Question about Teledyne Laars HEAT EXCHANGER ASSEMBLY, DP-350 - 10403602

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I have a Laars Mini-Therm II boiler that keeps tripping the flame roll out switch when it shuts off. I reset the switch and it runs again. the switch itself trips before it hits the temp shut down which is about 130-140 deg F. The high limit switch is set at approx 180 F. I installed a new flame roll out switch and high limit switch. I am sure there is circulation because the ''out'' vs the ''in'' delta T is 20 deg F.

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  • shannon koffman May 04, 2012

    What is the answer. I have the same problem

  • The heat exchanger (located internally) needs to be cleaned. We recommend calling a professional boiler service company. The boiler can be taken apart and the heat exchanger can be then inspected and cleaned. A procedure that we carry out numerous times with great success.



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Posted on Oct 10, 2010


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I need to reset my mini therm. The wwsd light is on and the water will not heat up more than 140. I need to operate it less the outside controle.

It's possible your outdoor sensor is defective. Part number E2347400. In theory, the WWSD LED flashes for outdoor sensor errors. It's intended to limit the system heat output when the outdoor temp exceeds 70F.

According to the Laars Mini-therm manual for models JVS and JVH, you can use DIP switch setting 3 to modify how the boiler works with the Warm Weather Shut Down (WWSD) outdoor sensor. If you turn off number 3, it inactivates the 70-degree WWSD. This should have no effect upon a call for domestic hot water, but may allow a call for space heat to be processed at the min setpoint of 150, if not the higher calculated setpoint.

The control access panel requires tools to remove the cover, to find the DIP switches, meaning it is not ordinarily intended for use by untrained operators.

Call a repairman to verify what you should be doing to bypass a malfunction temporarily, until they can get to you.

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1 Answer

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The only code I can find is 47 which is clean flame sensor there is a video on u tube on your boiler which may help you

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We have laars mini therm boilers,JVH225NCSS One goes through its start up Pilot burners lite,But shutdown within seconds, it continues to cycle but will not burn as it should. I've cleaned burners..

Might be the safety thermocouple is faulty or the pilot light is not heating the thermocouple bulbs - perhaps the brackets have become distorted and need realigning.

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Ignition at Orifice

The gas control valve is passing . It will need a replacement.

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I have a Teledyne Laars Mini Therm Copper Tubing Boiler that started to turn on and off several times before it would go back to normal and have the burners light for a while. I called in a tech and he...

The unit may not be recognizing the burner flame is on and constantly rolling back thru the start-up cycle. I am assuming the ignitor is what you mean by "box and wire" the tech replaced so it should be ok. The next step would be to look for corrosion on the terminal the wire connects to, around the plate the terminal itself is on and the ignitor assembly. If the signal from the probe that registers the heater is operational cannot get back to the ignition control module the heater will behave as you describe. There are other suggestions for short cycling found in the manual linked below. You will need to pich your exact model from those shown and roll down to the troubleshooting section.

For more information and/or assistance you can refer to the owner's manual here, contact the manufacturer here, call their tech support at 800.900.9276, or post a comment to this thread.


Jan 26, 2011 | Teledyne Laars HEAT EXCHANGER ASSEMBLY,...

1 Answer

Boiler keeps tripping flame roll out switch. boiler is new. boiler also blows t&p when shut off manually.

When you are getting a flame roll out control trip its One of three. Not enough air in the room for a proper combustion. Your chimney/ Flu piping is clogged not allowing exhaust gases to escape or your gas is not tuned properly

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1 Answer

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How long does it stay lit (if at all)? It sounds like the thermocoupler (about 10 bucks). Good luck

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Pool pilot keeps tripping,what might be the problem ?

One of the most common problems will be the flame sensor. If it doesn't sense the flame, it shuts down the burner. Good luck...Lee

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1 Answer

Have a problem with a laars mini therm ii boiler. the pilot keeps

hi. i have mini temp boiler 150 btu 5yers old . it is burning with know radiation .it is up to thempitio .but it will not shut off.flame is good radietor is hot ,help?

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Big old Hydro Therm boiler rolls out flame at start up for a split second when gas valve opens; it has a big pilot flame, and seems like a small explosion of gas; there good draft , good flame color any...

This may be normal it's hard to tell from your description , The flame could possibly rollout for a second or 2...depending on the venting , how far the vent is from the chimney shouldn't hear a "Mini Explosion" you may hear the gas ignite with a bit of a woooosh...depending on the size of the boiler this could be quite normal...Boilers can be dangerous when they get plugged up or dirty....although Hydrotherm makes an EXCELLENT Cast Iron Boiler...I would still have it checked by an expert to be on the safe should also have a "Slow Opening" valve which would eliminate that problem if the valve is working correctly , but it's possible it was replaced at some point with a regular opening valve and this could be the reason as well

Oct 16, 2009 | Heating & Cooling

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