Heater Won't Fire

[Kit]

I have a Pentair MasterTemp 400 spa heater. Yesterday I noticed that the water temperature of the spa was below the minimum set temperature of 77F. The heater light on the EasyTouch control panel was illuminated; but the heater itself wouldn't fire. On the readout display on the heater itself, there was a code "E01" & the "service heater" light was on. On the underside of the display, the LED7 & LED11 were also illuminated. No other LEDs were illuminated. Unfortunately, the user manual for the heater made no reference to either of these LEDs. So I am at a bit of a loss as to where to start diagnosing. Any guidance that you can provide would be greatly appreciated.

In the meantime, I plan to clean the filters, inspect the internal bypass & check the thermal regulator.

Thank you for any help you can provide.

Kit

 

[Poolbreh]

E01 is for thermistor I would check wiring and clean first than follow here.

If thermistor checks out I would do a resistor test to make sure board is good

 

[Kit]

Poolbreh: Thank you so much for the information. I pulled the thermistor which I thought looked surprisingly good considering it is about 8 years old. Nevertheless, I ordered a new one as well as a high-limit since it was inexpensive & had never been replaced. Interestingly, the thermal regulator proved to be defective since it would not open even in 150F water. So, with the new parts, the heater might fire up.

Oh, two quick questions: Until I get the new thermal regulator, can I run the system without the old regulator? Or would you advise that I simply shut the heater off while the pump is running? Thank you.

 

[1poolman1]

The heater will not work without the thermal regulator. If it fires at all, which it may, too much water will bypass the heat exchanger. The heater will make all kinds of banging noises and, hopefully, shut off. No heater should ever be made to fire without all factory-installed parts being in them. Just too dangerous.

 

[Kit]

Excellent advice. Until I receive the new thermal regulator, I re-installed the old one & disabled the heater on the EasyTouich panel.

 

[Kit]

Update to my original post: As indicated by the "E01" error code on the heater display, I replaced the thermistor. Heater would still not fire & the same error code was displayed. I found this to be curious. As I had mentioned earlier, I noticed that the thermal regulator would not open even under 150F running water. I am still waiting for the new thermal regulator to arrive. Question: Although the thermal regulator LED was not lit, is it possible that the "E01" error code might also be displayed if the thermal regulator is defective?

Thank you for your help.

 

[ajw22]

For a test replace the thermistor with a 10K resistor.

If the heater starts and reads 76F then you have a problem with the new thermistor.

If you still get the E01 then you have a problem with the wiring to the thermistor or the board.

Are there any signs that rodents have been in the heater?

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Temperature Sensors - Further Reading

www.troublefreepool.com

 

[Kit]

No signs of rodents whatsoever. I will replace the thermistor with a 10K resistor & report back. Naive question: Can I get a 10K resistor at Home Depot or Lowes? Or does this require a trip to an electrical supply store?

 

[wireform]

radio shack
RadioShack 10kΩ ⅛W 5% Carbon-Film Resistors (5-Pack)

 

[Kit]

Unfortunately no Radio Shack nearby.

 

[wireform]

Unfortunately no Radio Shack nearby.

https://www.mallscenters.com/brands/stores/radioshack/medford--oregon--rogue-valley-mall

 

[Kit]

Thanks for the info, but no longer in business.

 

[ajw22]

Amazon is the new RatShack

 

[Kit]

That’s always my backup. Thanks.

 

[Kit]

I am still trying to locate a 10K resistor locally before I order a 100-pack from Amazon. But before I do that...is it possible to test the thermistor itself with an ohm meter?

 

[Poolbreh]

I’m sorry I thought the video showed how to test for ohms and just realized it’s just showing how to replace the thermistor.
You can but it’s more prone to user error.

Temperature Sensors - Further Reading

www.troublefreepool.com

You would have the sensor in a few different temperatures of water and would compare the resistance to chart. Although the 10k resistor would be a far easier test.
As far as the thermal regulator not being open, it would most likely trigger hls and not error 1. Do you have an external bypass that is open?

 

[Kit]

I will order a 10K ohm resistor today. Forgive my ignorance, but I assume that an external bypass valve would be located "upstream" from the heater inlet to allow water from the filter to bypass the heater. Am I correct? If so, there is no such valve on my system. Thank you for helping me with this issue.

 

[Poolbreh]

Correct.

 

[Kit]

One final question (at least for now): If the resistor test indicates that the new Pentair thermistor is not defective, is there anything else that might trigger the "E01" error code (& prevent the heater from firing) before I replace the circuit board?

 

[Poolbreh]

One final question (at least for now): If the resistor test indicates that the new Pentair thermistor is not defective, is there anything else that might trigger the "E01" error code (& prevent the heater from firing) before I replace the circuit board?

Bad or corroded wiring.