John Bernard
07-15-2012, 01:13 PM
I always check each output duct with a laser thermometer to check the differential temperature from the return. Typically all temperatures are within a few degrees. Last week I found two ducts where the output temperature was the same as the return and so noted in the report. One duct was in an eating area next to a kitchen and the other in a utility room. The temperature at the kitchen duct output was about 62 degrees F while the eating area was 76 degrees F. These ducts were only about 12' - 15' apart.
An HVAC technician serviced the system and then measured airflow instead of temperature. There was a 30% difference in output from the formal dining room and the eating area and 15% difference between the kitchen and dining area. The utility room is a much smaller duct. Is this much variance normal? Are these tests (temp vs. air flow) apples and oranges? Should I offer to go back and retest temperatures? My client is wondering if the problem was resolved.
Below are the numbers provided by the HVAC technician
4) Check / Measure air flow:
- Dining: 235 cfm.
- Kitchen: 201 cfm.
- Breakfast: 167 cfm.
- Utility: 57 cfm
AIR FLOW MEASURES GOOD. NO PROBLEM FOUND.
An HVAC technician serviced the system and then measured airflow instead of temperature. There was a 30% difference in output from the formal dining room and the eating area and 15% difference between the kitchen and dining area. The utility room is a much smaller duct. Is this much variance normal? Are these tests (temp vs. air flow) apples and oranges? Should I offer to go back and retest temperatures? My client is wondering if the problem was resolved.
Below are the numbers provided by the HVAC technician
4) Check / Measure air flow:
- Dining: 235 cfm.
- Kitchen: 201 cfm.
- Breakfast: 167 cfm.
- Utility: 57 cfm
AIR FLOW MEASURES GOOD. NO PROBLEM FOUND.