Quality A/C and Heating Brands

Discussion in 'HVAC Heating & Cooling' started by vaman77, Aug 9, 2012.

  1. vaman77

    vaman77 New Member

    Messages:
    37
    Location:
    NJ
    Our central A/C and gas heating systems are the original for our home;now 19 years old. I know they have lasted beyond their life expectancy so I am obtaining quotes from different contractors.My question is what are the better brands and what are the ones to avoid?
    The first contractor came by yesterday and they install Carrier. When I asked why his answers made sense but I don't really know.
    Next week I'll have another contractor come by that installs for the Costco program and they install Lennox and I don't know much about it.
    Any opinions are appreciated.
    thanks
  2. BobL43

    BobL43 DIY Senior Member

    Messages:
    1,786
    Location:
    Long Island, NY
    You will need to consider more than just which brand is the one for you. Even more important than manufacturer, is the quality of the installing company and their technicians. Hacks can take the very best equipment, do a crappy installation, and give you lots of grief. On the other hand, finding and getting a good company to do the work can make the lower end equipment perform great and last a long time.

    The really hard part for the consumer is finding a good company; they are out there, but I personally believe they are out numbered by the hacks out there. I started out by first looking at the BBB web site, which I'm not sure is reliable any more, but it has info on companies and customer complaints, and if they have been resolved. Then I checked with the my county's department of consumer affairs. I am not a member of Angie's list, so I did not check there. I found a good company, but far from perfect. To their credit, they did have one of their service tech's come out and address and clean up any issues I complained about, which were mostly cosmetic. It is mind boggling to have to go through this and having to spend SO much money. I just got a new central AC system installed last month. I chose Trane equipment, as this company sells Trane and York, but the Trane had a higher SEER rating and gets a much bigger rebate from our local power company here.
    Make sure whoever comes out does a manual J and Manual D to measure all the room sizes, heights, number, size and types of windows, doors and their exposure directions. The Salesman that got my order spent more than 2 hours at my house, and most of that was spent going through my house with me and taking all these measurements to plug into the computer and determing the heating and cooling losses to decide which size and system and ducting was correct for my house.

    Good luck
  3. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    What BobL43 said.

    At 19 years they're still within the projected 20-25 year service life for gas-fired furnaces, and many AC systems will last that long too. But almost all ~20 year old systems were oversized for the actual heating & cooling loads, often by 3x or more, to the detriment of both efficiency & comfort.

    Old-schooler rules of thumb such as "a ton of cooling for every 500 square feet " or "25-35 BTU of heating per square foot" are literally GUARANTEED to oversize the equipment, which leads to shorter (and sometimes more frequent) on-cycles. Real heating & cooling loads are usually a fraction of that. It's common to see 4, 5, even 6 tons of central AC in homes with only 2 tons of actual peak cooling load. While that allows you to cool the place off more quickly when you come home after work, it often doesn't run enough during the less-warm days to handle the humidity, and you end up alternating between sticky and clammy. It's better to used right-sized equipment and programmable thermostats with not-so-deep set-backs. Similarly when the heating is 2-3x oversized you often end up having to settle with either wide swings in room temp, or short-cycling of the equipment if the hysteresis in the thermostat is set too low. Right-sizing the equipment is always more comfortable, and delivers efficient, comfortable, long on-cycles even with low T-stat hysteresis.

    Every good HVAC design starts with a room-by-room and whole-house load calculation (Manual-J or similar). Contractors that offer to do this without prompting (even if it's for a fee) move to the top of your list. A good load-calculation actually takes some time, so getting some compensation for that effort is reasonable. But look out for thumbs on the scale in their calculations, such as using too low a heating design temp or too high a cooling design temp, incorrect window or insulation values, etc. The 99% heating and 1% cooling outside design temps compiled by the ACCA are based on 25 year weather data for those location, and are plenty good enough. Lowering the heating design temp by 10F or increasing the cooling design temp only adds size & cost to the system.

    There is inherent margin built in to a Manual-J calculation, so try to avoid upsizing the equipment by more than 15% from those numbers should be avoided, even if it means going 10% lower than the calculated number due to incremental sizing within a manufacturer's line. For VERY well insulated modestly sized houses even the smallest hot air furnaces are oversized. If the heat load calc comes in under 20KBTU/hr at the 99% outside design temp (unlikely, unless it's a small very-tight house) it might be better to go with a different solution, of which there are several.

