My parents replaced their furnace last week somewhat on the fly since they had been having trouble with their existing furnace firing up during a recent cold snap in our area. They had not been having any trouble prior to this and faithfully had maintenance service performed. A replaced chimney damper didnt do the trick and they decided not to dump hundreds more into replacing other parts trying to fix it. Their furnace was a 23 year-old "low" efficiency furnace (vented up a chimney) so it was probably going to need replacement soon anyway.

I tried to coach my dad about his options to make the decision making process easier since I had built a new home 4 years ago and done extensive HVAC research at the time (and received quite a bit of great input from those on this forum, particularly "Steve J"). I ended up with a Lennox G32V two stage furnace with a variable speed blower and a Lennox air conditioner. My dad worked with one of the more reputable HVAC contractors in the area who had done maintenance work for him previously and who had attempted the most recent repair. This contractor was kind enough to credit them with 50% of the costly ($600) damper repair against a new furnace. This was the same contractor I had used previously in a prior home for a furnace install, maintenance and later central A/C install and maintenance and was very pleased with. This contractor talked with my parents about their options and focused on Lennox products. This contractor, while previously primarily a Carrier installer, has leaned more lately toward Lennox equipment. Anyway, the contractor suggested the Lennox G51 single stage furnace. I encouraged my dad to consider and at least price a two stage furnace since weÂve been so pleased with the comfort level at our new home. Our first high efficiency furnace at our prior home was a single stage, first generation Carrier Weathermaker installed in 1984  a cool draft blower! It also had its share of igniter problems  once replaced under warranty, the second time not.

Anyway, when my dad asked about a two stage furnace, the sales rep said that it would not be worth the extra expense ($700-$800 to upgrade to the G61 two stage) since they did not have a two story house, which two stage furnaces are more appropriate for. This is a man who has been in the business for almost 30 years, and heÂs the same guy who worked with me on my central A/C at my prior home and I was impressed with him knowing what he was talking about at the time. Out of three contractors, he was the only one who took the time to make sure he was properly sizing the A/C unit (he said 1 ½ tons, the other two said 2 tons, just as if thatÂs the size that worked for all the houses in my neighborhood). My dad also talked to the president of this firm who basically offered him the same reasoning about a two stage furnace. My dad said the Lennox Web site said nothing about this and the president said they didnÂt go into a lot of detail on the Web site. I told my dad I had some concerns with this statement since I was under the impression the number of stories of the home has nothing to do with it, and it was more an issue of longer, more even heating most of the time using the first stage. The sales representative also said that having a two stage gas valve was asking for more trouble down the road (implying they were prone to problems). Also, when my dad mentioned variable blowers, the sales rep said they are also prone to problems and costly to repair and replace. The rep also remarked that "those furnaces are so complicated that our techs need to take laptop computers out with them to service them".

When I went through the selection process four years ago, I was told that while the variable speed blowers are more costly to replace, they are more reliable in the long run. Besides, I was led to believe that when they first came out, replacement required replacing a control board/circuit board as well at great expense, and now the circuitry has been separated from the blower itself making blower replacement less costly. This firm threw out a figure of $800 to replace a variable speed blower. Is that reasonable?

My parents ended up with the single stage furnace (theyÂve had single stage furnaces for fifty years, are around 80 years old and may not be in their home much longer) as they could not justify the additional expense for the two stage. They are very happy with their comfort as compared to the prior furnace and find this one runs a bit quieter. However, IÂd appreciate any comments on the contractorÂs rationale steering them away from a two stage. After thinking about it for awhile, perhaps the contractor was thinking that because there are often issues with temps on each floor of a two story home differing, a two stage furnace which has longer run times would minimize that. [I have a two story home and for the most part we donÂt notice temp differences between floors most of the time and when we do, itÂs no more than two degrees]. Oh, by the way, this contractor is the same one who sold me one of those electrostatic washable furnace filters for somewhat over $100 years ago, saying it was much better than disposable filters. While it seemed to do a nice job, I was a bit upset when I saw similar filters in home improvement stores for around $30.

IÂm also considering starting to use this contractor again for maintenance since I have not been impressed with the firm (builderÂs subcontractor) that installed my current equipment. The installation was done well enough, but they had a heck of a time figuring out the two stage thermostat I opted for and I had to have them back several times when the A/C would not run properly since they had hooked up the thermostat incorrectly. They said they "rarely install those two stage furnaces and never install those two stage thermostats so they werenÂt familiar with them". I guess the installation instructions werenÂt clear enough.

Sorry for such a lengthy post. Bottom line  does it seem like this contractor knows what theyÂre talking about for two stage furnaces? Should I feel comfortable inviting this contractor to perform my ongoing maintenance? I suppose it matters more that the techs know what theyÂre doing, but if those on the other side of the business may not know what theyÂre talking about, what should I think? What kinds of questions should I ask before making that decision? Thanks.