Help design my new system please

[Mikesolar]

I asked a bunch of my fridge engineer friends on the other side of the pond, many of whom do use R290 or other HC refrigerants and the consensus is that it is not needed in this situation. The oil will heat up quick enough in most applications that the pot heater is not needed. This is assuming the system is indoors. Outdoors, I would have one regardless, and many Copeland pots have them built in.

[AC_Hacker]

Originally Posted by buffalobillpatrick

The Copeland/Emerson instructions entire back page is devoted to heaters...

Do you have a link to that document?

-AC

[jeff5may]

Originally Posted by buffalobillpatrick

The Copeland/Emerson instructions entire back page is devoted to heaters, 22 different models are listed for their many different compressors.

My compressor calls for PN 018-0094-00 40W 240V wholesale $13.06 but can't find any for sale yet.

So how many installers order them is unknown to me.

BBP

More like engineers and corporate buyers. To get in single quantity, it may be practically priceless. Or go to supply house and custom order (MSRP + Ship + Handle + drive to store), pay up front of course. If you're lucky, the part will still exist, be available, and not back-order for weeks.

For 40 Watts, just go buy a few feet of easy heat cable. Comes in 3 densities:3, 5, or 8 Watts per foot. Lasts for not ever, but close. Plug one end, power the other, the end. Or you can go buy an electric candle warmer.

I agree, if the unit will live in room temperature, refrigerant will not migrate to the compressor pot. When the unit starts, it begins to heat itself. In no time, compressor will climb in temp to above threshold for concern.

[NiHaoMike]

I recommend the approach of using large hose clamps to attach a few power resistors near the bottom. Very cheap and effective.

[AC_Hacker]

Originally Posted by NiHaoMike

...Very cheap and effective...

I am sure that if you use this you will not have a problem.

However, does a problem actually exist?

It is my understanding that the compressor heaters are used to reduce the viscosity of the oil/refrigerant mix so that the startup current isn't excessive.

When the compressors are installed where they are exposed to outdoor temperatures, heaters are important.

When the compressors live indoors, heaters aren't required.

Does anyone here know of any HVAC compressors that are designed into indoor systems where the compressors require heaters?

My experience is limited to a very small sample of indoors heat pump compressors, and no heaters are used. Why don't we see them in window air conditioners? Why aren't they used in home refrigerators?

But if they actually are widely used on indoors HVAC equipment I can accept it.

It just seems to me that strapping unrequired resistance heaters to a compressor, functions only as an ERD (efficiency reducing device).

-AC

[Mikesolar]

I've bought compressors, usually Copeland, with the wiring for the heater and I just don't attach it. Some of the European HPs have controls that will turn on and off the heater when needed.

All compressors I have seen are designed for both indoor or outdoor locations. The exception may be pots for a domestic fridge but I would have to check.

[NiHaoMike]

I read a few Copeland application notes and they say that a crankcase heater is indeed not necessary on package units, but might be on split systems with a sufficiently high charge. Accumulators aren't required on package units either, but feel free to use one if you already bought it. (If you aren't using an accumulator, put the suction sight glass between the evaporator and SLHX.)

It looks like scroll compressors are quite a bit different from the reciprocating compressors and rotary compressors that were commonly used in the past. Reciprocating compressors are easily damaged by liquid refrigerant and rotary compressors can have problems with refrigerant condensing in and diluting the oil on startup.

[buffalobillpatrick]

NiHaoMike,
"(If you aren't using an accumulator, put the suction sight glass between the evaporator and SLHX.)"
I bought exactly the parts that we agreed on earlier, including accumulator.

Bought a Robinair 15300 VacuMaster 3 CFM Vacuum Pump.

Seems best way to get nitrogen is from paintball business.



Hard copy is all I have.


http://ecorenovator.org/forum/attach...1&d=1395291492


http://ecorenovator.org/forum/attach...1&d=1395291492

[NiHaoMike]

Paintball nitrogen can be used if it's pure enough, so can CO2 or argon (albeit more expensive). Try a welding shop since they'll have some pure enough for your use.

[pinballlooking]

My local welding shop was nice enough to loan me a small nitrogen cylinder for the price of the gas in it plus a refundable deposit.