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Post by allan on Jul 7, 2014 2:00:27 GMT
Just got this 2 door DR3 this week. Previous owner complained of continuous loud rattle. Started it up and boy was it noisy. Installed a new 20 watt heater and let it heat for 18 hours. Still noisy. Put electric defrost heaters in each pig evap ang got them really hot. Started it back up and within 15-30 minutes it was quiet! Five days now and still sounds great. Both evaps fully frosted over the top and ice on float feed tube. Compressor dome is hot, and condenser coil is slightly cooler. Center of condenser is warm and same temp as float tank. I always heard that these machines run sweet with a full sump of oil, and it seems like the extra heat boiled the extra oil out of those huge pig evaps.
Installed all new start and run contacts in the control box and the wire on this one is still flexible and in great condition. With an 85 degree room and 30 degree box compressor running amps is 1.75!!!! Unbelievable. I think I will leave the 20 watt heater in the sump to make sure the SO2 stays out of the oil. Been so busy I haven't got the run times yet, this one runs long cycles. Can't wait to see what the cycle times are
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Post by allan on Jul 7, 2014 2:01:30 GMT
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Post by allan on Jul 7, 2014 2:04:37 GMT
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Post by ChrisJ on Jul 7, 2014 3:40:36 GMT
Wasn't GE's solution to this to add SO2 to get oil to return better?
I would assume if that was the case that the "fix" was done in the 1920s and if so why is it low again?
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Post by coldspaces on Jul 7, 2014 3:48:05 GMT
Nice Dr3 Alan. I love those style boxes with all the corner trim.
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Post by 35ckmonitort on Jul 7, 2014 8:52:21 GMT
Allan, congrats! That's a swell DR3 double door! How fun that is! Looks like she's in pretty good shape!
I just brought home my 1929 DR... Going to buy an ohm meter tomorrow and test it before I run it... Gotta make sure the heater is in working order.
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Post by jhigdon2 on Jul 7, 2014 23:27:45 GMT
A very nice old DR3. It's getting harder to Find working ones nowadays. You did the right thing by putting a new heater in it and letting it drive the refrigerant out of the oil, before running it, or else it could have been curtains for the compressor. These old double pig equipped DR3 ' S with the start/run cap are the most efficient of all the monitor tops. Sometimes I wonder why they didn't equip all monitor tops with start/run caps, but I suppose costs were an issue.
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Post by allan on Jul 8, 2014 1:33:43 GMT
A very nice old DR3. It's getting harder to Find working ones nowadays. You did the right thing by putting a new heater in it and letting it drive the refrigerant out of the oil, before running it, or else it could have been curtains for the compressor. These old double pig equipped DR3 ' S with the start/run cap are the most efficient of all the monitor tops. Sometimes I wonder why they didn't equip all monitor tops with start/run caps, but I suppose costs were an issue. Thanks. I took your advice and installed a 20 watt Heater instead of the standard 12 watt. I think the extra heat will insure SO2 free oil in cooler ambients! Have you ever tried to put a run cap on a ck? Should be a easy test? |
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Post by jhigdon2 on Jul 8, 2014 4:28:33 GMT
Yeah. I've done a little experimenting with run caps on Ck. It does drive the run amps down a bit. I tried a 7.5,12.5, and a 35uf. The 35 uf drove run amps way way down, but it increased wattage to around 300. So I think 35uf is too big for the 1/8 hp Ck. I never really revisited the experiment again, but I think if a person tinkered around with the idea a bit, good results can be had.
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Post by ChrisJ on Jul 8, 2014 13:00:41 GMT
Doesn't the run cap only effect the power factor, therefore decrease current yet have no effect on actual power consumption?
If that is true, it seems pointless unless you're being charged by volt-amps rather than watts, no?
I know we've discussed this before, but with my terrible memory I can't remember.
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Post by 35ckmonitort on Jul 8, 2014 17:28:17 GMT
Would it be suggested that I put a 20watt heater in my DR? Or would that not be necessary? Or should I just replace it with a standard 12 or 15watt?
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Post by jhigdon2 on Jul 9, 2014 22:48:16 GMT
Doesn't the run cap only effect the power factor, therefore decrease current yet have no effect on actual power consumption? If that is true, it seems pointless unless you're being charged by volt-amps rather than watts, no? I know we've discussed this before, but with my terrible memory I can't remember. |
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Post by jhigdon2 on Jul 9, 2014 23:02:38 GMT
There are lots of online help sources for selecting a run cap. Without a duel trace oscilloscope it's a little harder to select a cap that will achieve the phase shift needed between start and run windings. I have used a kill o watt to help select one however. You have to choose a start cap size that will lessen run amps,and wattage. When wattage starts climbing again is when you have selected a capacitor that is to big. I don't know if this is a widely accepted method but it seems to work for me. Power factor usually seems to end up in the 80-90%.
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Post by ChrisJ on Jul 9, 2014 23:18:41 GMT
I have a couple of Tek dual trace scopes I could use.
I'm assuming I would want to aim for a 90 degree shift between the windings?
Do you think there would be any risk of burning out the start winding running it this way or do you think it's 100% safe assuming you get the 90 degree shift?
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Post by cablehack on Jul 9, 2014 23:26:20 GMT
Experiments I tried on the CA-2 improving power factor made quite a difference in what I pay to run it. The reason is that poor power factor (about .49 uncorrected) causes unnecessary losses in the stepdown transformer. With PF of about .8 and a toroidal transformer, the wattage became absurdly low compared to what it used to be.
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