electricity monitor

tim smith

put a pressure switch on outlet pressure tap on gas valve that has n/o contacts. Then power up with transformer through contacts to 24v timer. This would accomplish what you are trying to do. The pressure switch is a standard item for add on power venting kits for water heaters to turn on power venter w/ a call for heat. Kinda cumbersome but works. Tim

Mike Dunn

electric usage monitor

I am looking for an inexpensive device that measures the amount of electricity an electric water heater uses over a period of time. I am trying to determine the true cost of making hot water for a period of time.

Jim_47

measure electric usage

What you are looking for then is a 240v recorder. Or....
if you measure the current for each element and record that figure.
Then using acouple of electric clocks, ( not digital but something like an old kitchen clock) wire the clock to only see one leg of the 240v at each element.
when the element turns on the clock will run. set both clocks for 12midnight and check the time and record it the next day etc. you will have an indication of the time it has run. and you would already know the current and voltage you can now figure KWH.

Rich L.

Hour meter

A good freind installed geothermal in a new house and the owners weren't at all happy with the electric bill! He bought a simple hour meter from Grainger and wired it into the control circuit of the heat pump. They recorded the time it ran over a 2 month period in the winter, used Ohm's and Watts laws to find energy used, used the KWH charges right off the customers statement to show them just how much energy the HP was actually using, and therefore cost to operate.

I think it's similar to this one: http://www.grainger.com/Grainger/items/3AE20

tim smith

Rich, I have used those on multi zone pumps systems

for apt bldgs so clients could log how much power each tenant was using. There may be a better way with like a Supco current data logger or the like. Wire in series w/ one leg of power to heater, not at each element and then it will log useage. Possible idea. Tim
http://www.supco.com/LCV Data Loggers.htm here is a link.

Rich L.

Supco

Tim, that would probably give you a more accurate picture yet! I was going for the "cheapie fix" on this one! At about $30 it's something you can do for one job and leave there for the home owner to monitor if they want. Kind of like your aparment pump deal. I haden't thought of these for a multi pump setup like you mentioned, great idea!

Rob Blair

Gas Usage Monitor

Do they make one that you can put inline to measure the amount of natural gas usage?

Rob

Derheatmeister

Tim, why not to ea. element vs Just the incoming? will it not give you a better picture on each element? Also there is data logging equipment that is not too expensive now a days.HM.

tim smith

Richard, re: ea vs incoming

You could do it on both but why not just monitor incoming w/ data logger. I posted link to good current logger above. I know this will be more expensive but will also be hand for future logging also. Simple and quick. Tim

tim smith

Not really but you could.......

use the pressure monitor logger and plug into outlet tap on water heater gas valve and then based upon how long it logs pressure to burner in hours times btu input would work. a thought, Tim

tim smith

one other note

Rich, you would need 2 hour meters as the elements work independantly of each other and not at same time which I am sure you knew. Tim

Mike Dunn

Found it

Check out the T.E.D. I can log the the kw usage for up to a month without any extra accessories.

www.theenergydetective.com

Doug_7

Red Lion Timer

I use a Red Lion Model CUB7T100 Programmable Timer, Positive Image Reflective, 10 – 300 volt signal input.

Program multi-range timer to display in Hours in increments of 0.01 hours.

Digital display shows total hours that it detects a voltage between 10 volts to 300 volts. Read display daily, weekly or monthly to get operating hours.

I use it on 24 volt boiler gas valves to measure firing hours. Also use it to measure heat demand hours, pump run hours etc. Would also work on elecctrical heating elements.

http://www.redlion.net/Products/DigitalandAnalog/Timers/Elapsed/CUB7T.html

Doug

Mike Dunn

firing hours

Do you have a formula that you can translate firing hours into how much gas was used during a particular time period?

Rich L.

BTU/h

I haven't done it Mike but would assume (gets me in trouble!) you could mutiply the hrs of operation by the btu/h input of the appliance to get gas usage for your set period of time.

Doug_7

Gas Use from Firing Hours

Conventional gas appliances have a nameplate capacity rating in Btu / hour. So if a gas water heater is rated at 200,000 Btu / hour and runs for five hour that is 1,000,000 Btu of gas used.

Then use any on-line energy converter to convert Btu into units of your choice. We measure natural gas in GigaJoules and 1,000,000 Btu = 1.055 GJ.

We are talking about measuring the gas use of Conventional gas appliances that fire at a fixed rate when ON as opposed to modulating gas appliances that fire at a variable rate.

I have used Red Lion Timers to determine actual efficiency of conventional hot water tanks. Wired across the gas valve with the scale set to 0.01 hours they determine gas use very accurately.

Measure the firing hours between 11 PM and 6 AM when no water is being used and you have the total standby losses. Do it again with DHW recirculation OFF and you have the recirculation heat losses.

Doug

Mike Dunn

dumb question

Hi Doug,

I have a dumb question. Where would I hook up this digital counter on a standard vent water heater gas valve. I have no visible wires except the thermocouple.

Greg_40

water heater elecatrical consumption

I work for a rural electric cooperative and we have been promoting electric water heaters for some time. In fact, we have a number of untis in employee's homes with a standard electric meter connected to the water heater. The family sizes vary from 2 to 6 in the homes.

We have studied the usage for several years and have a spread sheet with usage of various homes and can tell one thing for certain. That is in the winter, water is much colder entering our homes from a municipal system and the Delta T is great enough to show substantially increased usage in winter months than summer. This proves a fallacy of estimating annual water heating costs by reviewing a customer's summer gas, LPG or oil consumption only.

We have found that small households can save energy $$ (at present rates) often with an electric vs. gas water heater. Themagic number seems to be four household members- that is about an average break even with Nat. Gas costs, smaller households save $$. Larger families may suffer with recovery and quantity. We also encourage water conservation by giving any member a quality water saving shower head, sink aerators, etc.

With the outlook for increased electrical energy costs looming over all of us, all bets will be off in the next few years. Who would have imagined that LPG would cost $2.00/gallon a few years ago? Natural Gas has been basically stable over the last 20+ months, but it's costs still vary on a daily basis.

jp_2

got some explaining to do here!!!

how can electric water heating be more economical for a household of 4 but not for 5?

I don't see electric vs gas a nonlinear type of system?

around here, a btu from electricity is 4x the cost of a btu from nat gas.

Doug_7

Red Lion Timer on Dry Contact Closure

Sorry, all my gas valves are 24 volts.

There is also a Red Lion Timer Model CUB7T000 that times on a dry contact closure, rather than on a 10 to 300 VAC voltage, if that helps.

Doug