Replace entire 19 year old system or just broken AC?

Sue Brunette (formerly known as hockeychik)

16 years ago

My husband and I have differing opinions on what to do. Here are the facts:

We live in Minnesota and have a 19 year old natural gas furnace and central air conditioner. The AC is kaput so we are planning to replace it with a new higher efficiency model, at least SEER 14.

After getting a few estimates we learned that there are some federal tax credits available,as well as the local utility rebates, if we also replace the furnace. Does it make sense to replace both at this time even though the furnace is still working fine? Obviously, it isn't as efficient anymore, since it was installed in 1988. There is also a benefit to replacing the AC and furnace at the same time, as supposedly the installers give you a price break, and one even increases part of the warranty from 5 to 10 years on the furnace.

I'm thinking, go ahead and replace the whole system and take advantage of the extra federal tax credit. Who knows how long the furnace will continue to work? Besides, this would give us more efficient products too.

My husband thinks, don't fix it if it isn't broken. The furnace may continue to run fine for several more years.

Sure would like to hear others opinions on this quandry. Thanks.

Sort by:Oldest

Comments (12)

tigerdunes
16 years ago
chik

If your budget allows a complete changeout and this will be your home for many yrs to come, then I recommend getting rid of your old furnace and replacing with a properly sized Rheem or York modulating furnace with a matching 14-15 SEER AC condenser.

IMO
garyg
16 years ago
With a name like "hockeychik", I would do whatever you want. If your husband has a problem with it, smack him upside his head with your hockey stick and remind him who the #1 goal scorer is on your team.

