Defrost Termination

**engineerdave** · 10-09-2006, 07:31 AM

Do any of you know where I can download a training blurb on Defrost Termination? That's about the only thing in the Supermarket World that I couldn't find on Sporlan's site.

**Freezeking2000** · 10-09-2006, 08:52 PM

No I dont know, but if you so not want Ice on the ceiling or on the product on glass doors it has to work!

**engineerdave** · 10-09-2006, 10:25 PM

That's what I tried to tell the boys. Glazed-over eyes for everybody. Maybe I'll try again tomorrow when the receptionist is NOT eating a lollipop.

**black #1** · 10-09-2006, 10:51 PM

What kind of system do you have, electric or hot gas defrost? Theres several different types of defrost systems and controls, too many variables.

**engineerdave** · 10-09-2006, 11:11 PM

Walk-In Freezer, ice cream box. Norlake 3-pipe Condensing Unit, Heatcraft HGT090 Hotgas Coils. Initial call for the On-Call guy was "Unit on line, Fans not running". He corrected it by slightly tweaking the Fan Delay Temp setting. Now fans kick in immediately on Termination. Tried to explain about Fan Delay, don't think I got my point across. Looking for something to print & show the new guys.

**R12rules** · 10-09-2006, 11:44 PM

I hear tell Condensed Dave joined a union... can anyone here confirm that rumor?

I also hear tell he's wearing WHITE uniforms again!

Jus kiddin' ... that sort of thing brings Dave here quicker than you can say: FOSGENE!

Dave would know the place for find some material for your guys.

So would NormChris and some others here. Dont know how old Norm is, so I havent listed him as an "ol fart" yet.
But an "ol fart" is what you want when it comes to explaining defrost termination to the new guys.

Personally, I'd make a small project lesson out of this. I'd take a case that you had a wiring diagram for and everything worked fine, (that leaves out using a true or bev-air box),

... then go in and jimmi the wiring so the guys have to find out what's wrong.

Let them figure this out as a team participation thing.

might work

**Freezeking2000** · 10-10-2006, 07:44 PM

Originally posted by R12rules
I hear tell Condensed Dave joined a union... can anyone here confirm that rumor?

I also hear tell he's wearing WHITE uniforms again!

Jus kiddin' ... that sort of thing brings Dave here quicker than you can say: FOSGENE!

Dave would know the place for find some material for your guys.

So would NormChris and some others here. Dont know how old Norm is, so I havent listed him as an "ol fart" yet.
But an "ol fart" is what you want when it comes to explaining defrost termination to the new guys.

Personally, I'd make a small project lesson out of this. I'd take a case that you had a wiring diagram for and everything worked fine, (that leaves out using a true or bev-air box), ... then go in and jimmi the wiring so the guys have to find out what's wrong.

Let them figure this out as a team participation thing.

might work

Me too,

I do make sure I have some type of termination. I also prefer a pressure controll to start and stop the fans on hot gas and have a seperate termination thermostat. I set the termination which should be on the return line to maybe 60 degrees and the fan to 0 degrees or 10-15 psig on L/T gases.

**dirtyboy103us** · 10-11-2006, 07:19 AM

the problems associated with no defrost termination might help with trouble shooting and the bypassing this control
on systems...

when guys bypass termination klixon or fan controls then the problems increase quickly and they start to look for other problems/symptoms which are all caused by these systems not working together as designed

flooded starts, loss of oil, poor product integrity, and the list could go on and on

**icemeister** · 10-11-2006, 09:24 AM

Here's a short article about defrosting refrigeration systems that was published in Contracting Business back in Feb '06:

http://www.contractingbusiness.com/2.../ServiceClinic

It doesn't get into specifics, but it does present a good general overview of the subject.

**rookie 19** · 10-12-2006, 06:36 PM

your fans shouldn't turn on till coil is about 20 degrees but it can vary

The whole idea is to prevent warm air form being circulated

**stanbyyourword** · 10-13-2006, 03:46 PM

and moisture being sprayed off freshly defrosted coil

**engineerdave** · 10-16-2006, 09:41 PM

Icemeister -
Thanks man. That was perfect.

**mckim** · 10-19-2006, 10:37 PM

So many opinions wow!! Is this not the best trade or what!! Well with so many opinions please let me give mine!!

For starters lets keep it simple. What is Defrost Termination? And do we really need it or not? When we hear defrost we think of ice, blockage, no airflow right? What is the best way to prevent this? Iiiiii realy like the guys comment about using a pressure timer!! pressure tells all, but unfortunitly that was old school. We are more likely to find a 8145.20 or oo in most low temp smaller applications today. And not very many hot gas systems most are all electric defrost. Anyways my experience has taught me to look at the particular situration to determine the best way to keep the evap. clear of ice! If everything was sized properly yes use manufacture's recommendations. You cannotjust wire in x and assume you will be keeping all the ice off the coil you may have to move the klixon to different locations or depend on time! Does the refrigerant pump into the reciver durring defrost? Bottom line is -- is--is the coil clear after defrost? Remember most clocks are desighned to defrost the evap coil according to temp-- time (duration) is failsafe). Do whatever it takes to keep the evap. clear od blockage.

Mckim

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