Dimesions pure sine inverter question

[IdaSHO]

Somehow they have been pushing those EER numbers higher... I seem to remember reading something about a switch away from R-22 freon to R-410 or something around that number also.

Edit:
It's R-410A

http://en.wikipedia.org/wiki/R-410A



That's quite a big change if you ask me...

While the freon has changed, along with a few updated components to work with the added pressure, the actual technology has not, and probably never will.


And look into the ACTUAL efficiency ratings of R22 vs R410A

It isnt that big of a jump. Its negligible, at best.


The evaluation or efficiency of an AC unit is based upon one primary measurement....

Coefficient of Performance (COP) It is a ratio of power output vs power consumed.
Or in the case of an AC unit, temperature drop vs power consumed.

And the COP difference between similar R22 and R410A AC units is typically less than 5%

 

[dwh]

Bought a new Frigidaire ac today.. it works!!!! Thanks for the help guys . My buddy (120lb bulldog) is going to be happy!!!

Sweet. Can I have the model number please?

 

[dvorocks]

Here is the model air conditioner I used Frigidaire Model: FRA054XT7. The inverter is Dimensions 800W 12VDC PURE SINE INVERTER. I wonder if a honda 2000 generator would power 2 of them..

 

[IdaSHO]

Interesting.

I wonder if some models are coming with a soft start built into the control units.

Thats the only way a unit like that would be able to start (reliably) on such a small generator.


Have you tried it plugged into the house power yet? Does it SOUND any different when starting compared to an the generator?

 

[dwh]

Here is the model air conditioner I used Frigidaire Model: FRA054XT7. The inverter is Dimensions 800W 12VDC PURE SINE INVERTER. I wonder if a honda 2000 generator would power 2 of them..

Okay, that's a bloody nice inverter. Certainly not an 800w cheapo like I was thinking of. If they say it'll handle 1500w surge, I believe it. Even if your a/c startup is dragging down the bus voltage on the 12v side - that inverter has an in-rush delay on the 10.5v shutdown to compensate so it won't just shut down on a momentary voltage sage like the way I was talking about earlier. Very nice unit.

That Fridigaire model is not currently listed on the Frigidaire web site. The site shows 3 5k BTU window units, but only one is energy star rated. The model number you posted has a SEER rating of 10.7 which is a touch lower than the rating of 11 on the 5,200 BTU unit I mentioned earlier. According to the user manual (dated 2009) it does have a 3 minute delay start timer on the compressor (page 7 under "Additional Things You Should Know"). Manual doesn't list the specs. I found a spec sheet here:

https://d1vofmza27mmhi.cloudfront.net/product-pdf/frigidaire-fra054xt7-quick-specs.pdf

That shows basically the same specs as the 5,200 I mentioned earlier, and it does say it has the low-voltage startup (3-minute delay after fan start before compressor start). Since the specs are basically the same as the 5,200 I'd guess that it has basically the same 1300w startup requirement as the 5,200.

A Honda eu2000i is rated 1600w continuous, 2000w surge for up to 30 minutes. If the running watts of the one you have is 465w (listed on the spec sheet), and the startup is the same 1300w (actually 1322.5w) as the 5,200 BTU unit - then you're only talking about 1787.5w - which is easily within the 2000w max rating of the Honda. So yea, as long as they didn't both fire up their compressors at exactly the same instant, the Honda should run two of them.

 

[dvorocks]

Thanks. Yes its a very nice inverter. I can it for a few hours today with my truck just idling. Didnt drain the batteries at all. Pretty happy so far. I just hope it cools the cab enough.

 

[4x4junkie]

While the freon has changed, along with a few updated components to work with the added pressure, the actual technology has not, and probably never will.


And look into the ACTUAL efficiency ratings of R22 vs R410A

It isnt that big of a jump. Its negligible, at best.


The evaluation or efficiency of an AC unit is based upon one primary measurement....

Coefficient of Performance (COP) It is a ratio of power output vs power consumed.
Or in the case of an AC unit, temperature drop vs power consumed.

And the COP difference between similar R22 and R410A AC units is typically less than 5%

lol
A new type of freon isn't "a bit" of change in the technology?
Apparently your idea of "negligible" is much different than mine then (and probably that of most people who try to run anything off batteries/solar).


I recall seeing an A/C unit with R-410A that had a 12 EER 2-3 years ago (Haier, maybe?) which would represent an 11% increase in efficiency over my 10.7 EER R-22 unit (which was already among the better ones available at the time) however I'm not having any luck finding it again now. A majority of Energy-Star units currently do seem to hover around the 11.0-11.3 mark, yet that is all still better than my 10.7 unit.

I stand by my post stating A/C units have gotten more efficient over the last 8 years.

 

[IdaSHO]

lol
A new type of freon isn't "a bit" of change in the technology?
Apparently your idea of "negligible" is much different than mine then (and probably that of most people who try to run anything off batteries/solar).


.

As stated, the technology has not changed. It hasnt since its conception.

Slight increases in efficiency, yes.



My idea of negligible? easy....

No matter what AC unit you use, they are all energy hogs. So yes, 5% isnt going to cut it.

I dont run AC in my camper. Hell, I dont even run AC in my house. Simply due to operating costs.



When the technology actually changes and we start to see legitimate increases in efficiency, let me know.
Afterall, the change to R410A from R22 took more than 50 YEARS. And the change was for environmental reasons, NOT efficiency.


Still, a couple of 500MA fans go a LONG way in a camper.

 

[LeishaShannon]

No matter what AC unit you use, they are all energy hogs. So yes, 5% isnt going to cut it.

I dont run AC in my camper. Hell, I dont even run AC in my house. Simply due to operating costs.

