# water heater circuit

D

#### Dave

Jan 1, 1970
0
I am new here and have a question. Normally (at least here) a 220 volt
hot water heater is wired using 10/2 with ground. I have a timer box
connected and it works fine and has for years now. In order to connect a
110-120v circuit to operate a 110v timer (one that increments time in
units when the heater is actually using energy), one would initially
think seeing that the ground is there that you could connect to either
the red or black wire and the ground to get 110-120v. I guess it would
work but I want to do it correct according to code. My Intermatic Timer
box has a lug for the nuetral (if it exists) and also the ground. My
current setup uses only the ground, red and black. Am I correct that I
could run a new 10/3 with ground and connect all 4 wires to my timer box
and then use the nuetral, ground ,and one of the 120v wires to have a
correctly wired circuit to add my 110v intermittent timer to??
Dave

D

#### Dave

Jan 1, 1970
0
Hi again,
I already got it figured out and am going to do as I planned.
Thanks anyhow,

B

#### Blue Crown

Jan 1, 1970
0
I am new here and have a question. Normally (at least here) a 220 volt
hot water heater is wired using 10/2 with ground. I have a timer box
connected and it works fine and has for years now. In order to connect a
110-120v circuit to operate a 110v timer (one that increments time in
units when the heater is actually using energy), one would initially
think seeing that the ground is there that you could connect to either
the red or black wire and the ground to get 110-120v. I guess it would
work but I want to do it correct according to code. My Intermatic Timer
box has a lug for the nuetral (if it exists) and also the ground. My
current setup uses only the ground, red and black. Am I correct that I
could run a new 10/3 with ground and connect all 4 wires to my timer box
and then use the nuetral, ground ,and one of the 120v wires to have a
correctly wired circuit to add my 110v intermittent timer to??
Dave
Those time clocks come with 220 volt clock motors to use with water
heaters, that way you don't need the insulated neutral.

D

#### Dave

Jan 1, 1970
0
I guess I didn't make that clear enough now that I read it again. I am
connecting a solar batch heater to preheat my water going into the hot
water heater and using an idea from another guy, I was going to connect
an analog 110 volt "clock" or 110 volt counter (here is where I used the
word timer incorrectly) to the circuit to move the clocks hands only
when the heater element was using current. This way I could see how many
minutes a day my hot water heater was costing me $$. I have a "Little Gray Box" Intermatic water heater timer box and I thought it would be more professional if I added a duplex outlet to plug my analog clock into. So if I used a duplex outlet and used the ground and either the red or black wire, it wouldn't pass code. So I thought I would rerun the wire with a 10/3 with ground to add the nuetral and connect the duplex outlet to the nuetral and either the red or black to run my clock. Then I remembered the thermostats would give me some problems as if I connected as I just said, it would run my clock as long as the Intermatic timer "allowed" current to the "thermostats". So plan "B" is to use a current sensing relay so it energizes only when the heater is actually on. I am guessing I can get away with one if I put it in the right spot on my 2 thermostat hot water heater. Thoughts? Dave E #### [email protected] Jan 1, 1970 0 Dave said: I guess I didn't make that clear enough now that I read it again. I am connecting a solar batch heater to preheat my water going into the hot water heater and using an idea from another guy, I was going to connect an analog 110 volt "clock" or 110 volt counter (here is where I used the word timer incorrectly) to the circuit to move the clocks hands only when the heater element was using current. This way I could see how many minutes a day my hot water heater was costing me$$. I have a "Little
Gray Box" Intermatic water heater timer box and I thought it would be
more professional if I added a duplex outlet to plug my analog clock
into. So if I used a duplex outlet and used the ground and either the
red or black wire, it wouldn't pass code. So I thought I would rerun the
wire with a 10/3 with ground to add the nuetral and connect the duplex
outlet to the nuetral and either the red or black to run my clock. Then
I remembered the thermostats would give me some problems as if I
connected as I just said, it would run my clock as long as the
Intermatic timer "allowed" current to the "thermostats".
So plan "B" is to use a current sensing relay so it energizes
only when the heater is actually on. I am guessing I can get away with
one if I put it in the right spot on my 2 thermostat hot water heater.
Thoughts?
Dave

