MasterTemp 400 - heating up cycle

[drw4013]

Hello,

I have a MasterTemp 400 from 2017. For a while now, I have noticed it is taking a long time to heat up. Yesterday it took 90 minutes to go from 56 to 96. The temp also maxed out at 96 even if I set it to 102.

So I obviously need to have it serviced, but are there a few things I could check myself first?

Also, one thing I have been noticing is when heating up, it heats for ~60secs and then shuts off heat for ~60secs, continuously. That's not normal, is it?

 

[ajw22]

Check the thermal regulator.

If not the thermal regulator check the internal bypass valve.

Check the stack flue temperature.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

While running, press and hold the On button to display the exhaust temperature (Older Models).

The new models use the Menu to get the SFS.

Here is what the normal exhaust temperature should be:

• Below 250 degrees...very low
• 250 to 290 ..................low
• 290 to 350.................acceptable
• 350 to 480 ..................high
• Above 480...................error/shutdown.

Note: HD models can be up to 75 degrees higher. HD models use a cupro nickel exchanger and the efficiency is slightly lower resulting in less heat transfer and more waste heat.

If the exhaust gas temperature is higher then normal then water may be bypassing the heat exchanger through a broken bypass valve.

If you hold down the "pool on" button, it stays on 80, then flashes to 40, then back to 80, then the 80/40 reading and E05 indicate that the board is not getting a reading from the sensor. It's usually a bad sensor or damaged wires.

 

[drw4013]

Check the thermal regulator.

If not the thermal regulator check the internal bypass valve.

Check the stack flue temperature.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

While running, press and hold the On button to display the exhaust temperature (Older Models).

The new models use the Menu to get the SFS.

Here is what the normal exhaust temperature should be:

• Below 250 degrees...very low
• 250 to 290 ..................low
• 290 to 350.................acceptable
• 350 to 480 ..................high
• Above 480...................error/shutdown.

Note: HD models can be up to 75 degrees higher. HD models use a cupro nickel exchanger and the efficiency is slightly lower resulting in less heat transfer and more waste heat.

If the exhaust gas temperature is higher then normal then water may be bypassing the heat exchanger through a broken bypass valve.

If you hold down the "pool on" button, it stays on 80, then flashes to 40, then back to 80, then the 80/40 reading and E05 indicate that the board is not getting a reading from the sensor. It's usually a bad sensor or damaged wires.

Thank you, I will check those out. Do you know if the 60secs on/off is normal when getting up to temp?

 

[ajw22]

Do you know if the 60secs on/off is normal when getting up to temp?

Short cycling is not normal.

It is a sign of the heater internally overheating due to poor internal water flow so the safeties shut it down. Then it cools down and restarts. And the cycle repeats.

It is likely the thermal regulator is not opening at 120 degrees.