I hate it when what I thought was right turns out to be wrong

[Dan]

Have you ever had something ingrained in you so deeply that you are shocked to find out it may not be all that true? Some examples from me:

You should never mix refrigerants: Look at the mixtures that are out there today!

Gas defrost is superior to off-time defrost for fresh meat display cases: There are those who now believe that off-time defrost keeps better product temperature!

Using an EPR in a service meat case will provide the best humidification: There are those who now say that cycling on a thermostat will provide better humidification.

For me, seeing things held so dearly succumb as "old wive's tales" makes me wonder about what else I believe that may not be true. For example:

That parallel racks are inherently more efficient than conventional single unit applications: I ain't so sure anymore.

That gas defrost is more efficient than electric defrost: I ain't so sure anymore.

That heat reclaim from discharge gas is "free" heat. I ain't so sure anymore.

Of course, these are simply narrow observations from a supermarket guy.

I keep thinking how many different ways I was taught to brush my teeth, that eggs, salt, aspirin, and pork were bad for me and then later good for me, and back and forth.

I wonder if there are more instances that others could share - within the trade, of course, of having a firmly held belief just doing an about-face on them as the world goes on?

[Prof Sporlan]

<i>Using an EPR in a service meat case will provide the best humidification: There are those who now say that cycling on a thermostat will provide better humidification.</i>

Interesting thought. With the EPR, you have essentially constant refrigeration at lower coil TDs vs some periods of little or no refrigeration, and then refrigeration at potentially much higher TDs. Added to this problem is temperature control.... better temperature control should provide best humidification which would seem to favor the EPR. But if the coil surface is oversized, the EPR may run TDs too low for proper TEV control...... If the EPR is set incorrectly... forget it! Time for non-adjustable valves????? :)

<i>That parallel racks are inherently more efficient than conventional single unit applications: I ain't so sure anymore.</i>

That argument will go on forever.... :)

<i>That heat reclaim from discharge gas is "free" heat. I ain't so sure anymore.</i>

Actually, reclaim heat was never free, assuming one could lower head pressures below what was useful to heat a room. But elevating head pressures somewhat to heat a room may prove more economical than using natural gas, or electricity, to heat the room. An economics problem that isn't particularly easy to solve.....

[Dan]

Originally posted by Prof Sporlan [/B]

Actually, reclaim heat was never free, assuming one could lower head pressures below what was useful to heat a room. But elevating head pressures somewhat to heat a room may prove more economical than using natural gas, or electricity, to heat the room. An economics problem that isn't particularly easy to solve.....
[/B][/QUOTE]

It is a question that has been dogging me for years. But I keep thinking that if I am throwing heat off a condenser on the roof, that I am wasting the heat if I require heating inside a building. But we get into questions regarding the quality of heat, etc, and as you say it becomes an economics problem that isn't particularly easy to solve.

The odd part about refrigeration is that we often use the refrigeration to make things warmer in the controlled space than in the space we choose to discharge the heat.:)