You can do that. One possibility: a current transformer
with a diode in series and a (properly chosen) resistor
in parallel, feeding an optoisolator in series with a
1K resistor. The other end of the optoisolator actuates
a relay via a transistor. You'll need a power supply at
the relay circuit end. Physically, the current transformer
is installed at the water heater, and you connect it to
the diode, parallel resistor, series resistor and
opto-isolator with a run of thermostat wire. I'll try a
diagram of the sensor side of the circuit:
Diode 1K
AC ----+----|>|---/\/\/\-----+
/ |
\ burden v Opto
/ resistor -
\ |
AC ----+---------------------+

The lines labeled AC are the two wires from the current
transformer. With power off, disconnect one of the
power wires to the heater, pass it through the center
of the transformer, then reconnect the power wire.
The burden resistor is REQUIRED for safety. I used a 33
ohm, 50 watt resistor in my circuit, which reacts (lights
an led) to 5 amps in the primary. I wanted huge reliability
in my burden resistors, so I used a pretty high wattage
resistor.
I used model TR-3025-S current transformers from
Toroid Corporation of Maryland - see:
http://www.toroid.com/
and click on current sensing transformers on the
right side of the screen roughly 1/2 way down.

For a schematic of an opto-isolator relay driver
circuit, see:
http://www.mg.dropbear.id.au/powermod/circuit.html

D

#### Dave

Jan 1, 1970
0
Ok, thanks for the detailed info. On the Toroid slection they offer 15,
30, 60, or 90 am for the current transformer. Which one is best? I
checked the website for the opto-isolator relay driver circuit and the
image doesn't come up.. I also am curious if being that the heater has 2
elements and 2 thermostats, if I need to make 2 of these for accurate
readings as the heaters can operate independent of each other. That
being said, I also found a nifty little already made device that may
work and its about $35 already made. Check this out and let me know if it would work ok, (other than its somewhat bulky size). http://www.gogeisel.com/Catalog/aprilaire_current_sensing_relay_-_120_volts_953547.htm Thanks, Dave E #### [email protected] Jan 1, 1970 0 Dave said: Ok, thanks for the detailed info. On the Toroid slection they offer 15, 30, 60, or 90 am for the current transformer. Which one is best? I checked the website for the opto-isolator relay driver circuit and the image doesn't come up.. I also am curious if being that the heater has 2 elements and 2 thermostats, if I need to make 2 of these for accurate readings as the heaters can operate independent of each other. That being said, I also found a nifty little already made device that may work and its about$35 already made. Check this out and let me know if
it would work ok, (other than its somewhat bulky size).

http://www.gogeisel.com/Catalog/aprilaire_current_sensing_relay_-_120_volts_953547.htm

Thanks,
Dave

Dave,

I looked at the site and I can see the relay, but
I don't see any details on it, so I can't say for sure
if it would work. My guess - and it's only a guess - is
that it is not a good choice. It is for a humidifier, which
probably draws a lot less current than your hot water heater.

If you build your own, I'd use the 30 amp toroid. Your
heater will draw less than 30, but more than 15 amps, most
likely, so the 30 amp one is best.

Regarding accuracy:
You are looking for an on-off indicator, not a measurement.
Your clock can only measure time, not how much power was
used. Your water heater will draw current and operate
the circuit, regardless of which thermostat in the water
heater turns on.

I don't know why you couldn't open the site I posted:
http://www.mg.dropbear.id.au/powermod/circuit.html

I'll describe it - you can draw a schematic from the
description. The emitter of the 4N25 optoisolator
connects to a 4.7K resistor. The resistor connects
to the base of an NPN transistor. (A 2N2222 would be a
good choice - the schematic shows a BC547B). The emitter
of the transistor goes to ground. The collector goes to
the relay coil. The other lead from the relay coil goes
to plus 12 volts, and to the collector of the 4N25.
Also there is a 1n4001 diode in parallel with the
relay coil with the banded end connected to the plus 12
volt side.

