ReplyI guess, I would figure to big a duct was just as bad as to small, if you take out a 3 ton and replace it with 2 ton, like to measure the static on that system.Originally Posted by 54regcab
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Depends on how bad the ductwork actually is. If ductwork is tight but can only deliver 800CFM at a reasonable static pressure, swapping a 3ton out with a 2ton may be a good solution if the customer won't pony up for ductwork upgrades and/or if the house only needs 2 tons of cooling to begin with. My point is never install a system that the ductwork can't deliver.I would even take that to another level, it's not like any existing change out is going to deliver its rated capacity period, regardless of manufacture or size, without upgrades.
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I guess, I would figure to big a duct was just as bad as to small, if you take out a 3 ton and replace it with 2 ton, like to measure the static on that system.
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A too large duct system is a rare find indeed... At what static pressure would you consider a duct system too large?I guess, I would figure to big a duct was just as bad as to small, if you take out a 3 ton and replace it with 2 ton, like to measure the static on that system.
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LOL!!
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So, while they're trying to drown us in the earth friendly thing and we have such things like Eco-Liberation front, let's look at some stuff I pulled from equipment detailed performance sheet. All of these are based on identical design systems.
The difference in X13 vs PSC in lab conditions appears to be around 60W/ton.
The original R22/PSC setup is the base line with 13SEER/11.8 EER
410A/PSC is the worst.
410A with X13 (when setting is moved to "low" blower) breaks even with original model at the AHRI EER conditions. Above 100F or so, it becomes worse than R22/PSC model.
The magic of unrealistic technical conditions used in AHRI 210/240 SEER calculation measures continuous cycle performance at 82F and depreciate about 5-10% for on/off cycle losses, then divide by total power use. The compressor input is fairly low at this condition, so it makes the evaporator fan motor power use more significant relative to compressor.
Fail gas 410A/X13 combo is assigned a SEER value of 14 while the EER is up a whopping 1.5% to 11.94, compared to 13 SEER 11.76 EER of PSC/R22.
So, even though it's just an inferior refrigerant circuit system with a blower motor that use 120W less under the unrealistic AHRI test conditions, it is technically qualified as 14 SEER, and therefore the price is higher than the 22/PSC setup as is the service cost due to motor failure.
The original model uses FREON R22 and PSC technology with no electronic non-sense except for low voltage controls circuit. Sales EER of 13, EER 11.8
Gross value,which ignores the heat/power of evaporator motor's influence is
24.8MBTU/1.81kW: 13.70 EER
Include the effect of evaporator allowing 0.236kW for motor:
24MBTU/2.04 kW: 11.76 EER
2nd generation downgrade model. Different metering device and compressor intended to use with water loving POE and fail gas R-410A.
Everything else is identical.
Sales EER of 13, EER 11.1`
Gross: 24.4MBTU/1.89kW =12.91 EER ( R22 setup: 13.7)
Net: 23.6MBTU/2.12kW = 11.13 EER (R22: 11.8)
3rd generation uses X13 electronic motor to compensate for reduction in performance caused by inferior refrigerant gas R410A and restores the performance back to R22 PSC system. All else is the same as mandatory downgrade to 410A.
Sales EER of 14, EER 12
Gross: 24.4MBTU/1.89kW: 12.91 EER
Net 24MBTU/2.01kW: 11.94
117W evap motor allocation
Same as downgrade model, but with X13 indoor motor. The 0.11kW system power and yes... 400 BTU capacity difference lol comes from evaporator motor power difference.
These are my calculations based on performance sheet interpolated for 82F ambient performance and my understanding of cyclic derating factor. The old R22 system:
25.6MBTU net x 92.5%/ 1.824 kW = 12.98 EER(sales) = 13
downgrade:
410A PSC 25.3MBTU Net x 92.5% / 1.824kW. 12.86 EER(sales) =13
The X13 electronic computerized motor compensates for the loss due to inferior refrigerant R410A so it doesn't suck nearly as bad as the straight R410A downgrade model. Because the compressor kW input is rather low at 82F ambient, the 120W evaporator fan motor difference, or three 40W light bulbs for your front porch yields a one point boost in Sales EER.
25.7MBTU net x 92.5% / 1.70kW = 13.98 EER(sales) = 14
The fan's calculated power is 0.117kW for x13 and 0.234kW for PSC. The fan power remains almost constant in a standard test. The 50% reduction is with test lab ducts with tap set to AHRI mode. The difference in watts between PSC and X13 narrows with increasing static pressure. i.e. real life conditions usually mean lesser difference.
