Replacing 2 systems with one, considering Carrier or Lennox hybrid gas/heat pump

[njbillt]

My questions for you professionals are so I can make an informed decision and I highly value any advice. I am not a DIYer.

My current HVAC plant which is about 20 years old uses 2 Rheem 105k oil fired furnaces, and two 2.5 ton Amana AC units. One for system for each floor of the house. My neighbor had a similar "2 of everything system" replaced by a single 5 ton Carrier Infinity heat pump and a single multi burn variable speed gas furnace, and they turned his 2 zones (up/down) into 4 zones, presumably with dampers. I am considering a similar system now that gas service is available on my street. My neighbors heat pump is Carrier's Infinity line, is supposed to be top of the line in terms of efficiency and durability. His uses a 2 stage scroll compressor. Carrier also offers the same 5 ton capacity in a unit with a 2 stage reciprocating compressor. The scroll seems to be slightly more efficient than the reciprocating, but again both are 5 ton. So the first question is: which type of compressor is best? Next question: is a hybrid system really going to pay for itself, or should I just go with a gas furnace/AC? And I guess my final question is, is my "2 of everything, one for each floor system" an antiquated system and is it wise to replace it with a big scalable system like my neighbor. And any preference on Carrier or Lennox, or any other suggestions are appreciated too.

[t527ed]

it could be done and made to work fine with one system but i would prefer to have the 2 seperate systems.

in any of the high efficiency equipment the smaller units of the same model are always more efficient than a 5 ton unit is.

with 2 systems if one goes down you have the other section of the house to "hide out" until repairs are made.

4 zones on a 5 ton system is more than likely to end up with undersized zones that will require a dump zone or even if the controls slow the blower down enough the a/c unit or furnace will probably be short cycling on the discharge air sensor.



i sell Lennox so what one do you think i prefer............:D

[dash]

Opposite viewpoint here.

I prefer zoning systems,only one each to maintain and replace down the road.

Your getting 4 zones instead of two,better controll of room to room temperature,better use of setbacks for unused areas,quicker response from setback of less then all zones,and extra capacity in a zone for parties,small ones ,not large.

the only good point ,IMO,about two systems ,is if one is done,you very likely have the use of the other.

The Infinity zoning is well equiped to handle retro fitting of a zoning system,better then most.However it can't overcome severely undersized ducts,best that they check the duct system ,before install.If your neighbors is working well,chances are yors will,assuming the same HVAC guy did both homes.

Hybrid heat,Carrier system is really nice,gives you a fuel choice ,based on price of each,as prices can change.

[njbillt]

This is the input I was hoping for. Having lived with my dual system for 18 years I know the advantage of having redundancy. The down side of having 2 systems is maintaining them.

[BaldLoonie]

If you are running 4 zones, I'd prefer the Bristol TS and its 50%/100% staging to the scroll which is more like 75-80% on low. That way when 1 zone is calling, you aren't trying to force as much cooling into 1 small duct.

I would think the Infinity zoning would be the way to go over any other when you are trying to do what you are doing vs starting from scratch and properly designing a duct system.

[beenthere]

2 systems is nice as you do have a back up if one system fails during the night. You can make due on the one that is still working.

If going with one system and four zones.
The Bristol TS, with Infinity zoning would be my preference.

[njbillt]

I could live with just the 2 zones, up and down. We have been living that way for years, and it's already ducted that way. It was my neighbor that had his up/down 2 zones split to 4. It's only my wife and I, and we zone off unused rooms simply by closing doors. Works for us. For some reason I thought the Carrier had a Copeland scroll compressor, which I read has excellent reliability. I had to Google that Bristol compressor as I had never heard of it. That thing scares me. Looks like a lot of moving parts. http://ts.bristolcompressors.com/cts.html Is that considered a reciprocating compressor? I know the Lennox I was considering does have a Copeland 2 stage scroll. What brand uses the Bristol TStechnology?

[beenthere]

Carrier has 2 lines of the Infinity 2 stage.
One uses the Copeland scroll, the other the Bristol TS.
Yes, its a recip.

They have been out for awhile now, and are proving reliable.

