Air Conditioner upgrade question

[Beano's Fourth Chin]

So, we've got what I would say is a medium sized Norman house. around 1800 sq feet. Half upstairs - Half downstairs.

Our 1970 air conditioner has been sad lately and won't cool off the upstairs like it should. We're in the midst of bidding out new ACs and I have a question.

First a little more background:
The 2 bids that we have that we are considering the most seriously are for a 2 unit (one for the upstairs and one for the down) and a single unit (in the attic) with 2 thermostats and a baffle or butterfly valve or whatever it is that will regulate the flow between the two floors.

The guy quoting 2 units says he can install a single unit, but won't guarantee it because we won't be happy. The guy quoting the single unit says he can install 2 units if we want, but it's overkill and would be a waste of money because the 2 unit one is a lot more expensive (almost twice as expensive).

Dear Abby,

WTF? Do you have any experience with this type of conundrum?
P.S. Also we have an internet poster that is being mean. Should we ban him?

[jkm, the stolen pifwafwi]

http://www.hvaccomputer.com/hvac/newfeatures.asp

[jkm, the stolen pifwafwi]

http://www.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12440

[Vaevictis]

First question: What's the tonnage they're quoting you?

[IB4OU2]

So, we've got what I would say is a medium sized Norman house. around 1800 sq feet. Half upstairs - Half downstairs.

Our 1970 air conditioner has been sad lately and won't cool off the upstairs like it should. We're in the midst of bidding out new ACs and I have a question.

First a little more background:
The 2 bids that we have that we are considering the most seriously are for a 2 unit (one for the upstairs and one for the down) and a single unit (in the attic) with 2 thermostats and a baffle or butterfly valve or whatever it is that will regulate the flow between the two floors.

The guy quoting 2 units says he can install a single unit, but won't guarantee it because we won't be happy. The guy quoting the single unit says he can install 2 units if we want, but it's overkill and would be a waste of money because the 2 unit one is a lot more expensive (almost twice as expensive).

Dear Abby,

WTF? Do you have any experience with this type of conundrum?
P.S. Also we have an internet poster that is being mean. Should we ban him?

Beano,

We have an oversized (single unit) Carrier heatpump that does great for our home. We have about a 2500 sq ft. home equally proportioned upstairs and downstairs and it does a great job. The only issue I have with the system is when it gets close to zero in the winter the unit really struggles to heat the house and keep it around 75 degrees inside.

[birddog]

i live ib colorado, 6,500 feet closer to the sun. the only positive is my wife wanders around the house in her delicates. BOOYAH!! seriously it's 91 degrees in my house because i have no a/c.

[Okla-homey]

Dood,

Get the dual units. Seriously. You'll thank me later.

[Beano's Fourth Chin]

First question: What's the tonnage they're quoting you?

2-2 tons
1-3.5 ton

[Beano's Fourth Chin]

Dood,

Get the dual units. Seriously. You'll thank me later.

I realize that's ideal, but 14 grand vs. 7800 I'm thinking hard about my options.

[Mjcpr]

Beano,

We have an oversized (single unit) Carrier heatpump that does great for our home. We have about a 2500 sq ft. home equally proportioned upstairs and downstairs and it does a great job. The only issue I have with the system is when it gets close to zero in the winter the unit really struggles to heat the house and keep it around 75 degrees inside.

Couldn't you just set some of your $100 bills on fire in the fireplace?

[1stTimeCaller]

I realize that's ideal, but 14 grand vs. 7800 I'm thinking hard about my options.

Try having 3 or 4 contractors quote you the dual system and see if it really should cost 14 grand. That seems crazy to me.

Peem on the way

[Mjcpr]

I realize that's ideal, but 14 grand vs. 7800 I'm thinking hard about my options.

Holy crap.......I had no idea replacing an a/c unit would be nearly that much.

[IB4OU2]

Couldn't you just set some of your $100 bills on fire in the fireplace?

We don't have a fireplace.........:( :)

[Vaevictis]

Hmm, roughly the same, so I expect it's an airflow issue as to why the first guy says what he is saying (other than greed).

Main thing to keep in mind is that if you do one big one, you have to be really careful about the airflow. My parent's house, for example, has one big unit and two thermostats with some kind of valve thing, and usually what happens in the middle of the summer is that one half of the house is like 15 degrees colder than the other half of the house... even when the thermostats are set identically.

If you can afford it, I'd spring for the two like Okla-homey says, with mechanically isolated ducting. If you don't want to afford it (or can't), like I say, you need to be very, very careful on the airflow control.

[Beano's Fourth Chin]

Hmm, roughly the same, so I expect it's an airflow issue as to why the first guy says what he is saying (other than greed).

