Wet bulb and dry bulb

johnjohn89

To measure wet bulb from which return? Last week I work on two unit both systems using piston ,one in attic other on basement and I put thermometer (humidity meter) on return inside the unit but someone told me I can’t do that? Have to measure wet bulb in living space,put thermometer on return on 1st floor or 2nd floor, can’t measure wet bulb in attic or basement inside unit? That’s why I don’t get that? I watch YouTube they do something put thermometer on return inside the unit to measure wet bulb and dry bulb on supply! Can anyone explain please…

mattmia2

You are trying to measure the heat load coming in to the evaporator so in the duct after everything ha mixed together from the various parts of the building is ideal.

Get this:
https://heatinghelp.com/store/detail/modern-refrigeration-and-air-conditioning

A used older edition is fine.

EBEBRATT-Ed

you can measure the wet and dry bulb in the space or in the unit at the evaporator inlet. If there is significant difference your air ducts have leakage or are not well insulated.

johnjohn89

EBEBRATT-Ed said:

you can measure the wet and dry bulb in the space or in the unit at the evaporator inlet. If there is significant difference your air ducts have leakage or are not well insulated.

Thank u

johnjohn89

mattmia2 said:

You are trying to measure the heat load coming in to the evaporator so in the duct after everything ha mixed together from the various parts of the building is ideal. Get this: https://heatinghelp.com/store/detail/modern-refrigeration-and-air-conditioning A used older edition is fine.

Thank u

mattmia2

EBEBRATT-Ed said:

you can measure the wet and dry bulb in the space or in the unit at the evaporator inlet. If there is significant difference your air ducts have leakage or are not well insulated.

I have found that where the returns are on the floor because it was designed as a heat only system that the return air is quite cool so I guess you might get close if you measured by the floor.

GW

In the duct, you want to know what the system is moving for energy. Dry split doesn't tell you much, wet split is where you have a real clue. 10 plus is good. if the house is all heated up, you might see 15.

mattmia2

Depends on what you're trying to measure. If you are trying to measure the performance or charge in an AC system then you want the air just before and after the evaporator. If you are just interested in comfort then you'd measure in the space.