Good Day:

Our furnace is a Heil SP80 model #NU65100BFB2, 100K BTU output, converted to LP gas. The main gas valve failed (Honeywell SV9500M 2682, converted, dead solenoid)

We have just put in a new main gas valve (Honeywell SV9501 M2056), and personally put in the gas conversion from NG to LP. The output pressure on the manifold is exactly 2.5 kPA (10"WC) (as reqested in the new literature for LP), confirmed the jets on the manifold as #54 LP orifice. We used a $4000 NIST calibrated Digitron to check the pressure through the enitre heating cycle.

What's getting me a little concerned is that the flame (nice blue, no yellow, no visible sooting) across the manifold outlet to the heat exchanger is considerably larger than the original valve. The jet is the size of the shell on the HX, and a ribbon of flame is seen across the outlet of the manifold. THere does not seem to be any negative reaction, but the flame characteristics are just different than before. The unit does not overheat, and seems to cycle properly.

We bought the building with the furnace installed and have no literature. I am not sure if the unit was operating properly when we moved in.

Is there another way to insure that this is the correct set up? Is the 2.5 kPA the right value, or will this get adjusted lower for particular instances? I am an oil guy, first time around with a propane unit. Does anybody know where to get an old copy of the installation manuals?

Make sure the pressure is set to the furnace label and not the gas valve. Propane as well as natural gas can be fired at different pressures so you have to use the design pressure for the unit you are working on. It will be on the furnace label.