With universal PSC, you either overshoot or undershoot the CFMs as they're not customized. The unit tailored "custom AHRI low tap" setting is set to provide as close as possible to 400 cfm/ton at static conditions of AHRI performance testing lab conditions as opposed to the field. These units ship in "high" setting.
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Most systems don't deliver the full 400CFM/ton with either motor due to ductwork issues. Dumping the multi speed PSC and going with a single high speed would get PSC efficiency closer to that of an X-13. There is little wattage savings going from High to Low speed on a PSC motor, I can't think of single furnace that goes below min temp rise with the blower on high speed.
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here's the factory calibration on a particular 3.5 ton X13. The red line is the PSC motor this motor replaced in order to get a one SEER point boost.
The system ships configured for green tap, but comes with a warning that you won't get the AHRI performance unless you switch to blue tap. What the hell is this supposed to mean? You look at it. You tell me. Is there really a legitimate purpose for the reduce 100 cfm blue tap mode to exist? Cuz as far as I can tell, there ain't.
Seriously, what would happen if you were to swap out the X13 with a PSC? Apparently the system's power use goes up by 0.15kW from the base of 3.58kW and you lose all of 1,000 BTU of capacity... out of 3.5 tons if you did it on them in middle of their efficiency test lab under some conditions that will never be seen in real life. It's so catastrophic and may prevent them from being able to round the SEER up to the next higher up-sell value.
In real life, the difference is probably less, because the fan speed will likely never get switched to lab test mode. It will probably be so little that you can't prove the difference outside of a test lab. Really too bad for someone who got sold the upgrade.
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1400CFM ton at 0.3" static? I'd like to see that outside of lab conditions!! The factory default "green tap" is more appropriate for real world conditions, that's why it ships as such. Customer will pay for the "SEER boost" but not for ductwork upgrades no matter how bad they are needed. What gets me is when you see high SEER units with more tonnage than the customers old system, but no ductwork upgrades.
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And another today. CBX27UH Will be changing tomorrow and scrutinize his static. Straight up 3 ton hp with matching AH. Two level, 2500sq' 2 returns, inline merv 10 media, yadda yadda.... This one made it 3 years....
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Yes, airflow is to blame in this situation...... get some numbers tomorrow hopefully.
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It's for a 3.5 ton unit. So, 400CFM/ton. I know there's field variations, but to blast 14 SEER prominently on the sell sheet and shipping with a default setting that would not achieve it is questionable tactic.
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And it continues.............
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PSC and a relay he needs hhhhhhmmmm
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To get the rated SEER requires a certain air handler and tonnage to begin with which rarely happens. The "up to" tonnage is typically awarded to the smaller units (under 3 ton) which are rarely installed. My own 2 ton 14 SEER AC that I bought in 2012 was manufactured in 2009. In the 3+ tons they sell like hotcakes, 90 days old is more typical.
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The examples are from package units to exclude combination changing trick.
When you don't exclude combination changing....
Out of 7,000 or so units... Each dot represents SEER/EER rating match. For example, 12 SEER/12 EER would be on 12/12 point.
Look at the disparity of real EER within the same sales EER class as the EER,sales go up. Different tricks up their sleeve.
The one that stands out boasts a sellsheet EER of ~17 with a 10 EER. I wonder how they pulled this one off.
These data points are from a 2001 study when R22 was the norm.
When 410A was mandated, modifications in system were necessary to offset the back pedal.
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14-16 SEER is worth buying IMHO, you do actually get a bigger outdoor coil and TXV. Once you go beyond 16 SEER sales EER takes over with silly hat tricks that don't save the homeowner on their power bill.
For homeowners that are truly concerned about their bill, tightening up the house/ductwork and downsizing the unit is what REALLY saves. Get a unit just large enough to keep up at design conditions, or even fall a degree or 2 behind. Good luck selling a smaller system when your competition is quoting them the same size 500sqft per ton system they have had for the past decade. Customers are so scared that their system might fall behind a degree or 2 when it's 95+ outdoors that they almost always opt for the larger system. Competition sells "magic bullet" high SEER systems w/o ductwork improvements or house tightening. If customers old AC is junk they will save just because they get a new unit, and you have another believer in the magical SEER...
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As you can see from the chart, there's great disparity between units. So, a 16 Sales EER unit can have a worse EER than a 14 Sales EER from another manufacturer. In Goodman vs Rheem in another thread, Rheem used TXV on their 13 SEER, Goodman used piston. I am liking the recent two point performance standards for rebates such as 12EER/14SEER to make it harder to play reallocation.
