Hello everyone,
I have a question. I want to look at a scenario of energy consumption and costs for ductwork thermal and leakage losses outside the thermal envelope as compared to the ductwork being inside the thermal envelope. Below is the key information. I saw under the detailed data edit mode, the option to imput duct losses information under the air side tab. My understanding is that you can estimate a leakage rate based on the percentage of air lost in the duct system. Also, the thermal losses can be estimated either by the UA of the ductwork or the temperature difference between the supply temp and air distribution supply temp to the space. I opted to choose the UA option. Below is the information that I input.
Description of Value
Value
Units
Ductwork R Value
4.7
ft2??F?h/BTU
Ductwork Leakage Rate
0.15
Percent
Estimated Supply Ductwork Surface Area
1,440
Square Feet
New Unit Rating
15
SEER
Return Duct Surface Area
240
Square Feet
UA for Supply Duct
306
Btu/h-F
UA for Return Duct
51
Btu/h-F
Duct Zone
Roof Zone
There are a couple of things that I have noticed.
1) When I select a residential system (split system), the duct leakage option is grayed out under duct losses. Why is that?
2) When I change the information for the duct losses as shown, to 0 for the UA of the supply and return duct, and 0 for the leakage rate, I get the same values for the LS-D and LS-E reports for the MBTUs for the roof zone.
I am new to equest and any help you can give me will be greatly appreciated.
Thanks,
Brian Wiggins
(803)-521-4991