Gas refrigerators....

[arbilab]

Thanks, yes I know LRA lasts a second and is twice (not 10x) FLA. It's when the lights dim slightly. 800W = ~1hp and yes that would be generous for a small fridge. 1/2hp sounds more like it. Does that conversion take into account motors in this class are under 80% efficient?

Again this is a SMALL fridge and the ones we're talking about are not small. They are also not 15yo.

If we put 0.5hp, 120V and 80% efficiency into Electric Motor Calculator, it comes back with 6FLA. 1/3 less if 3 phase, so if these new motors are electronically commutated there's a 33% saving right there.

Did I mention I wrote a patent speculation 8 years ago for an inverter-modulated HE HVAC condenser? Elements of it may have been patentable, but some elements were already in use (in laundry eqpt, who knew?) and it would have cost more than my net worth to find out if I had a claim.

 

[philr]

Don't forget that the total amps. on the data plate of the fridge also includes the defrost elements which can run combined with the interior lighting and sometimes other things at the same time so the wattage isn't necessarily related to the compressor's run or start winding. 

 

 

Even on this 50 years old Frost-Proof fridge, the total amps on the data plate is 6A. The compressor itself draws 3.6A at 115V but that's with the start winding on... It draws much less when it runs (even combined with the mullion heaters, fan motor and defrost timer and the few lights inside when you open the doors... ).

 

 

That's what I got on a watt meter with the compressor running.



 

Here's the info on the data plate. 

 

 

[arbilab]

Of course the defrost heater and compressor never run at the same time, while the mullion heater runs all the time and the defrost timer adds its 7W. Nothing's ever simple.

 

[arbilab]

BTW, what the hell is a mullion? One thousandth of a bullion?

 

[davetranter]

PhilR

BEAUTIFUL old Wattmeter (Reply#20) I'll post a pic of mine when I can borrow the camera again...

For reference/interest, U.K. electricity price from my supplier 15.74 pence (£0.1574) per KWh, plus 'standing charge' of 11.5 pence (£0.115) per DAY.

I still only have a 'sketchy' understanding of how gas refrigerators work, but understand that they are not exactly 'high efficiency' appliances.

All best

Dave T

 

[washer111]

Defrost Heater "Oomph"

It seems I'm going to have to correct someone... I think Robert might have to shackle my hands and make me stare at things that are "wrong" from now on, haha.

 

At least one our refrigerators (Two separate units), the heater for the freezer is around 800-900w, whereas the one for the fridge is about 200-300w. When the freezer is defrosting, you can feel the heat pulsing from the air flow vent in the top back of the freezer. 

 

And regarding energy usage, a slightly larger capacity Bottom-Mount Freezer from F&P now use the same (or maybe slightly less) electricity than the standalone fridge does now! Gotta love Active-Smart technology and better Matsushita compressors

 

[cfz2882]

fridge amp draw.

I checked a 1977 kelvinator FF fridge and found it pulls 4.2 amps with it's 1/4 hp compressor-rating plate on fridge specs 6 amps.This fridge is pretty modern by mid-'70s standards with thinwall expanded foam insulation-I might test it against my 2000 vintage KM fridge (6.5a rated)and see which uses more KWH over a month of use:lots of varibles involved in such a test that could skew results though.I have a 1988 dometic absorbsion fridge from a wrecked camper,but I have not tried it-heard they can get plugged with ammonia chrystals if they are not operated level...

 

[docker]

plugged with ammonia chrystals

Absorbtion fridges must be level so that the flame is vertical. The crystals form from standing. If the fridge is not working, we put it on a truck & take it for a drive down the roughest track we can find & let the fridge bounce around. Another trick is to turn the fridge upside down & let it stand for a couple of days.

 

[davetranter]

PhilR

As promised (Reply#23), here's pictures of my Wattmeters. A pair of multi-range (50-5000W, subject to limit of 1000V and 20A) Wattmeters by H.W. Sullivan of Kent, England. I have included the cheap Chinese digital just for comparison ;-)

All best

Dave T

 

[davetranter]

'Money Shot'

I still have no idea where that term originates... Only ever seen it on this forum.

DT

 

[norgeway]

The fact remains...

The fridges made up into the 60s that are manual defrost are very cheap to run, its only the frost free models that were energy hogs, many manual defrost models drew less than 3 amps, and too, the ones with a positive latch door,ran about a third as much as new fridges do...and kept your food much better.

 

[philr]

Thanks for the pics Dave!
As for the term "money shot" I had no idea either (as my first language is French) but a quick Google search helped me figure!

 

[philr]

As Hans said, manual defrost fridges are cheaper to run. But some equivalent manual-defrost and frost-free fridges share most of their parts including their compressor. The extra energy needed is for the blower motor(s), the defrost timer, the defrost heaters (which are on for short periods) and what accounts for the biggest difference is the extra work that's required from the refrigerating system that has to run constantly for about two hours to balance the temperature after the defrost periods. 

 

However, newer frost-free fridges beat both older types as they have much more efficient components. But many seem to lack the long term durability of older units.

 

[paulg]

Mullion heater defined

A mullion heater is heater to prevent condensation from forming on mullion (the cabinet structure between two doors of a cabinet).