Yo: THE King

Posted by Jean on February 21, 2009, 3:56 pm

How's your head today?

If you're ever gonna get out of the truck, you'll have to learn how to
deal with this shiite. ;)

I would like your imput on the following. I'm trying to figure out
efficiency of this heat pump. Here's my calculations.

Indoor 72 F. Outdoor 40 F

To get CFM of air handler:

Temp in = 72 Temp out = 91 TR = 19
BTUH = 237 VAC x 20 A x 3.412 = 16,173

CFM = BTUH / (TR * 1.08)
CFM = 16,173 / (19 * 1.08)
CFM = 16,173 / 20.52 = 788

To get BTUH output of heat pump (w/o heat strip):

Temp in = 73 Temp out = 93 TR = 25
BTUH = CFM x TR x 1.08
BTUH = 788 x 25 x 1.08 = 21,276

To get BTUH of energy input:
237VAC
Heat pump fan = 0.59A
Heat pump compressor = 7.6A
Total heat pump W = 8.19 x 237 = 1,941

BTUH = W x 3.412 x 1.08
BTUH = 1941 x 3.412 x 1.08 = 7,153

COP = hh / hw
where
COP = Coefficient of Performance
hh = heat produced (Btu/h)
hw = equivalent electric energy input (Btu/h) = 3.412 Pw
where
Pw = electrical input energy (W)

COP = 21,276 / 7,153 = 2.97

EER = hc / Pw
where
EER = Energy Efficiency Rating
hc = cooling heat (Btu/h)
Pw = electrical power (W)

hc = 21,276
Pw = air handler fan + heat pump fan + heat pump compressor
Pw = (1.36 + 0.59 + 7.6) X 237 = 2263.35
EER = hc / Pw
EER = 21,276 / 2,263 = 9.4

Formulas from:
http://www.engineeringtoolbox.com/heat-pump-efficiency-ratings-d_1117.html

Data from:
http://www.alpinehomeair.com/related/Goodman_GSZ13_Specs_0508.PDF
Page 18
GSZ130241A* / AR*F182416**

These are for a 2 Ton, R410A, 13 SEER @ 40 F outside
Data sheet shows:
MBh 19.8 COP 3.06 EER 10.5 Amps 7.0
Hi PR 212 Lo PR 54 <------ WTF???????????

Unit is running hot and heavy (350/100 from HVAC tech quick check)
Still waiting for HVAC tech to come back and start diagnosis....

Am I full of shit? (I mean about THIS stuff)

Posted by Jean on February 21, 2009, 4:02 pm

>How's your head today?
>If you're ever gonna get out of the truck, you'll have to learn how to
>deal with this shiite. ;)
>I would like your imput on the following. I'm trying to figure out
>efficiency of this heat pump. Here's my calculations.
>Indoor 72 F. Outdoor 40 F
>To get CFM of air handler:
>Temp in = 72 Temp out = 91 TR = 19
>BTUH = 237 VAC x 20 A x 3.412 = 16,173
>CFM = BTUH / (TR * 1.08)
>CFM = 16,173 / (19 * 1.08)
>CFM = 16,173 / 20.52 = 788
>To get BTUH output of heat pump (w/o heat strip):
>Temp in = 73 Temp out = 93 TR = 25
>BTUH = CFM x TR x 1.08
>BTUH = 788 x 25 x 1.08 = 21,276
>To get BTUH of energy input:
>237VAC
>Heat pump fan = 0.59A
>Heat pump compressor = 7.6A
>Total heat pump W = 8.19 x 237 = 1,941
>BTUH = W x 3.412 x 1.08
>BTUH = 1941 x 3.412 x 1.08 = 7,153
> COP = hh / hw
> where
> COP = Coefficient of Performance
> hh = heat produced (Btu/h)
> hw = equivalent electric energy input (Btu/h) = 3.412 Pw
> where
> Pw = electrical input energy (W)
>COP = 21,276 / 7,153 = 2.97
> EER = hc / Pw
> where
> EER = Energy Efficiency Rating
> hc = cooling heat (Btu/h)
> Pw = electrical power (W)
>hc = 21,276
>Pw = air handler fan + heat pump fan + heat pump compressor
>Pw = (1.36 + 0.59 + 7.6) X 237 = 2263.35
>EER = hc / Pw
>EER = 21,276 / 2,263 = 9.4
>Formulas from:
>http://www.engineeringtoolbox.com/heat-pump-efficiency-ratings-d_1117.html
>Data from:
>http://www.alpinehomeair.com/related/Goodman_GSZ13_Specs_0508.PDF
>Page 18
>GSZ130241A* / AR*F182416**
>These are for a 2 Ton, R410A, 13 SEER @ 40 F outside
>Data sheet shows:
>MBh 19.8 COP 3.06 EER 10.5 Amps 7.0
>Hi PR 212 Lo PR 54 <------ WTF???????????
>Unit is running hot and heavy (350/100 from HVAC tech quick check)

OOPS That is what he says it should be. He measured 410/96

>Still waiting for HVAC tech to come back and start diagnosis....
>Am I full of shit? (I mean about THIS stuff)

Posted by The King on February 21, 2009, 6:19 pm

snip

>>Still waiting for HVAC tech to come back and start diagnosis....

He's a lucky guy! :)

Posted by Jean on February 21, 2009, 7:08 pm

On Sat, 21 Feb 2009 18:19:50 -0500, The King

>snip

>>>Still waiting for HVAC tech to come back and start diagnosis....

>He's a lucky guy! :)

I left the installer HVAC guy completely alone. He worked for about 3
hours - brazed pipe (all holes predrilled and tubing threaded through
loosely), purged,topped up charge and fired it up. All wiring had been
done and checked. Furnace was already running on aux heat. He said
everything was fine so I gave him $540. I've since learned that there
were a number of items he failed to check out. (Such as turning off
fan to cause icing and checking defrost cycle).

The new HVAC tech says the thing might have been overcharged or maybe
"bullet" on indoor coil overtightened or ????

I think I'm gonna watch this time and at least write down some
measurements for a record. At least I now have a basic understanding
of what to expect vis-a-vis pressures, temps etc.

I've come to the conclusion that the quality of the HVAC tech is more
important than brand or model.

The problem is finding one..... I hope this guy is good.

Posted by on February 21, 2009, 7:11 pm

>On Sat, 21 Feb 200
>I've come to the conclusion that the quality of the HVAC tech is more
>important than brand or model.

Yep.

>The problem is finding one..... I hope this guy is good.

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