07:45AM | 11/28/05
Member Since: 11/27/05
7 lifetime posts
Hello all:

I'm new to the board and hoping someone can help me. I have two conditioned zones in my house with a Janitrol GMP N0804 REV B in one and a Janitrol GMP 075-3 REV B in the other, both with matching cooling coils and condensers with a total of 5-1/2 tons of cooling capacity. My house is 3200 square feet, well insulated, double paned glazing etc., but the cooling has never worked very well. The supply air is quite cold, but the overall cooling is poor (eg. when its 90 degress out, the cooling has to run for 3 or 4 hours to get the interior temp to drop 8 or 10 degrees). So my questions are as follows:

1. Is the cooling capacity adequate for the house size?

2. Is there a way to increase the airflow to push more cold air? If so, is it something I can get the thermostat to switch so the increased air flow only comes with the cooling demand?

3. Is there anywhere on line I can get Janitrol literature for these two units?

Thanks in advance!


08:51AM | 11/28/05
Member Since: 11/27/05
7 lifetime posts
Thanks for the reply. I realize that cooling load calcs would answer the load question, but I was looking for a rule of thumb answer. The house is 4 years old, tight, well insulated (R-19 walls, R-30 ceilings and floors), with about 18% dual glazing distributed about equally on the four orientations in a climate zone with a 1% cooling design temperature of 85 degrees, and relatively dry when cooling is required. Does anyone know if 5 to 6 tons of capacity is about right?


10:19AM | 11/28/05
Member Since: 11/27/05
7 lifetime posts
Okay. For the lower zone, a UAdeltaT calc at a 1% design temp yields 4,200 btu/hr. The west glazing gains a max of 12,050 btu/hr per ASHRAE solar heat gain factors. I forget the specific heat and density of air, but even if you add fifty percent of the conductive gains for infiltration, and a like amount for internal gains, you still come up way short of 3 tons, which is what I have cooling the zone. So something does not compute. Am I missing something? Does anyone have a rule of thumb for air conditioning sizing?


Post a reply as Anonymous

Photo must be in JPG, GIF or PNG format and less than 5MB.


type the code from the image


Post_new_button or Login_button

For an eclectic table setting or outdoor lighting, try a riff on this project from The SITS Girls blog—converting mason ja... It turns out that many bath and kitchen cleansers contain chemicals that are dangerous to the skin and eyes, and often pro... So often we paint tiny nooks white to make them appear larger, but opting for a dark, dramatic wall color like this one—Be... Chocolate-colored walls and large window frames allow the exposed wood beams to take center stage in this small screened p... If you're not crazy about the idea of commingling plants and pool, this modern variation may be more to your liking. The s... Yes, a freestanding garage can become its own tiny house. Artist Michelle de la Vega has all the comforts of a modern resi... There’s nothing like a new set of cabinet hardware to refresh a room. The possibilities are endless: Go modern, rustic, or... Pursue what's known as the stack effect. To achieve it, open the windows on both the upper and lower floors, and as warm a... Like no other floor type, a checkerboard design works wonders to underscore the retro kitchen theme. Vinyl flooring, ceram... Twine lanterns add pops of crafty—but sophisticated—flair to any outdoor setting. Wrap glue-soaked twine around a balloon ... When securely fastened to a tree or the ceiling of a porch, a pallet and some cushioning make the ideal place to lounge. V... Incorporate nature into your lighting scheme by securing a dead tree in a concrete mold and draping your pendant lamp from... For the cost of a can of exterior paint , you can totally transform your porch. Paint the floor a hue that complements yo... In this urban apartment, a standard-issue patio became a serene and green perch by replacing the typical concrete with gro... If you put the washing machine in the mudroom, you can stop the kids from walking through the house in dirty, grass-staine...
Newsletter_icon Google_plus Facebook Twitter Pinterest Youtube Rss_icon