Sta Rite heater SR400HD blower

[Ken21]

I have a Pentair Sta-Rite Max-E-Therm 400HD m/n: SR400HD LP Gas. The back of the control board light called for a replacement of the AFS, 42001-0061S. The switch was replaced along with all the clear tubing. Now, when turned on, the heater blower turns on and the heater fires and starts to heat for about a minute then turns off and the Service Heater light comes on, then the heater blower starts again and the Service Heater light goes out and the heater fires again. This cycle continues. On and Off. Any suggestions as to what might be wrong?
I also replaced the High Limit Switch (HLS) which the back of the control board light called for. Water flow is at 45gpm.

 

[ajw22]

Welcome to TFP.

Check the thermal regulator.

As a test remove the thermal regulator and see if the heater works normally.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[JamesW]

Are you getting an error light?

If not, check the flame current.

 

[Ken21]

Welcome to TFP.

Check the thermal regulator.

As a test remove the thermal regulator and see if the heater works normally.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Thank you for the information. I will inspect the Thermal Regulator

 

[Ken21]

Welcome to TFP.

Check the thermal regulator.

As a test remove the thermal regulator and see if the heater works normally.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

I tested the Thermostat in hot water. It did not open at 120, or at all, even at 200. I'm ordering a new one. Thank you very much. Hopefully this was the issue. The heater appears to work fine right now without the thermal regulator. fingers crossed

 

[JamesW]

Are you getting an error light?

If the Heater "Service Heater" LED comes on, there has to be an Error Light on the board or on the Fenwal.

The following are the LEDs:

1. .....PS (Pressure Switch)
2. .....HLS (High Limit Switch)
3. .....SFS (Stack Flue Sensor)
4. .....AFS (Air Flow Switch)
5. .....AGS (Automatic Gas Shutoff).
6. .....Service System
7. .....Thermistor
8. .....Heating
9. .....Pool On
10. ...Spa On
11. ...Service Heater.

If none of these error lights are on, then the Fenwal will show the reason for the "Service Heater" LED.




Try running the heater with the thermal regulator left out.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Heater Flame Sensing - Further Reading

www.troublefreepool.com

Testing the Flame Sense Circuit.​

The Fenwal has two test points for flame current FC+ and FC-. Flame current is the current that passes through the flame from sensor to ground.

The best way to measure the flame sense current is with a true RMS meter. Measure the current with a good true rms meter that can measure dc current in the microamp range.

To measure flame current, connect a True RMS or analog DC micro-ammeter to the FC+ and FC- terminals. Readings should be 1.0 µA DC or higher. If the meter reads negative or below "0" on scale, meter leads are reversed. Reconnect leads with proper polarity.

If you don't have a RMS meter you can just test for voltage between FC+ and FC- terminals to confirm if you have flame sense. Each micro-amp of flame current produces 1.0 VDC. For example, 2.6 VDC equates to 2.6 µA. Voltage is an indirect indication but easier to do with typical DIY equipment. But it's still very difficult to measure unless you make up some pin wires to clip your voltmeter to. Or you can order some insulated micro clips for the test.

The reading should be 3-8 volts and this corresponds to the millionth's of an amp signal your flame sense signal should reading. If you try to check this be very careful since you can easily short the 24 vac circuit which can blow the transformer before the 2 amp fuse blows.

When not operating, the flame current should read 0 volts dc and 0 microamps dc. DC amps and voltage should be zero when there is no flame.

When there is a flame, there are ions in the flame that can carry current from the flame sensor to the burner and then through the ground back to the Fenwal. This electro-chemical principle is used for flame detection in most newer gas heaters because it has proven reliable and safe since it detects an actual flame rather than the technique of measuring temperature to infer a flame used in older heaters.

 

[JamesW]

 

[Ken21]

Are you getting an error light?

If the Heater "Service Heater" LED comes on, there has to be an Error Light on the board or on the Fenwal.

The following are the LEDs:

1. .....PS (Pressure Switch)
2. .....HLS (High Limit Switch)
3. .....SFS (Stack Flue Sensor)
4. .....AFS (Air Flow Switch)
5. .....AGS (Automatic Gas Shutoff).
6. .....Service System
7. .....Thermistor
8. .....Heating
9. .....Pool On
10. ...Spa On
11. ...Service Heater.