[firecontrol]

I'd personally go with the Carrier zoning with one system.

If putting two complete systems in is done for nothing more than to provide for redundancy incase of a failure of one of them, then what happens if the power goes out due to a bad storm and you don't get power back for days? Following the same logic I guess a standby generator for this possible scenerio would be a good idea. What if the frigerator goes out? Have a spare just incase? All I'm saying is that for a small price you could go out and buy a half dozen electric heaters to keep around just incase your heat goes down and for some reason it can't be fixed within a couple of days. If the air conditioning goes down a nice day or two stay at a hotel with a pool would be a cheap option to purchasing two systems to be maintained.

Just my opinion.

[machery]

I'd stick with the 2 seperate systems. Better control of the house and cheaper to operate. Why fire up the monster 5 ton unit to cool off a 1 of 4 zones? While the rest goes out the relief dampers? You run one system on one floor without running the other.....well you know since you already have that setup. The 2 smaller units combined current is probably lower than the 5 ton unit itself. If one system fails and/or needs replacing, it's cheaper to replace than the one 5 ton. My 2 cents

[beenthere]

Some of what you said would hold true on some zoning systems.

The Infinity, doesn't use a bypass or dump zone.

Its a modulating zoning system.

[heatpumpguru]

Carrier 5 ton 3400 sq ft home with ARZEL and 4 zones sweet. I had to use existing ductwork and I have seamless comfort. I keep the PRICNESS wing at 76 and the SWEATY KING at 72 and first floor and basement zone are at 72ish without running.

[njbillt]

This is all good advice and I thank everyone that replied. I don't think it would be cost effective to replace everything with 2 new systems, even though I would like the redundancy. This is why I asked about the 2 different compressor technologies regarding durability. Not only is it now more important that it stays online, I'll also be using the compressor for heat too. I have some concern about wearing out the compressor making heat. After all, I can make heat several way; I can only make cool with the air conditioner. But I remember the old days when my dad used to run the air conditioner in his car once in a while in the winter just to keep things lubricated. My car now has an automatic climate control system where the compressor clicks in and out year 'round, and after 168,000 miles and 13 years, it still works great. So my justification for a heat pump is it will last longer because it used more. I am going to get quotes on either the top of the line Lennox or Carrier hybrid systems. Thanks to "beenthere" for schooling me on a reciprocating compressor. I had an idea how a scroll worked. If there is a thread debating between the 2 types, I'd be interested if someone could steer me there. Thanks again.

[t527ed]

the reason your dad ran the car a/c was because it was belt driven and had a seal that could dry out and start leaking.


we don't have that on residential units.........:cool:

[njhusky]

njbillt..I'm regular member not a pro, but have just installed a zone system...that is not really running that well.

In hindsight, I would rather have 2 units, but didn't want to spend the extra cash...now I wish I would have.

From what I've read here, the Carrier seems like the way to go. I have a Trane and the dump zone is causing all types of tuning issues...bottom line, if I could sell this system for 1/2 of what I paid for it I would do it tomorrow and install a different brand. I will never buy Trane again

Also--make sure you do a lot of homework on your contractor. Have them go over in detail how the system really works before you buy.

[VA GENT]

I'd personally go with the Carrier zoning with one system.

If putting two complete systems in is done for nothing more than to provide for redundancy incase of a failure of one of them, then what happens if the power goes out due to a bad storm and you don't get power back for days? Following the same logic I guess a standby generator for this possible scenerio would be a good idea. What if the frigerator goes out? Have a spare just incase? All I'm saying is that for a small price you could go out and buy a half dozen electric heaters to keep around just incase your heat goes down and for some reason it can't be fixed within a couple of days. If the air conditioning goes down a nice day or two stay at a hotel with a pool would be a cheap option to purchasing two systems to be maintained.

