COP/SEER question

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I know what the two are, my question however is this,
What actually effects the ratings the most?
I'm under the impression its in this order:
Condenser size Evap efficiency Compressor designs
I really don't think for A.C and Heat pumps that the compressors have changed that much, have they? I'm speaking of course of r-22 units. What has really changed from lets say 10 seer to a 12 seer? I see a larger coils and due to that a smaller compressor, but did the compressors actually change any?
Rich
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Rich,
Coils have grown to be enormous, compressors I don't think are changing that much, and ID blower efficeincy (VS).
I am waiting for the new compressors they are using in the ductless, to be used in regular split systems. Maybe the more engineering related posters on here could input on the possibilities of that.
The same thing is happening with furnaces.
Trane is coming out with their new furnace next month, all they did was add another heat exchanger pass. I think they are going to call it the XV95, XV90's will be obsolete.
--
Bob Pietrangelo
snipped-for-privacy@comcast.net (home)
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Several things occurred over the years.
1. Larger condenser's resulted in lowering the head pressure and raising the sub-cooling some. This allowed for less horsepower needed. An increase in sub-cooling gives better performance at the evaporator because of a better adiabatic exchange. [Less latent heat].
2. The advent of the scroll compressor has reduced the power requirements increasing the EER. The scroll has less moving parts and a scroll design that allowed less liquid / vapor refrigerant to flow over those parts. Less friction.
3. The return to TXV control has given the evaporators better performance [although many refrigeration tech's have always known that TXV's give better load / performance resulting in better superheat control. [Better superheat control gives the compressor less compression ratio's and less oil sludging from higher ratio's.] Also the use of "equalized port" gives better TXV performance, and the use of positive shut off valve [keeps the liquid in the condenser where it belongs on shut down.]
4. The increase of use for 2-speed compressors [staging is generally referred but not necessarily correct.] This allows for lower power draw during those days when air conditioning demand is relatively low.
--
Zyp

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Zyp,
Great post! The only thing I question is the 2 stage compressors being a true energy saver. I think they are more geared towards comfort issues than anything else. They're savings over a 15-16 SEER singel stage system is nominal during a cooling season, and their HSPF usually a little lower.
Your thoughts
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Interesting thread as I had been thinking about this for some time, but got beaten to the punch in asking. I know the mfgs have gotten all the "easy gains" they're going to get. Not mentioned yet is getting optimum air flow through the condenser coil (ok- outdoor coil in the case of HP) with the minimum power usuage by the motor, including using ECMs outside. I have been wondering though, how much more efficient new recips are compared to older and even REAL old ones, as in the old slow speed Tecumseh B and JE models among others. Of course I have a Frankenstein project in mind-- for my own use. Thanks Larry
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The savings of 2-speed / 2-stage comes two fold.
1. Not having the equipment start and stop saving on high "in rush" current during start up with each cycle.
2. When smaller amount(s) of cooling capacity is required, the compressor, [and current draw] can match the load more closely.
What the manufacturer's have done commercially is make available 'staging' compressors by 'unloading' cylinders. Why can't they do the same residentially? They can and have. The problem though is cost. They can "separate" the scroll plates and reduce capacity. They can unload recip's cylinders and reduce capacity. But the cost currently on the resi market is too high to do that.
Somewhere around the early 70's one manufacturer [G>E] produced a condenser with two small compressors. The indoor section had two evaporators. One furnace [air handler.] The only problem was cost. Energy was cheap. They sold quite a few, but alias, the $$$ won and the design was scraped.
--
Zyp

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With a two compressor system, I believe you will have more inrush, especially during design temps. I am comparing overall capacity and efficiencies between a 3.5T XL14i, and a 4T XL19i. The 19 has about 5000btu higher capacity at 47 degrees (comparing heating cycle of a heat pump system, cooling is slightly different but not dramatically), the capacity of both at 17 degrees give the edge to the XL14i. The HSPF of the two is only a difference of .01HSPF. I didn't compare the COP.
The amount of energy used to cool a space utilizize a 2 T compressor or a 4 T compressor is not much different That pretty much negates the energy savings other than moving up in SEER about 1.5 points. The benefit of the 2T is that it will run longer and make the house more comfortable, rather than running at full capacity and not allow the system to properly cool all parts of the house.
I strongly feel that the only benefit is on a comfort level to adapt to heat gain.
There is one combination where the equipment combinations become greatly increased, and that is down around 2.5 Tons w a drastically oversized id coil.
.....and I think that is across the board with most manufacturers. Once you get up in the 3.5-5 capacities they all fall into a more even playing field efficiency wise, unless you are using aftermarket coils with false ratings.
I also find it comic that Carrier is touting the most efficient unit in the industry, with Geothermal on the market. They are pricing their equipment so close to Geo, life should be good. If only we could get loops subsidized!
Zep, I am not trying to Dis you, I am enjoying the discussion.

