Slow leak near sensor plug in heater

swamprat69

Well-known member
Mar 30, 2019
271
Las Vegas, NV
If it just spins, the threading is probably stripped. If you are lucky it is just the threading on the part rather than the jacket and can be fixed by replacing the sensor. If it is the female jacket thread (hopefully the sturdier of the 2 different materials) stripped or both threads crossthreaded you may have a bigger job of it. When you say "thermocouple" do you mean the cylinder seen at the bottom right of your photo? That looks like a sensing bulb. Where does the capillary tube coming out of the end of the cylinder terminate at the other end? On the refrigeration side of a system, a sensing bulb is usually strapped to a pipe and insulated and connected to a refrigerant metering device such as a TXV (thermostatic expansion valve). But what I see in the photo has a rim at one end of the cylinder making it unsuitable for making good contact on a straight piece of pipe (unless strapped at a bend in the piping). It does look like it might be made to fit in a "well"??
 

sagosto

Well-known member
May 28, 2019
119
Mahwah, NJ
The top jacket where the wires enter seems to tighten up while the bottom jacket doesn't seem to tighten (spins and spins). Both of the jackets (e.g. white material) appear to be the same. Which are you referring to? And, how can I tell what sensor that is for?

Yes, the cylinder at the bottom. It's literally just laying against the metal. The other end of the cylinder has attached wires but it isn't easy to follow them to see where they are located.
 

swamprat69

Well-known member
Mar 30, 2019
271
Las Vegas, NV
This looks like the manual for your heater. https://www.royalswimmingpools.com/rp2100manual.pdf Refer to page 25 for a photo of the water (In/Out) header (Black Polymer Jacket with sensors attached). This looks like the temperature sensor adapter that is leaking. Amazon.com : Raypack 006714F Sensor Adaptor Digital Elect : Garden & Outdoor. It looks like it is leaking at the middle white part connection to the header which is a male pipe thread. Page 25 number (3. AFT Models) has instructions for removing the thermostat temperature sensor. I would replace both of the white parts. It looks like the other sensor is used with a well for millivolt heaters, but I don't know why it would be included in yours if it is not used other than manufacturer ability to meet higher demand for either Millivolt or AFT units and the order and ease in which the parts are put into the units when they are made?
 

Pool Clown

In The Industry
Sep 5, 2008
2,136
Silicon Valley, CA
Remove the sensor, then the white fitting from the header. The threads on the white fitting are softer than the threads on the Capron header which makes the white fitting sacrificial in case of over tightening. Hopefully the white fitting threads are stripped and you can just replace it. While it is apart, thoroughly clean the Capron side of all thread compound and inspect the thread area and shoulder area for cracks just to be sure.

The dangling part is and old temp sensor that the tech didn't remove.
 
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sagosto

Well-known member
May 28, 2019
119
Mahwah, NJ
@Pool Clown -- You nailed it. It's the old sensor left intentionally to remind that it was replaced.

A bit of teflon tape between the 2 fittings fixed the leak completely. I suspect compression due to mother nature overtime is the root cause. But, do I replace the fitting given it is not leaking?