Replacing 2 old ACs- Go zoning or keep 2 ?

3,109 Views | 16 Replies | Last: 6 yr ago by Joe Cole
Joe Cole
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I'm about to replace two units that are about 20 years old. House is a small 2 story and I currently have a 2 ton for the upstairs and a 3 ton for down.

I have had a few estimates and installers seem split on going back with one big 5ton unit capable of zoning or keeping it a 2 and a 3. Price works out that one unit is slightly cheaper and the other benefit is only one unit to service in future


I feel like the setup I have right now is that I am basically manually zoning it. We don't really use the upstairs much until time to sleep and I could probably get by with a single stage unit for up there

Does anybody have any recent experience with the newer zoning units vs just using 2 smaller units ?

The zoning unit they try to sell is a top of the line Lennox XC25 with iHarmony controls. Reviews on iHarmony aren't great and it just seems more high end than I need, but the price is actually about the same for one top of the line compared to 2 smaller units

jtp01
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AG
Downside to one unit, when it goes out, you have no AC in the house. In our last house, we had 2 units and one went out over a holiday weekend and we were able to condense sleeping arrangements to the north end of the house where the other unit was still working.

Just a thought. It allows for flexibility.
AgEngineer72
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AG
I am interested in this discussion too. One thought comes to mind- 2 units provide a level of redundancy.
Joe Cole
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I am going to have 3 more guys come out today and see what they say. It's been really interesting to sit back and observe these tech's have completely different opinions on which way to go.

Also the range on estimates for what is a fairly straight forward job of replacing 2 units is amazing! I have called some independent small guys and also some big guys that advertise heavy. Now I see how they afford the advertising...charging about 5-8k more than someone else


One thing about the zoning units to me is that it's just more moving parts that can break down. My current units are 10 seer so just going to the low end 14 seer single stage units will be an upgrade. One thing that the higher end units seem to get you is a reduction in humidity.

InMyOpinion
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I recently went through this with a new build

Options were
1 - 5 ton 2 stage unit with 4 zones
Or
2 units each with 2 zones. one for bed 2/3 and upstairs game room/bedroom another unit for main areas and master suite. Both units were single stage.

I opted for the single 2 stage unit. Primarily for the benefits of the 2 stages of cooling. We have had to make minor tweaks over the last year to balance zones / airflow / bypass damper but I have been very happy with it.

The unit running longer throughout the day in stage 1 keeps the overall comfort level (lower humidity) very nice compared to my previous house which had single stage - 3 zones.

I believe the Lennox XC-25 is the best unit they have. The benefit with that unit for zones is you don't have to have a bypass damper because it is completely variable.
EcoZapp.AC&Air.Purifiers
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Give us a call or an e-mail if your in CS/ Houston/ Waco/ Austin.
We enabled a ~16 year old AC blow ~48F from ~62F on Tuesday. Today we did the same in making 2 older systems work better than new.

If it doesn't work we don't charge you, but when it does work we still don't charge but ~$1000 for two units to maybe last years longer. Pending there is no major mechanical work needed, but if it's making air cold, we'll make it more efficient.

https://www.facebook.com/EcoZapphome/

BrazosDog02
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This is all my opinion and i may be full of ***** This is what i found to be true for what i know.
Having resarched heavily and been involved with both of my ac installs, I can offer some insight. First, before you finalize anything you ought to get a heat load calculation done. A reputable service company should be able to handle this. I've done them so I expect a pro to be able to.

Second, comfort is related directly to proper sizING of the unit. There is a design temperature target for different regions. When the outside temp gets to the design spec and you set the the temp inside to its spec, then a properly sized system should run continuously and maintain that temperature in perfect equilibrium all things being static and equal. That's the idea and theory. So, a single stage unit should properly dehumidifier your home as well as a vs system if it's sized right. Lots of hacks can get away with half ass work and calculations because the ac technology has officially surpassed their intelligence. So they can drop a VS system in a cover some slop.

Also, a vs system in no way ever precludes the bypass damper in a zoned system by default. Ever. It can. It might. But that is totally dependant on system design, zone size, heat load and home build. Your contractor has to understand that. As I said, ac systems are smart and they will only slow the blower speed down to the point that it is safe for the equipment. If you put a 5 ton system in with a VS blower, and you have one zone calling for 1 ton of cooling, that system likely cannot slow itself down enough to not destroy the unit. So, you will have a lot of air forced through a ducts that aren't designed for it and it will be noisy. It needs a bypass for that type of design...or a dump zone...or a combo of all three.

You can pretty simply see when a contractor is a hack by talking to them.

