[Greenbuilding] [BULK] Re: Air Conditioning for Phoenix

[George J. Nesbitt]

Thank you Keith.

Perhaps I was too concise.

SEER rating is better suited for the more humid east (north and south) 
coast, where dehumidification is more of a concern, and outdoor 
temperatures aren't as high as in the west. EER is more important out 
west where dehumidification is less of a concern, and outdoor 
temperatures can be 95 deg F and higher. 2 machines with the same SEER 
can have very different EER's.

I did not mean CFC's. When we switched from CFC's to HCFC's and HFC's we 
reduced the Ozone depletion potential, but didn't reduce the Global 
Warming potential (I posted on this some time ago). The exception is 
R-410, I didn't realize this is a HFC (I am EPA Certified, but that 
doesn't mean I know and understand the chemistry), that you for 
correcting me.

Unfortunately I am installing 2ea R-22 air conditioners rite now, my 
supplier didn't stock R-410 TXV models, and I don't want to have to 
replace them, and couldn't wait to order them. I would like to use R-410 
only in the future.



Keith Winston wrote:
> Hi George! You make a lot of concise, good points. A couple 
> additions/modifications (I know you know most of this, it might be 
> helpful to others):
>
> Your EER/SEER comment is a good one. The Fujitsu 21 SEER mini-split 
> heat pumps I mentioned are 12.5-14.5 EER, depending on size and mode. 
> Which is respectable. Also, Lawrence, they are high efficiency heat 
> pumps in heating mode (HSPF 10.5-11), which helps with your heating 
> problem... They work down to very cold temperatures, so in that 
> climate they aren't even working hard in heating mode. I see that 
> they're only rated to cool to 115, though when I look at the 
> performance curves I imagine they'd work above that, but they are 
> already derated to 75% capacity at 115. I can send those to you if you 
> want, it was hard to get them. Okay, end of advertisement!
>
> R410a is a near-azeotropic HFC blend (maybe you meant "No CFC"?). 
> Which is about as good as you can do, refrigerant-wise. It has no 
> scheduled phase-out, since it has no Ozone Depletion Potential (ODP), 
> but it still has a Global Warming Potential (GWP) of about 1600, which 
> means that if a bit over a pound escapes, it's equivalent to a TON of 
> CO2. (Note: there are a lot of regulations covering the release of 
> refrigerants. So this issue is not the same as, for example, Tigerfoam 
> that I wrote about a couple weeks ago, where 7 lbs of R134a [HFC, 0 
> ODP, 1300 GWP] is NECESSARILY released for each 600 board feet of 
> product, with a GWP of 1300 resulting in about 5 TONS of CO2 
> equivalent, or as much as many of us release in a year of driving, 
> give or take). R22 is of course an HCFC, which is scheduled to be 
> phased out for new uses in 2010, and all uses in 2020.
>
> I'm not intending to be nit-picky, just clarifying.
>
> Keith
>
>
> George J. Nesbitt wrote:
>> *GREEN COOLING*
>>     Fix the *building shell* first as much as possible.
>>        1. Cool roof would be high on my list, but if you need 
>> "approval" then it might not happen. If you insulated the roof 
>> underneath then the benefit is too society in reducing the "heat 
>> island effect".
>>        2. Radiant Barrier, if you have to have a darker roof and if 
>> you don't insulate the roof, than I absolutely recommend a radiant 
>> barrier (help keep the attic and ducts cooler). Roofing is starting 
>> to be made in darker coolers that have reasonable cool roof properties.
>>        3. Insulate the roof, to bring the attic and ducts into 
>> conditioned space, either by placing rigid (polyisocyanerate) on the 
>> roof deck, or spraying foam (cellulose would also work in phoenix) on 
>> the underside of the roof deck.
>>        4. Windows, add low e film, overhangs, trees, replace, etc. to 
>> reduce unwanted summer heat gain.
>>        5. Air leakage reduction never hurts. Build tight, ventilate 
>> right.
>>        6. Paint the house walls a light color.
>>        7. Insulate the walls if they aren't already.
>> Now for the *mechanical.
>>        1. *Manual J or ASHREA 90 room by room load calculation 
>> (accurate).
>>        2. Manual S equipment sizing calculation, don't add size, if 
>> anything the load calculation is as much as 1/3 to large. Don't 
>> oversize.
>>        3. Manual D duct design.
>>        4. Manual T grill/register design.
>> Now for the *equipment.
>>        *1. Swamp cooler, the oasis is the best, direct, indirect 
>> evaporative cooling. Developed with funding from the California 
>> Energy Commission, and Davis Energy Group.
>>        2. There is another one, but can't think of it's name at the 
>> moment.
>>        3. Split system refrigerant cooling. Forget SEER, it is tested 
>> at 82deg F outside temperature, and 50% RH, you want a high EER, 
