[DIY66]

I am currently reviewing estimates on replacing a split gas furnace and ac unit. The ac is a 3ton Tempstar, but was originally 2.5 ton (unknown brand/model). I replaced the ac last summer with a used 10SEER 3ton I found for sale locally online to get us through the year since I was contemplating additions to the house. The furnace is an 80% efficient 100,000 BTU natural gas. We never did add on to the house, but are ready now to replace the 20 yr old system since the tax credit and rebates seem to make it a good time.

The duct work is in good shape and does not need replacement, but we are considering a Bryant Evolution Hybrid system with the 16Seer Heat Pump and 95% gas furnace. ($8300-$9600) All of the contractors that have come to the house have given estimates for the same size unit as replacement. Some of them took measurements of each room, others just asked the square footage of the home while others just checked the size of the current system. It is around 1310 sq ft. All of the contractors quoted a 3 ton replacement as opposed to the original 2.5 ton size.

The 2.5 ton used to run a very long time, but did eventually shut off. The 3 ton runs a long time, but seems to get the job done a little bit faster.

My question (if your still reading my rambling) is that with the Evolution system with its humidity control and multi speed blower, two stage heat pump etc, is the sizing as important as it used to be now that the system is capable of controlling the humidity in other ways than just on/off?


Thanks

[hvac1000]

Sizing is more important today than ever before. Just because a system has adjustable parameters or two speeds does not mean it is a miracle worker to cure size problems.
A manual J has to be done to get the exact size of the units and a manual D should be done to make sure all the main trunk lines and secondary runs are large enough to make the system work properly.
Using the existing unit sizes for replacement is a NO NO. Most if not all furnaces were installed oversized to start with and the A/C size is critical for moisture removal or you will be cold and clammy.
It is expensive to make duct changes so many people for go that since your system duct is existing. All units of the same capacity will heat and cool so the brand name makes no difference since the install is the most important thing. Remember the more doodads your equipment has the more expensive it will be to repair after the warranty is over. (EXAMPLE Variable speed blower motors).

Below is a check list of sorts to help you pick the best contractor.

As for cost of a system let your common sense and wallet be your guide but spare no expense on a qualified installer since they are worth there weight in gold.

[dac122]

I can't say it any better than HVAC1000. Its sounds like some did a partial Manual J by at least measuring living volume, so those are the guys you might want to call back for a more detailed eval. Be sure they include door and window types, insulation, siding, south facing orientation, etc. as those are needed for a proper Manual J.

HVAC makes a key point with VS blowers. If you are going that route be sure you get a Manual D done to be sure your ductwork is up to snuff for that VS blower otherwise you're going to be disappointed, especially when you think of the coin you dropped.

Finally, don't forget to ask for some low end quotes like a 92% AFUE and 13 SEER Heat Pump. You wallet may just like you, despite the fed credits. Your dropping some serious $$$$ so don't overlook all your options.