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The 14i is a single compressor single stage unit, the 19i is a dual compressor 2 stage unit. the 16i is a single compressor 2 stage unit that unloads approx 30-35% capacity. The 16i wins on the HSPF factor per mfgrs lit. I'm thinking this is because of the larger heat rejection from a single compressor built to unload...
The HSPF is basically a seasonal COP calculated off the actual performance of the unit as the outdoor temp varies throughout the season, though I'm unsure what/where they're basing the design temps of the "test season"
The big change in compressor technology has been around for decades & is slowly resurging. Trane & Westinghouse both had inverter driven compressors years ago, in fact Westinghouse had a system that was quite close to the modern Variable Flow Refrigerant Zoning systems that Mitsubishi, Diakon, & Toshiba have on the market now. The combination of a soft starting inverter driven compressor & the linear expansion valves that meter refr. flow to meet the actual load requirements, means the flow is constant & the compressor idles along at a constant rate. I've worked extensively with the Mitsubishi City Multi system commercially & have even seen a couple of the R-series units used in large (very large) residential applications. The R-series incorporates a single outdoor unit that can serve up to 24 indoor units, w/sizes from 1/2 a ton up to 8 tons. The indoor units can operate in either heating or cooling mode regardless of the other units operation mode. This allows for simultaneous heating & cooling off a single outdoor unit. By routing the hot gas or cold liquid, via the branch controller, to the calling units, the outdoor unit can idle down to approx 15% of rated capacity, it can also be overdriven up to 130% of rated capacity to cover the extremes. The systems in operation throughout the US are showing a 25-30% savings in cost of operation vs. roof tops & standard Nat. Gas & A/C airhandlers, VAV reheats etc..
The best part is, the City Multi line now includes a single phase 4 ton unit that can support up to 8 indoor units with a connected capacity of 5 Tons. Although this system is an "either/or" heat/cool unit that can only operate in one mode at a time.
I'm hoping they'll incorporate a cupronickel coaxial watersource heat exchanger that can be connected to a geothermal loop system, & the industry will never be the same again...
good luck geothermaljones st.paul,mn.

'staging'
can
recip's
market
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Excellent post, thanks
I've never heard of a linear expansion valve, I might have them in the field on some of our equipment and haven't noticed because nothing has failed.
As to the 8 indoor units, I'm assuming these are all split wall mount units, ptac type?
Rich
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Thanks, The linear expansion valve has multiple positions (near 60, I think) & can be monitored to analyze the systems operation. Position of the valve will settle in to near constant position as long as the load remains constant. As loads shift due to solar loads or migrating students etc... the valve adjusts to the need & the outdoor unit can ramp up or down as needed.
As for PTAC, Nah. The wall mount unit is one of numerous indoor units. There's a 1 way & 4 way ceiling cassette either recessed or suspended. Serviceable from below & w/ built in condensate pumps (near 30" vert lift). There's the wall mount, a ceiling surface mount, exposed & recessed wall cabinet units, and ducted units from 1-8 tons. There are more styles coming as well. All of these indoor units can be used on the single phase 4 ton unit PUMY048 (S-series)
Check out mehvac.com under VFRZ CityMulti for submittals, tech, install, etc...
3 Phase outdoor units, either R-series (simultaneous heat & cool) or Y-series (either heating or cooling) start at 72,000 btuh & go up to 234000 btuh. They must have at least 50% connected capacity to operate, & can have 150% connected capacity. They can overdrive about 30%, but the connected can be higher to cover the shifting peak loads etc... Meaning the 72 unit can have as few as 36000 & up to 108000 connected with a max 93600 load... The 234 unit, which I really like can go from 117000 up to 351000 (29.5 tons) & max oper. cap of 304000 btuh. They've even got a couple water cooled units of 72000 & 96000 btuh. They're brand new, but I've seen a little lit. on them. Again, I'm waiting for a geoloop system interface & life will be good...
goodluck geothermaljones st.paul,mn.

