Regulator for bench testing

[Gary88]

Hi
Thanks for letting me in here. I want to set up a bench testing area for my suburban furnace SF 30FQ. I HAVE A 10 lb propane tank. What regulator do I need to make this work. I have a 10 lb tank, standard tank that comes with a gas grill. Thanks in advance.

 

[Gary RV_Wizard]

Any standard LP gas regulator will work - they all produce standard pressure - 11 WC (water column) inches. If your BBQ tank has an external regulator (not built into the grill itself), that will work fine.

 

[Kirk]

If it were me, I would get one with a low pressure hose as well and you can find some less expensive ones from Amazon.

 

[Gary88]

I have a BBQ grill regulator on the propane tank now and the furnace is on the bench. When I fire up the furnace, it lights, then goes right out. I have an extended warranty on it and multiple RV Techs have worked on it and replaced almost every thing. Furnace works when they leave. But furnace does the same thing next time I go to use it. I was thinking the gas regulator on the RV may not be releasing the proper pressure. Any ideas?

 

[Gary RV_Wizard]

If it lights the gas pressure is fine. The usual cause of "quickly goes out" is a flame sensor malfunction. If the controller cannot sense a flame within several seconds of ignition, it will close the gas valve to prevent a potential explosion. The other possibility is poor flow in/out of the air & exhaust tubes. A gas furnace is extremely sensitive to air/fuel mix proportions and any disruption in the tubes will likely cause problems.

 

[Ray-IN]

I have a BBQ grill regulator on the propane tank now and the furnace is on the bench. When I fire up the furnace, it lights, then goes right out. I have an extended warranty on it and multiple RV Techs have worked on it and replaced almost every thing. Furnace works when they leave. But furnace does the same thing next time I go to use it. I was thinking the gas regulator on the RV may not be releasing the proper pressure. Any ideas?

LP pressure should be 11" water column (0.42psi) when running. It will not run properly below 10".
reference: Standard LP gas pressures and natural gas pressure settings found in gas piping and at gas appliances

 

[woof-n]

Yep, What Gary said, Air proving switch or flame sensor. I am thinking air proving switch or blocked tube if works fine on the bench but not in the camper.

 

[Kirk]

Most RV manufacturers use flexible tubing for heat ducts and if one or two are crushed that can cause enough air flow restriction to make the sail switch closing intermittant. I have seen that happen more than once. The heat sensor is part of the ignition probe so you might want to just change it while you have the furnace out to eliminat it as a possibility as they are not expensive.

 

[Ray-IN]

Most RV manufacturers use flexible tubing for heat ducts and if one or two are crushed that can cause enough air flow restriction to make the sail switch closing intermittant. I have seen that happen more than once. The heat sensor is part of the ignition probe so you might want to just change it while you have the furnace out to eliminat it as a possibility as they are not expensive.

I agree. I've also seen RV furnace plenums have knock-outs for 5-7 ducts, but the RV builder only used 3, which itself can possibly cause sail-switch problems and/or overheat condition.