do the painting (She saw what I had budgeted for this and wants it all) She also says not to do the floors.
i hope to have everything ready by June 1. my help does not show up.

Pictures will be coming. I have not updated my website either.