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Typical
Hot Tub Heater Circuits
| The
simplest to diagram is the 120 volt 1.5kW circuit.
Generally, there are several main controls (switches) in the "loop" that
operates the heater. These include the thermostat
(temperature
knob) and high limit (also
a temperature sensing switch, designed to trip at a certain “high” temperature
is usually 120 degrees) a pressure switch or flow
switch, and possibly a relay or contactor
(heavy duty relay) to handle the voltage required by the heater and maybe
to activate the low speed pump. For more information on the many
different types of switches and relays
click here |
These controls will be in a loop.
The
black wire indicates the path of the voltage. It is your hot wire
in to the heater junction box. The voltage path is:
1. To the thermostat
2. Out of the thermostat
and into the high limit
3. Out of the high limit
and to the element.
The neutral (white) goes directly
to the element and ties with one of the indicator light wires. Obviously
the green goes to ground. It's important to note that this path
is the same no matter what color the wires are. For some reason
some thermostats will have a factory red and a factory black. The
electricity still follows the same path. This type of thermostat is just
an open or closed switch (also known as a single pole switch). Power
passes through it if it's closed and doesn't if it's open. The wire
going to the high limit is still following the same electrical path if
it's black or red. Electricity doesn't care
what color the wire is. |
Adding
the Pressure Switch
Note
that the red wire to the low pump still resides on the downstream
side of the high limit. This allows the pump to be activated first
so that the pressure switch will close allowing the voltage to go through
to the element. The pressure switch is there as a safeguard to assure
water flow before allowing the heater to fire. I call it a conditional
switch. The condition of water flow must be present before the switch
will close. |
Many
times just opening your heater junction box (with the power
off of course) will be quite illuminating. If water comes pouring
out you have a problem! Element replacement may be necessary!
If your controls are corroded or wires are burnt or melted the fix could
be as simple as replacing a burnt wire. This can happen when there
are low voltage situations (not a dedicated line) or loose screws, wire
nuts not tight, or loose connectors. When replacing a wire be absolutely
sure it is of the right size to carry the current you are sending through
it. 120 volt heaters at 1.5 kW draw 12 amps and wires should
be #12 minimum and copper! Lamp cord is not acceptable! 240 volt
elements at 6 kW draws 24 amps and should have a minimum wire size of #10. |
Do
you have a 240 Volt heater?
| 240
volt heaters utilize a contactor
that may or may not be present in the heater junction box. It is
often located in the controller box. Convertible 120/240 volt controls
also use this method. The contactor is there to send power
to the heater element after power makes the loop through the controls.
This allows for the use of smaller wire sizes through the control loop
since they will only be operating the "coil" of the contactor. This
is referred to as "pilot duty" as the smaller wires through the controls
only activate the coil of the contactor. The heavy current will flow through
the contactor points and utilize larger wires on the path to the element
when the coil of the contactor is energized. If upon opening your
heater you find two small wires through the thermostat and two more small
wires through the high limit, with two heavier wires to the element this
will be a "pilot duty" situation and a contactor will be involved somewhere. |
| The control loop is the same:
T-stat, high limit, pressure switch (or flow switch) and then to the contactor
coil. When the T-stat is engaged, the low pump activated and all
other switches are closed you will hear the heavy click of the contactor
being pulled closed as the heater activates. |
There
are often extra wires present on both the coil and the high current sides
of the contactor. Neutrals
are often bunched together on the coil connector.
Tracing the hots is the key to finding out what you want to
know. Follow that wire back to it's source. Find out what the
source is. It's called seat of the pants trouble shooting.
In the process you'll find out how the pump comes into the heater equation.
It will be there I promise you! You may have another relay there
for the sole purpose of turning on the low pump. To learn more about
switches and relays click
here. |
If you've figured out
your problem, congratulations! It's not so hard once you know how
things are supposed to work! If you don't find what you need in the
Spa Babe's catalog please call us.....we
have access to anything and everything, even the parts "no one can get!"
New PHone Number 813 235 4574
If you are still stumped
we're a phone call away! Or if you are enjoying your quest, the answer
may await in the next category! Click on!
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