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Here we've got a leak from the inside of a
thermo-well, (sometimes referred to as a 'dry-well'). It's basically a hollow tube inserted
into the pvc plumbing (usually on the suction side of the plumbing, going to the pump). In
order to repair the problem, the thermostat sensor must carefully be removed, the thermowell
removed, replaced, then the thermostat sensor re-inserted into the new
thermowell. |
| On this particular type of thermowell, there is a
small cotter pin that must be removed prior to removing the rubber plug and the thermostat
sensor. I use a pair of needle nose pliers to straighten it out and pull the cotter pin
through the mounting holes. Extreme care must be exercised not to damage the small copper
capillary tube coming from the thermostat. |
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With the pin removed, I carefully remove the sensor
from the tube. Note the presence of a lubricant on the sensor. This is used to more
effectively transfer the water temperature from the inside of the metal tube to the sensor
itself. Don't clean this off, it is beneficial to regulating temperature. In this
instance, the lubricant compound has also helped to prevent corrosive damage from the water leak to
the capillary assembly. |
| With the termal sensor removed, all we have to do
now is to unscrew the old thermowell from the pvc fitting. Use care not to stress the pvc
piping very much, or you could cause leaks in other parts of the system. If your thermowell
was installed with epoxy sealant, or other kinds of hardening sealant, you may have to break the
threaded pvc fitting, in which case you'll have to replumb this assembly with fittings from the
local building supply or hardware store. |
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In almost all cases, removal is easily accomplished by
using a pair of pliers, rotating the thermowell counter-clockwise. |
| Pulling out the old thermowell. You may have
a bit of water come out, but if you're ready for it, the new thermowell can be put in within
seconds. |
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Typical leaking thermowell... with a small hole
corroded into the end of it. |
| This is the replacement thermowell, smaller and
less expensive than the original... but it works very well for the application, as long as the
thermostat sensor diameter does not exceed the diameter of the well. In this case, I've
lubricated the threads of the plug with water-lube, to ensure a positive seal on the
threads. |
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Installation is very simple. All I do is screw
the new thermowell in place by hand.
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| And it's ready to accept the thermal
sensor. |
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Carefully pushing the sensor in as far as it will
go.... |
Now I will carefully dress the capillary tube in a
fashion that will keep the sensor in place. (The previous installation used the cotter pin
for this).
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| Note how I used a simple nylon tie-wrap to hold
the sensor in place. You can use electrical tape or even duct tape to achieve the same
results. Next thing, fill up the spa
and check for leaks.
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