    In any ducted air system the system efficiency depends on the duct design (compliant with Manual-D) and good air sealing. If the ducts aren't sealed with mastic or FSK tape (2" aluminum) at every seam and joint, it's worth sealing as much as you can after the fact. If the ducts run outside of conditioned space (as in an attic, above the insulation) it's worth paying to test the duct leakage and remediate, since any duct leakage outside the pressure boundary of the house inevitably leads to driving pressure differences that drive outdoor air infiltration to levels many times the mere stack-effect or wind-washing drives, adding to the heating & cooling loads.
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Excellent summary by Dana. Covers all the key points, and in terms which are very informative even for the layman/consumer.
  5. DonL

    DonL Jack of all trades

    Messages:
    3,812
    Location:
    Houston, TX
    That was nice.

    I would have recommend Montgomery Ward.
  6. Runs with bison

    Runs with bison New Member

    Messages:
    891
    Location:
    Midwest
    Oversizing the furnace seems to be the most common sin. Most are already vastly oversized, and when a 95+% unit is compared to an 80% or 65% unit the input Btu ratings that you typically will receive for quotes mean little, unless you do the math to put them on the same output basis (which is all that matters for sizing.) If a contractor wants to replace an 80 kbtu/hr 80% unit with an 80 kbtu/hr 95% unit then he has introduced ~19% overdesign...and chances are the old 80% unit was already 25-50% over designed. Result will be a unit that runs infrequently and inefficiently during normal winters.

    One thing to remember though is than other than southern climates the minimum furnace size is set by the air handler frame size, which is in turn set by the AC size...not the furnace. (Frame size is tied to standard blower sizing increments and throughputs.) So to minimize furnace over design, outside of the warmest regions, one must minimize/nail the AC sizing. If your AC can already keep up in even the most extreme heat (such as the 117 year record summer we are easily breaking) then it is already oversized. If someone wants to go larger, they have missed the design. If your system is keeping up and they want to go marginally smaller to get to a lower frame size and smaller furnace that is within reason, then they probably have it nailed down. And if you are wondering, if your AC isn't running full out on the hottest day for hours, nonstop, and barely holding set point...then it is oversized.

    Most decades old ductwork is already below what is considered good design sizing for today. Going with higher capacity equipment is probably not feasible anyway. But going with lower capacity equipment could end up being substantially more efficient/quieter.

    Multi stage AC and furnaces will provide better comfort as they will run about twice as frequently (and more quietly) on all but the most extreme days. I have both now and they are a huge comfort improvement over the old single stage units they replace. Temps here have topped out at around 108 F in recent summers, and bottomed out at about -14 F in winter. My 2nd stage AC doesn't kick on until about 95 F sustained, and has no trouble at 108 F...indicating about 25% overdesign based on set point and offsets I've observed. The furnace rarely runs in 2nd stage since 1st stage is about 60% of max. When it kicks on the extra burners it is very cold outside, mostly sub-zero. I had the min. size furnace put in for the AC required air handler. The size choices I had for blower/furnace sizing worked out to either 4 ton AC for my present unit, or 3 ton AC for the next increment of blower. I went conservative with the 4 ton, but from what I see now, 3 ton would have worked...but very close. Since I have dual stage units, that is more than close enough. With single stage, comfort would suffer.
  7. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    "If a contractor wants to replace an 80 kbtu/hr 80% unit with an 80 kbtu/hr 95% unit then he has introduced ~19% overdesign...and chances are the old 80% unit was already 25-50% over designed. "

    In most mid-sized NJ homes an 80% DOE nameplate efficiency 80KBTU burner (=64KBTU out) would be closer to 100% above the actual heating loads. A reasonably tight circa 1993 NJ-code-min house 2500' house could easily have a true heat load @ +10F (the 99% outside design temp for New Brunswick) under 30KBTU/hr.

    Without knowing much else about the house than it's 19 years old doesn't really cut it, that's why real heating pros do heat load calculations on the real house using it's real dimensions, location, U-factors, and R-values. Better heating pros would even do leakage testing on both the ducts & house. (That would add a grand or so in service cost, but it may save you that much in reduced equipment sizing, and is more likely to yield a comfort premium.)

