Variable-Speed Furnace - Worth It?

[HornGrad'01]

Any HVAC installers on this site? The blower on my 18 year-old furnace just went up and given its age, I thought I may go ahead and replace the unit.

Wondering if there is any reason to go above a 90% efficiency unit to a multi-stage variable speed unit. Will I ever recoup my costs living in Texas? Understood that the milder climate areas like the Southwest were not necessairly a perfect match for the higher cost units.

Was looking at American Standard. ANy reason I shouls look at another brand.

 

[tallgrant]

The big advantage of using the variable speed unit is typically in energy usage. The unit will end up running on a low setting for a good portion of the day, and kick into high gear only when it's not keeping up.

We've got a couple at our office- we can barely notice they're running most of the time because it's just constantly going on low.

I guess the biggest question is how long you intend to be in the house. I'm not sure how long the payback is in energy cost, but if you intend to move out in the near future it may not be worth it. But if you can afford the material cost up front, it can save quite some money.

 

[MTF]

Any other viewpoints? I'm looking at an extra $1000 for the variable speed option. Worth it? Thanks.

 

[accuratehorn]

I believe the compressor for the A/C is variable speed, we looked at them recently. This seems ideal in Texas heat, don't know about the furnace situation.

 

[brntorng]

A year and a half ago I installed two complete American Standard (rebadged Trane) variable speed systems in my house. I went with the highest SEER single speed compressors. I've very happy with the systems. They run on low speed much of the time and are almost silent at that speed. My cooling costs are about half of what they were previously with 20 year old indoor units, one 15 year old outdoor unit, and a 2-3 year old 12 SEER outdoor unit. I would definitely make the same decision again since the house is much more comfortable than it was. I avoided the two-speed compressors because they're basically just two compressors working together. Since the compressor is one of the weak points in the system I figured a dual speed compressor would just reduce the reliability of the overall system.

You don't mention it, but you probably know that you won't improve your efficiency much unless the complete indoor and outdoor units are matched which typically means replacing both. Also, keep in mind that you may qualify for city rebates and federal tax credits if you choose your system properly.

I would highly recommend the American Standard dealer (serves RR and Austin area) who did my installations. He's a one-man operation (except during the summer peak) and keeps his overhead very low. As a result no one could touch his pricing and the quality of his work was top notch. Million-Air A/C & Heating, 740-4818.

Trane/American Standard systems are very hard to beat. There may be other good ones, but you can't go wrong with either of these.

Something else to consider when installing a new system: It's very important that the size of the air conditioner (tonnage) is matched to the house. Too big and it won't dehumidify adequately; too small and it won't cool adequately. If humidity and cooling of your existing system have been fine, then replacing it with the same size should be ok. However, if either of these has been a problem you should seriously consider having a heat load analysis done to make sure you get the right system. An HVAC engineer can do this for you for a couple of hundred bucks. I had it done and discovered both units were originally the wrong size. The units recommended as a result of the analysis have done a much better job.

 

[Franco]

Your simple payback for going to a variable speed will be at least 15 years.

 

[Summerof79]

**** man- just replace the blower motor! It's probably less than $300. Now if you WANT to spend the extra money on a new unit the go ahead. But if you blower moter is all that went out that's a no brainer, replace the motor. If you are handy you can probably just replace the motor itself and use the old cage for about $100. That's what I did in my Condo, mainly as I was hot at the time and wanted Air before I could get a service call

 

[brntorng]

Certainly just replacing the blower motor is a fairly easy and low cost job. However, if you plan on being in the house very long you need to consider a complete system replacement. 18 years is about the lifetime of an HVAC system and a new system will be much more efficient. Payback on a complete system is around 5 to 10 years depending on your use pattern plus it could have additional benefits.