Question about Jandy Laars Lt 400,000 Btu Heater

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Heater is off and code says prs

Want to turn on heater for spa

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  • marshtcat May 07, 2009

    Raypak heater won't ignite and says to clean filters which we did and the codePRS displays

  • jmc68 May 11, 2010

    where is pressure switch located on jandy laars lx pool heater? says it is bad

  • ifixpools May 11, 2010

    This is a lack of water flow or the switch not sensing flow when you actually have it.

    What is the application? Gas heater or above ground spa?


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Assuming you have water flow, the pressure switch is bad. It is not sensing flow.

Posted on Jan 01, 2009

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1 Answer

Could I get a wiring diagram?

if on control panel its calling for heat sounds like bad heating element if not calling for heat bad temp sensor at about 75 degrees it should ohm out about 78 ohms

Aug 27, 2014 | Optimus Flow Thru Heater, 2 Psi Prs, for...

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I have a pool heater RP 2100 you set the temperature it calls for the spark -then there's usually a poof and the flame icon comes on, and the heater heats up. Now set temperature, Calls for heat -the spark...

make three attempts to get heater running. most electronic ignition heaters will lock out after 3-4 times. after it locks out error codes should present themselves.....such as ignition failure, prs, etc.
ensure proper gas and water pressure. check voltage supplied to your raypack's igniter aswell. if heater fires up then instantly shuts off, then it may be the flame sensor

Oct 04, 2013 | Pool & Spa

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Raypak p-r405a PRS message. tried adjusting pressure switch, no change

clean out pump basket, backwash filter for starters. jump the pressure switch if nothing changes. if burners fire then replace the pressure switch

Dec 06, 2012 | Raypak Pool & Spa

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Screen has prs clean filter screen and service flashing

pressure switch is open. clean out pump basket and backwash the filter.... if you have proper water flow, jump the pressure switch....if heater fires up replace the pressure switch

Jun 11, 2011 | Raypak RP2100 DIGITAL POOL HEATER R206...

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I received a notice that the filter needs cleaning. How do I do that?

THis is a PRS code (clean filter/strainer) correct?
This simply means that either there is no water flowing through the pool heater (possibly due to a dirty filter)
If you know you have good water flow, then your pressure switch has failed. Replace the pressure switch.

May 31, 2011 | Rheem M406A 399K BTU Cupro Nickel Pool or...

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The display says PRS and the heater does not start

Thank you for posting your question here on

That unit will not fire until you resolve the pressure switch issue which is what PRS indicates; either the flow is reduced too low meaning the pump/filter system needs to be thoroughly cleaned or the switch or control board has failed and need to be repaired.

Start with a cleaning of all baskets and filter to see if the light clears and the heater works; if not look at replacing the pressure switch. It is not uncommon for the switches to fail but check it with a meter set to ohms if you can. Power off the heater first and pull one of the wire leads off. Put the probes on the terminals with the pump running and see if you have a circuit. If not, replace it. If the switch tests fine the problem is in the control board and it will need to be replaced.

If this answer does not fix your problem, please comment with additional details prior to rating the answer. You may also contact me thru our website at Positive feedback is appreciated once your problem is solved!


May 21, 2011 | Rheem M206A 206K BTU Pool and Spa Propane...

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It usually references the pressure switch and the pressure switch is one of the safety features that keep the heater from firing without adequate water pressure (signifying the pump is running and therefore water flowing through the heater). It can often turn off the heater even with the pump running if there are enough restrictions to the water flow such as clogged filters or debris in the skimmer or strainer baskets.

Nov 12, 2009 | Pool & Spa

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