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Tech08 02-15-2009 08:26 PM

Purchased Amana 93% Furnace - Convert from LP back to NG
Hi all,

I hadn't posted back in my first post that had many questions as I was looking for a better furnace. I have since found a better furnace with a higher efficiency.

Amana 93% Gas Upflow Furnace -
Currently LP, needs changed back to NG.

Now the question.

The gas control valve was just replaced (before I bought it) and looks good. The person I aquired it from did not have the NG Regulator Spring since he used LP and didn't save the other items.

Isn't all I need to do is R & R the regulator spring and TADA, it's set to run NG?

If this is correct, does anyone know if these springs are generic? I have searched the web with few results.

I was also told that I might be able to turn the regulator screw CCW a couple turns and that should function the same as replacing with correct spring (If I cannot locate one).

I was also told that I would not need to obtain new orifices.

Thanks for the insight.

beenthere 02-15-2009 09:40 PM

You been told a lot of lies.

Did they tell you it was also only used on weekends by a little old lady from Pasadena.

Get the OEM conversion kit.
Your not looking to kill your family are you???

AndrewF 02-15-2009 10:44 PM

This is an area one shouldn't guess or mess around with. Follow the manufacture specs to convert it back to NG. Life is too precious to "guess" the settings and risk the result of a fire.

KGP 02-16-2009 09:26 PM

I just did the exact opposite on a Goodman (95%??) 45000BTU unit for my Garage back in December converting a new unit from NG to LP. I followed the manufactures instructions and it cost all of $60 for the kit. I found it by going to a supply house and asking for the conversion kit for my unit. The kit consisted of new orifices and springs. I borrowed a manometer from a friend, set the pressure for both stages to manufacture spec and have not had a problem since.
I am by no means an HVAC guru and dont know a thing about your specific unit. Just telling you switching it was not brain surgery to give you some encouragement!

SKIP4661 02-17-2009 08:26 PM

You will need to replace the gas valve regulator spring and burner orfices. The manifold pressure will have to be properly set to the factory required pressure with a manometer. The orfices can be drilled out but an orfice bit kit will be required for the proper gauge. Best to let a pro set it up for you.

Tech08 02-18-2009 08:43 AM

I spoke with an Amana dealer and showed them the spring that I removed (for verification) and one of the orifices.

It would appear that when the gas control valve was replaced, the spring was not changed. So the guy I bought the furnace from was using a NG spring with LP orifices.

I now have the correct NG orifices as well as the spring. Evidently the guy I bought the furnace from didn't realize that gas valves ship from the factory set up for NG use.

I also had a new plenum made (75$) 19w X 20L X 29h.

I was also instructed that with PVC venting (I will use 2" ASTM D1785) that I need to have 1/4" rise (horizontal run) per foot, a.k.a 1" per 4 foot.

This is going to look ugly. I have hung many types of pipe and always leveled it horizontally. To me this is like installing something wrong...if it isn't level.

I can get behind the idea of having condensate drain back down the pipe, but I just can't get the visual out of my head.

Thanks for the comments.

beenthere 02-18-2009 01:43 PM

Sewage pipes are pitched.
So it shouldn't look any worse then your other drain pipes.

If it drained toward the outside. It would freeze in the pipe, and cause no heat problems.

Tech08 02-18-2009 07:46 PM

Thanks for the reply. I consulted the manual again and it also states 1/4" rise per 4 feet. However; the Amana dealer said 1/4" rise per 10 feet. That would look much better.

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