Converting to natural gas/RobertShaw Unitrol 7000-BER-1/403-501-729

[Jerry64]

We are going to natural gas from LP and would appreciate and help to find out what kit we need to change the furnace over.........New man on board so please be gentle....... Thanks JerryB.

[jumptrout51]

Natural gas utilizes a larger orifice than LP.
The orifices will have to be changed also.
There should be an orifice size designation printed on the furnace.
If not,the furnace manufacturer will provide the info.

[Jerry64]

Looked on furnace label and no orfice size on it.It is a 125,000 BTU but I would like to lower it to 85-90K BTU if possible.......Thanks,JerryB.

[JWWebster]

Post pictures of the unit

[Jerry64]

[jumptrout51]

Who is the furnace manufacturer?
Model Number?

[Jerry64]

CHJ-125-D4 is the Model# and Tag says "Manufactured for Heat Controllers of Jackson,Mi.......JerryB.

[Jerry64]

The site shows they deal in Comfort-Aire products......JerryB.

[JWWebster]

You gonna have to go 10 orifice bits smaller than the size of the orifices are now. That means plugging and re-drilling each orifice. The pilot assembly needs to be changed to LP and the gas valve needs to have that plate removed with the red screw and a flat plate reinstalled on there. Nothing to it. See the picture? (click to slightly enlarge) that is a nat gas reg. It has to be removed from that valve and a flat plate put in its place. I have some of them in my Robertshaw stuff. (retired Robertshaw distributer)

[JWWebster]

That is a 24 volt, half" in half" out Robertshaw natural gas valve. The blue wires coming out from under the safety thermocouple go to a limit.

[JWWebster]

I noticed you aint got no tape on the nipple. If air or humidity gets into that valve it won't be worth a dayum. Duct tape that valve or lose it.

[Jerry64]

The furnace was converted from NG to LP when it was installed 29 years ago.Now I need to re-convert it back to NG and the furnace guy is long gone.....JB

[Jerry64]

It has a 3 burner tube and the tips are 49's now with LP.......JB.

[JWWebster]

The only thing to do is install a 3.5 reg as shown above. Open all orifices 10 sizes bigger and change the pilot light to a nat gas one. Plenty of furnace men are still around. Check with your local nat gas supplier.

[Jerry64]

Thanks for all the info JW......much appreciated.I can do the work on it..Just need a little guidance.......... .....JerryB.