| Thermostat Replacement or Calibration, With
Side Control Housing |
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Note that the purpose of this section is to
show you how to increase the temperature setting or replace the thermostat
switch on an electro-mechanical, capillary tube type thermostat switch. This
requires disassembly and reassembly of the spa side control housing, or removal
of the thermostat device from a heater casing, deck mounting plate, or other
switch encasement, and the reassembly of the switch and its
components.
If you have a thermostat that has a very small
COPPER or Stainless Steel tube coming from it, then you should be able to
perform this procedure. Note that some later model controls utilize electronic
or digital thermostats which do not have this small tube, and actually looks
like a black inslulated wire. With this type of control, the ONLY recommended
course of action is to REPLACE the entire control box or thermostat
assembly.
Recalibration is NOT an exact procedure. Since
these types of thermostats only provide relative indications of hot or cold
water, replacement with a new capillary type thermostat is recommended for
safety reasons.
In view of the fact that most of these types of
thermostats will lose their maximum temperature sense rating over time, and
recalibration is all that is typically required, this procedure is presented to
show you how an experienced spa technician may solve this problem quite easily,
without actually having to replace the thermostat switch.
SpaSide Controls
Explained
Safety
Warnings!
| Remove Power from the spa/hot tub BEFORE performing this
procedure. Failure to comply with this requirement, can lead to
electrical shock and/or electrocution! |
Disclaimer
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Thermostats of this
type provide RELATIVE indications of temperature, (ie, hot or cold only), and
re-calibrating a thermostat to make the heater perform at a higher temperatures
is a SERIOUS procedure. Inappropriate or incorrect calibration can lead to
overheating of the equipment, fire, melt-down of plumbing or jets, injury or
death to occupants of a hot-tub/spa.
The calibration procedure
illustrated here is AGAINST (not in accordance with) manufacturer
recommendations, and will void your warranty. |
Disclaimer |
READ FIRST BEFORE YOU
CONTINUE
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This is a
typical side control panel for a spa. It will have air push buttons... maybe
more or less than what is pictured here. The leading manufacturers of these
side controls are Len Gordon, Pres-Air-Trol, and Tri-Delta (now known as
Tek-Mark), however, the spa manufacturer's logo will typically be displayed on
the faceplate. Using a digital health type thermometer is the best way to
determine the spa water temperature, and the calibration of the thermostat
device.
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| If you're calibrating a thermostat device that is contained in one of
these types of side controls, unplug the side control plug from the spa control
box. It will have 5 or 6 prongs on it. |
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Lift up the corner of the face plate to expose the screws that are
holding the side control to the spa shell. This may require the use of a knife
or other sharp thin tool to pry up the corners. Use care to avoid damage to the
face plate. On
some spas, the screws may not be made of stainless steel, and may be rusted
beyond recognition. Typically, on these, the corners of the face plate may
already be lifted up because of the rust. Do whatever is necessary to remove
the screws. In many cases, the screws will simply snap off with a little prying
or twisting of a screwdriver. Try not to do any damage to the plastic side
control housing.
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Remove the side control assembly
from the spa and you will see 4 to 6 screws holding a bottom plate in place.
You may have to break the manufacturer's seal in order to gain access to the
thermostat compartment. |
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Very
carefully... pull the assembly apart. If you have a side control where the
thermostat won't come out of the assembly, then click
here for
further instructions. Watch for neon bulbs that are attached to a printed
circuit board; try not to disturb them too much. Be sure that when you
disassemble the box that you observe the position of all components inside for
re-assembly. |
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| Typical assembly. Note the neon glass
bulbs that are attached to the printed circuit board. Normally two of these
will be darker than others, the HEAT and READY indicators. This is normal for
neon bulbs. Now, if
the objective is to replace the thermostat, remove the two or three screws
holding the wires in place to the thermostat switch, and remove the old
thermostat. Be sure to remember which wires go where. If your heater operation
ends up working backwards (on when it should be off), then you switched two of
the wires; (the ones that are right next to each other. Once this is done, skip
to the reassembly section below.
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| At this point, the only way
to determine how LOW your thermostat has drifted, is to turn the thermostat
SHAFT back and forth to hear the audible click of the switch mechanism.
Visualize the point in rotation where the 'click' sound occurs in the ON
position, (when turning the shaft clockwise). Remember that the idea here is to move the ON point farther BACK in
the rotation of the thermostat shaft, in order to get the heater to make the
water hotter. This is NOT an EXACT procedure that requires mental judgement on
the part of the individual doing the calibration. All assumption for the
results of this operation are your own.
Now, using an allen (hex) wrench, turn
the calibration screw (accessible through the frame of the thermostat)
clockwise approximate 1/4 turn at a time, until the thermostat ON position
moves BACK in the rotation to a point that is estimably lower than the original
setting.
As an example, (using a typical old
thermostat in use in the field), the ON point with water that is in the 80
degree farenheit range, will normally be in the late 20% of the clockwise
rotation, ie, midway through the HOT indication on the control panel. What I
usually do is adjust with the allen wrench so that the ON point moves midway
into the WARM area indicated on the control panel. This is typically at the 55%
point in the thermostat's rotation.
To complete this operation successfully,
it will require you to go through quite a few on/off switch activations by
rotating the shaft back and forth while you adjust t he allen
screw.
The desired end result of this operation
is a thermostat that allow the water to heat to a maximum of 104 degrees
farenheit. However, if you have ANY doubt as to what you are doing here, your
best alternative is to replace the thermostat with a new one calibrated at the
factory, and not try to calibrate it yourself.
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Re-Assembly Is simply the reverse of dis-assembly. Very
carefully insert the printed circuit board into the provided slot in the
plastic housing, and the thermostat at the same time, being sure that the index
(flat spot) on the thermostat shaft coincides with the index on the plastic
shaft in the control box.
Once the box is together, be sure that
the neon bulbs on the printed circuit board lay in the proper indicator
"slots" of the housing, and that none of the attachment wires on the
bulbs are twisted or shorted with one another.
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| Respecting the copper
capillary tube, as well as the rubber seal around the base, mate the back of
the the housing to the main body, insert the screws, and tighten them
down. Be sure that when you
tighten the screws that you don't squeeze out the rubber seal. The seal should
only be compressed a small amount... (NOT flattened!!)
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If you were
able to remove the original screws without breaking them, and if they aren't
rusted or corroded, reuse them and attach the control panel back into the spa
mounting hole. Otherwise, use new screws. If you had to break off the original screws, you
can either try to drill them out (definitely NOT recommended), or apply 100%
silicone sealant between the control box and the spa shell. Be sure to let it
cure properly before allowing moisture or water from the spa to get on the
control.
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When you have finished the above procedure,
plug the side control back into the control box, and re-energize power. The
thermostat setting should activate the heater according to your
adjustment. |
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