Main thing to keep in mind is that if you do one big one, you have to be really careful about the airflow. My parent's house, for example, has one big unit and two thermostats with some kind of valve thing, and usually what happens in the middle of the summer is that one half of the house is like 15 degrees colder than the other half of the house... even when the thermostats are set identically.

If you can afford it, I'd spring for the two like Okla-homey says, with mechanically isolated ducting. If you don't want to afford it, like I say, you need to be very, very careful on the airflow control.

How old is their house? Apparently (according to quote dude) the new controls are a lot better than they used to be.

[tbl]

No doubt. I just installed a 1.5 ton for my basement and it was $2,200 out the door. Labor, indoor/outdoor unit, ducts, installation... everything. Listen to Smokie "You better shop around".

[Okla-homey]

I realize that's ideal, but 14 grand vs. 7800 I'm thinking hard about my options.

Look at it this way. It's like two engines vs. one engine. They will prolly last longer than a single unit carrying the entire load. Plus, if one goes out temporarily, you can evacuate to the part of those house with functional HVAC which is a plus. Invariably, the things crump on really hot or really cold days.

Finally, having lived in many climes, I don't recommend heat-pump technology for folks who live in areas where it routinely gets in the the low thirties in the winter. They just don't have enough "oomph."

Note: "oomph" is prolly not a term used in the HVAC trade, but you get my drift.

[1stTimeCaller]

are they replacing the duct work?

[Vaevictis]

Dude, $14k seems insane to me. When we were pricing for data centers, you could buy like 20 ton Leibert under-the-floors, installed, for that much.

[Vaevictis]

How old is their house? Apparently (according to quote dude) the new controls are a lot better than they used to be.

3-4 years old.

EDIT: And FWIW, it has nothing to do with the age of the house; it has to do with ****-poor engineering. I could have done a better job than the people who built that house, and the only thing I know about airflow is the bernoulli equation (for which the assumptions fail in this case). Yes, it's that bad.

[Mjcpr]

3-4 years old.

See, they've improved a ton recently.

They've started using space age polymers now.

[1stTimeCaller]

there's always the wait until the end of summer if you can technique to getting lower prices. As you can expect, every HVAC man in town is swamped and has more business than they can handle right now. Prices will get cheaper as it gets cooler. If you can stand it in the meantime.

[IB4OU2]

Look at it this way. It's like two engines vs. one engine. They will prolly last longer than a single unit carrying the entire load. Plus, if one goes out temporarily, you can evacuate to the part of those house with functional HVAC which is a plus. Invariably, the things crump on really hot or really cold days.

Finally, having lived in many climes, I don't recommend heat-pump technology for folks who live in areas where it routinely gets in the the low thirties in the winter. They just don't have enough "oomph."

Note: "oomph" is prolly not a term used in the HVAC trade, but you get my drift.

I agree with the Oomph part when it gets down and stays below 15 degrees for a long period of time, the heat pump struggles.

[Dio]

2 units

YWIA

[stoops the eternal pimp]

What SEER rating are they quoting

[BajaOklahoma]

We have two units because we added a second floor and it was easier/cheaper to make it a separate system.
When we compare the electric bills from the summer before and after we added on, there was actually less electricity used. Temps were comparable. But the smaller unit was more efficient.

[Tiptonsooner]

Finally, having lived in many climes, I don't recommend heat-pump technology for folks who live in areas where it routinely gets in the the low thirties in the winter. They just don't have enough "oomph."

Note: "oomph" is prolly not a term used in the HVAC trade, but you get my drift.


Not anymore, heat pumps will maintain temps inside when it is at 0 dgrees F outside. No problem if the ductwork is right.

Two systems are the way to go Beano. Zone systems are a great deal and do work, if everything is perfect. (Zone system- meaning one unit, multiple stats)
If the ductwork is not entirely worked and designed for the zone system, all deals are off. With two seperate systems you will be completely comfortable, upstairs and down.

I am a HVAC contractor and I will be glad to answer any question I can to help.

[Okla-homey]

Not anymore, heat pumps will maintain temps inside when it is at 0 dgrees F outside. No problem if the ductwork is right.



Does that involve the auxilliary heater coil firing up when the pump can't hack it or have they actually cracked the temp differential problem? Seems like it used to be a max of 40 degrees difference between outside temp and inside temp on heat pumps (or something thereabouts.)

[Tiptonsooner]

I don't even have heat strips in mine at home for aux heat. That being said, mine is designed correctly also.

[Norm In Norman]

Why the hell aren't you asking BSG all this?

[SOONER44EVER]

Check your inbox.