If any of this is new to you, you might want to get
some help. My concern is the use of the current
transformer. You need to disconnect a wire feeding
the hot water heater, run it through the transformer
and reconnect it. You can't afford a loose connection
to the water heater - and you can't afford sloppy
wiring to the current transformer. It MUST have the
burden resistor connected when the heater is powered
on, so you need to be sure of your wiring. The output
side of the optoisolator is non critical, as long as
you wire up the relay contacts to your duplex receptacle
safely.

D

#### Dave

Jan 1, 1970
0
Thanks for the info. I got the schematic with a different browser and
then rebooted my pc and all is well. Check out the link below as it has
sensed can be changed by the amount of turns of the wire in the pickup.
The output is 110 volt so I am guessing the output could surely run a
clock and even a night light for instance if I wanted a visual. I am
capable of doing the connections, and I have made some circuit boards in
the past and have soldering equipment etc...but I was just thinking if
the relay I can buy will work and is cheaper then it would be the way to
go...What I do like about your idea though, is the possibility it is
smaller to connect the toroid where I need to put it. As far as accuracy
I know I have 2 4500 watt elements so if I know how long each one is
"on" I can do the math and come up with a pretty accurate estimate.
Thanks again,
Dave

http://electronicaircleaners.com/da...Code=ElectronicAirCleaners&Product_Code=RP-51

E

#### [email protected]

Jan 1, 1970
0
Dave said:
Thanks for the info. I got the schematic with a different browser and
then rebooted my pc and all is well. Check out the link below as it has
sensed can be changed by the amount of turns of the wire in the pickup.
The output is 110 volt so I am guessing the output could surely run a
clock and even a night light for instance if I wanted a visual. I am
capable of doing the connections, and I have made some circuit boards in
the past and have soldering equipment etc...but I was just thinking if
the relay I can buy will work and is cheaper then it would be the way to
go...What I do like about your idea though, is the possibility it is
smaller to connect the toroid where I need to put it. As far as accuracy
I know I have 2 4500 watt elements so if I know how long each one is
"on" I can do the math and come up with a pretty accurate estimate.
Thanks again,
Dave

http://electronicaircleaners.com/da...Code=ElectronicAirCleaners&Product_Code=RP-51

Dave,

Thanks for the link - it worked well. My guess is that
it will work for you, now that I've seen it. You could
call the company to make sure, and ask them if it will
work to detect a current of up to 30 amps. I didn't see
a spec for the maximum current it will work with. Your
heater will definitely draw more than the 4 amp minimum
they specify.

If the company says the model 51 will work with up to
30 amps, you can install it anywhere you have access
to the branch circuit wiring. It does not have to be
installed in the water heater. What you would need to
do is install a junction box where you want to put
the relay. You would need to cut the wires that go
from the circuit breaker panel to the water heater,
and route them through the junction box, splicing
them inside the box with wire nuts. The relay bracket
would go over one of the hot wires. Generally speaking,
there is not enough slack in the existing wiring
to allow you to do that. But say you can install
a j-box within reasonable distance to the breaker box.
You could disconnect the cable from the breaker panel,
pull it out and route it into a j-box, than add a
new piece of cable from the J-box to the breaker
panel. If the wiring is exposed in the basement,
that is a good option. You could run a 110 volt
circuit into that same j-box, and install the relay
and the duplex receptacle in the same box with the
240 volt heater circuit and the 110 volt circuit.

D

#### Dave

Jan 1, 1970
0
I was going to connect a junction box onto the Intermatic Timer Box that
is currently allowing my hot water heater to come on only twice a day
for 2 hours in the AM and PM. First I was going to rerun the 10/2 with
ground to a 10.3 with ground to make available the correct 120v circuit
for a duplex outlet. Being I already have a breakpoint in the wiring
thanks to the Timer Box, I can connect the relay to the red or black
thats lengthened and pulled into my added junction-box. I can connect
the releay to either the red or black, and the now available white wire
(nuetral) to complete the 120v circuit correctly to a duplex outlet.
When the existing Timer Box allows the current to flow, if it does
indeed flow, the amps sensed by the relay should complete the circuit to
the outlet(s). The little "timer motor" I am hoping doesn't draw the 1/4
amp or 30 watts or the relay would energize when the timer allows
current flow and give me false readings (basically show me the unit used
current 4 hours a day as set by the 2 hrs AM and 3 hrs PM). That all
said and thought about, I checked my Timex brand electric clock I bought
with my Kill A Watt Meter and it doesn't draw the specified current on
the load end of the relay! Arrghh. So I guess I need to find 3 watt
clock or add a night light to the outlet, or hunt down a cheap hour
meter in 110v. I found a Cramer brand that would have worked but it is
not available from the Surplus Center as it was in their old catalog and
not their new one...Anyhow, it looks like I am almost there unless the
relay, by NOT seeing the correct current IE: too little doesn't cause
damage to itself which I am assuming it just won't switch.
Thoughts?
Thanks,
Dave

