Taking bids for a new system

Old 09-22-15, 08:42 AM
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Taking bids for a new system

My current heating and A/C system is a Rheem and it is about 16 years old so I am pretty sure it will have to be replaced soon. I've had several HVAC contractors give me bids to install a new system. Most of them are offering Trane, Carrier or Lennox systems (I am only interested in those 3 brands). It has come to my attention that Rheem furnaces have a 3" exhaust pipe coming out of it and the other 3 I mentioned above have a 4" exhaust pipe. Most of the contractors that bid on this have indicated that if they install any other brand besides Rheem they will have to replace all the existing 3" pipe that's going threw the roof with 4" piping. However, there is one contractor (Trane dealer) that has indicated that it would not be necessary to do this because the BTU requirements are not large enough to require the 4" flue that are being quoted by other contractors. Of course, his quote is the lowest one.

I don't want to risk my or my families health over cutting corners. Is it overkill to replace the 3" piping with 4" or is there a valid need for it.

p.s. Getting another Rheem is not an option.
Old 09-22-15, 08:51 AM
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Is it overkill to replace the 3" piping with 4" or is there a valid need for it.
That is determined strictly by the manufacturer of the furnace. There are charts supplied by the mfg. that spell out exactly what is required based on length of exhaust and size of furnace.

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