If none of these error lights are on, then the Fenwal will show the reason for the "Service Heater" LED.

View attachment 536937


Try running the heater with the thermal regulator left out.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Heater Flame Sensing - Further Reading

www.troublefreepool.com

Testing the Flame Sense Circuit.​

The Fenwal has two test points for flame current FC+ and FC-. Flame current is the current that passes through the flame from sensor to ground.

The best way to measure the flame sense current is with a true RMS meter. Measure the current with a good true rms meter that can measure dc current in the microamp range.

To measure flame current, connect a True RMS or analog DC micro-ammeter to the FC+ and FC- terminals. Readings should be 1.0 µA DC or higher. If the meter reads negative or below "0" on scale, meter leads are reversed. Reconnect leads with proper polarity.

If you don't have a RMS meter you can just test for voltage between FC+ and FC- terminals to confirm if you have flame sense. Each micro-amp of flame current produces 1.0 VDC. For example, 2.6 VDC equates to 2.6 µA. Voltage is an indirect indication but easier to do with typical DIY equipment. But it's still very difficult to measure unless you make up some pin wires to clip your voltmeter to. Or you can order some insulated micro clips for the test.

The reading should be 3-8 volts and this corresponds to the millionth's of an amp signal your flame sense signal should reading. If you try to check this be very careful since you can easily short the 24 vac circuit which can blow the transformer before the 2 amp fuse blows.

When not operating, the flame current should read 0 volts dc and 0 microamps dc. DC amps and voltage should be zero when there is no flame.

When there is a flame, there are ions in the flame that can carry current from the flame sensor to the burner and then through the ground back to the Fenwal. This electro-chemical principle is used for flame detection in most newer gas heaters because it has proven reliable and safe since it detects an actual flame rather than the technique of measuring temperature to infer a flame used in older heaters.

The Service Heater light is off. No other error light are lit. The heater is running without a thermal regulator installed and appears to be working normally. The pool water went from 70 to 72 in about an hour. I'm running the pump a 60gpm. This is a VERY helpful site.
Thank you all.

 

[JamesW]

Check the stack flue temperature.

 

[ajw22]

Test the new thermal regulator to see it opens at 120F. We are seeing defective new thermal regulators.

Penatir thermal regulators are more reliable then non-OEM but even new Pentair thermal regulators have not opened at 120F.

 

[JamesW]

Exhaust Gas Temperature.​

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.

Note that the thermal regulator prevents water from circulating through the heater when the heater is off so that cold water circulating through the heater does not produce condensation.

This will probably not be a problem for short periods of time, but if the pipes are getting a lot of condensation, then you should have the thermal regulation in.

Operating with no thermal regulator is done at your own risk since the manufacturer has not approved of doing this.

 

[Ken21]

Test the new thermal regulator to see it opens at 120F. We are seeing defective new thermal regulators.

Penatir thermal regulators are more reliable then non-OEM but even new Pentair thermal regulators have not opened at 120F.

I will definitely check the regular in 120 water before installing it. Thank you

 

[Ken21]

Exhaust Gas Temperature.​

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.

Note that the thermal regulator prevents water from circulating through the heater when the heater is off so that cold water circulating through the heater does not produce condensation.

This will probably not be a problem for short periods of time, but if the pipes are getting a lot of condensation, then you should have the thermal regulation in.

Operating with no thermal regulator is done at your own risk since the manufacturer has not approved of doing this.

Thanks for that information. I'll turn the heater off until I install the new thermal regulator.

 

[JamesW]

It’s probably better to operate without the regulator than not operate since the thermal regulator is open during operation anyway.

The main issue is when the heater is not operating and you have cold water circulating through the heater causing condensation on the heat exchanger, which can cause corrosion and possibly sooting as the heater is fired.

If you are going to leave the heater off, reinstall the thermal regulator to prevent cold water from circulating through the heat exchanger, especially if you see condensation on any of the equipment like the filter or the pipes.