Crankcase Heaters

[HPGui]

I have had an Amana ASZ16 + CA*F4860*6A*+TXV+A*V80905C dual fuel system since mid 2008. My climate is mild, with avg. winter lows of about 37 degrees F. The system works well. However, at the start of each heat run, the HP's OD unit gives off a pronounced groan that lasts about 5-7 seconds before the system settles down. After that, the sound is much lower. One Amana regional rep on this site thought that the startup noise might be the result of refrigerant pooling. He suggested a crankcase heater to prevent the pooling and lower the noise. My own Amana rep is not so sure it would make a difference. So, here are my questions:

1) Is the startup sound I've described typical?

2) Is it likely to decrease if I install a crankcase heater?

3) How much extra energy would a crankcase heater consume?

4) Are there any downsides to using a crankcase heater?

[gravity]

a crankcase heater will keep liquid refrigerant from migrating in the compressor whe not running. that is most likely the noise ure hearing. u will get no system degrade. not much at all power consumption. they run usually .15A at 240 volts 240x.15=36watts an hour. no downside to using it either. a heatpump should have one. also look into a compressor blanket. they really help

[enervac]

Crank case heater is must to ensure the refrigerant with oil does not affect the compressor and its lubrication.Many of the scroll compressors atleast at lower capacities are not provided.

[Tsubaki]

I believe that the the dual fuel manufacturers have miscalculated on the CCH's. The problem with the dual fuel units is that when the temps do dip down and stay for a few days down close to zero the compressor is sitting idle while the gas heat is humming away. Typically a regular heat pump with electric aux backup heat continues to run the compressor so it never stays off long enough for the refrigerant migration to get to the cold points like a dual fuel unit does. I just got a CCH added onto a 5 ton dual fuel unit today hopefully that will cure all the problems. I do wish that there was a way to set the CCH up so it does not stay on all the time it is really only needed when the unit is utilizing aux heat so that the compressor is ready to fire up once the temp comes back up to your balance set point (mine is 30f) Maybe the silly things do not use much energy I am not sure. My guy says their is no way to make it work that way but I suspect he has a lazy streak.

[HPGui]

I believe that the the dual fuel manufacturers have miscalculated on the CCH's. The problem with the dual fuel units is that when the temps do dip down and stay for a few days down close to zero the compressor is sitting idle while the gas heat is humming away. Typically a regular heat pump with electric aux backup heat continues to run the compressor so it never stays off long enough for the refrigerant migration to get to the cold points like a dual fuel unit does. I just got a CCH added onto a 5 ton dual fuel unit today hopefully that will cure all the problems. I do wish that there was a way to set the CCH up so it does not stay on all the time it is really only needed when the unit is utilizing aux heat so that the compressor is ready to fire up once the temp comes back up to your balance set point (mine is 30f) Maybe the silly things do not use much energy I am not sure. My guy says their is no way to make it work that way but I suspect he has a lazy streak.

In my case. the need for a CCH is not limited to when aux heat is running. Any HP off time seems enough to cause refrigerant migration. My NG aux heat almost never runs except for defrost cycles, but the HP slugs on startup every time, even at 49 degrees F.

[BaldLoonie]

Mine is noisy on startup and the scroll does have a strap on heater.

[SJProwler]

Mine is noisy on startup and the scroll does have a strap on heater.

BL said "Strap On"


Sorry, it's been a day....

[Tsubaki]

HPGui that is interesting. It looks like that unit is a split system. Makes you wonder if their is something unusual with the install maybe the way the lines are routed or the charge level. That really sounds odd to be slugging at upper 40's. Might just be a Amana thing. This is a Frigidaire DF6SF package unit so it should be charged correctly and all plumbing should be correct. It was actually at 19f ambient when it changed back from gas to heat pump mode after about 4 or 5 days of near zero that is when it slugged. It was worse than a baby crying it almost brought tears to my eyes my heart rate went up and I ran to the tstat to cut it off. I ran the heat pump after it got back up above 30f and it never did it again still seems quiet like it was before so maybe no damage they say the scrolls are tough as nails. I think it was just an unusual circumstance that the factory folks never took into account maybe. I feel confident that it will do OK now but it just bothers me that the crankcase heater runs all the time it was marked 70 watts so I guess that would be like having a 70 watt light bulb always turned on which is probably not that much maybe a dollar a month? Does anyone know how to figure out what it would take to run 70 watts 24 hours a day for a month? I guess it is kinda like my old bossman used to tell me when I had to fork over some cash for wrecking the company truck or something Quote "Son its only MONEY"