Using performance that would be typical on a 100F+ day (and usually during time of the day when kWh is the most expensive..)
At 10 EER, it takes 120kW/100 tons of cooling or 100kW/100 tons at 12 EER.
Higher ODB means higher kW drawn by each unit and the number of units running at the same time on hot days is putting the grid capacity to the limit and increasing brownouts and power outages. When it's something tame like 75F outside, the kW per each unit is lower and over a large number of units, the total number that runs simultaneously is less, so the grid isn't pushed to the limit. Sales EER however places emphasis on power use reduction during times when reduction is less important and assumes power costs the same 24/7. ECMs are dirty buggers that cause a lot of harmonics on power line that lowers power quality when they're used in large quantity.
Software controlled air handler motor industry have vested interest to push for failure prone computerized line voltage components since they stand to gain from them. They're a service nightmare for questionable return on investment.
Utilities like PG&E have a special demand shedding thermostat that they can control to some extent and make them take turns (wait time of few minute of no real consequence to comfort) to minimize the number of compressors running at once on the grid. If they sense grid capacity is getting pushed, they'll do a managed rolling black out just to AC units. One thing ecowhiners don't realize is that it's not that there isn't enough gas to run the generator. It's just that the generator isn't big enough to run all the A/C units at once, so they can avoid the issue by having A/Cs take turns, thus avoiding black outs or rate increase associated with substation upgrades. When utilities start offering some discount for participating in something like this, this cuts off dollars from your power bill.
On an 82F day, the needed condenser airflow is less than a 95F day. A slight tweak to fan geometry can reduce cfm to balance the condenser fan wattage and refrigeration system efficiency and I am talking about orders of 20-30w shavings. This saves watt input when it is 82, but it can actually be detrimental on hotter days. and thus we have those 16 SEER/10EER units. When they can no longer get around meeting both requirements by reallocation game, a change such as 800 RPM motor brings about across the board efficiency gain.
Sensible EER is the new parameter being talked about. Generally, I find materials published by the Government of Socialist Californian state quite authoritative and objective on this subject.
Non bleed TXV reduces the performance decay during off cycle. So, there's less performance decay with each on/off cycle. The self unloading characteristics of scroll compressor lets non-equalizing metering device to be used with PSC without a start relay/capacitor.
AHRI standards allow the use of either standard value or measured value for cyclic performance decay. If measured value earns a higher sticker value, then you know what they will do. . .
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Seems like they put a LOT into the "sales EER". Have you thought about charge level vs. Sales EER? Charging procedure could be optimized to increase sales EER, but loose real EER. With a typical oversized unit, most consumers would never know.
Good point about time of use electric rates, they are becoming more common. If you have a smartmeter installed, time of use rates are probably available. Here is how our local utility does it: http://www.ogepet.com/programs/smarthours.aspx
When I bought my own system I looked a FEATURES rather than brand. Large coil face area (16sqft for my 2 ton unit), Single row coil (easier to clean), TXV (helps a LOT with humidity during part load conditions), 800RPM fan (efficiency boost + much quieter). Sales EER 14.5, Real EER 12.5. Real EER is scary competitive with the 16+ SEER systems. Electric Bill hasn't been over $90 since it was installed in 2012. 1600sqft, built 1999, 4 people, 75f setpoint off peak/80f on peak.
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(This is an editorial piece reflecting my interpretation and views and geared towards service and technically oriented technicians and students. Data included is meant to justify what I am saying. It is based on my practical technical point of view and I am aware the sales oriented types will find it disagreeable over semantics or significance of certain things. If I goofed something which I've done plenty of times , or you disagree, discussion is encouraged. )
ABSOLUTELY. Sales EER is everythingto them. I mean EVERYTHING. Sales and Marketing Team LIVE on it. 14 SEER is available in common production units already. It's not some space mission going air conditioner with unreasonable requirements. The minimum legal standards sets the floor on what can/can not be sold, but there is far more to it. It is the scoring system used to qualify units for rebate programs. Equipment manufacturers and their lobbyists have a lot of influence on the final rules. I think this is how we ended up with .. let's test at 82F and call it good.. absurdity in standards.. If a competing interest find the standards unduly exclude their new technology or feels it is somehow biased, they file lawsuits against the DOE.
http://www.achrnews.com/articles/126...ndards-lawsuit
A "plus one" model that qualifies for rebate without a major production cost difference was a gravy unit that can be used to motivate customer to buy new equipment they wouldn't have otherwise or markup by the rebate amount so the net price "after tax credit and rebate" is about the same as legal minimum model.
