Question about Jandy Laars Lt 400,000 Btu Heater

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High Limit switch corrodes over time. Then it causes a High limit fault. Is there a cheaper place to get the high limit and low limit switches? I see them for $30 to $40 on the internet.

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  • Jandy Master
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Bad header replace then replace high limits

Posted on May 25, 2016

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Posted on Jan 02, 2017

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SOURCE: High Limit Swtiich message

The high limit switch is one part of a safety loop circuit that must work before a heater can fire. It's purpose is to ensure tha tthe heater will shut off in the event of a thermostat failure or if the internal core gets too hot due to a lack of water flow. If the switch is failing, it needs replaced. There are 2 so you can replace both or make an attempt to determine which one is bad. It is best to replace the pair.

Posted on Dec 21, 2008

  • 125 Answers

SOURCE: high limit

that means you need to replace the high limit assembly

Posted on Mar 04, 2009

  • 128 Answers

SOURCE: Jandy LX250 LT Pool Heater High Limit Switch

Jump the High limit switch. If it fires the switch is bad

Posted on Aug 23, 2009

  • 246 Answers

SOURCE: My Jandy LT 400k heater shuts off when the fan

my guess is you are a pool guy so im not going to awser this one

Posted on Oct 15, 2009

  • 64 Answers

SOURCE: My High Limit light comes on, along with service light.

Check your high limit switches. These can be found in the header. There will be two, and they are right next to eachother. You may pull them out and they may look like they are corroded or have gritty stuff on them. If that is the case, they will need to be replaced. However, this is usually an indication that the stud sensors in the header are corroded and the new sensors switches will again go bad. Unfortunately, the stud sensors are brass little posts, that were poorly made on some jandy heaters. They are available on a part, but near impossible to replace. So, it means you will likely need to replace the entire header or keep on replacing the high limit switches. HTH

Posted on May 30, 2010

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1 Answer

I need to know where the high and low limit switches are located on a Winrich Dynasty pellet stove

The Low Limit Switch, goes in the combustion fan housing. The High Limit Switch, goes in behind the Room Blower.
Here's a repair site for you to check out, in more depth. Hope this helps!

Nov 21, 2014 | Pool & Spa

1 Answer

My temperature says HI. but my temp is not warm

The error code is HL, not hi
This is telling you the high limit switch is tripping(safety feature)
Lack of flow, corroded heat exchanger, bad high limit switch, bad thermal regulator.....
Take these steps to try and get it narrowed down.
With heater off
Locate the high limit switch, unplug the two wires connected to it, put a jumper wire in between those two wires. Turn on the heater, if it fires you need to wait till it heats all the way up. If if heats up with no fault in the cycle then most likely it's a bad high limit switch, if it continues to trip then thermal regulator, it may need both parts.
If it doesn't fire at all then you will probably need a professional

Aug 17, 2014 | Pentair Minimax NT Heater

1 Answer

Dryer not heating model #LEA30A amana commercial quality

You need to unplug it and locate the high and low limit switches. These sense the heated airflow temperature. If it gets too hot, the high limit switch kicks off until it cools back down. The low limit switch is used most if the time to cycle the heating element on and off during a normal cycle. I suspect the low limit sensor switch is "open" (has gone bad) and needs replacing. When completely cool, both switches are supposed to be in the On or closed circuit position. You can test them with a ohm meter, looking for low resistance similar to when the two ohm meter test leads are touched together. Again, make SURE the power is off at the breaker or the dryer is unplugged.

Feb 27, 2014 | Amana Dryers

1 Answer

Fan works, but not AC cooling

start with checking a/c pressures is compressor cycling? does it have electric cooling fan? it should come on with a/c. usually there is a low limit/high limit switch. if pressure is low, say below 22psi @ low side port, switch will cut compressor. A quick electric "jump" of low limit switch will confirm clutch,compressor operation,but if pressure is low you may want to add freon. know your a/c system r-12 or r-134a,iv'e found converting to r-134a cheaper than purchasing r-12. r-134a takes a special pag oil and should not be used/mixed with ester oils. i could say more on subject but that's a start,of course always wear safety glasses and approach high side port with caution,which most newer cars don't have. thanks

Jun 27, 2012 | Heating & Cooling

1 Answer

Compressor cut out after 5 minute aircond working

Sound like the unit is going off on the high limit switch or low limit switch. If its going off on high limit your condenser coil is probably very dirty and needs to be cleaned. If it is going out on low limit its most likely low on freon and has major issues.

May 17, 2011 | Heating & Cooling

1 Answer

Furnace flashing open high limit

Hello, A limit switch will open when the furnace overheats due to low airflow, . check air filter, clean blower wheel, and check to make sure the blower wheel is running at proper speed and not dragging sometimes cause by a weak capacitor. Anything that restricts airflow will cause a limit switch to open.

Mar 07, 2011 | Goodman Heating & Cooling

1 Answer

I have a thin twin stacking whirlpool washer/dryer. The high limit switch is kicking off the element within 2 mins of running. So heating element heats up red hot, then clicks off after 2 mins. I have...

I think you are on the right track with a faulty high limit switch. When i serviced these units we always replaced the operating thermostat and the high limit switch together they came in a kit. The operating thermostat in theory should never let it get hot enough to trip the high limit switch, which is really just a safety backup for the operating thermostat. Get the kit and replace both, and also make sure your exhaust vent going outside has good flow at the outside vent,a restricted vent system will cause similar issues.. Good Luck

Oct 07, 2010 | Whirlpool LTE6234D Top Load Stacked...

1 Answer

Jandy LX250 LT Pool Heater High Limit Switch

Jump the High limit switch. If it fires the switch is bad

Jul 16, 2009 | Jandy LAARS LX250 - NATURAL GAS, DIGITAL...

4 Answers

High limit switch open on armstrong furnace

If you know where the high limit switch is you can always cut the two wires and wire them together causing the limit to close. But what you have to watch out for is why the high limit is not closing. That means in your return air either you have a dirty return air duct, dirty filter, or you don't have all your registors open to allow the heat to escape the heat exchanger. Just watch over riding the system. The high limit switch should either be on or behind the blower, in the middle of the system right under the heat exchanger. any other questions about hvac just ask.


Mar 23, 2008 | Heating & Cooling

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