Jandy LXi Heater Loud Humming

[kshepela]

I have a 7 year old Jandy LXi that has been mostly trouble-free up until about a month ago and no changes have been made to the system since installation. It started making the exact sound from this video (note: I know this is a JXi but sound is 100% identical):

Details:
1. Sound only happens with the heater on (pool or spa mode)
2. It starts up about 1:30-2:00 minutes after being turned on

Here is what has been checked so far:
1. Air Flow - I took off the top and vacuumed/removed any debris to ensure unobstructed airflow.
2. Water Flow - My pool guy wanted to increase pump speed but I don't have a variable speed motor so can't do that. I also appear to have adequate flow back to the spa to operate the jets.
3. Build up in Heat Exchange - There is no visible reason to believe that we have build up (chemistry is good, there is no physical evidence of calcium build up in the pool and there is no signs of debris when cleaning out the salt cell), but my pool thinks he can flush it out with a water additive. I suggested flushing directly by with while vinegar or low dose of muriatic acid/water but not sure if folks here recommend this (Jandy said it wasn't in their manual so can't recommend it).
4. Gas Flow - Nothing has been added to the gas line there shouldn't be a flow issue. In the forum that I took the video from it recommended replacing the Thermal Regulator Value for the JXi but I don't see this part on the LXi. Is there a comparable part that could be causing the issue?

Any other thoughts would be more than welcome.

Thanks,
Kevin

 

[ajw22]

Welcome to TFP.

You have something vibrating internally either in the gas flow, water flow, or exhaust. Something broke off and is caught someplace and is vibrating causing the buzzing sound. No telling where or what.

You or a technician need to start poking around inside the heater to find it.

You can take off the sides and if you have a stethoscope try and isolate the area the sound is coming from.

@swamprat69 @ps0303

 

[swamprat69]

Homemade stethoscope = a screwdriver with the handle placed to your ear and the blade placed on a surface

 

[ajw22]

Homemade stethoscope = a screwdriver with the handle placed to your ear and the blade placed on a surface

I was going to suggest that but it can take a trained ear to operate properly.

 

[Poolbreh]

That’s a jxi not lxi. The thermal regulator and internal bypass are located in manifold I would check both.

 

[ps0303]

A moan like that is usually water flow. A dirty filter or an old filter cartridge, if yours is that kind, can cause water flow issues. When I say old cartridge, it can appear to look clean but the pleats in the filter cartridge can hold back water flow. If it were the thermal regulator the unit most likely would throw an error code for a hi-limit but it's worth checking out as well.

 

[kshepela]

A moan like that is usually water flow. A dirty filter or an old filter cartridge, if yours is that kind, can cause water flow issues. When I say old cartridge, it can appear to look clean but the pleats in the filter cartridge can hold back water flow. If it were the thermal regulator the unit most likely would throw an error code for a hi-limit but it's worth checking out as well.

Thanks Paul. Flow seems to keep coming up as a potential culprit. Two quick questions for you since I can't turn the pump speed up to check:
1. I am reading that filter grids for DEV48 generally last 7-10 year and I am right on the edge of that time period. Would you recommend replacing regardless of appearance? I actually just cleaned them and recharged them after the sound appeared and I didn't notice any difference.
2. Is it possible to run the system briefly without the filter grids in to see if that is the issue?

 

[Poolbreh]

You are right I’m not seeing a thermal regulator for the Lxi. It does have an internal bypass in the manifold that you can check.

 

[ps0303]

Well I am not much of a filter guy but if it were a cartridge filter I would pull the cartridge and see how it runs. I believe these DE filters usually have a multi-port valve and one of the settings might be a to bypass the filter.

 

[kshepela]

Update on heater:
1. Water Flow - A couple thoughts here: 1) The LXi doesn't have a VersaFlo or another bypass so it is my understanding that the water flows through the heater 100% of the time and without the heater on there is no sound so I am ruling out water flow for now.
2. Build up in Heat Exchange - While there was no reason to believe that there was build up it turns out there actually was. I used a recirculating pump to run a 10:1 solution of Water/Muriatic acid and it knocked a ton of Crud loose (I used rubber testing caps with a hose bib rather than buying the Jandy parts and building service valves). I reassembled and the noise is gone and hasn't reappeared after running for over 2 hours.

New issue revealed itself (maybe was there the whole time but I only focused on the noise)...As I was testing, and after running for about 25 minutes, I noticed that it stalled out at 88 degrees on my iAqualink app. I then tested the water and found that it was at temp and that the temp on the LXi unit was at temp as well. I am assuming that this means that the Temp sensor is shot but I wanted to confirm I am replacing the correct one. Best I can tell I am replacing the sensor that sits in between the pump and filter - is this correct?

Also, anyone have an opinion on aftermarket products like this - Temperature Sensor Replacement for Jandy®/Zodiac® Systems by Optimum Pool Technologies ?