    Were it a 75 year old wheezy duct system spilling 30% of the air flow in unintended places in a similarly air-leaky house where the pressure differentials created by that duct leakage drives air-infiltration to insane levels, it might actually be right-sized for the "as-is" condition. But fixing the leakage (both ducts & house) would be more cost-effective than up-sized equipment and provide more comfort to boot.
  8. vaman77

    vaman77 New Member

    Messages:
    37
    Location:
    NJ
    Thanks for all the replies! Most helpful! A question I have about our home and I pose it to every contractor giving a quote. Our home is pretty energy efficient;when it was built in 1993 it received some sort of certification about it's energy efficiency.Since we moved in I've sealed ducts with mastic and aluminum tape. It's about 2700 square feet and our gas and electric average about $200/month.
    But there is a[problem. The house faces west. The furnace and ac are on the north end of the house.On the south end is a side entry two car garage. Above that garage are two bedrooms. Cooling and heating them is problematic especially for the one on the very end. It's cold in the winter and hot in the summer. It has two ducts.
    One contractor told me that a new system with two stage fan would help;I thought that was only for heating so not sure how that would help. He advised that if the new system did not help then maybe zoning the system would be the next step.The other one said the plenum is at least part of the problem.It's 20 x 8" coming out of the blower and said a certain length of it needs to be larger.How big a difference would this make?

    The current ac is a Coleman(from 1993) and the spec plate on the outside is worn so it's impossible to know the unit's size. Is there any other way to determine?
    The second rep told me if I'm fairly serious they would send someone out and more specific calculations as he's unsure if a 3 ton unit is enough or if 4 is needed.

    Advice is appreciated especially on the issue of the warm/cool room

    thanks
  9. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    It's highly unlikely that this is a cooling-tonnage problem. Better-built homes built since 1990 usually real margin on cooling even at 1000'/ton, and with a 3 ton you'd be at (2700/3=) 900'/ton. It is far more likely to be a duct design or flow issue combined with a heat gain/loss characteristic different from the rest of the house. If yours is currently 3 tons (tbd, but it's probably not smaller than that) bumping up to 4 tons would just yield shorter cycles and lower comfort everywhere without fixing the room-to-room balance problem.

    If I understand it correctly, the north wall of the north bedroom is a partition-wall with conditioned space, and it's south wall is a partition to the other bedroom (also conditioned space). By contrast the room on the end has an exterior wall on the south wall, which would explain why it has more issues than the other bedroom. Depending on the exact room dimensions the end bedroom could have 1.5-2x the amount of exterior wall, and probably more window area assuming it has some south-facing glass which means it's heating & cooling load are higher than the other bedroom. You can take some of the edge off the cooling load with an awnings shading the south windows in summer, but only increasing the flow to that room relative to the other will improve the room to room balance issues. If the exterior walls of garage is not insulated that too can add to both heating & cooling loads experienced by the rooms above, even if those rooms have insulated floors (which they almost certainly do.)

    The roof configuration and attic insulation over those rooms also comes into play. If it's R30 or 38 fiberglass, blowing 6" of cellulose (another R20+) over the existing insulation would improve the both winter & summer performance by more than the nominal-R value, since fiberglass is far more air-permeable than cellulose (leading to substantial de-rating of R from convection loops mixing in cold attic air when it's only 15F outside) and somewhat translucent to infra-red (so under a hot roof deck the temp 2" into the fiberglass can be a handful of degrees hotter than the attic air.) A cellulose overblow is a relatively cheap way to improve both conditions, restoring full performance across temperature to the fiberglass under it.