Just my opinion.
Or as has been mentioned on this site before, get a couple of window shakers and store in garage in case a 1 system situation fails!:)

[njbillt]

I'd stick with the 2 seperate systems. Better control of the house and cheaper to operate. Why fire up the monster 5 ton unit to cool off a 1 of 4 zones? While the rest goes out the relief dampers? You run one system on one floor without running the other.....well you know since you already have that setup. The 2 smaller units combined current is probably lower than the 5 ton unit itself. If one system fails and/or needs replacing, it's cheaper to replace than the one 5 ton. My 2 cents

If I wasn't considering the hybrid heat pump system I would just get 2 new heaters and AC units. I'm afraid 2 heat pumps and heaters would be too expensive. I do like the redundancy though. Ideally, a heat pump/gas hybrid for the downstairs, where I am when the temp is best for a heat pump during the day, and a regular gas furnace/AC unit for the upstairs where the bedrooms are where I am only at night, when it's most likely too cold for the heat pump to run ... Does this make sense? There's no way this 2 system set up costs less than one 5 ton.

[beenthere]

I will never buy Trane again

Also--make sure you do a lot of homework on your contractor. Have them go over in detail how the system really works before you buy.

Its not Tranes fault the salesman mislead you.
Trane has equipment that will do what you want.
Your contractor, just didn't sell you that equipment.

[beenthere]

Does this make sense? There's no way this 2 system set up costs less than one 5 ton.

If your going to set the temp back on the second floor during the day, and want quick recovery, yes.

[njhusky]

Its not Tranes fault the salesman mislead you.
Trane has equipment that will do what you want.
Your contractor, just didn't sell you that equipment.

Beenthere...if there is something else from Trane, please let me know

You have been incredibly helpful and are a sure expert in this area. However, it appears that to me that a bypass damper is a much less efficient way to control things than to be able to control fan speed. Why dump air into the return instead of into the house? My guess is that solution was put into place before the sophistication of today's motor control technology--but I'm sure I could be wrong.

[njhusky]

Carrier 5 ton 3400 sq ft home with ARZEL and 4 zones sweet. I had to use existing ductwork and I have seamless comfort. I keep the PRICNESS wing at 76 and the SWEATY KING at 72 and first floor and basement zone are at 72ish without running.

I'm jealous...my brand new 4 ton trane can barely keep by 2000 sq ft house at 75 on a hot day

[beenthere]

Alittle late now.
But Trane has the comfortlink system.

I forget the name of their technology that had the ability to control blower speed.
Weather the old tech could do as much as you want or not I can't say.

I still think that much of the trouble is that your installer doesn't have your system wired correctly, or set up right.

When in first stage, you shouldn't have loud air noises.
And comfort r should be enabled.

[t527ed]

Does this make sense? There's no way this 2 system set up costs less than one 5 ton.



it will absolutely cost more than a single 5 ton system.

between the higher efficiency of the smaller systems and the longer run times of a properly sized unit i think you will be better off in the long run.

i would get someone to run the #s for you, heat pump for the second floor would probably still be a good idea the way our utility rates are going.

where at in nj?

[njbillt]

I am also in Burlington County, in Southampton township.

[t527ed]

we are lennox dealers, e mail in profile if interested.

[jramunni]

I'm jealous...my brand new 4 ton trane can barely keep by 2000 sq ft house at 75 on a hot day

Let me add a little salt...
I cool my 3 zone, 2000sq ft home with a 2 ton a/c. Two zones 1st level and one zone 2nd floor. Here is some data from the Heat PumPro board that is rather enlightening about zoning;

Min ODT 78 deg f
Max ODT 91 deg f
Avg ODT 84 deg f

Total Run Time - 39 hrs
2nd stg Blower- Y2 38 % (Y1 only 62%)

Serving Zone 1 (1st fl Main) 3 %
Serving Zone 2 (1st fl kitch) 38 %
Serving Zone 3 (2nd fl Bd Rms) 62 %

Serving Single Zone 70 %
Serving Two Zones 29 %
Serving All Three Zones 1 %

The zoning allows for a focused effort of supplying cooling capacity to the parts of the house that have higher loads. The lower load zones (1st fl Main) tend to remain at set-point not stealing capacity that can be used for the hard to cool/heat areas.

[Daltex]

I cool my 3 zone, 2000sq ft home with a 2 ton a/c.