[sooner_born_1960]

I remember the last time bsg got involved in this debate. Good times.

[slickdawg]

Dood,

Get the dual units. Seriously. You'll thank me later.


Beano, LISTEN YTO HOMEY!!!! LISTEN TO ME!!!!

I've got $4,000 reasons to have seperate units upstaris and downstairs.

When we built in 99, the AC guy swore that one unit could handle upstairs
and part of downstairs. IT GETS ROASTING HOT UPSTAIRS.

So I bit the bullet, put in a 13 seer heat pump, and it does all of the downstairs, while the upstairs is on its own unit. It works great now.

DO IT!

[Jimminy Crimson]

dual unit.

my house in norman is roughly the same size as yours with half up/half down.

i have one unit. it sucks. a lot.

[Newbomb Turk]

get a 1 story home.

[CatHunter]

We have a unit on each floor. (5 stories)

Plus, a small one in the garage for my Yukon.

[OUDoc]

Knock out the upstairs floors and have 20 foot ceilings.

Or get 2 units. That price seems high though.

[BoogercountySooner]

I just built a 2600 sq ft. house that is shaped like a U. We had 2 units installed a3 ton and a 3.5 ton unit. I shopped around and got it for $8500 including ducts and installation. I was shot prices much more than that but I was diligant to find a cheaper price from a reputal installer and did.

Is your ducting connected that supplies the 1st and second floor now? If it is I would assume that one large unit would get it done. If your downstairs cools or heats better than the upstairs close your downstairs ducts enough to direct more air to the upstairs.

[TheHumanAlphabet]

I realize that's ideal, but 14 grand vs. 7800 I'm thinking hard about my options.

Spend the bucks, you won't regret it when you are cool...

I have a 4 or 5-ton unit on my 1800 s.f. house in Houston. We oversized the compressor and undersized the coil to max out the dehumidifaction, plus added an expansion valve. Cool as a cuke and set at 75 degrees. We spent about 10K for new system and ducts (our ducts were crap) and set up new zones with plenums.

[BlondeSoonerGirl]

A professional has been contacted.

Please hold...

[tbl]

Two units, but DO NOT go with that high price. There are people out there that will do it for half that, gaurantee you.

[BlondeSoonerGirl]

One bigger unit (prolly a 4 ton) and 'zone it'. Ask about a 'zone system' which is a unit with a controller board in it that controls dampers.

Acts like two separate units but much cheaper. And it won't get overworked.

[BlondeSoonerGirl]

Oh and who're you getting quotes from, Beano?

This matters and I can help you.

[Beano's Fourth Chin]

So far we've gotten 3 or 4 quotes and are waiting on a couple of people to also come by. I forget their names.

It's not fair that it had to get to 108 yesterday. Until that happened, we were able to schedule those people to come by pretty easily, now, they're like. Umm. we can't come by because we're toooooo bizzzzy. Wah.

I'll get the acual place names from my wife and then post them here. The two guys that came by this morning were wearing blue matching polos if that helps.

[Mjcpr]

The two guys that came by this morning were wearing blue matching polos if that helps.

Probably dolemite and yermom. I'd throw that one out.

[OUDoc]

The two guys that came by this morning were wearing blue matching polos if that helps.
Mormons? Oh, wrong thread.

[slickdawg]

Aggies and sheep...... whoops, wrong thread.

[phead903]

I think it was already asked, but what SEER rating are the units that they are quoting? If your current unit is over 15 years old, it's probably only a 6 or 7 SEER at the most. The new standard (the lowest SEER rating that manufacturers can build) is now 13 SEER. There are still some 10 SEER units in the pipeline, since the new standard didn't go into effect until January of this year.

The higher the SEER rating, the more efficient the unit is, and the lower your relative cost will be to cool your house. Now the payback between 10 and 7 SEER is pretty good, and the payback between 13 and 7 would be great.

Ask the contractors that are gving you quotes to show you a payback schedule to let you know how quickly you can recoup your expense in energy savings. Any contractor worth his salt will have that information readily available for a customer along with the ARI (Air Conditioning and Referigeration Institute) certification that guarantees the rating for the unit you are considering.

Don't be afraid to ask questions of any contractor that you are considering buying from. Usually the more information they will give you, the more reliable the equipment and the installation will be.

You can visit www.hvac-talk.com (http://www.hvac-talk.com) for more background information if you wish or www.ari.org. (http://www.ari.org.)

[Beano's Fourth Chin]

Our current seer is whatever they put in when they built the house in 1970. I think it's about 1 seer.

The quotes were for 13 or 14 seer. I've been building a 25 seer in the garage, but I can't get it to work yet.