Goodman GMS9115DXA furnace and CLQ48-1 14 SEER

[mtap1112]

Background: My AC's compressor burned recently. From many inputs and a lot readings from this forum, I've decided to replace my 10 years old AC and 13 years old gas furnace with new ones (at first, I planned to just replace the compressor, then the entire AC and finally the entire system). My house is 32 years old, 2 level colonial with basement, about 2700 SF on 2 floors.

Out of 3 proposals I received (Goodman, Trane and Carrier), I've tentatively decided to go with the proposal consisted of Goodman CLQ48 4 tons 14 SEER AC and GMS9115DXA gas furnace 5 tons single stage multiple-speed (the installer installed the entire Bryan system for my sister-in-law 2 years ago but now recommended GOodman). Before signing a deposit check this coming Monday, I'd like to get your experts' opinions as to if the proposed combo system makes sense. I am getting kind of nervous on my decision.

Thanks for your help.

Thanh

[RoBoTeq]

That's a nice matchup, but....you may do a bit better with a 95% furnace.

With the GMS95115D** furnace you will most likely be eligible for a $150 tax credit and if you go with the GMV95115D** you will most likely be eligible for a $200 tax credit and have a more efficient and comfortable blower system.

Also, don't know if your contractor is going to have a problem finding that particular model. He/she may have to go to the new GSC14048-1 condenser that does not have as good a warranty.

[mtap1112]

Thank you RoBoTeq. I will discuss in more detailed with my contractor with regard to model GMS/GMV95115D furnace. I actually did ask him briefly about moving up to a higher end model (i.e. 2-stage variable-speed) but he mentioned that it's not worth it. I told him about my second floor being hotter in the summer and colder in the winter (about 6-8 degrees difference b/w first and second floor) but he said that's normal for older home with single zone ducting system. He also said that dual-stage and variable-speed would not help to improve that 2nd floor problem and that I should go with the GSM9115DXA. Please let me know if you think 2-stage and variable-speed furnace would improve my second floor heating/cooling. I don't mind to pay extra for improving my 2nd floor confort.

Thanks,
Thanh

[RoBoTeq]

There is no guarantee that a two stage, VS furnace will help with your second floor situation other then to assume that by running longer in lower heating there would be more constant air to the second floor. Otherwise; no system is going to compensate for a bad duct system.

However; the comfort features of a two stage VS furnace are usually worth the cost for overall comfort, even more so with problematic situations.

The cost factor dwindles when you consider the DOE tax credit. That is $200 directly off of the bottom line of your tax debt or $200 additional to your tax credit to be returned.

[mtap1112]

Thanks again RoBoTeq. Sorry if I keep coming back with question. Since my 2nd floor get very weak air coming out of the registers, would VS furnace deliver weaker air to my second floor when it's in the low/optimized heating mode? I read many threads discussed about VS vs. multi-speed but still not 100% sure if I understand them correctly. Let's say, my contractor set the multi-speed furnace to high at installation, I would assume then that the air coming out of the registers would constantly be strong compared relatively to VS. Is there something wrong with my logic?

[RoBoTeq]

Air is oportunistic; it will go to the point of least resistance.

There is a chance that if your ducting is restrictive to the 2nd floor that while most of the air in high speed may wind up going to the first floor you may wind up with a higher "percentage" of air going to the 2nd floor when there is less air while in the lower stage.