Serving Zone 1 (1st fl Main) 3 %
Serving Zone 2 (1st fl kitch) 38 %
Serving Zone 3 (2nd fl Bd Rms) 62 %

Serving Single Zone 70 %
Serving Two Zones 29 %
Serving All Three Zones 1 %

The zoning allows for a focused effort of supplying cooling capacity to the parts of the house that have higher loads. The lower load zones (1st fl Main) tend to remain at set-point not stealing capacity that can be used for the hard to cool/heat areas.

That's what I was thinking if you have a house that has dedicated parts (floors) for different times of the day. You can use a slightly larger than Manual J'd system for the floor with the largest heat gain, zone it to the other area and set back the floors (areas) not in use and the system will do great unless you need the whole house at the design point at one time at the OD design temp. which would be never in my case. The recovery time would be less due to the other zone not calling. You could have a 10* spread between zones and still maintain humidity control over the entire house.

Am I missing something?

[jramunni]

That's what I was thinking if you have a house that has dedicated parts (floors) for different times of the day. You can use a slightly larger than Manual J'd system for the floor with the largest heat gain, zone it to the other area and set back the floors (areas) not in use and the system will do great unless you need the whole house at the design point at one time at the OD design temp. which would be never in my case. The recovery time would be less due to the other zone not calling. You could have a 10* spread between zones and still maintain humidity control over the entire house.

Am I missing something?

Not sure about your sizing method, although my house, according to a manual J load calculation, requires a 3.6 ton a/c and I do fine with a 2 ton. I will have to look at the print out and see what the individual zone loads are.

I am also not sure if you could actually maintain a 10 deg spread between zones. I am sure my 2nd floor zone would drift to a 10 deg spread, and I believe I could, at will, drop it 10 deg in less than 60 min if it was the only zone calling. I don't believe my 1st fl zones would ever drift 10 deg warmer than my 2nd fl (in cooling).

Zoning has tremendous savings potential if it is designed properly and allowed to operate to save energy with programmable set-back stats.

Much of the design criteria and savings potential are influenced by the type of structure and the usage patterns of the HO.
jr

[njhusky]

JR--interesting info...and it backs up what I suspect....if entire house needs a 4 ton system, is there any reason why I couldn't get my 1 zone to drop more than 20 degrees if the system is working properly?

[jramunni]

JR--interesting info...and it backs up what I suspect....if entire house needs a 4 ton system, is there any reason why I couldn't get my 1 zone to drop more than 20 degrees if the system is working properly?

20 deg is a lot of cooling...it will depend on the application, duct capacity, register types and their location, relative size of "1 zone" etc. You should be delivering 50% to 100% more cooling capacity when serving a single zone that is less than 50% of the total duct volume. If that cooling capacity is distributed effectively (plenty of upward velocity from a floor register) you could potentially drop a degree every 5 to 10 min so a 20 deg make up would take 1.5 to 3hrs

[beenthere]

If your zone panel is set up not to use second stage when only one zone is calling.
It may take a long time to get 20° or more temp difference.

[jramunni]

If your zone panel is set up not to use second stage when only one zone is calling.
It may take a long time to get 20° or more temp difference.

Yes it is...

Zone 1 (1st fl Liv area) 30%
Zone 2 (1st fl kitch area) 30%
Zone 3 (2nd fl bd rms) 40%
second stg output to Blwr @ 70%

This allows low wattage blower operation until I need the volume
If I had a two stg a/c it would stg up based on supply air temp

[beenthere]

Yes it is...

Zone 1 (1st fl Liv area) 30%
Zone 2 (1st fl kitch area) 30%
Zone 3 (2nd fl bd rms) 40%
second stg output to Blwr @ 70%

This allows low wattage blower operation until I need the volume
If I had a two stg a/c it would stg up based on supply air temp
LOL.
Sorry, I was ansering njhusky.

[Daltex]

Not sure about your sizing method, although my house, according to a manual J load calculation, requires a 3.6 ton a/c and I do fine with a 2 ton.

I am also not sure if you could actually maintain a 10 deg spread between zones. I am sure my 2nd floor zone would drift to a 10 deg spread, and I believe I could, at will, drop it 10 deg in less than 60 min if it was the only zone calling. I don't believe my 1st fl zones would ever drift 10 deg warmer than my 2nd fl (in cooling).