When the technology actually changes and we start to see legitimate increases in efficiency, let me know.

If i've got the conversion correct our R410 unit has an "imperial" EER of 19.5 (2000W of cooling for 350W of input , a metric EER of 5.71)

There is no problem running it on a small 350VA inverter with a modest solar setup during the day. Running it overnight does require a decent sized battery, our 300Ah @ 24v manages the job ok.

 

[IdaSHO]

What unit of measure are you using for the conversion? Shall I assume joules?

1 BTU = 1055.05 joules

Also, Id love to know the make and model of the unit you are using.



Fun to crunch the numbers and see just how efficient they are, and see if they are actually what the MFG claims they are.

I have found that many AC units (household) claim BTU ratings well beyond even what the circuit can handle.

 

[LeishaShannon]

Correct if me i'm wrong:

2000W output = 6824BTU/hr
6824BTU/hr / 350W input = 19.5 EER ?

Its a MHI SRK20ZJX-S :

Measured consumption with my fluke scopemeter 125 is ~173W (AC) on low. The batteries see ~200W due to inverter conversion losses.

Its a variable speed compressor so its output can range between ~3000BTU/hr and 10577BTU/hr, which is great because when you first turn it on a hot day it'll crank out 10500BTU for 30 minutes or so and then drop the output as required to maintain the requested temperature.



Thats a graph of its usage over a day in summer this year, you can see the initial short burst of 600W input (10500BTU/hr output) to get the camper down to temp and then the variable nature of the unit during the day.

When running its silent inside, far quieter than the caframo fan!

 

[IdaSHO]

No need to do any conversion....

The EER/COP is listed on that chart :sombrero:


Also, is yours a 240V unit? That chart shows all 240V

If so, how are you powering it from a 24/12v system?


And looking simply at voltage and amperes shown on that chart, the unit you are using is NOT drawing only 350W

Im looking at the "max running current" of 8 AMPs. At 240V /8 Amps = 1920 watts???
Even if they have the data mixed up with the "inrush current", at 240V/2.2 Amps = 528 Watts.



So yes, its fun to look at the actual numbers and compare it to the MFGs claims :ylsmoke:


It looks like a nice unit though. Does it vent to the exterior?
Many do not, so any cooling they do is a wash due tot he amount of heat it adds to the equation.

There is no free lunch. If you are removing heat from air, it HAS to go somewhere

 

[LeishaShannon]

No need to do any conversion....

The EER/COP is listed on that chart :sombrero:

Isn't that the metric EER? http://www.buildingscience.com/docu...g-and-cooling-carbon-emissions-and-efficiency suggests that the imperial EER can be calculated by multiplying the metric EER * 3.1412 , which gives the ~19.5 EER I calculated.

Also, is yours a 240V unit? That chart shows all 240V

If so, how are you powering it from a 24/12v system?

Yup 240v powered by Victron Multiplus and my little Phoenix 350VA unit for ****s and giggles one day just to see if it could do it

And looking simply at voltage and amperes shown on that chart, the unit you are using is NOT drawing only 350W

As mentioned, it uses a variable speed compressor rather than fixed. The electrical draw ranges from ~170W (3000BTU) to 350W (5600BTU) to ~550W (10500BTU)

Im looking at the "max running current" of 8 AMPs. At 240V /8 Amps = 1920 watts???

Yes, I'm not sure about this. Maybe its a guideline for the minimum CB/fusing required? My fluke samples a few million times a second and hasn't seen current anywhere near this high even on start up.

So yes, its fun to look at the actual numbers and compare it to the MFGs claims :ylsmoke:

As shown in my chart the manufacturer's claims line up with what i'm seeing the in real world. On a 36c (97f) day in summer we averaged less than 200W keeping the camper at a nice cool 23c (73f)

AC technology has come a long way in the past few years and this is the second most efficient I could find. There is another called the Daikin US7 which has a metric EER of 5.95 or imperial of 20.3! Unfortunately that unit was a bit big for our camper.

That said energy efficiency is only half the battle, I think you also need a really well insulated camper to fully realise the dream of solar powered AC. No point moving all that heat out only to have it seep back in!

 

[IdaSHO]

Oh I agree. Energy efficiency is out the window if you do not have a well built, tight, and insulated cabin.
That's exactly why I built mine the way I did. Factory built units simply are not done to my standards.
And if they were, I simply could not afford them!



With regard to EER and COP, that looks to be an error on the chart.

The site you linked refers to the conversion from EER to COP, and has nothing to do with imperial vs metric.


While they are both methods to measure efficiency, they are not one in the same as the chart seems to elude to.
Not quite anyhow.... They are both ratios of energy output / energy input.

The catch is that EER uses specific units of measure, BTU and watt-hour.
COP is simply a ratio, using no specific units of measure. Most importantly, it doesnt use TIME.


This link should explain it better than I can...

http://www.powerknot.com/how-efficient-is-your-air-conditioning-system.html


Basically, EER = energy OUTPUT in BTUs / electrical energy INPUT in watt hours

While COP = energy OUTPUT / energy INPUT



With all of that said, and looking at that chart, Id have to say that the numbers indicated would probably be COP, and not EER.


Clear as mud?

 

[LeishaShannon]

So the "real" EER 6824BTU / 350W = 19.5 ?

Pretty big step up from the R22 models of just a few years ago!

We have no problem running it 24/7 on solar over summer which is what we set out to achieve. Its starting to get a bit cooler now so it'll be interesting to see how it goes heating the camper, it doesn't get real cold here (maybe 0c for a few hours max) so hopefully it'll manage OK. If not the alternator might get a work out on the cooler days