Question about Pentair MINIMAX NT TSI IGNITER

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The Digital Panel on the front of my Pentair MiniMax heater says "LO" (where it normally displays water temp.) What does that mean?

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LO simply means that the temperature sensor of this heater is reading the water at a temperature of 58° or lower.
Because of the condensation that will occur at these temperatures, the heater is designed to remain off!

Posted on May 25, 2015

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Posted on Nov 18, 2009

  • Scott Corey-reid May 10, 2014

    or clean pump basket or check continuity of pressure switch. its not just a filter issue joespools!



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Posted on Jan 02, 2017

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LO on Display

"LO" means lock out. This means that the heater has failed to fire, and will not attempt to do so again until it is turned off and back on.

Either the heater is getting no gas, the gas valve is not opening for any of several reasons, the signal to spark is not being sent to the ignitor, the ignitor has failed, or the heater is failing to detect that the burner has been lit. Best to get a tech on it.

Jan 26, 2014 | Sta Rite Sr400na Max E Therm Pool & Spa...

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Pentair Pool Heating Rapidly Increases Temp on Panel then shuts off.

Check the Thermal Reg in the header and also make sure you have adequate water flow thru the heater, make sure your filters are clean and there are no external by-pass valves open.
If you remove the Thermal Reg in the header and the heaters seems to run fine the replace with a new one.

May 03, 2017 | Pentair Minimax NT Heater

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Pentair Minimax NT heater -- panel doesn't respond.

if connected to control make sure heat is enabled

Jun 22, 2017 | Pentair Minimax NT Heater

2 Answers

The heater won't ignite. Just getting display LO.

On a Pentair, this means Lockout.
its a safety precaution that disables the heater. To unlock, simply power cycle heater off and then back on.
If this continues, diagnostics required to identify reason for non ignition.
Does Service light come on?
if so, you can either remove the front panel and look up behind the circuitboard, or actually the backside of the control panel circuit board. or remove the top of the heater, there are four wingnut each corner on the bottom side of that top cover. your goal is to clearly see the backside of that touchpad. There will be a red light and you want to see the letters next to it. this will be the indicator of the problematic situation.
Report back any findings in the comment section or in a new question on this forum.

Jan 29, 2011 | Pentair Minimax NT Heater

1 Answer

The temperature on digital readout says a certain temp. but the water is not that hot yet. and there is about a 20 degree difference in tempature of water and readout.

Your temp sensor has gone bad. This is a small tube with wires coming from it. You will find this on the left side of the water manifold. Follow the wires to the front of the heater and unplug it from the temp board. Install the new one in the reverse fation. good luck.

Mar 18, 2010 | Pentair MINIMAX NT TSI IGNITER

2 Answers

Digital display shows LO what should i do

LO is a limit string open. This is what I refer to as a saftey circut. It will peobally be a dirty filter or a plugged up basket. The heater need enough water flow to run or it will overheat and cause damage to the heater. Without enough flow the saftey circut shuts the heater down before this can occur. If it is more than this it is probally time to get a repairman involved. Good luck and remember this is a box full of fire that runs on high voltage.

Mar 05, 2010 | Pentair Minimax NT Heater

1 Answer

Pentair Pool Heater reads HI

I am not sure if you have found the answer to your issue, or not, but just in case. The display showing HI means that the heater is "reading" the water temp at over 114 degrees.

This will go away if you change out the Thermister on the inlet manifold for the heater.

Jun 06, 2009 | Pentair Minimax NT Heater

2 Answers

Minimax pool heater cuts out at 91 degrees when remotely set for

Turn the temp set knobs on the front of the heater all the way up do both pool & spa temp.
If that doesn't help flip the selector switch on the front of the heater the pool temp. This switch doesn't control what heats up Pool or spa it just selects the heater on and which thermistat to use

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Pool heater will not heat

Im no pro, but I know there is an air sensor behind the main board. If the fan is running you probably have a problem with that sensor. If your lucky the air hose could have just popped off.

Mar 20, 2009 | Pentair Minimax NT Heater

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