The sizing method I was referring to is to size the unit to the zone with the highest heat gain (ductwork designed to handle full load on each zone) and use the zoning for example to drop the upstair bedroom from 80* to 70* at night while the downstairs climbs from 74* to 80*. The time for the downstairs to rise to the new set point would allow the full load to be delivered upstairs dropping the temp much faster than an individual unit sized exactly for just the upstairs. This is assuming the load for each zone is close to each other.

Never thought of that approach before but it does sound interesting.

[jramunni]

The sizing method I was referring to is to size the unit to the zone with the highest heat gain (ductwork designed to handle full load on each zone) and use the zoning for example to drop the upstair bedroom from 80* to 70* at night while the downstairs climbs from 74* to 80*. The time for the downstairs to rise to the new set point would allow the full load to be delivered upstairs dropping the temp much faster than an individual unit sized exactly for just the upstairs. This is assuming the load for each zone is close to each other.

Never thought of that approach before but it does sound interesting.

You would just need to be sure the occupied programs were staggered and your good to go. My guess is a 10 deg set-back would get you at least a 3 hr window to focus on your "1 Zone".

[njbillt]

Hello again. An update from the originator of this conversation. I have been following the thread with interest even though it got a bit too technical for me. In my original question I talked about my neighbor who had his 2 systems (one for each floor like mine) replaced with one big 5 ton, and zoned 4 ways with Carriers Infinity zoning. Even though my question regarding adding zones was more "should I”, rather than how it's done, it's interesting to eavesdrop on you guys talking tech.

Unlike my neighbor, I have decided to keep 2 systems, for redundancy. I got differing opinions on this here too, but right now my downstairs air conditioner is broken, and if I didn’t have 2 systems I’d be typing this on my laptop from a motel room. I don't know yet if I'll be adding zones but I do have one area of my home that would benefit from being a separate zone; my den has a cathedral ceiling with a loft above. There are returns in this area for each floor/system, but it never seems to know which should run because the thermostats are in the middle of the main part of the house. It’s hard to describe without a picture but the house is a center hall colonial, but between the garage and the main house there is a 2 story section containing the den, laundry, and powder room. This area is more of an issue with cooling because it has 2 large sky lights, which tend to over heat it. Ideally, this should be a 3rd zone, but since I'm doing 2 complete systems, I may not be able to afford it. I have a guy coming out in a few days to look things over.

The units he can install are Carrier and I want the Infinity S (for scroll?) and if anyone has been following this thread they know I questioned the 2 compressor technologies as well. The installer works for a very reputable company, and has 10 years experience, but he is pricing this as a side job. He has done work for friends and family and they were happy with both pricing and his work. The only concern I have with this is whether Carrier will honor their warranty when it's installed this way. So that's where I'm at. No new questions really but I promised an update, and as always, I welcome advice.

[beenthere]

If you have the area with the high ceiling zoned. And its a small zone. The 2 stage recip would be better because of its lower capacity in first stage.

If this side job johhny, buys the equipment and installs it, Carrier will honor the part warranty.
But who you gonna get to honor the 1 year installer warranty?

Any company can get teh warranty parts for a system another contractor installed. They can also charge you handling fee's since they didn't install teh system.

I advise most people that think a side job johnny is their best solution, to go with a standard single stage system. Side jobbers don't seem to have the time to come back out and work on them in the middle of the day when tech support is available.

[m kilgore]

I agree with Beentherre. If side job Jonny is going to do the job I would just get a low end system. The higher end stuff requires more knowledge to size and set up and most installers don't have that kind of experience.

Also as said how do you know how long he may be around and doing side work. If he goes away then there goes your labor warranty if one is supplied anyway. The parts warranty comes from the manufacturer but the labor comes from the installing contractor. Buyer beware.