E

#### [email protected]

Jan 1, 1970
0
Dave said:
I was going to connect a junction box onto the Intermatic Timer Box that
is currently allowing my hot water heater to come on only twice a day
for 2 hours in the AM and PM. First I was going to rerun the 10/2 with
ground to a 10.3 with ground to make available the correct 120v circuit
for a duplex outlet. Being I already have a breakpoint in the wiring
thanks to the Timer Box, I can connect the relay to the red or black
thats lengthened and pulled into my added junction-box. I can connect
the releay to either the red or black, and the now available white wire
(nuetral) to complete the 120v circuit correctly to a duplex outlet.
When the existing Timer Box allows the current to flow, if it does
indeed flow, the amps sensed by the relay should complete the circuit to
the outlet(s). The little "timer motor" I am hoping doesn't draw the 1/4
amp or 30 watts or the relay would energize when the timer allows
current flow and give me false readings (basically show me the unit used
current 4 hours a day as set by the 2 hrs AM and 3 hrs PM). That all
said and thought about, I checked my Timex brand electric clock I bought
with my Kill A Watt Meter and it doesn't draw the specified current on
the load end of the relay! Arrghh. So I guess I need to find 3 watt
clock or add a night light to the outlet, or hunt down a cheap hour
meter in 110v. I found a Cramer brand that would have worked but it is
not available from the Surplus Center as it was in their old catalog and
not their new one...Anyhow, it looks like I am almost there unless the
relay, by NOT seeing the correct current IE: too little doesn't cause
damage to itself which I am assuming it just won't switch.
Thoughts?
Thanks,
Dave

If the sensing part of the relay "sees" less than
the rating, no problem - it just won't switch on.
There will be no damage.

On the other side of the relay, the instructions
call for a minimum load of 3 watts and a maximum load
meet the minimum is great.

Your timer motor will draw very little current -
no where near enough to activate the relay.
Sounds like you are in great shape!

D

#### Dave

Jan 1, 1970
0
Thanks for all of your input into my project. I will let you know how it
goes when it all comes together. Maybe off topic but I am using two
tanks to make this batch heater and one is from a gas hot water heater.
In the 2 tank system, once the water is hot and moving, the primary tank
will preheat the water going into the secondary tank before it goes into
my in house hot water heater. Do you see an advantage to putting the
tank from the "gas" hot water heater as the primary over the secondary
(or vise versa) as the design has a 4" hole down the center for the
flue? I know when the hot water rises due to stratification, it will go
to the top. But the area and the hole in the center must make some
difference as to its best position as far as a preheater, or the tank
getting the preheated water...
Thoughts?
Thanks,
Dave

E

#### [email protected]

Jan 1, 1970
0
Dave said:
Thanks for all of your input into my project. I will let you know how it
goes when it all comes together. Maybe off topic but I am using two
tanks to make this batch heater and one is from a gas hot water heater.
In the 2 tank system, once the water is hot and moving, the primary tank
will preheat the water going into the secondary tank before it goes into
my in house hot water heater. Do you see an advantage to putting the
tank from the "gas" hot water heater as the primary over the secondary
(or vise versa) as the design has a 4" hole down the center for the
flue? I know when the hot water rises due to stratification, it will go
to the top. But the area and the hole in the center must make some
difference as to its best position as far as a preheater, or the tank
getting the preheated water...
Thoughts?
Thanks,
Dave

Dave,

Sorry, I don't know which one should be first, or if
there would be any difference.

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