[High Efficiency Sadness]

Back in September we replaced our old(2001) 80.0 AFUE Amana furnace (and AC) to a new Two Stage 96% High efficiency model from Goodman (AMVC961005CNBB).

The sales guys said that we should see a sizeable decrease in gas use compared to the old furnace, as did much of what I had read online. Sadly this was not accurate.

Since installation, the monthly gas usage has been higher than it was before the new furnace was installed. Even when breaking it down day by day and taking into account the weather/temperature, the amount of gas being used to keep the house at the same temperature it has always been is higher.

Is this common? The folks at the HVAC company that did the installation sent someone out to check everything, and all they could say was they didn't know why it would be happening.

[** The amount of gas used is not being based off of the cost of operating the furnace **]

Any kind of feedback or advice would be greatly appreciated.

 

[eggs]

Back in September we replaced our old(2001) 80.0 AFUE Amana furnace (and AC) to a new Two Stage 96% High efficiency model from Goodman (AMVC961005CNBB).

The sales guys said that we should see a sizeable decrease in gas use compared to the old furnace, as did much of what I had read online. Sadly this was not accurate.

Since installation, the monthly gas usage has been higher than it was before the new furnace was installed. Even when breaking it down day by day and taking into account the weather/temperature, the amount of gas being used to keep the house at the same temperature it has always been is higher.

Is this common? The folks at the HVAC company that did the installation sent someone out to check everything, and all they could say was they didn't know why it would be happening.

[** The amount of gas used is not being based off of the cost of operating the furnace **]

Any kind of feedback or advice would be greatly appreciated.

That is NOT common. There could be a few issues or fact here. Cost of Gas has gone up a lot recently. When comparing, need to compare the therms, not the bill. Goodman is a good mid line furnace, but the model number AMVC961005CNBB crosses to an Amana. Although Dakin is the actual manufacture and they also make Goodman, there are differences in them. Do not confuse GMC with Chevy or Buick. Back to your issue, poor installation can cause your problem. Fist off, are there 2" or 3" PVC pipes leaving the furnace? How far is the PVC run to the outside? Is the PVC pipe pitched back to the furnace, no sagging pipes to trap water? Is there just one PVC pie or two? What speed is the heating set for on the blower motor? Is this a 1 story or 2 story house? Every one of these factors mater. Lack of air flow would make the furnace run longer in the attempt to heat, so filter size maters also - 1", 2", 5" thick.... That is a variable speed blower and speeds can be changed. If only one pipe is leaving the furnace, then it is using inside air for combustion which that air would come into the house from outside through windows and doors. If the exhaust / intake pipe are 2" and the run is longer, that would have a major issue on the how the furnace would run. Sagging pipes trap water and restrict air flow which has the same results. If you had an 80% furnace before and this one now, as long as nothing else has changed in the home and the install was good (ie correct size furnace....), then you should of seen about a 10-15% decrease in fuel usage. Also note that the chimney could cause issues as it is no longer in use. Is there a water heater using the chimney? If so, a damper and chimney liner MUST be installed. There is a lot to know when spec'n out furnaces, and I have seen a lot of hacks out there that lack proper training, yet think they know it all.