Remember that side jobs are done cheaper because there is usually no insurance involved, company parts are often used with company tools and most times its a tailight warranty. Also is this guy licenced with your city or state? Are permits needed?:rolleyes:

[njbillt]

Cubic feetwise, it's a lot of space. It would be nice to zone separatly, but for simplicity and cost I may skip it. Is there no point in going with a 2 stage system if I'm not zoning? Keeping the 2 systems is easier for a side job because it doesn't involve ducts, assuming I don't opt for a 3rd zone. He recommended a Carrier 2 stage sytem even before I told him I wanted it. He says he installs 2 stage systems all the time, and in fact installed one for a freind of my inlaws which is how I learned of him. I have confidence in his ability. I was worried about the parts warranty if it wasn't installed by an authorized installer. I realize there is an element of risk doing it this way. If I use this "side job Johnny", I'll make sure he stands behind the labor for one year. He knows I have concerns about the warranty. He is a friend of the inlaws side of the family so I trust him ethically and technically.

I'm leaning towards a Copeland scroll only because it's been around longer and has fewer moving parts. I'm sure both have pros and cons. Does one cost more than the other?

[beenthere]

You should know by now, we don't talk price.

2 stage is used in a lot of non zoned systems.

What makes you think scrolls have been around longer then recips?

[onegreywolf]

I have just found this site and would like your opinion and guidance on how to judge the following proposal.

My home has Air Con. only on the 2nd floor, bedrooms, the air unit is outside and the air handler in the attic. The system is about 20 years old and needs replacing. The heating system is in the basement and is a gas GE furnace about 25+ years and would like to replace it with a new and more efficient system.

After a visit and measurements of area upstairs, downstairs, and counting of windows. I was given this quote:

Main Floor: 1-#AUH100R ultra high efficiency Am. Stan. "Freedom 95" gas furnace rated 95% with variable-speed indoor fan motor
system.
1-#4A7A3036 3-ton, Am. Stand. Allegiance 13 seer central cooling unit ref. R-410A.

Upper Floor: 1-#4A6H3036 3-ton Am. Stand. heat pump.

What is the difference between a dual system and a 2-stage operation?
I understand from your postings I need to make sure that I do not get an over sized unit.
The square feet up-stairs is equal to the square feet down-stairs. Upstairs, there are 3-bed, 2-bath and 2-large walk-in closets. How do I make sure that the 3-ton up and down is ok and not 3-ton down-stairs and 2.1/2 ton up-stairs better?
Does the Am. Stand. Allegiance Air have a dual stage compressor? If not, should I get one that has it?
To heat the upstairs is the Heat Pump a good suggestion? Is there an other way to go?

Any feedback you can give me is appreciated.

[njbillt]

Okay. Well, I wasn't asking specific pricing, just a general question about the 2 types of compressors. I said in my original post I wanted to be an informed consumer before I purchase and it's only because Carrier offers both that it a consideration. I read several articles about the 2 types. One was on this forum. http://www.hvac-talk.com/vbb/showthread.php?threadid=105187 and there is a good explanation on Wiki-pedia too, and again, there are pros and cons to both. I don't want that to be the focus of this thread because I have gotten a lot of good insight from you pros. I can't find the part about it being a more proven technology, and may be mistaken about that. I was surprised how many people have the same concern though. Just Google scroll vs. reciprocating and you'll see. beenthere, I believe you are the one that informed me Carrier used the Bristol TS and I have to tell you, after going to their web site, I was fascinated by the ingenuity of the design. It left me wondering, does a reciprocating compressor have to be 50% or 100%? Do both pistons have to be the same displacement? Just wondering.

[beenthere]

Currently, they are only available in 50/100.

I think in other displacements like 60/100, or 40/100, there would be a balance problem.
They would have to add weight to the smaller piston.
Could also cause flucuations in pressure when both pistons are used, due to higher volume of refrigerant being 1 piston/cylinder is larger.

[beenthere]

I have just found this site and would like your opinion and guidance on how to judge the following proposal.
Any feedback you can give me is appreciated.

Get more estimates.
Screen the contractors over the phone, to make sure they are going to run a load calc.

I think the one you have is flawed.

Start your own thread, too confusing when you hi jack a thread.

[onegreywolf]

I apologize for interrupting a thread. Thank you for your reply.