Pentair Mastertemp Heater Issues - New Pool Owner

[Hardyboy568]

Hello!

I've been an inground pool owner for all of 45 days. I've enjoyed learning about pools and certainly swimming in the pool with my kids. I've been checking chemicals regularly, but I've been running into some heater issues that I'm hoping someone can provide some insight on. I know I've got quite a bit to learn yet, so very open to any feedback. I wont try to turn my heater on until these issues are resolved.

I've got a Pentair Mastertemp 250 that was installed this year before I moved in. It is heating a 35,000 gallon pool with 2 skimmer baskets. The issues I am running into is the Service Heater light comes on sometimes after an hour, sometimes after several hours. If I shut the heater off and turn it back on, it works for a while and then shuts off. I've been running my IntelliFlo4 160 variable speed pump on the 2nd or 3rd speed setting. I've been cleaning the skimmer baskets and the basket in the pump regularly.

The other issue is the LCD screen that displays the temperature sometimes turns completely black. (attached)

Here are my questions:
Is the Service Heater light turning on due to user error, or is there a problem with the heater?
Is the LCD screen turning black due to user error, or is there a problem with the heater?
What speed should I run my variable speed pump at when I have the heater on?
Is SwimUniversity a valuable resource or are there better resources?

I really appreciate anyone input!

 

[JamesW]

The LCD is probably turning black due to excessive sun exposure. Try to block the sun from getting on the screen.

Check the LEDs on the back of the circuit board to see what error is indicated.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

You need about 25 to 30 gpm for the heater.

I would recommend a flow meter to verify the flow rate. F-30200P flow meter.

 

[Killer95Stang]

I'd probably look into a warranty claim if that heater is only a couple months old. Did it have a heater before, and this was just a replacement? What rpm's are you currently running, and what are Pentairs flow rate claims at the given rpm's? Can you list all the equipment you have in your signiture, that would help people understand your system a little more.

 

[Hardyboy568]

The LCD is probably turning black due to excessive sun exposure. Try to block the sun from getting on the screen.

Check the LEDs on the back of the circuit board to see what error is indicated.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

You need about 25 to 30 gpm for the heater.

I would recommend a flow meter to verify the flow rate. F-30200P flow meter.

Thanks James. I will take a look at flow meters. The LCD only turns black if the heater is running. After the heater is off for 30 minutes or so, the LCD is back to normal.

 

[Hardyboy568]

I'd probably look into a warranty claim if that heater is only a couple months old. Did it have a heater before, and this was just a replacement? What rpm's are you currently running, and what are Pentairs flow rate claims at the given rpm's? Can you list all the equipment you have in your signiture, that would help people understand your system a little more.

Thanks for the info. This had a heater before and this is a replacment unit as the other one was 20 years old and starting to go out. I'm not sure how to check my current RPMs - How do I do that? I can look at the Pentair flow rate claims and post that research back here.

I just updated my signature to include some specs about my pool.

 

[Tres Gatos]

A dirty filter will also cause overheating.

 

[JamesW]

An LCD screen going black is usually due to overheating.

That might indicate a problem.

When the heater starts, press and hold the On button until the exhaust temperature is displayed.

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.

It could be a low flow problem.

Your pump is really old.

If you can verify the rpm and the filter pressure, we can estimate the flow rate.

I would get the flow meter to verify the actual flow rate.

Until you get a flow meter, feel the returns to make sure that you have good flow.

Check the circuit board for error LEDs when the heater turns off.

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.

 

[Hardyboy568]

An LCD screen going black is usually due to overheating.

That might indicate a problem.

When the heater starts, press and hold the On button until the exhaust temperature is displayed.

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.

It could be a low flow problem.

Your pump is really old.

If you can verify the rpm and the filter pressure, we can estimate the flow rate.

I would get the flow meter to verify the actual flow rate.

Until you get a flow meter, feel the returns to make sure that you have good flow.

Check the circuit board for error LEDs when the heater turns off.

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.

This is very helpful James.

I had the heater on for a few minutes and the exhaust temp came in at 240 which is very low. Do I need to test it after the heater had been on for an hour or so?

The returns have very good pressure when I have the pump to 3 or 4. We’ve got a slide we turn on when my girls are swimming, so that is why we have the pump so high. I’ll keep an eye on it though.

I watched the video To determine the error LEDs. When the heater shut off, the only light was Service Heater. I followed the process map on the manual and it brought me to do some diagnostics:

Continue to observe heater for several minutes. Cycle heater on and off several times. Observe for delayed or rough ignition, poor combustion, premature extinction of flame, evidence of boiling, or operation of any diagnostic LED. Go to pertinent trou- bleshooting section if any malfunction is observed.

some of this seems a bit over my head for a rookie. I don’t hear the ignition kicking on until about 5 seconds after the heater is turned on... is that a delay or normal? I felt the pipe leaving the heater to see if it was very hot to indicate boiling, but wasn’t sure how well heat transfers through PVC. Didn’t feel different than the intake pipe.

I will get a flow meter as I believe it would be helpful to be able to easily see the water flow rate.

Regarding RPM and filter pressure, here is what I found. The pump has 4 speeds:
Speed 1 (750 RPM), Speed 2 (1500 RPM), Speed 3 (2350 RPM), and Speed 4 (3110 RPM).
The previous owner told me to run it at Speed 3 when the heater is on, so that is 2350. Pressure from my sand filter is 15-20.

thank you for your input.

 

[Hardyboy568]

I’ve been backwashing 1-2 times per week. Is this the norm?

A dirty filter will also cause overheating.

 

[JamesW]

I would check the gas pressure. Low temperature could indicate a weak flame.

What is the gas line size and length?

 

[Hardyboy568]

the OD of the pipe is 1 inch. Length is 11 feet. Attached pictures for reference. From the condition of the pipes, it looks like they used the same pipes for the old heater.

 

[JamesW]

I would check the gas pressure and the flame current.

Heater Flame Sensing - Further Reading

www.troublefreepool.com