Best of luck to you.
Related Discussions
A/C replacement or complete system?
Q
Comments (9)
Arcas, I can appreciate your calculations (I spent a month doing the same thing while also getting multiple estimates from 10 contractors), but after researching I discovered is more than just rate of return from system efficiency. As previously stated there are differences in build quality, controls, noise, and most important installation quality. For your analysis I will assume you include any local utility and state rebates (That reduced a qualifying furnace and HP by $400 a piece where I live or $350 for an A/C). In the OP's case it is the following for VA: Gas Furnace (ENERGY STAR qualified): $250 Heat Pump (ENERGY STAR qualified): $300 There are also manufacturers rebates to account for(although I think that season may be over at the end of June). I will also assume you could care less about noise as you get a good bit more of it in a basic system (I know as it's night and day from my old system to my new one) or the excellence of an Infinity controller in the OP's case (it can control dehumidification in the summer, a humidifier (if desired), tell you when you need to replace your filter, and let you know if something is wrong with the system). A nicety, yes, but some people like to have a better quality and more capable item. Kind of like buying a car. Regardless, Option 2 should include the tax credit as it should be a qualifying A/C system (since you should be able to replace the inside coil for compatibility purposes and 16 SEER should qualify. This is assuming you don't have ancient furnaces). This would drop the difference to only $382 which you would gain back in the expected life of the system. Option 3 doesn't take into account you have a brand new furnace which will not have to be replaced for at least 10-20 years. Unless you have relatively new systems. Either way you shouldn't have to replace them if you drop in a straight A/C since that can be tax qualifying on it's own. (see option 2) You should not assume equal usage either due to varying heating and cooling loads, but I get that it is for simplicity. Option 4: Well, not going to argue costs there as you are getting 4 new systems. The $1500 can be made useful especially if you have good local rebates for high efficiency systems. I have no idea how old your furnaces are, but if they are more than 15 years then it's likely they won't be long for this world. In the OPs case if they keep the furnace and sell in 5-10 years expect to give credit for a new one (I know I asked for credits for systems I knew needed replacement when I bought). As with many things in life there are many factors to take into account(more than I was willing to spend time on), so in the end I suppose the answer must be it just depends...
...See More
How to replace 25 year old package unit south LA.
Q
Comments (12)
Thank you for the questions tigerdunes. Downstairs unit is a 5 ton AC/nat gas package system. The downstairs 5 ton package unit did not sufficiently cool the house (partly because the ductwork in the crawl space had/has breaks in it). I think the package system was chosen because only a portion of the downstairs has useful attic space. A 24x24 foot area of the house is two story and the rest is single story with two of the downstairs areas having roofs with very small pitches, almost flat, thus no room for ducts. The living rooms and bedroom areas have gable roofs with attic access. The ductwork is under the house in the crawl space and there are floor registers in the hardwood floors. It is difficult, if not impossible to figure out how to get ductwork to the downstairs portion of the house which is covered by the second story except by running it in the crawl space. I am told some of the ductwork is rectangular metal which is in good shape and can be reused but some is round and has holes in it and must therefore be replaced. The upstairs unit is not a package unit. Ideally, it should also be replaced but it can probably limp along a bit longer. One technician recommended we put in one unit to take care of the upstairs and a portion of the downstairs with two thermostats and add a second unit to cover the rest of the downstairs. Since I do not see how ductwork could be put in to manage this without dropping the ceiling, this doesn't sound like a good idea. I think we should delay replacing the upstairs unit unless it really is a good idea to try to get the upstairs unit to service a portion of the downstairs. I think we need to focus on the downstairs. Probably need two package units for the downstairs to cover the present 2700 sq. feet and the 400 to 600 square feet we are planning on adding. What kind of package unit? What size? Would a heat pump be an idea? Hope I answered the questions and thank you for your thoughts. B
...See More
Adding A/C and HP to 80 year old home! Big difference in quotes!
Q
Comments (2)
Can't really improve upon tigerdunes minimun specs above, efficiency performance dehumidification (if sized correctly..)staging electric strips. R-8 should be for all ductwork supplies and returns. All connections should be mastic..not foil or duct tape but paint on mastic and/or mastic tape. load calc to show how much air is needed and how to distribute air.(duct sizing & design) I'd invest in the room by room load calc and see how they plan to size the ducts and lay them out. you don't mention where ahu & heaters will be located. one in crawl space the other in attic? both in conditioned space with ductwork in attic and crawl? one thing to know going in is that sheet metal duct is best under houses. animals love flex duct, while you can usually deal with mice in attics..coons, possums can wreak flex duct. also sheet metal duct ( I call it hard pipe) leaks air at all connections. in addition to screwing duct together all joints and seams should be mastic sealed...before duct is wrapped. duct wrap should be stapled, and taped with duct tape (fsk tape) 80 years ago we built houses for ventilation. tall ceilings, balloon framed walls. to add central air to these homes is to change the dynamic of the house. in my area we usually foam floors with closed cell as it is the most cost effective way to both air seal and insulate the floors. here is a link to LaHouse (LSU Baton Rouge, La) about insulating floors: http://www.lsuagcenter.com/NR/rdonlyres/D33F711D-DC4B-4E4C-9ED6-A97DCE9DB026/79806/pub3187insulatingraisedfloorsHIGHRES.pdf you'll have to cut and paste for it to work.. if ductwork is in attic, another option is to foam the roofline and keep ductwork in a conditoned space. this will minimize problem areas like recessed lights that are not air tight, which allow attic air and insulation particles to enter the house. we use open cell installed in rafter bays and covering the face of the rafters. in my experience with older homes you have to fix the house in terms of air leakage and insulation for the central installs to provide comfort, dehumidification and savings. otherwise you just throw more tons of a/c at a leaky structure. insulating floors and attic would be to your benefit. air sealing the house is a good investment. there are lots of energy raters in Texas. you should talk to a few and get more information before spending so much for a/c. unlike a lot of audits an energy rating unbiased information that provides a blue print for efficiency, recommendations specific to your home and performance & install verification. best of luck.
...See More
A/C Help: Replacing System
Q
Comments (19)
Yeah I'm high and dry thankfully, the roads are a mess up here so traffic delays will likely be a nightmare for a few weeks if it can stop raining more a while to let us dry out. I think part of the problem you're getting is the manufacturer dealer you are using. You see Trane and American Standard are mostly one in the same. They force contractors that use them to exclusivity deals meaning they can't offer other options that are made by other manufacturer's. If they went behind Trane / American Standard and offered these solutions they would probably get chopped off at the knees. The other part may be that they pre-purchased equipment to get better pricing and they have a lot of that equipment in stock from the past year. That is about the only rhyme or reason why I think they are probably telling you these things, because they are totally inaccurate. Certainly any 5 ton system SEER rating will diminish when it is operating in 2nd stage, but in terms of running in 2nd stage usually this will only be in the hours of heavy loads. Typically between 3pm and 6pm. Certainly if we get a heat wave it may run more in 2nd stage during longer spans than those times above. You can easily prove this to yourself when you watch the weather forecast on TV. Pay attention to the highs and lows of the day. Notice that lows are over night (usually) and the highs aren't hit until around 3pm-4pm usually. Well if the average low in summer is around 70 degrees there is far less load on the home than the high of 95 degrees or more. In other words a two speed AC system will most likely run in first stage for hours outside the 3pm to 6pm window. Which means 1/8 of the day it runs in 2nd stage... unless a heat wave or you're cranking settings etc. The flip side is that because the system has 2 stages it runs longer in 1st stage... during all this time it is removing humidity. Lower the humidity and you feel much more comfortable. When deciding make sure the system is a 2 stage with a 2 stage thermostat minimum. SEER ratings are tricky because you could have a 17 SEER single speed air conditioner. The single speeds are the ones not worth it because you don't get the dehumidify punch from those... they are either on or off. Realize it's not only just about efficiency it's also about comfort.
...See More
Sue Brunette (formerly known as hockeychik)
Original Author
16 years ago
Hey garyg, I like your thinking! hee hee
jy_md
16 years ago
When the A/C condenser broke down last summer, we replaced the whole system. But it was about 35 years old. In our case, it was obvious that 1) we probably couldn't count of the furnace lasting much longer; 2) it was easier to do everything at once.
udarrell_2007
16 years ago
If it were me with the budget to do it, I would replace both with a 14 or 15 AC SEER & have the duct system thoroughly checked out & retro-ed to work perfectly with the new higher efficiency rated equipment.

