Receiver goes back into cond coil ?

[UmmScott]

On condensing units wothout subcooling circuit there is no check valve.
Why is here necessary?

Because those condensing units.. like heatcraft, russell, trenton, etc have actually good low ambient controls like a headmaster or variable speed fans so theres no need for a check valve.

Unlike a crappy low cost, cheaply designed kolpak unit.

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[TechmanTerry]

That check valve also prevents migration.

[itsiceman]

I wonder who figured out the check valve thing. Can they get away with less total charge that way or is it about the same?

[Out in the cold]

Ok .... but why

Whats the benefit

They have worked forever without them

Does it stop the bubbles when the fan kick on and off ? I did notice there werent any bubbles ....

It's not really a question of them working/not working, they will work fine with or without. It's an efficiency kick. The subcooling circuit, the check valve preventing temporary flashing at the expansion valve, variable speed fans, etc. are all a direct result of the AWEF mandates imposed on the industry in 2020. The cheaper units in particular had to make some efficiency improvements in order to meet the new regulations.

[TechmanTerry]

I wonder who figured out the check valve thing. Can they get away with less total charge that way or is it about the same?

I would say this style of x-tra SC'ing cond unit thing needs a little x-tra freon for the slightly x-tra liquid line length.

[Snapperhead]

Thats just what we need .... more crap that can go bad

[itsiceman]

I would say this style of x-tra SC'ing cond unit thing needs a little x-tra freon for the slightly x-tra liquid line length.

Maybe it's a wash then. I can't see them adding the check valve with the sole purpose of it running better with the fan cycle.

[R600a]

Maybe it's a wash then. I can't see them adding the check valve with the sole purpose of it running better with the fan cycle.

Unless that's what it took to get them to break down past warranty instead of in warranty.

Sent from the Okie state usin Tapatalk

[icy78]

That check valve also prevents migration.

Hey Terry!

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[VTP99]

I've always added a check valve when adding a HPC valve.
I believe it's in a Sporlan bulletin as well.
As for the migration I've never added a heat tape to a condenser but I have on a receiver.

[ammoniadog]

Interesting. Thanks for posting that icy78. But why would we care if refrigerant migrates from the "warm receiver to the cold condenser" during the off cycle? I suppose it's so you don't have a few seconds with a flashing sight glass upon startup again? Doesn't seem like a big deal to me. Am I missing anything?

I'm guessing the scroll compressor has a check valve built into it as well, correct?

[itsiceman]

Interesting. Thanks for posting that icy78. But why would we care if refrigerant migrates from the "warm receiver to the cold condenser" during the off cycle? I suppose it's so you don't have a few seconds with a flashing sight glass upon startup again? Doesn't seem like a big deal to me. Am I missing anything?

I'm guessing the scroll compressor has a check valve built into it as well, correct?

They have a hard time starting back up when it cold out.

[Out in the cold]

Thats just what we need .... more crap that can go bad

Can't argue with that!🙂

[Out in the cold]

I may be wrong here but here's what I think they are trying to accomplish.

We often install outdoor units with heated and insulated recievers around here for extreme cold conditions. Its necessary to keep receiver pressures high enough to come out of pumpdown after long off periods when it's -20F or colder outside. A unit with an HPR or "headmaster" acts as a quasi-check valve since it closes to the condenser when the receiver pressure drops, thus helping prevent (but not necessarily eliminating) migration back into the condenser which would happen readily when its cold outside since the condenser is obviously designed for heat rejection. Since this unit has only fan cycling they may have added it to discourage migration and low head pressure when it comes out of pumpdown. I have seen several of these units however that work just fine in pretty cold weather without the check valve. I think it also serves the purpose of preventing flashing due to the fan cycling as mentioned too.

[Swf]

Would there be a different best practice for charging this unit in regards to this design?
Not sure if there would be any idiosyncrasies

[pecmsg]

Would there be a different best practice for charging this unit in regards to this design?
Not sure if there would be any idiosyncrasies

Normal charging when warm outside but extra refrigerant is needed for the flooded condenser. Its in the IOM.

[TechmanTerry]

The need for a receiver heater is based on 0*F and colder and a few other reasons.

[Out in the cold]

Normal charging when warm outside but extra refrigerant is needed for the flooded condenser. Its in the IOM.

Except it doesn't have an HPR valve?

[ttowngremlin]

ICM control will work with that motor.

Which one do you prefer?

[indy2000]

Which one do you prefer?

you should be able to pick the one best for your application

https://www.icmcontrols.com/products/?category=41