Upgrade my furnace to central air?

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kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: Upgrade my furnace to central air?

Post by kevm14 »

kevm14 wrote: Fri Jul 30, 2021 7:43 am Total fail on my part. After being back ordered for months, it is now $1,972 and I no longer see the 16' line option. I suck.

Oddly if I press scratch and dent there is still the 16' line option and the price is $1,420.35 but then it still says on back order. How can a scratch and dent be on back order?
I called them to ask about the scratch and dent. Same warranty. The back order is because the linesets are back ordered. But since you can't even back order a 16' lineset this seems like the way to go. He said about 3 weeks. They have scratch and dent units but the line sets I guess are new.

A happy coincidence is the scratch and dent price has dropped to $1,283.85. I am just going to order and try to put this into my todo list around the house. Still have to run the electrical. And figure out a mounting method (stand or brackets off the house).
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: Upgrade my furnace to central air?

Post by kevm14 »

Ordered with the PVC line set cover as well as the wall mount brackets. Total with freight was $1,605.85.

The electrical part is another step. I have to run 12 or 10 gauge from my breaker box to the outside garage wall, add a disconnect switch and electrical whip. The disconnect switch and whip is only like $43 for both. Then like 50 feet or whatever of 10 or 12 gauge, plus a 20 amp breaker. But I am going to call my local (very local) electrician neighbor and see what he would quote to just do that part for me. Maybe if it's like under $400 then I'll go for it because that would put this at a $2,000 total investment.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: Upgrade my furnace to central air?

Post by kevm14 »

Looks like 10 gauge is twice the price of 12 gauge. Probably not worth it.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: Upgrade my furnace to central air?

Post by kevm14 »

I think this is still in play though for a future time.

I was comparing the cost/benefit of outfitting the rest of my house with mini-splits vs doing some kind of central setup. I think the central setup will be more cost effective.

Mini-split setup;
I just added the 18k BTU single zone to the great room. Then I would add another 12-18k single zone unit for the living room/dining room (and kitchen kinda). Then for each bedroom, a 3 zone 27k unit with three 9k heads. Total cooling capacity: 4.75 to 5.25 tons. This is on the high side of what this house needs (probably closer to 4 tons). Cost of just the mini-split condensers, air handlers and line sets: $5,636 (before tax, shipping and the electrical work). That does give me a total of 5 zones which is cool but that seems like a lot plus a lot of additional installation work.

Central setup:
Probably a 3 ton condenser and a 3 ton coil. For a condenser there are many options, both A/C only and heat pump. In fact I can get a 20 SEER Mr. Cool condenser which appears to be the same type of unit as a mini-split. Then add a coil to my furnace and figure out the controls and ductwork. Plus lines. Electrical. Condenser options range from a Mr. Cool 20 SEER 3 ton unit for $1,671 (or $985.57 scratch and dent) to a Goodman 16 SEER for $2,190 and A/C only options are cheaper. A 3 ton Goodman in a large size is $438.00 and Mr. Cool options go down to $392 or so. Again this would need extra stuff. I don't know if I could use any TXV or if it is a good idea to mix a Goodman coil with a Mr. Cool condenser. Anyway, coil + condenser ranges from $1377.57 to $2109. Even with the extra stuff this is going to come nowhere near what the mini-split setup would. But it also only has 1 zone (plus the existing great room zone) and is probably less energy efficient. This wouldn't be a true DIY option but I could make it work if I could figure out ducting (and I would have the entire spring/summer/fall to have the furnace ducting apart). Realistically this is all I need. The rest of my house is pretty open. I would also tend to close down the great room ducts in the summer and open them somewhat in the winter. I say that because I expect to want some oil heat in the great room. This would be regardless of this option or the additional mini-split option.

Bonus: https://iwae.com/shop/3-ton-goodman-eva ... 10471.html

This Goodman looks like it would fit perfectly on top of my furnace!

For rough numbers I think it would be safe to assume the central option should be a solid 50% of the price of doing additional mini-splits. That's because I'm capitalizing on my existing air handler and duct work. Plus only doing one more electrical run. One line set.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: Upgrade my furnace to central air?

Post by kevm14 »

According to my furnace manual and confirmed with the tape measure, the outlet of the furnace cabinet is actually 26" x 23-1/4". That Goodman doesn't include a TXV and the model that does is 30" tall which is too tall for my ductwork. So I need a short one that is 3 ton and as close to those outlet dimensions as possible, with TXV. I actually have someone at hvacdirect.com looking into it for me. Also sent a note to IWAE.

I may not get it exact with a cased coil. I just like the case because it seems like it would make the duct job way easier. Plus the integrated TXV also saves a bunch of labor. Problem is the size I need is really encroaching on 3.5 ton and larger units as that is normally how you'd equip a furnace of this size with central air. But I don't want to cool the whole house, just the house minus the great room.
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