Lennox Harmony System
I've been told that the Lennox Harmony Zone System is unique in the marketplace. My understanding is that it is the only system that seemlessly controls a variable speed blower using electromechanical dampers and a series of static pressure sensors to do so. If coupled with a modulating furnace apparently it can also control the amount of heat the system is calling for be it one zone or several. So the only thing that is missing from what appears to be an ideal system is the cooling side.
Certainly a two stage compressor with this system would make sense as would a two compressor unit like the Trane 21i if it is compatible. Ultimately an inverter based, variable speed AC unit would be the best solution using today's conventional offerings such as the Nordyne stuff from the likes of Amana and GE or possibly a inverter based heat pump like the Carrier system. Unfortuately these are expensive solutions and in the case of Nordyne max out at four tons plus there may be an incompatibility issue between brands.
In my case, the heat pump, which I am told is only slightly more expnsive than an equivalent AC unit, would not be used for heat as my natural gas costs are low relative to my electricity costs and that relationship is unlikely to change for the better. So I am not sure this makes sense from a cost perspective but I am certainly willing to consider it.
For general reference I own a 20 year old 3400 sq.ft., two story home (1st floor 1800ft. 2nd floor 1600ft.) in northern California. I would like three zones (two down and one up). My 20 year old, 5 ton York system is ducted for three zones, which I manually control at the air handler each season and my house is very comfortable year round. But I need to replace it soon.
So here are a few questions. Have I described the Harmony system correctly and is it indeed unique in the industry? I would like to have a zoned system (two or three) that has real world effeciency withouot spending a ton of money. So what is the least expensive plan for the AC component assuming that the Harmony system is the best option for zoning? If I don't need a fully modulating furnace how many stages of heat would be appropriate again assuming that I have to use the Harmony system?
I may be wrong but bypass circuits and dump zones just don't make sense to me so I would like a design that does not use these.
I beleive that a two system solution would be a great but expensive alternative. If I decided to go with two systems what tonnage/btu combinations would you recommend?
This is blue sky stuff but from a layman's perspective and with a reading knowledge only I can't help but wonder. Has anybody ever seen a system with two compressors and one coil or perhaps two stacked coils one for each compressor? Or is it possible to use two compressors and two coils with each coil in its respective air supply? What I am trying to get away from is two complete and separate systems in order to potentially keep the costs down.
If you do zoning, the system AT LEAST 2 stage heat (if gas) and 2 stage cool. And each zone should not have CFM less than 600. We install many Harmony III panel. They are not as you described. But close though ...
As for the system size, please have the contractor to do the load calculation for you. We are not even close to qualify to tell you since we have no idea the color of your house
I agree with HVAC-TALK community about load calculations and getting a good contractor. A lot easier said than done in my area. I'm having a hard time just getting someone to do a Whole House Performance analysis (blower door, duct blaster, IR camera, manual J, etc.) for me and I'm willing to pay them $100 and my electric company will pay them another $200!!! Try to find an experienced contractor willing to do a good design and install...forget about it!
I may have to convince Travis at Sky Heating in Oregon to fly down here and help me out.
Are the Harmony and Infinity comparable or is one superior to the other?
Do you think that two small simple systems are a lot more expensive that a large one with zoning and all the other stuff I need?
No. you cannot mix Harmony with other sytem because the blower CFM will not match with the PIAS setting of the board. I THINK the same for other manufacture (that's is why they call it a proprietary).
I always prefer 2 systems:
1) With 2 systems AND they are all 15 SEER, then they are 15 SEER. When you put the system as zoning, the system SEER will significantly reduced due to lack of air flow per design and more of short-cycling of the equipment. Zoning is for comfort and not for SEER.
2) With 2 systems, I can run to the one that is still working for shelter.
What state are you located in?
Originally Posted by mhitim
Make your expertise uniquely valuable.
Make your influence uniquely far-reaching.
California near Sacramento
Agreed, 2 systems is the way to go for a house that large. I split them up/down for most house designs. Once system go over 15 SEER the payback time starts to exceed the life expectancy of the equipment. An easy way to get "extra SEER" is to buy equipment that is just big enough to get the job done. Keep your eye on the prize, think reduce energy costs, not just get big SEER numbers. The EER is typically within 1 between a 15 SEER and 21 SEER units. The 21 SEER gets it's extra SEER by reducing cycling losses with 2 stages. However this does not increase the EER.
Originally Posted by just_opinion
Don't go by tons per sq ft. It's not unusual for an upstairs to require TWICE the cooling per sqft as the downstairs. Reverse holds true for heat, the upstairs rarely needs much heat.
I really like the idea of two systems for a variety of reasons but I've always assumed that it would be the more expensive solution. Is it likely that a system with "less expensive" equipment may be cheaper than a single, large, high SEER, two stage unit plus an expensive zoning system controller and electronic dampers? If so I would assume that you are suggesting two single stage ACs but at what SEER rating?