    Zoning each of those two rooms separately would certainly fix the problem. By virtue of being over the garage their heat loss is going to be different from the rest of the house, and whereas the rest of the house gets some cooling benefit of earth-coupling which moderates temperature swings due to higher thermal mass- they're both slower and shallower in the main house than in the bedrooms over the garage. If you take the step of micro-zoning those two rooms it would be better to have 2-stage blowers, since the CFM requirements of a single small zone is far lower than the rest of the house. If the rest of the HVAC is in good shape despite it's age, it may be less cash outlay to put in a 3/4-ton mini-split heat pump in each room (or probably better- a 1.7-ton 2-head multi-split like the Mitsubishi MXZ2B20NA ) as micro-zone heating & cooling for those rooms. Either ductless solution would run about 5 grand or maybe a bit more. It's not cheap, but it would yield VERY steady room temps and maximal comfort year round, at 1.5-2x the cooling efficiency of your ~20 year old central system, and would comparable operating costs to natural gas in heating mode. But if it can be done with reconfigured ductwork & zoning valves using existing systems (no swap-out of furnace or AC) that would likely be the cheapest way out.

    If you ARE swapping out systems, do the room-by-room load analysis even if it costs extra, and don't oversize. You'll pay less for the equipment up front and you'll be more comfortable.
    Last edited: Aug 24, 2012
  10. Runs with bison

    Runs with bison New Member

    Messages:
    891
    Location:
    Midwest
    I have a somewhat similar set up in climate that runs considerably hotter than NJ in summer and colder in winter. The primary issues I see with the bed rooms are likely several fold: 1. Lack of supply and return air in the rooms--they are going to have more surface area for transfer, plus they are at the end of the trunk. 2. Lack of insulation between garage and floor of the rooms. 3. System cycling too much.

    You might be able to manually balance the system by nearly closing some of the least important registers. Basically this is manual zoning. Works for us, though it is far from perfect. Make sure that you have sufficient returns. Having plenty of registers in a space doesn't help much if there is insufficient return.

    Checking for insulation between garage and bedrooms shouldn't be too difficult. Don't be fooled by some insulation stuffed at the end of the joists as an ineffective fire break...pull it aside and you might be looking at 15+ feet of emptiness. Our home is the same vintage and has zero insulation between. This is something I will eventually address, but haven't so far because I will have to rip out textured ceiling and refinish. I found the problem when trying to figure out why I had water stain in one portion of the garage. Turned out it aligns with the uninsulated metal duct pipe passing through the space.

    You can have both two stage air and two stage heat. My old system was single stage, the new is two stage AC/furnace. In essence the unit runs about twice as long as it did before, but at about half the fire/cooling rate of the old unit. This provides a better distribution throughout the home.

    Since your home is about the same size (2800 sq. feet here) and vintage as mine and yours has better certification and a somewhat milder climate, I would bet your AC requirement is 3 ton or less. I've got excess capacity at 4 tons now. The 2nd stage on mine kicks in on sunny days once outdoor temps exceed 95 F (its been consistent with this for 2 summers.) The rest of the time 2 tons is sufficient. From what I can tell, I could hold set point of 79 F with 3 tons at around 105 F. The frame size for your AC will almost certainly set your minimum furnace size. The furnaces are sized to match the air handler. With the Rheem/Ruud system I have the break point on frame sizes was at 3 tons. Above 3 tons required an extra burner or something like that in the frame.

    The 20x8" section could be an issue (I've got the same size going one way, but another smaller branch going the other.) A dual stage unit will suffer less from a restriction like that since it runs mostly in the lower stage with lower air flow anyway.
  11. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    " Our home is the same vintage and has zero insulation between. This is something I will eventually address, but haven't so far because I will have to rip out textured ceiling and refinish"

    What's stopping you from drilling 1-2 holes per bay and blowing it full of cellulose (rather than a full demo+ refinish)?
  12. Runs with bison

    Runs with bison New Member

    Messages:
    891
    Location:
    Midwest
    Two things primarily:
    Existing damage in some seams from duct drips (which I seem to have cured by sealing what I could reach.) And wanting to replace the existing ducts behind that sheet rock with better sealed and insulated runs.

    A smaller issue is that I'm not sure how cold the garage will become in deepest winter once the ceiling/floor space between is insulated. Should still be alright but the plumbing in there might require some attention.