Your home will likely benefit from two systems or one big one, but which setup will depend on more than a couple factors. As stated,, two systems offers redundancy. I love redundancy. The ac pro should help you decide. Maybe you want a VS 2 ton and a super kick ass multistage VS 3 ton with zoning. You still have 4 zones and regardless of your opinion, it's not a manual zone. For what it's worth, I LOVE EWC controls for zoning. They have systems to work with all makes and models of ac and they have modulating bypass dampers. Your bypass is not open all the way or closed all the way. The ac may ramp down for a small zone and the bypass will open 25% to keep pressure and air flow in check for instance.

Ac stuff has come a log way, just make sure your contractor talks about all of it so there are no surprises.

And I wouldn't have anything other than a multistage vs system if it were me. I can sit in 78 degree room with my ac rolling 43% humidity and be cold. They are quite systems and as you mentioned, you can dehumidifier without a lot of effect on temperature. There are certain times of year that your ac won't run much and won't dehumidify. That's where the vs shines.
Joe Cole
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great info Brazosdog

I ended up having 3 more people come by yesterday just to see what they would say. I have accumulated enough info at this point that I could do a case study on HVAC bids and contractor talk. I went and looked at my thermostat when you made comment about 78 degrees and 43% humidity and ironically, that is what my house is at right now

First off the big name companies are a good 5-7k higher than mom and pops. Virtually same equipment, same everything and still 5-7k higher. Second, if you really start talking to a tech, most all of them will tell you they don't like zoning. I personally like having 2 systems, one for redundancy and two, I am basically manually zoning it myself. A lot of it depends on how the house is setup

Most of the bids I have are in the 13-15k range and the big names are all at 20 if not higher

I had one last mom and pop come yesterday that a friend of mine has used and I knew they would be cheap. I don't have the actual bid yet , but the guy ball parked it at 8k. Almost too good to be true so having to check it out. One thing is they are using Lennox Merit series which is a step down from the XC series that most people have been bidding and he is going to use the plenums I have because they are metal and nothing wrong . That is knocking 600 off right there. I have read up on Merit series and like anything else good and bad . The units he wants to install are single stage, but his whole thing was upgrading to an ECM motor that works at an inverter to essentially make it a two stage system and capable of 16seer.

If everything checks out, it's going to be hard for me to pay 15k range if I can get the job done for 8k and still be cool. Sure , I would love some vs high end machine, but fact is we don't use air a lot and my current system is 20 years old and single stage that works so I am used to it.
fourth deck
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Had the Merit series installed for both upstairs and downstairs in 2014 and 2015 respectively. In 2014 it was cheaper because 13 SEER was the minimum and a year later I had to buy 14 SEER. The rep quoted the more expensive systems from Lennox but when asked if it was worth it, indicated that it wasn't really worth it for myself since I had all flex duct which wouldn't take full advantage of the better systems. The other difference is that Merit series is made in Mexico while the higher end Lennox series are US-made. Both units are currently running like a champ.
BrazosDog02
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Op, what are the warranties on the models you are looking at? 10 year parts is a perk of higher end units and you can roll in labor too depending on contractor. That means little now, but at 9 years it may work to your favor. Some brands will come out, rip out the old condenser, and put in a new one under their warranty. So you may want to check that if you are going to be there a while.
dubi
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Help me interview for a new AC! This is overwhelming!
Joe Cole
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Brazos , you are correct, the XC (elite) line come with a 10 year warranty and the cheaper Merit series is 5 year, but installer said it would be 10. I called Lennox twice to talk to two different reps and both said the same thing, if you call in and register the Lennox within the first 60 days , the warranty automatically becomes 10 years

I'm stuck waiting right now as the company I expect to have the low bid is on a bit of a delay as the owner had some kind of back injury. Should hear something back this morning. I did have another mom and pop out yesterday that sells Merit line and his bid was under 10k


BrazosDog02
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This is something you play with while your system is dying. I have gone through 10 years of AC companies. The one I used to use was pretty good and did the original Lennox install, but at the 10 year mark started trying to sell me a new unit every time something went wrong. I had the same few techs for the entire time. Then, I went through a lot of small companies and mom and pop shops, some OK, some not. When I selected my AC company that i have now for a new install, I simply went on Angie's List and started reading. I paid for the subscription. I wanted a quick way of weeding out. I stumbled on 3 or 4 that sounded pretty good. As I recall, some didnt service my area, one didnt know about heat loads, and then it came to picking between two that sounded like they knew what they were doing. I am overly anal about systems, how they work, what they are installing, why, how they are going to do it in a tight space, air flow, etc. The one I selected was receptive to my questions and request for knowledge and they gave me 4 options from cheap to crazy high ( 14 seer to 22 seer) after I explained what I disliked about my OLD system. I read their website about what they sell and basically asked them why they like what they sell. Then listen.