Since my NG is currently about $1.20 per therm and is cheaper to use than electricity (and I don't think this will change anytime soon) I have always assumed that a heat pump would not be a good option for me. Would you agree? Since I will be using two furnaces for heat would you stay with the "simple" theme and avoid variable speed blowers and multi-stage burners? If so what do you recommend for the furnaces for the two systems?
FWIW I manually "zone" my house now. My house actually has 3 zones already ducted with manual dampers on each one at the air handler. Each season I go into the attic and with the help of my wife I adjust the flow of air at the air handler to favor the upstairs or down. With this strategy I can keep the upstairs within 2 - 3 degrees of the downstairs. I can't really talk about efficiency but it is comfortable and I've never had a coil freeze or any other problems that i'm aware of. It would be very easy to keep the three zones or convert them to two.
Our temperatures rarely get below 32 or over 100 and we are very dry here as well. When we use AC it is only about two to three months a year supplemented by a whole house fan almost every night during the Summer and we use heat about 4 months out of the year. We set our stats at 78 in the Summer and 65 in the Winter.
Any help is greatly appreciated.
The problem is your super high SEER vanishes into thin air when you start choking off the airflow with the zoning dampers. Running 2 separate systems about 14-15 SEER while making sure they are sized correctly will be what gets you low energy bills and maximum comfort. Once you go over 15 SEER, efficiency gains are mostly from reduced cycling losses. If you have a 21 SEER and 15 SEER both running "wide open" with a 95 degree outside temperature energy consumption will be very close since there isn't much difference EER. It's when the temperature drops to 82F that the 21 SEER will have the advantage due to reduced cycling losses. Slightly undersizing will also reduce cycling losses in either system.
For heat, the furnace is the way to go for downstairs. For upstairs you will need to run the numbers, a standard air handler with electric heat make more sense depending on the cost difference and the price of power per KWH. If the upstairs uses little heat over the winter a furnace is hard to justify from a payback time prospective. Figure the cost per BTU for each fuel, and get a quote for the air handler vs. furnace. Calculate the number of hours the system will need to run in order to break even.
VS systems are nice, but buy them for comfort more than energy savings. In most areas you won't have a reasonable payback time for the VS blower. VS blower motors cost a lot more to repair/replace than standard motors.
2 systems is the way go. If you are going zone with a high efficiency system your entire duct system would likely have to be replaced to have it sized properly. High efficiency systems are very temperamental with static pressure changes in the system. Your best bet would be to listen to what 54regcab stated in his last post, since you have so little demand for heating and cooling you need to make sure the units/units are sized properly.
What you and jtrammel are saying makes perfect sense to me. One thing is for sure is based on 20+ years of experience I push 85% of my heat into the to downstairs zone in the winter and 85% of my cooling into the upstairs zone in the Summer and I have about 2-3 degrees difference between the floors. I am told this is very good. Certainly it is very comfortable. I just don't want to have to mess with the dampers as I am getting older and climbing into the attic may not be possible in the next ten years or so if you know why I mean. None of us will escape Father Time so we may as well face the music and plan for it. So I need to duplicate what I have with modern equipment and I think I will be very happy.
Thanks a lot for your input is is very helpful in what is a very confusing selection process.
These are rough guesses based on typical Oklahoma house construction and gas/electric rates: Using your 78F inside temp with 85% going upstairs it's looking like 3tons upstairs, 1.5 tons (smallest you can buy) downstairs. Since you don't go below freezing I'd do 45k furnace (smallest you can buy) downstairs and 5KW electric heat upstairs. You will need to do the math using your rates and do a load calculation for your particular house. Look at your utility bills over the past year to get an idea of what it takes to heat/cool your house, this will help in the equipment selection process. If you find you have a high load try to reduce load before deciding to buy larger equipment.
Do not be scared of undersizing, I just replaced a 3 ton A/C in my 1600sq ft Oklahoma house with a 2 ton (old unit had leaking A-coil). My coworkers though I was nuts deviating form the "tried and true" 500sqft per ton, but it was 101 degrees yesterday and my house didn't go over 78 inside (setpoint is 76). Yes the unit ran continuously, but that's the way it's supposed to be.
A quick guide on SEER:
13 SEER is minimum, typically builder grade equipment: EER's around 11.
14-15 SEER is better made, larger coils, most have TXV metering on indoor coil and scroll compressors. Some units upgrade to 850 RPM condenser fan motors (quieter outside unit), Hi/low pressure switches, full metal coil guards. EER around 12. Best value in areas with power rates under 15 cents per KWH.
16+ SEER will normally have all the goodies that are optional on 14-15 SEER equipment. To get extra SEER the units will do things like multistage or dual compressors and variable speed blowers on the indoor unit. Sizing and installation more critical to get right and actually see the real world 16+ SEER. Typical EER 13. Worth considering for areas with power rates over 15 cents per KWH.
Last edited by 54regcab; 09-02-2012 at 08:29 AM.