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INWO
12-28-2008, 08:43 PM
Being an electronic technician, I am often called on to design control systems for HVAC. But refrigeration and air flow calc is my weakness.

Will measuring the input and output air temperatures across a geothermal heatpump coil give me enough information to determine if it has sufficient airflow?
Assuming a properly operating system.

The system in question uses an open return and I'm not sure I can get a reliable airflow reading from measured static pressure.

I'm new to this site. If this is too much of a DIY question can someone point me in the right direction for some basic info? :o

Alantoy13
12-28-2008, 09:07 PM
Checking a temp rise would be one way to check and see if it was working. BUT REALLY you need to get on the phone and call a service tech who knows what they are doing with water source heat pumps.:D

Pascone10
12-28-2008, 09:42 PM
Being an electronic technician, I am often called on to design control systems for HVAC. But refrigeration and air flow calc is my weakness.

Will measuring the input and output air temperatures across a geothermal heatpump coil give me enough information to determine if it has sufficient airflow?
Assuming a properly operating system.

The system in question uses an open return and I'm not sure I can get a reliable airflow reading from measured static pressure.

I'm new to this site. If this is too much of a DIY question can someone point me in the right direction for some basic info? :o

if you look in the spec book for your geothermal it will have the info for delta T for different parts of the system ex. water heat exchanger, also for the air differential.

if this is a split system look at the manufactures specs for their unit (air handler)

LILLIGHTNING
12-29-2008, 02:07 PM
Turn on all electric heat strips only. Then use formula (watts x 3.412) divided by (1.08 x temp rise). Watts can be found by measured volts x amps of elements only. This is approximate CFM. When taking supply temp measurement, stay downstream of plenum a few inches out of view of elements.

INWO
12-30-2008, 08:38 AM
Tnx for replies.

I have all the specs for the units that I work on.

Was aware of the relationship of watts, air flow, and temp rise, but not the formula. tnx for that!
What I was looking for specifically was one parameter that could be monitored, that would give me indication of air flow being reduced to the point of damaging the system.

As most things I guess there is no simple answer.