Hoping to know more about the two-stage furnaces

I Would like to get some information on how to pick a furnace filter? I was thinking of furnace rental, as the furnace in our home is working poorly now. I’ve checked the filters and other things related to it. But, I didn’t find anything unusual. I believe the reason to be its age. We have been using it for more than 19 years. I’ve found [link removed], from where I was thinking of renting one. The one currently we have in our home is a single stage furnace. We find it comfortable. One of my cousins suggested renting a two-stage, which she says is more comfortable than the single stage. She also suggested me two furnaces: 95AF2V from Aire flow and XV95 from Trane Furnaces. I don’t know about these two nor about the two-stage furnace or its uses… If anyone could explain or give me some insights on these, that would be a great help. Thanks in advance...

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You don't give us a lot to go on here. "Furnace is working poorly"? Furnace filter is OK, but you have a question about picking filters?

A 19 year old furnace is getting along a bit, but is hardly an automatic candidate for replacement. I'd get that serviced first, and find out why it's working poorly.

If it is a non-condensing furnace (there's only one exhaust tube coming off the furnace, and it's made of metal) -- then it's at most about 82% efficient. You can probably save a good deal on your gas bills by replacing it. If it needs more than a few hundred $$ in repairs to get working "not poorly" -- replace it.

But if it's based on condensing technology (there are one or two plastic tubes coming off the furnace) -- then it's already close to 90% efficient. A two-stage (95% efficient) furnace can't save enough gas to be worth doing -- keep your existing furnace until a trained technician tells you it's no longer safe and reliable.

And, I can't figure out any way that a rented furnace could be cheaper than one purchased outright -- someone has to make a profit on the loan they are offering you, in addition to a profit on the furnace itself. And you have no way of knowing how to separate out the two parts of the transaction unless you are a good financial analyst. Pay for the furnace outright, and get your best price. Shop for the loan separately, and get your best price. 

In the buildings we work in, the only people that lease hardware (always just water heaters, never furnaces or boilers) are the owners of apartment buildings -- and  they do it solely because, when you operate real estate, there are big tax advantages (in the US) for doing things that are otherwise really not very smart.  

Regarding filters... The primary purpose of a filter is to protect the blower and other furnace components, and secondarily, to improve indoor air quality. The least expensive type of filter is fiberglass mesh. It's also the least effective as it only captures a relatively small percentage of particles that pass through it. Pleated filters do a much better job, but they come in a wide range based on the performance rating (MERV, except 3M Filtrete uses 'MPR'). Unless there's a reason to go higher, I typically recommend MERV 8 or MPR 600 for most folks, which cost less than higher performance filters. Be sure to get the same thickness as your existing filter (filters come in 1", 2" and 4"). Here's a good place to read about filters: Your Filter Connection

As Don noted, it's hard to advise you on your furnace since you didn't explain why you think it's working poorly, even though you said it's comfortable.

If you do end up replacing the furnace, make sure you go with the right size. Your existing furnace is probably oversized.

The easiest and most accurate way to determine the correct size is to time the on / off cycles on your existing furnace when it's as cold as it normally gets. For example, if the furnace operates 60% of the time over two full cycles during the coldest part of the day (typically just before sunrise) and your current furnace is 100k capacity, then you would go with a 60k or 70k replacement. If you go with a more efficient model, use the output capacity rather than input capacity when doing the math.

If you have an idea of how much you spend on heating per year (average), you can estimate whether it makes sense to spend the extra bucks on a higher efficiency model once you get comparative quotes. But if your existing furnace is working, you're not going to save enough to justify buying a new one.

Also keep in mind that unless a 2-stage furnace is sized closely to the actual heat load, it will end up operating as a single stage furnace most if not all of the time.

Lastly, I agree with Don on leasing. I've never heard of leasing a furnace. I can't imagine it would be to your advantage. A good bit of the cost is labor and mark-up, and you're going to pay those costs either way.

Furnaces require occasional servicing by professionals and that should be the first step. Your post includes a direct link to a furnace rental provider in Toronto so, in combination with lack of a clear question, this post could be perceived more as an advertisement  for that company than a bona-fide request for information. Furnace rentals should only be done if there are no other options. As with any lease, the commitment and payments will be excessive in comparison to buying. If selling the property, the rental will become an issue and often the seller is forced to do the buy out to facilitate the sale.


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