field
units,
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I will certainly check those things out after this summer rush.
BTW, welcome to the group.
Rich

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Been here for years... Just got sick of a few feuding idiots...

can
due
need
150%
the
with
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Great reply, and I might add these where my same conclusions. Technically, I would love to see the manufactures get back into Hot water recovery on their units with fan cycling to obtain higher seer's. Is there a manufacturer that has this with an air source unit to date?
I further think that the next energy savings will not be coil size since there is a limit as to how low you can get the high side pressures with existing refrigerants. I think the next substantial savings will be a new type refrigerant, one that will allow even lower head pressures and still allow for maximum BTU removal with little circulation per pound.
Besides the scroll, I didn't think there was really a great difference in compressor designs. If Danfoss can improve the electronics and magnets then maybe they can get the cost down to move on with their bearingless compressor for residential. I was told at ASHRAE in Chicago they have in prototype a 5 ton unit that will fit in the service mans pocket! Amazing for sure.
So, to continue, with the current refrigerants, what do you see the maximum SEER/COP obtainable?
Rich
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What about new refrigerants that have different properties?
If memory serves, thermal efficiency has something to do with Delta-T.... and most of the systems today spend a LOT of energy moving the working fluid/gas from one state to the other....and getting a high Delta-T. I would think that by using a different fluid that didn't need as much force to move from one state to the other, but using MORE of it...you could drive efficiencies up more... Or not even do a state change... keep everything in gas form, just hot/high pressure and cool/low pressure....
I can see some drawbacks... dehumidification would be one.... the other is that you migh need to change the system overall pressure/charge from season to season to move the ideal temperature points.... Thats another flaw of the working fluid today, too wide a working zone... Ground source is an example of the efficiencies that can be obtained if the working temperatures are kept in a closer range...
Just some more fodder for discussion...
Bob Sisson
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You are right Bob S. The stable ground temperature is what makes the ground source heat pump work well, especially in colder climates. The COP is more consistent.
I honestly think what will come as "new" and "efficient" will be the "electronic" heat transfer using the bubble effect of the electron. No refrigerant needed. Currently you can find something along these lines at the local auto store sold as a small ice box for your car. You just plug 'er in to the cigarette lighter and away she goes. If you reverse the plug, you can create heat in the little box too. Efficient though? I don't think right now. But maybe someday.
--
Zyp

"Bob Sisson" < snipped-for-privacy@inspectionsbybob.com> wrote in message
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Very limited and very in efficient....
They use them commercially with slab chambers for coroner labs. I suppose one reason is getting someone that would climb into one of those chambers to weld a leak!
Seems that Borg Warner was the originator of the first ones out.
http://www.thermoelectric.com/2005/old/photo-3.htm
More about them here http://search.yahoo.com/search?ei=UTF-8&fr=yfp-t-501&p=thermoelectric+refrigeration+history&SpellState=n-580264438_q-dK1.mTrSX8rqKQwp%2FA3wugAAAA%40%40&fr2=sp-top
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drive
in
Are you on drugs, or do you really not understand HOW a refrigeration system works?
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kjpro @ usenet.com wrote:

Both, why do you ask?
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Delta-T....
I
force
everything
system
I'm guessing Bob doesn't understand the reation that occurs during the flash point.
For Bob: --->Adiabatic change means that there is a change of state WITHOUT the expense [cost] of energy. No energy is lost or added, just a change of state with a change in heat from a sensible to a latent heat. So when the flash point occurs, and the liquid is flashed, about 25% of the liquid changes state to cool the remaining 75%. But with a high sub-cooling effect, then there is less change. Somewhere around 20% flashing to vapor... instead of 25% giving better performance. The big energy cost is the compressor pumping the heat latent refrigerant back up to condensing pressure to bring out the superheat. Check out a Mollier [my spelling may be off] chart on your favorite refrigerant. You'll see what I mean.
Has anyone heard about those "superchargers" that used a small amount of liquid to "refrigerate" the liquid before entering the metering device giving a higher sub-cooling effect? There were some out in the early 80's but I haven't seen any on the market. The theory then was the denser liquid would provide better performance. Anyone?
----- Zyp
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Are you smoking dope? JUST KIDDING!!! Seriously, I haven't heard of the 'superchargers', but the principal I assume is the same as a heat exchanger, to elliminate flash gas at the TXV outlet to improve capacity/efficiency.
Rich

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