Mastertemp 400 Cycling...driving me crazy!!

[wgipe]

My Mastertemp 400HD is in its 3rd season. At the beginning of last season, it started throwing HLS errors and cycling every 15 minutes or so. Pentair can't get anyone to actually respond to a service call in my area, so I'm stuck replacing parts on my own as they play part replacement bingo .... So far, the blower and control board and membrane have been replaced with no improvement. They had me take the thermal regulator out to see if it was gunked up, but it looks brand new. I've seen where replacing the regulator has fixed this issue in several other cases. Is it possible mine's just screwed up? Is it safe to pull it and run it without to see if that'd the case?

Any ideas from the forum before I fix it permanently with tannerite? This things going g to be the death of me!

 

[JamesW]

Check the stack flue temperature before it fires and watch it when it turns on to see what the stack flue temperature reading is.

 

[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.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[wgipe]

Check the stack flue temperature before it fires and watch it when it turns on to see what the stack flue temperature reading is.

Thx. Watching it now. I originally posted that it was a SFS error - but it is a HLS error. Not sure if that changes things. I've edited the original post to correct that.

 

[JamesW]

Is the bypass set correctly?

I know that you have the flow switch, so that should prevent operation with low flow.

 

[wgipe]

Is the bypass set correctly?

I know that you have the flow switch, so that should prevent operation with low flow.

View attachment 491508

It is indeed set correctly.

 

[wgipe]

It just threw another HLS error. SFS was steady around 290-294 the whole time.

 

[JamesW]

Remove the thermal regulator cap and pull out the thermal regulator and look at the top to see if you can see the internal bypass valve disc.

 

[JamesW]

It looks like this, but you can only see the disc looking at the top of the tube.

You can see the other part if you look into the water inlet hole.

Take pictures looking into each hole.

 

[wgipe]

This?

 

[JamesW]

 

[JamesW]

 

[JamesW]

If the internal bypass valve is ok, it might just be a bad high limit switch.

 

[JamesW]

If it was a water flow problem, the stack flue temperature would be too high.

Most likely, it is just a defective high limit switch.

 

[JamesW]

You can test the thermal regulator using hot water to see if it opens correctly.

It probably wouldn't hurt to replace it if it is suspect.

 

[wgipe]

Had to break out the bore scope to get in there... Does this help?

 

[wgipe]

If it was a water flow problem, the stack flue temperature would be too high.

Most likely, it is just a defective high limit switch.

Is there a way to test the HLS?

 

[JamesW]

See video posted above.

The thermal regulator has the temperature stamped on it for where it should open.

You can run with the thermal regulator removed to see if that makes a difference.

I suspect that it's probably a bad high limit switch.

 

[JamesW]

Looks like the internal bypass is ok.

Probably a defective high limit switch tripping at low temperature.

You can test it in hot water to see where it trips.

 

[JamesW]

The high limit switch (HLS) opens if the heat exchanger outlet temperature goes above 135° F (57° C).

Try water at 120 degrees and then 125, 130, 135 etc. until the high limit switch opens.

Use a multimeter set to ohms.

It should be zero ohms until it gets to 135 degrees Fahrenheit and then it should read O.L (Open Line).