High pressure trip w/ low charge

[rscamaro]

Yeah i blocked off the condensor to 120° CST and gave it 18° SC.

Too much subcooling for a 410a unit with microchannel coils.

...Ron

[supertek65]

Sometimes EEV controls condenser fans.

This could do it.

[KB Cool]

Too much subcooling for a 410a unit with microchannel coils.

...Ron

Why? IOM says 15°-17°. I figured 1 degree over aint gonna matter.

[AiResearch]

The digital scroll is actually a cool
device. It allows a greater range of capacity control than traditional unloaders on a recip.

It is designed to load / unload frequently to deliver a specific output. 40% load time = 40% capacity. Better load matching.

Most units are sized for peak load and run there a small percentage of time. So you have an oversized 10 ton scroll cycling on and off. Over and over. Hard on the compressor for sure. This compressor can stay running and stay healthy.

Oil management with these is a whole different topic.

[Carrene #2]

Why? IOM says 15°-17°. I figured 1 degree over aint gonna matter.

Damn, I swore to myself that I was done with this.
I'm weak.

Do the words "critical charge" ring a bell?

Best of Luck :

Dick

[KB Cool]

Damn, I swore to myself that I was done with this.
I'm weak.

Do the words "critical charge" ring a bell?

Best of Luck :

Dick

Come on! Who's to say my thermocoupler aint off by 2 degrees!!!

[rscamaro]

Come on! Who's to say my thermocoupler aint off by 2 degrees!!!

With the microchannel coils I pretty much always go to the low side, and I don't think 15-17 degrees SC is correct for the microchannel unit, I may be wrong but I don't think so. Sounds right for the standard copper/aluminum coils though.

If you haven't seen just what the MC coils look like, you really need to take a look. What you have is pretty much a 1"x 1/8" flat piece of aluminum with say 10 to 15 capillary tubes running the length of the aluminum bar. They don't hold very much refrigerant in them. It is very easy to trip the HP switch with even a slight overcharge.

...Ron

[KB Cool]

Ok i'll keep that in mine if i have to go back!! I figured i couldn't go wrong by following the manual's charging instructions!

[Dallas Duster]

You do what ever you want to it It's the customers machine and he can pay you to make any modifications to it that he wants. For all I care you can put a TXV on it and go with it.

Ok i'll keep that in mine if i have to go back!! I figured i couldn't go wrong by following the manual's charging instructions!

[ckartson]

Carrene #2 you made the most sense. I figured a plugged drier but couldn't figure high pressure trips. I also assumed a pressure switch not a DDC controller. I am not familiar with the equpment being described. Was this an actual pressure switch shutting the comp down or a program in the controller? What brand?

[KB Cool]

You do what ever you want to it It's the customers machine and he can pay you to make any modifications to it that he wants. For all I care you can put a TXV on it and go with it.

Yeah, it'll be a good learning experience!!!