Leave the fans running.
Less trouble that way.
The headmaster will do the job better than a fan cycling control can ever hope to.
Cycle the receiver heater as the unit is wired to cycle it.
This is a piggyback question from my last post regarding headmaster replacement. If it interests any of you, the repair went well and I learned a thing or two from your helpful posts. As some of you probably suspected the headmaster was not the only issue, if even the issue at all. The system was undercharged and thanks to your help I was able to adjust the charge correctly using the Sporlan PDF.
Now on to my next question. Low ambient conditions and fan cycling based on pressure. As I have already stated the condensing unit uses a headmaster but I thought it also incorporated fan cycling. The pressure control that I thought controlled the fans actually controls the receiver heater. Now this is where I am looking for advice. In my mind the receiver heater should be energized continually, like the crankcase heater. And the fans should be controlled to cycle on and off to HELP maintain head pressure. I would think this: Pressure control cycles fans to maintain 210-220 head and then if it drops below 210 my headmaster will start by-passing as a back up so to speak. I figure two things working together to combat low ambient is better and more efficient.
Please advise........
Leave the fans running.
Less trouble that way.
The headmaster will do the job better than a fan cycling control can ever hope to.
Cycle the receiver heater as the unit is wired to cycle it.
Well alrighty then, will do.
Thanks.
I do need to ask the question though, why?
Why is the receiver heater on a pressure control?
What is the benefit and or drawbacks of continuous run vs cycling?
All the receiver heaters I've ever seen were wired to a thermostat sensing ambient air temperature. Don't need it unless ambient is below like 60*f I thought. If receiver heater were always on even when hot outside, that would be an unnecessary added load on the system, I think? (In TX where I live, I have only seen a handful of receiver heaters, and I don't think I've ever seen one that wasn't bypassed or unwired.)
Headmaster is superior to fan cycle, because it can maintain a constant head pressure. Fan cycle will cause head pressure to rise rapidly until fan kicks on, then drop rapidly until fan cycles off, etc. This rising and falling of head pressure can lead to inconsistent TXV operation. The TXV will give better more consistent superheat with a stable head pressure that the headmaster provides. It's also common on small condensing units with fan cycle for the sightglass to sometimes flash right before fan cycles off, which obviously confuses the TXV as well.
If its 100* outside you don't want to be heating your receiver. It makes the system less efficient and raises head pressure. You only want to heat the receiver in low ambient conditions, thus the pressure switch.
Understood.
Thank you all.
Does it even get cold enough in CO to need to heat receivers?
The winter will average 20* to 30* with dips down to -30*....That's cold !!!