    I've considered blowing if full of insulation, might still go that route.
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,820
    Location:
    New England
    If the plumbing is run towards the warm side of the space and you add insulation, it's usually okay, but if it's on the cold side of the space and you add insulation, you're just keeping any heat that may be available from getting to the piping, and it can be a BIG problem.
  14. vaman77

    vaman77 New Member

    Messages:
    37
    Location:
    NJ
    Thanks for such great insight.Two more questions. Do you think the plenum is an issue? Is the cellulose that much more efficient than fiberglass batts? I have decided that our money would be better spent on insulation rather than a new system but never really considered cellulose until your post.
    thanks again
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,820
    Location:
    New England
    Properly installed cellulose is a better insulation than fiberglass. It packs tighter, has less air infiltration, and has a higher insulation factor. Fiberglass makes a decent air filter, so it doesn't really stop air well. There are a couple of different fire retardents used with cellulose. They both work, but one smells if it gets damp. Course, insulation shouldn't get damp!
  16. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    Batts of any type have inevitable installation error issues that impact performance. Compressions & gaps allow air to convect around batts with very little impedance to flow. Low density batts (like R19s & R11s) have high convection rates at the temperature extremes even within the batts, and do very little to slow down stack-effect or wind-induced infiltration, as Jim points out. The loss of performance can be significant, particularly in homes that were built without air-tight detailing at the sheathing &/or gypsum. In attic applications without top-side air barriers the effective R of low density batts at 0F outdoor temps loses about a third or more to convection, and it has the summertime radiated heat translucency problem cutting into performance too. High density "cathedral ceiling" batts do MUCH better, but only if installed perfectly for a perfect fit.

    Blown or sprayed insulation fills all gaps, and cellulose at ANY density is an order of magnitude more air-retardent than low density fiberglass. At "dense pack" density (3lbs+ per cubic foot) it's two orders of magnitude more air retardent. In an open blow attic situation it takes at least 3" of cellulose overtopping, but it will in fact restore the effective-R of the fiberglass to something close to it's tested values when you do, simply by the air-retardency of the cellulose blocking the convection loops between the open-air of the attic and the fiberglass.

    In wall cavities blown new-school fiberglass at 1.8bls or higher density can be as air-retardent as 3-3.5lbs cellulose, but it's usually more expensive. At 1.0lbs density it's no better than R13 batts, whereas low density (~1.8-2.2lbs) cellulose is still pretty good, but either would settle in wall cavities over time in NJ climate, where dense-pack would not.

    Cellulose with "borate-only, sulfate-free" fire retardents doesn't stink when wet, and doesn't cost appreciably more than products that use sulfate fire retardents. The sulfates are cheaper than borates, but are corrosive to metals (particularly copper, but iron too) when wet, and banned in some countries. Cellulose designed for wet-spray (sometimes referred to as "stabilized" cellulose) contains water-activated adhesives, but no sulfates, and it's fine to dry-blow them rather than wet spray. For DIYers using box-store outlets it's sometimes hard to find the borate-only goods, but it can be special ordered even through box stores (but it may not have the same liberal return policy give to the off-the-shelf stocked items.) It's not a disaster to use sulfated goods, just be sure to remove it quickly if it ever gets wet from roof leaks/ice-dams, etc., and your nose will tell you when that happens. I have several places in my house insulated with sulfated goods, but it's never gotten wet, either from bulk moisture or condensation. YMMV

    FWIW: The worst application of suflated cellulose story I've heard never should have happened: Cellulose was installed in an historic building built with clapboards directly on the studs (no sheathing, not even planks), guaranteeing that wind-driven moisture would keep the outer layer of the cellulose damp, if not soaked. The 200+ year old nails all began to rust through, the place became structurally unstable and began to sag, and the place had to be condemned. The same might have happened even if borate-only goods or fiberglass was used, but probably would have take years rather than mere months, and there may have been time to save the building. Almost all professional cellulose installers know better than to do that.
  17. vaman77

    vaman77 New Member

    Messages:
    37
    Location:
    NJ
    Thanks! Most helpful. Any insight on my plenum question?
  18. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    If the plenum is undersized and restricting flow it's an issue, but how big that issue is relative to the rest of it depends. It won't fix the balance issue between the two end rooms, but it can only help the overall air-flow. Without sufficient information on the whole duct system it's hard to say how critical that is. Duct system issues aren't always well suited to re-design-by-web-forum beyond the more obvious stuff.

    If you've already FSK-taped &/or mastic-sealed every seam & joint (as well as on the airhandlers), and caulked the duct-boot to the floors/walls/ceilngs at the registers that's about the most you can do without re-sizing ducts where they're restrictive.
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