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dayton heater with honeywell smartvalve no heat

I have a Dayton model 4LX55 controlled by a Honeywell SV9540 smartvalve. This unit has previously worked for several years without issue. Last year it stopped producing heat but the blower would run and the pilot/flame would ignite. Following the troubleshooting instructions in the manual I replaced the HSI flame igniter (Honeywell Q3400A). It worked for a while and then started to act up again by running through the heat cycle, turning on burners, turn on blower and after a short time the burner would shut off and the blower keeps running. It then goes into a cycle mode and repeats the process every 5 minutes or so.

On the SV9540 I get a six blink LED fault code after the first cycle which indicates system lockout. Troubleshooting procedure calls for 1) low or no gas pressure, 2) HSI bad 3) flame sense rod contaminated or in wrong position 4) pilot burner in wrong position. I don't think item 1 is the problem so 2-4 could be the issue.

Is it possible that the HSI is bad again through improper handling and how do I check it for proper operation and orientation. Also any other troubleshooting tips appreciated.

Thanks in advance.

Rich B

Oak Harbor, WA


  • Try cleaning the flame sense

    rod just be careful to not break the fragile igniter part of the Q3400A pilot/igniter/sensor.

    Typically gas pressure is not a problem, is this natural gas or propane?
  • re

    Thanks for the reply. This is a propane unit.

    Rich B

    Oak Harbor, WA
  • Rich, Seeing as it is propane

    have your propane company check pressures for you on both the inlet and outlet side of the gas valve just to be safe and to be able to eliminate that as the problem.
  • re

    Tim, I cleaned the flame sensor as you suggested with some 600 grit lightly and checked alignment of the pilot assembly. Put it back together and seems to be working, ran for about 10 minutes without any issues. When faulty I could not get it to run with heat for more than 5 minutes and kicking a 6 blink code. We will see what happens when it gets colder. Thanks again for the help thus far.

    Rich B

    Oak Harbor, WA
  • icesailoricesailor Posts: 7,265
    Gas Pressure:

    You still need to check the gas pressure. It could be a bad regulator. I've seen them. You should be able to check it yourself.

    Oil burner technicians check pump pressures, Gas technicians should check gas pressures. Take things for granted at your own peril.
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