Pentair Mastertemp 300 Keeps cycling

wetlands08

New member
Aug 6, 2024
2
new york
Surface
Vinyl
Chlorine
Liquid Chlorine
Hey everyone,

I need your expertise on a troubling experience I had today with our pool company, which is the same company that installed our pool heater about five years ago. They came out while I wasn’t home, and my wife dealt with them. The company charged us $300 for the visit, which I would have been fine with if the work had been properly done. However, the technician claimed he couldn’t get the blower to turn on.

When I got home later in the day, I discovered that the reason the blower wouldn’t turn on was that the technician never moved the thermostat setting up from 69°, which I had set during my troubleshooting attempts. The technician told my wife that we needed a new blower and that it would be cheaper to buy and install a new heater than to replace the blower.

After realizing that the blower does come on when the thermostat is adjusted, I don’t trust anything the technician said.

I have a video that I’m attaching, along with a description of the issue. The heater worked fine in May but was off for about eight weeks in June and July. When we turned it back on, a horrible smell emanated from it. I removed the panels and found evidence of mice inside, though there doesn’t seem to be visible damage to any wiring. The heater turns on for about 15 seconds and then turns off, repeatedly cycling like this. During the brief periods it’s on, it does produce hot water from the jets, and the water flow to the unit is unobstructed.

Given this situation and what the video shows, could there be another issue at play? What would you recommend I do? I feel that the company didn’t troubleshoot the problem correctly and is pushing me towards an unnecessary replacement. If it is actually the blower, which I doubt, I can get one for about $600 and am confident I could replace it myself.

I don’t trust their diagnosis now, and I would greatly appreciate any advice you can offer.

Best, Joe

Video
 
Last edited:
It is not the blower if the heater is firing and not giving you AFS errors.

What is your filter PSI? When did you last clean your filter?

Check the thermal regulator and internal bypass valve.

The mice may have done more damage then you think to the heater. Check internally in the heater for where they nested and what they chewed on.

They could even have crawled into the burner can.

 
In the video you only showed the heater cutting off once. The Fenwal ignition control will try 3 times for ignition before it will throw a code. Let the heater try longer to see if the Fenwal ignition control will throw a code. There are multiple reasons that the heater may be cycling. Do you have a multimeter and know how to use it safely and correctly.
 
Hey everyone,

I need your expertise on a troubling experience I had today with our pool company, which is the same company that installed our pool heater about five years ago. They came out while I wasn’t home, and my wife dealt with them. The company charged us $300 for the visit, which I would have been fine with if the work had been properly done. However, the technician claimed he couldn’t get the blower to turn on.

When I got home later in the day, I discovered that the reason the blower wouldn’t turn on was that the technician never moved the thermostat setting up from 69°, which I had set during my troubleshooting attempts. The technician told my wife that we needed a new blower and that it would be cheaper to buy and install a new heater than to replace the blower.

After realizing that the blower does come on when the thermostat is adjusted, I don’t trust anything the technician said.

I have a video that I’m attaching, along with a description of the issue. The heater worked fine in May but was off for about eight weeks in June and July. When we turned it back on, a horrible smell emanated from it. I removed the panels and found evidence of mice inside, though there doesn’t seem to be visible damage to any wiring. The heater turns on for about 15 seconds and then turns off, repeatedly cycling like this. During the brief periods it’s on, it does produce hot water from the jets, and the water flow to the unit is unobstructed.

Given this situation and what the video shows, could there be another issue at play? What would you recommend I do? I feel that the company didn’t troubleshoot the problem correctly and is pushing me towards an unnecessary replacement. If it is actually the blower, which I doubt, I can get one for about $600 and am confident I could replace it myself.

I don’t trust their diagnosis now, and I would greatly appreciate any advice you can offer.

Best, Joe

Video
Get a piece of green wire (or buy Pentair's outrageously expensive kit) and follow the instructions on the attached file. It sounds like your heater is not sensing the flame and it may be due to a bad/corroded ground that doesn't allow the very-tiny current to flow.
Since you have the heater open, it is a 15 minute job that may solve the issue.
 

Attachments

  • MasterTemp_and_Max-E-Therm_Heater_Groundwire_Kit_Installation_Instructions_English (1).pdf
    307.9 KB · Views: 2
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.