Hussmann M5X-EP meat cases

[hvacmd2002]

I will be installing 32' of Hussmann M5X-EP cases in a few weeks. I did not order nor sell these. A retail grocer/wholesale grocer has ordered and purchased them. They are coming through with electric defrost. I know from looking back at the HVAC-Talk archives that some of you prefer this over air defrost for meat cases. I figure quicker is better, but what about the meat? What does it want? Currently we have 32' of Tyler case with the reversing fans for defrost.

When I checked the data sheet on the Hussmann cases, it said hot gas and electric are not recommended. What's the thought on defrost for meat cases? They are going on a single outdoor unit. No rack.

I doubt we can change the order to air defrost. But do we just not hook up the electric? What do you guys think?

[crackertech]

I wouldn't hook up the heaters either. 3-4 x a day time off with fans running would Wouk just fine.

[hevysrf]

If decide to use the electric, be sure the termination klixons are properly positioned and wired if you are using and old style clock. The old timers used to say refrigeration stats in parallel, defrost term stats in series. If you are using an energy management system the sky is the limit, some prefer to use discharge air temps for termination.

[icemeister]

I wouldn't hook up the heaters either. 3-4 x a day time off with fans running would Wouk just fine.

Hussmann recommends off-time defrost, 30 minutes X 4 per day.

http://www.hussmann.com/en/Technical...7_J_M5X-EP.pdf (See p.3)

The way I see it, back in the days when meat cases ran with evap temps of around +10°F a lot of frost built up and electric or hot gas was the only way to defrost quickly. These M5X-EP cases run at 28°F evaporator for 32°F discharge air.

[eddiegoodfellar]

I didnt know you could order them with electric heaters.

[mspanky]

The hot gas and electric defrost specs are listed on a separate page. 20 minutes, term at 48* for this case and if it is ordered with heaters then use them.

http://www.hussmann.com/en/Technical...iveDefrost.pdf

[captaincompressor]

The meat case I service is an old aluminum coil hussman. Air defrost 4x per day. We run the case 34 F. It's a 10 degree coil so coil sees 24F. During humid months we get some frost. Air defrost works fine.

[bob_scheel]

I would install an EPR and use it to control the case temp. This will keep the temp steady and also the evap temp higher so you get less frost. Most of the walmart's we install and service use air defrost and EPRs. We run 28 degree discharge air and the case tstat is set at 25 degrees so we have 100% runtime in between defrosts.

[mspanky]

I would install an EPR and use it to control the case temp. This will keep the temp steady and also the evap temp higher so you get less frost. Most of the walmart's we install and service use air defrost and EPRs. We run 28 degree discharge air and the case tstat is set at 25 degrees so we have 100% runtime in between defrosts.

It's not on a rack, therefore no EPR.

[hvacmd2002]

Thanks to everybody for your help. And thanks to mspanky for the defrost link. My electrician will be thrilled with the data, since we were provided with no specs, and we couldn't locate info on defrost