AC testing

[corndogking]

I need to measure the energy consumption of installed residential AC units (condensing unit only) for a research project. We anticipate that many times the home owners will not be home when we show up to make the measurements, and the system will not be running. In these situations, we have been considering applying 24 VAC to the condensing unit contactor to start the unit for 30 seconds or so , so we can make a measurement. Are we likely to cuase any harm with this procedure? Perhaps heat pump units that have a electrically operated control valve that wouldn't be in the proper position? Thanks for your help.

[CJT]

Do you have the homeowners' permission? If so, perhaps you could arrange a time when they would be home to make your measurements. If not, perhaps you should consider another project.

[Noon-Air]

Exactly what measurements are you trying to get?? How is this data going to be used??

You do realize that any amperage draw readings will not stabilize or be correct unless the system is correctly charged, and operating properly. With heat pumps, you can't just jump the contactor and expect it to run correctly, because it won't. With the new high efficiency heat pumps and condensers with ECM motors, jumping the contactor won't even make the fan come on, and with a 2 stage compressor, only one stage will be energized.

[<kjpro]

Why wouldn&#39;t they be home? Why would you be measuring their units?

I see you want to make a service call after your little &#39;trial and error&#39; testing.

Yep, you sure are... I&#39;d look into what happens when you connect two transformer outputs together.

I&#39;d suggest that you NOT start messing with things you DO NOT understand. Unless, you have money that you want to spend to repair/replace the things you blow up in your testing.

[Anonymous]

Yup, I would break both your legs if I ever caught you near my A/C.

Unless the fan is moving air accross the evaporator, inside the house, your gonna cause the low side pressure to drop and the lineset and evaporator to freeze.

You think a 30sec cycle will show you anything? It won&#39;t.

-Canadian Heat

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[Bubba]

You need to talk to DANgER our local resident "jumper". He is good at chit like that. He can jumper anything.......door switches, safetys, limits, fans, etc. Bubba

[Bob_Loblaw]

[e-mail] wrote

I call bullshit!

[Tekkie®]

My next project is called vandalism. But for you don&#39;t use any kind of tool to energize the contactor. Use your tongue, after all you&#39;re done licking windows with it.

[Barry]

Probably going to pump the condensing unit down and steal it, or the copper, or the refrigerant.

Barry