OEMs, company owners and commissioned sales techs have their eyes peeled for gravy that will be paid by another customer(tax payers and public purpose charges on utility bills) but only initiated by the decision of the homeowner.
You can only do "+1" so many times with minor bolt-on substitution and a bit of buffing and polishing.
The actual difference between the base and +1 model is allowed to be completely pointless total hogwash as long as it meets the requirements on paper.
https://www.smud.org/en/business/sav...bates-HVAC.pdf
Here, you can see that a package unit will get $250/ton rebate for meeting 14 Sales EER/12 EER. The rebate has dual rating which recognized the flaw sales and marketing was using to puff up sales EER at the expense of real EER.
Here's the kicker.
The rebate model uses ECM to get 12 EER/14 Sales EER and under that program, qualifies the HO
for $250/ton rebate. So, if they quote the plus one at price that is exactly rebate amount higher than the base model, the rebate amount minus the wholesale equipment price is added profit.
Suppose you come across the older version of distressed unit with dented panels.
Suppose it just sat in corner of the warehouse, because the rebate deal has been moving the rebate version fine.
EER is 11.8 and sales EER is 13, has a PSC and politically incorrect R-22. The capacity is the same. The difference is 15 watts per ton of power use at EER test conditions and utility won't cut a check for rebate and it adds 15 minutes to hammer out the dents and it doesn't come with the profit gravy.
The EER is also superior to welfare rebate model in 100F + weather and there is no electronic crap to blow up in the blower motor. So, this one will be as efficient as the rebate model, but less likely to generate service call for motor failure and do not contribute to power quality issues associated with ECM.
If they make 12EER/14 SEER the base, it compromises the "plus one" marketing tool.
Have you thought about charge level vs. Sales EER? Charging procedure could be optimized to increase sales EER, but loose real EER. With a typical oversized unit, most consumers would never know.
There ya go. When properly charged, you'll see that there's negligible difference in performance in hotter temperature. Non-bleed TXV decreases on/off cycle decay. As for the double edged sword... it is far more resistant to performance decay (EER and capacity) to fixed orifice. So, a system could have a one pound/year leak on start-up and it is much more likely for it to ride past the one year warranty period without symptoms. Gives a real helping hand to hacks so the leak is less likely to get caught during the one year labor warranty.
Right now, it is discretionary in many places, but once they start using time of use capable meter every time they install/swap meters, it's just changing things on your account at the billing office. There's no telling it will not become mandatory in a foreseeable future in the form of "off peak discounts".Good point about time of use electric rates, they are becoming more common. If you have a smartmeter installed, time of use rates are probably available. Here is how our local utility does it: http://www.ogepet.com/programs/smarthours.aspx
You knew what to look for. Unfortunately, the Sales EER is the only thing preached to the typical customer. Increased EER is not something they even thought about or can find without some research, but when the government steps in and wants to raise EER to 12.2; OEMs moan and groan as it undermines the effort of what they thought was a clever 15 Sales EER 11.1 EER system.When I bought my own system I looked a FEATURES rather than brand. Large coil face area (16sqft for my 2 ton unit), Single row coil (easier to clean), TXV (helps a LOT with humidity during part load conditions), 800RPM fan (efficiency boost + much quieter). Sales EER 14.5, Real EER 12.5. Real EER is scary competitive with the 16+ SEER systems. Electric Bill hasn't been over $90 since it was installed in 2012. 1600sqft, built 1999, 4 people, 75f setpoint off peak/80f on peak.
If they had to raise the EER without having to downgrade the sales EER, that could actually cost money. so, you can see why it is a crisis to them.
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ICanHas,
Can you speak to the auditing companies that form these partnerships with power companies, promising to lower the demand on their grids by offering enhanced "tune ups" that measure air flow and enthalpy change as well as the actual rebates?
My suspicion is that they know what you have been expounding upon, but realize it is the rebates that will ultimately entice people simply install new equipment - equipment that is inherently more efficient than their twenty year old stuff; regardless of the seer or eer rating.
Is the Religious Right to blame for Christianity's decline?
They argued that, as the Religious Right became increasingly visible and militant, it became associated with Christianity itself. And if being a Christian meant being associated with the likes of Jerry Falwell, many peopleespecially political moderates and liberalsdecided to simply stop identifying as Christians altogether.
http://www.theamericanconservative.c...nitys-decline/
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