Brand is not that important as long as you have a good warranty and your installer does the job right. Just talk to them. It's not overly hard to know when someone is jerking your chain on an install or information. If an installer can't tell you about heat load or duct sizing, that's a problem. If he doesnt know what the warranty is on the system he is selling...thats a problem. If he comes to your house and looks at your unit and then offers 3 options to replace without ever going inside or opening a tool bag....to me...that's a problem. If his technicians and installers are CONTRACTED AND NOT EMPLOYED by him...that's a HUGE problem for me.

Warranties: Read them. Find out what it is for the unit you are interested in. Is it a replacement warranty? 5, 7, 10 years? Does it require a continuous maintenance contract with the installer or other AC company? If so, how much does that cost?

From here you can start asking about UV Lights, Electrostatic filters vs. box filters, zone board brands, thermostats...how much do those cost? Do they recommend them? Why? Which can I get rid of and save money? Is it worth the savings?

Im looking for a long term relationship here. Even with all this, my company is a bit unresponsive to annual maintenance checks. They aren't completely on the ball, so it's up to me to remind them and schedule when my thermostat reminds me. My system is not perfect. LOL.
Joe Cole
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update here

I had my 2 new units installed today . Learned a lot about the process .

I was quoted all kind of different prices and models, the big boy's estimates are often double or triple what a mom and pop will do it for

I recommend finding a mom and pop with great reviews on installs. The install team is really the key in the process. A top of the line unit will not work good if it's not installed properly

I ended up with 2 units like I originally had instead of zoning. Zoning is probably great when it works but it's more moving parts and more things to break. I had a few techs pretty much come out and say avoid zoning

Quotes ranging from 7500-22k , now the 22k was for more higher end units with better seer ratings, but when you put the pencil to it, it's hard to ever recover those costs.

I went with the "low end" lennox Merit series. The company I use gets great pricing thru Lennox but also sells American Standards. The AS would have been several thousand more and after doing some research I found out they use a certain type of metal pattern in the outside unit that is really bad if you have cottonwoods , which I do so it was easy to not even worry about them

Merit series is well reviewed despite being the low end. All I can say is the install looks great and the unit is kicking out 51 degree air. I could have easily paid double for the same results

Will it fall apart or get hole in coil after 3 years ? Maybe. Will a Lennox XC25 also do that? Maybe. If these things die in 10 years, I can pretty much fully replace them again or even 2 more times and be at less money than some of the estimates for top of the line.


fourth deck
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AG
Not sure about your case, but my installers submitted the warranty extensions for me.
malenurse
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Quote:

I ended up with 2 units like I originally had instead of zoning. Zoning is probably great when it works but it's more moving parts and more things to break. I had a few techs pretty much come out and say avoid zoning
So, having two separate AC's, controllers, compressors etc is fewer moving parts than one AC with a zoning system?
tgivaughn
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Joe Cole: now that was helpful & thoughtful to post the thought process and results. I must agree with the logic, especially when thinking ... do I really want 5 tons coming on every time just one room calls for air? Then not using one unit most of the time seals that deal.

Can you share the name of the best deal that won your job? Inquiring minds want to know.

When we replaced our system, we had Aeroseal seal duct insides which found we were losing about a Master Bedroom amount of air in multiple leaks, even though all metal supply, short ductboard return. They closed that down to coat closet leaks ~ as good as it gets. That's the only place you might inspect & DIY repairs ...

Today, they offer dual compressors in some size units and mini-splits that save the most by turning on the least amount of compressor possible. I see your size demands did not fit those options. That's the only other concern when it comes to HVAC re-dos.

If you fear these lesser units (your words) might fail quicker, hopefully it's only the compressor = one day, back in business, no Federal case and cheaper than one might think.

Kudos for your real life post.
Joe Cole
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"
Quote:

I ended up with 2 units like I originally had instead of zoning. Zoning is probably great when it works but it's more moving parts and more things to break. I had a few techs pretty much come out and say avoid zoning
So, having two separate AC's, controllers, compressors etc is fewer moving parts than one AC with a zoning system?"


I understand your point. All I know is the zoning board for a zoned system is very expensive and when it goes you are in for some $$$. A zoned system requires automatic dampers on every duct. I'm not an expert, but there actually could be more moving parts on a big zoned system vs what I have in my 2 little units. Maybe I do have more moving parts, but the parts are not that expensive to replace. I'm not against zoning, just wasn't best option for my setup.

Avg estimate on a 5ton zoned system was around 13k. I did my whole project for 7500.

I already had 2 units so not really a change for me. We use the air upstairs very little so it works better for me to just manually zone it like I always have.

tgi- I used American Air Masters out of Haltom City
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