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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8171
Experience:  Furnace, A/C and heat pump specialist.
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I have a Paloma gas (Serial #T0021928976, manufactured April

Customer Question

I have a Paloma for natural gas (Serial #T0021928976, manufactured April 2009). The unit was operating before being moved to its present location. Venting at the new location will require boring through an 8" brick wall, so it's important to test it first. When turned on, the unit arcs, the pilot ignites, the main burner ignites. Within a few seconds, the main burner and pilot go out and arcing resumes. Is this likely a fault, or the result of a lack of proper vent installation? Before the installation is completed, I want to be sure the unit will operate properly once permanently installed. If this is a venting issue, is there a means of testing before continuing with construction?
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

What is the model on the unit and do you get an error code?

Customer: replied 1 year ago.
Paloma Model BZ. There is no model number. There is no read-out, so no codes. I've gone through the manufacturer's troubleshooting steps, but they don't address this problem.
Expert:  airheatman replied 1 year ago.

Many of these units have vent sensors but as you stated, there is no mention of such on this particular heater. I suspect for some reason the module is not recognizing the flame and therefore shutting back off. Have you checked all of the wiring connections to make sure a wire did not get bumped loose during the relocation?

Expert:  airheatman replied 1 year ago.

Also make sure the flame sensor is clean and ceramic has not gotten cracked.You can clean flame sensor with emory cloth

Customer: replied 1 year ago.
I've checked all of the wiring, unplugged and re-connected all multi-plugs and spade connectors. I've checked case grounding and gas connections. I've adjusted pilot flame sensor positions to see if that would make any difference (it did not). All sensors are visually clean and corrosion-free. The company website states that the vent must be properly installed for the unit to work, though I found no sensors to confirm vent back-pressure/resistance. This is a direct vent appliance with a 4/6.75 vent. I tried partially restricting the exhaust vent to simulate proper venting, it made no difference.
Expert:  airheatman replied 1 year ago.

I do not see a sensor on it that would shut it down if not vented properly If the flame is staying on the flame sensor, it appears it would stay lit.I am going to pen to other experts to see if they have more input on this.

Customer: replied 1 year ago.
Thanks. When the main flame goes out (after a few seconds), the pilot also goes out. Sometimes, the main burner will re-ignite a few times, other times, all gas goes out and the starter arc resumes without gas release to the pilot.
Expert:  airheatman replied 1 year ago.

It is very possible the unit and pilot will not stay lit without the vent because it is not getting enough fresh air.Looking at the manual, I do see that the vent is similar to a mobile home vent.One chamber brings fresh air in and other chamber takes exhaust out.

Customer: replied 1 year ago.
I understand the direct vent concept. I have a short section of vent pipe installed (4" inside 6.75"). There is adequate flow in each section. As I said above, I've tried to operate the unit with and without a vent terminal cap installed, there is no difference. Since it appears that the pilot extinguishes immediately prior to the main burner, I will test the pilot circuit first. It's difficult, as the entire sequence operates only for a few seconds.