>> tested at 95 deg F (still cool for Phoenix). The higher the outdoor 
>> temperature the lower the EER (or SEER for that matter). Stay away 
>> from the 2 stage condensers, they aren't as efficient on high. 
>> (better to under size and let it run longer). Install an air handler 
>> (furnace?) with a ECM variable speed motor. Install a return duct to 
>> the outside for fresh air, and run air handeler 24/7 (or a percentage 
>> of the time) on low speed (60-80 Watts).
>>        4. Water cooled split system. Consider the Freus, and there is 
>> at least one other, hight EER even at higher outdoor temperatures 
>> (although some loss).
>>        5. No HFC, HCFC refrigerants, use R-410A (Puron is one trade 
>> name). The Freus is R-22.
>> Now for the *Installation*.
>>        1. R-8 duct insulation, especially if the ducts are in the 
>> attic, R-4 if they are in conditioned space.
>>        2. Insulate the plenum's, and the air hander too.
>>        3. Install the ducts and test to less than 6% of design 
>> airflow (400cfm/Ton cooling, ie 12,000 BTU's).
>>        4. Test the airflow with a Trueflow to check for 
>> 400-450cfm/Ton cooling.
>>        5. Braze the refrigerant lines with an oxy-acetylene torch, 
>> using 15% silver solder, and run nitrogen in the lines.
>>        6. Put the refrigerant lines under a vacuum to 500 microns, 
>> and not less than 800 after 15 minuets.
>>        7. Verify the charge using Subcooling (install a TXV).
>> Now for the *operation.
>> *       1. Use a programmable thermostat, try to live with not less 
>> than a 78deg F indoor temperature.
>>        2. Enjoy comfort without breaking the bank, or killing the 
>> planet.
>>
>>
>>
>> Keith Winston wrote:
>>> Hi there,
>>>  
>>>> I'm going to push the limits of what he can handle as it is.  A metal
>>>> roof makes a lot of sense in Phoenix, and that is the second part of
>>>> this project that I didn't mention.  Living roofs are great, but 
>>>> involve
>>>> structural mods that I'm not willing to consider on someone else's
>>>> house.        
>>> What about: put your metal roof on purlins (not all mftrs allow it, 
>>> but some do) to create an air channel underneath, vented top and 
>>> bottom (hopefully it's a simple roof -- include insect barriers in 
>>> the vents). Use a radiant barrier under it, pointing up.
>>>
>>> Insulate the roof from within the attic with spray foam, in the 
>>> meantime sealing up the attic so if there are any ducts in there 
>>> they are inside the envelope. Sorry, he has to move the nesting 
>>> dolls. Check with your local foam contractor to see how willing/able 
>>> he/she is to work around crap, but probably it needs to be empty. 
>>> Hire a few young people to clean it out! Leave the insulation that 
>>> is probably already on the floor, to make the attic a lightly 
>>> conditioned space. Then you get the reflective metal roof, a radiant 
>>> barrier properly installed, a convective air space to keep the whole 
>>> assembly from getting TOO hot, a tightly insulated roof, interior 
>>> ductwork... have I missed anything?
>>>
>>> Say, did you ever find indirect evaporative coolers? We can't really 
>>> use them here in DC, too humid. I see that Mastercool has an 
>>> indirect modification available 
>>> http://www.adobeair.com/masterCool.html, I can't find it on their 
>>> website but call and ask them. The other one is here: 
>>> http://www.oasysairconditioner.com/, which looks impressive.
>>>
>>> Another possibility is a Freus water cooled evaporative air 
>>> conditioner, quite different from a direct or indirect/2 stage 
>>> evaporative cooler. It is a compression-cycle machine that uses a 
>>> spray of water on the condenser coils to improve performance.
>>>
>>> http://www.freus.com/
>>>
>>> They don't have a good website. You'll probably gain more 
>>> information here:
>>>
>>> http://www.toolbase.org/TechInventory/TechDetails.aspx?ContentDetailID=793&BucketID=6&CategoryID=6 
>>>
>>> http://ezinearticles.com/?Evaporative-Water-Cooler---This-Water-Cooled-Condensing-Unit-Is-No-Swamp-Cooler&id=269729 
>>>
>>> http://www.ecosmartinc.com/productdocs/1-Freus-Overview.pdf
>>>
>>> I'm not sure whether it makes more sense to use less electricity, or 
>>> spray the Ogalala into the air to be whisked away...
>>>
>>> Also, I have used/installed the Fujitsu 12RLQ mini-split heat pumps, 
>>> which are 21 SEER units. If you have an open floor plan and can get 
>>> away with just one or two sources, it's a good prospect. Of course, 
>>> you may need to consider ventilation, though with swamp cooling it's 
>>> part of the picture. See if an HRV is justified in there, it might 
>>> remove a bunch of the moisture while still cooling makeup air. I 
>>> like the Venmar units.
>>>
>>> Warmly, Keith
>>>
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>