[wormy]

THere are several ways to turn off the crankcase heater when
it is not needed.
The following is a very very simplified view.
Keep in mind this is a summerized version to give you a peak into the inner workings.

A suction accumulator would help prevent slugging issues.
Slugging is where refrigerant in liquid form returns to the compressor. You want the refrigerant in vapor form when it enters the compressor.

Crankcase heater helps prevent the refrigerant from mixing with the compressor oil when the compressor is
in an area that is cold in relation to the rest of the system. IF it does, when the compressor starts up, it reacts like a can of Coke shaken up and you pop a top on it. The refrigerant/oil mixture erupts into a foam
and the mixture can be picked up and sent out of the compressor. The compressor ends up running without
oil for a while till it comes back.


I R Sleepy.... going to bed.... later folks

[jeff520]

70 Watts X 24 hours X 30 days/month = 50,400 WattHours = 50.4 KWh

At 10 cents per KWh = $5.04 per month

I have two crank case heaters in my XL19i, and during the winter I just kill the breaker to the condenser so that I do not waste power keeping the compressors warm. My average monthly usage in the winter is around 400KWh, so the CCH load is very noticeable.

[Tsubaki]

Hmm 5 bones per month that is a bit more than I thought. I really only need the CCH to run when the ambient temps are below say 40f. I wonder if there is a line voltage outdoor tstat that could just be wired in to feed the CCH when the ambient is below a certain temp. If that eliminated say 8 months out of the year then we are saving say 40 bones per year and lets just say it runs for 10 years we have 400 bones in our budget to get this control equipment bought and installed. Heck if no one has already done it we may patent this sucka and make a mill or 2. Give me a idea of if there is such an animal as this in existence so I can get my boy to get it put on for me before I go flat broke here.

[CynicX]

Typical residential system crank case heater is wired to run in the off cycle and is tied into a thermostat switch on the discharge line that is only active below 55-65 degrees.

Needless to say it doesnt run 24/7 or when its hot out. Pretty much only when its required.

Kits through manufactures generally come with the thermostat.

Carrier for example (quick google)

http://www.xpedio.carrier.com/idc/gr...it/48n-3si.pdf

[Tsubaki]

That is the exact information that was needed apparently Nordyne does not have that option? Anyway I shall see what I can get done maybe Nordyne actually does have the same setup, I wish my hired help was not so darn lazy. This forum is a wealth of information.

[CynicX]

That is the exact information that was needed apparently Nordyne does not have that option? Anyway I shall see what I can get done maybe Nordyne actually does have the same setup, I wish my hired help was not so darn lazy. This forum is a wealth of information.

I pulled up a couple Nordyne schematics and none of which mention a temp switch for the crank case heater. Regardless if you can see the compressor it would be mounted near it on the small line coming out of it. If its a scroll (round) the line will be toward the top, if its a reciprocating (oval) it will be toward the bottom.

A good tech should be able to look at it and get a crank case heater that works for it with stat...

[Tsubaki]

CynicX,
Most of these tech boys around here are busting wide open trying to do installs and such where the big money is at. The mention of slowing down long enough to do a retrofit that could possibly void some kinda Nordyne warranty just for the consumer to save a few bucks is TOTAL NONSENSE and is apparently a serious NONO. If the local Nordyne supplier does not list the tstat for the CCH for this particular unit then you just forget that any such thing even exists. I will stop agonizing over the extra dollars spent and just be happy that I fit into the teeth of the wheels as they turn and nash heck Obamaer is gonna take care of me anyway man. I know that sounds Cynical, it is just the way the Bidness works I guess, we will just have to learn to accept things as they are.