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Maybe, just one day. I just installed a reznor udap 150 unit…

Customer Question
Just one day....

Just one day. I just installed a reznor udap 150 unit heater replacing my old unit heater. it fires up for about 3 minutes then cuts out even though the thermostat is still calling for heat

Contractor's Assistant: Did you double-check the thermostat's settings? And what about the filters?

No filter in the udap

Contractor's Assistant: Do you plan on doing the work yourself?

Yes

Contractor's Assistant: Anything else we should know to help you best?

The led light comes on saying that it is calling for heat yet is wont turn back on for about another 5 minutes. surely it should heat until the thermostat tell it to stop

Submitted: 10 months ago.Category: HVAC
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Customer reply replied 10 months ago
No it says its operating normally. LED is green flashing constantly which means the thermostat is calling for heat
HVAC Technician: airheatman, HVAC Technician replied 10 months ago

Does the green flash slow down when thermostat is off?

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Customer reply replied 10 months ago
Not tonight as I am at home. I was hoping for an answer from here. I could call tomorrow night as i'll be there
HVAC Technician: airheatman, HVAC Technician replied 10 months ago

WE can troubleshoot when onsite tomorrow night.Just come back to question then

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Customer reply replied 10 months ago
No it just stays flashing the same pace and I checked that is normal op.
Customer reply replied 10 months ago
Have you had much experience with the reznor unit heaters?
HVAC Technician: airheatman, HVAC Technician replied 10 months ago

It should stay flashing until thermostat is satisfied.Otherwise we should get an error code.Yes, very familiar with the Reznor.HVAC contractor since 1989 and been in the business since 1974.

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Customer reply replied 10 months ago
OK cool. im pretty sure the green light stops flashing when there is no call for heat. I just flashes fast even though the thermostat is still calling for heat. So the thing comes on for 3 minutes then stops for about 5 but the whole time the green light is flashing. So it gets the room to temp but not efficiently.
HVAC Technician: airheatman, HVAC Technician replied 10 months ago

Actually light will be just steady on until call for heat and flash on call. But anytime it is flashing it should stay on unless a pressure switch or limit opens

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Customer reply replied 10 months ago
the room was at 7celcius and I had the therm set to 25. so the light was flashing constantly as was call for heat. then it did as i said but even after the flame stops the light keeps flashing and the room is still only at 7 celcius
Customer reply replied 10 months ago
it does this on and off thing until the room gets to temp.
HVAC Technician: airheatman, HVAC Technician replied 10 months ago

Here are a few things you can check when you get there.

Make sure grounds are all good

Make sure pressure switch is staying closed

Make sure the ceramic on flame sensor is not cracked

Make sure polarity is right

Make sure the 9 pin connector I making good contact and all wires are seated good in the connector

Make sure gas pressure is staying within the 3.5 to 5" WC range

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Customer reply replied 10 months ago
Ok i'll check all that. Only thing I wont be able to check is gas pressure as i dont have the manometer or what ever its called.
HVAC Technician: airheatman, HVAC Technician replied 10 months ago

But in all actuality if the burners are ever off, thermostat calling for heat and we do not get an error code such as open limit, weak flame, open pressure switch,etc, the circuit board is failing to do it's job.

New does not necessarily mean good as these boards must all come from China or Mexico.

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Customer reply replied 10 months ago
yep for sure i had a brand new dishwasher that the Main board blew up in the first week. Is it bad that it is coming on and off like that? I would hate to change out the board and it not be the problem
Customer reply replied 10 months ago
i'll take another look at it tomorrow. PCB is $250 from the first place I looked at so not a cheap part exchange
HVAC Technician: airheatman, HVAC Technician replied 10 months ago

I understand. Thought it was new and figured warranty would cover, You might also try bypassing limit and once unit starts the pressure switch One may be opening board just not giving error.

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