Make sure the compressor is a Copeland Scroll & the metering device to the E-Coil is a TXV. Then the quality of the installation (with regular maintenance) has everything to do with the systems performance & longevity of operation.

Everything in the entire system has to be properly matched to enabled the equipment to come near achieving its EER & SEER Ratings. udarrell _ 2007

Here is a link that might be useful: udarrell.com
Sue Brunette (formerly known as hockeychik)
Original Author
16 years ago
Thanks for the advice so far. I have another question. Since it isn't looking like we will replace the furnace at this time,just the AC condenser and coil, does anyone know if the Federal tax credit applies? It looks like you can get the $300 credit if you get the appropriate AC system but they seem to list furnaces on the info too, so I don't know if the system seer and eer ratings are affected by the furnace as well? I probably didn't explain that very well. I know one of the salesman said that we could get the federal tax credit if we put in a furnace and ac but I am not sure about just the ac.
Thanks in advance.
tigerdunes
16 years ago
chik

it is unlikely that you will qualify for federal credit buying a new condenser/coil alone because of your old non var speed inefficient furnace. The credit is for a complete system.

Sorry
busboy
16 years ago
Keep in mind that by changing out everything you are going to save BIG$$$ with the enery costs on the new systems. As energy prices increase, and they will, your time to payback will get shorter and shorter.
garyg
16 years ago
"Keep in mind that by changing out everything you are going to save BIG$$$ with the enery costs on the new systems. As energy prices increase, and they will, your time to payback will get shorter and shorter."

- With Maryland electric rising 65%, replacing my 21 year-old, 7 SEER, heat pump with a new 14 SEER unit has reduced the payback time from 10 years to 4 years. A 4 year payback is very reasonable.
Sue Brunette (formerly known as hockeychik)
Original Author
16 years ago
I'm still undecided.
So just how much do you pay in Maryland? Our rates(at least this last month) are about 93cents per therm plus the monthly charge of $6.50 and the taxes for gas. Electric rates are about 10.6cents per kWh plus an $8 monthly charge and taxes.
Wondering how we compare.
garyg
16 years ago
Hockeychik:

It really doesn't matter what I pay in Maryland because my bills (and everyone else's) are based on many variables including house size, house age, construction, lifestyle, # of people living in the house, utility prices, phases of the moon, etc. Too many variables make up utility costs.

If you replace a 1988 80% effficient gas furnace with a 2007 80% efficient gas furnace, you gain nothing in efficiency (but you do get a new gas furnace). If you get a 95% efficient gas furnace, you get 15% more efficient in gas usage (a 15% savings in your heating bill), a variable speed fan in the new air handler, and may qualify for the Federal tax credit that you want. The only "warning" is that a new, high-efficient, gas furnace may require modifications to your flue such as installation of a flue liner. I am not knowledgeable on gas furnaces so you need to investigate this so that you are educated on gas furnace requirements.

If your a/c is 19 years old (mine was 21), you can assume that it was a 7 to 8 SEER unit. By going to 14 SEER, you should save about 40% on the cost to run your a/c per hour of run time.

It's OK that you are not sure what to do. This is a big decision with big $$ so take your time and think it through.

Again, good luck.
kooldudenorthernva
16 years ago
I would change out the whole system. Not only for the federal tax credit issue but from a practical standpoint, your furnace will need to be replaced soon. You will pay less to have the whole thing changed out at once than to do it piece meal. When your furnace does go kaput it may be in the dead of winter when contractors can and often do charge a big premium. Also, matched systems work much better. If you change out the AC only you are not making it easy to match it to a new furnace.

The new high efficiency condensing furnaces require venting through plastic pipes so attatching to an existing flue is not an issue. The savings isn't all with the more efficient use of gas--with a new furnace you are going to save about $200 or so a year with a more efficient blower which is used with heating and air conditioning.

Replace entire 19 year old system or just broken AC?

Comments (12)

tigerdunes

garyg

Related Discussions

Sue Brunette (formerly known as hockeychik)
Original Author

jy_md

udarrell_2007

Sue Brunette (formerly known as hockeychik)
Original Author

tigerdunes

busboy

garyg

Sue Brunette (formerly known as hockeychik)
Original Author

garyg

kooldudenorthernva

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

Replace entire 19 year old system or just broken AC?

Comments (12)

Related Discussions

Sue Brunette (formerly known as hockeychik)Original Author

Sue Brunette (formerly known as hockeychik)Original Author

Sue Brunette (formerly known as hockeychik)Original Author

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

Sue Brunette (formerly known as hockeychik)
Original Author

Sue Brunette (formerly known as hockeychik)
Original Author

Sue Brunette (formerly known as hockeychik)
Original Author