At 1ºC, Do Air Defrost is not enough?

[georgedvf]

Hello!

I'm having troubles with a Cooler at 1ºC (Set point) where air defrost appears to be not enough, it's a ***** system(R-22), a lot of ice is remaining even after I extended time and frecuency of defrost cycle. But I've seen a lot of coolers at 1ºC where air defrost was used and there was no such a problem.

Do you think there's a way to know what is causing this issue in my case and not at the other cases?

Thanks in advance!

[Grizzly]

Sorry George.
But as far as my experience goes a set point of 1.
Is way to low for an ambient defrost.
Grizzly

[tmm]

georgedvf, I suspect that your problem is the evaporating temperature? Do you have a fan speed controller or have you wired a pressure switch to modulate the condenser fan?
You can set the unit to run and maintain limits which will not cause the excessive build-up of ice which you are experiencing.
Attach your gauges and watch the temperatures!

Hope this helps, TMM

[nevgee]

Ice build up is down to air infiltration .... running yjr frig system lesswill not achieve suitable temepratures ..

Grizzly said it ... you can't expect ambient defrost when youre running at 1 deg C... you'll need to fit a defrost heater or convert to hot gas defrost.

[lowcool]

ive installed many rooms with pump down at 1 deg C. set point with 2 deg C differential,32 minute defrost every 6 hours.i agree with tmm check why your evaporator temp is so low and if pump down make sure solenoid valve is properly seating.
cheers

[Grizzly]

ive installed many rooms with pump down at 1 deg C. set point with 2 deg C differential,32 minute defrost every 6 hours.i agree with tmm check why your evaporator temp is so low and if pump down make sure solenoid valve is properly seating.
cheers

I bow to your experience!
Does not the product being stored and it's through-put influence things?
Still you live and learn!
grizzly

[nike123]

Hello!

I'm having troubles with a Cooler at 1ºC (Set point) where air defrost appears to be not enough, it's a ***** system(R-22), a lot of ice is remaining even after I extended time and frecuency of defrost cycle. But I've seen a lot of coolers at 1ºC where air defrost was used and there was no such a problem.

Do you think there's a way to know what is causing this issue in my case and not at the other cases?

Thanks in advance!

You probably have high heat load infiltration and your compressor off times are short and on times are too long. Also Grizzly said that 1°C set temperature is to low for ambient defrost. It need 4 times more time to defrost same amount of ice than when ambient is 4°C.
Try to increase temperature deferential at thermostat if that is acceptable for your stored goods.
Describe what is stored in what packaging and what are daily activities in that cooler. Could you observe what are compressor ON/OFF times.

[lowcool]

sorry nike and grizzly i dont mean to nasty or sarcastic but its one of my passions too have cold beer.george if you set your defrost to what i have recomended with pump down im sure your problems will be resolved get back to us and let us know.depending on humidity of ambient conditions you may have to increase the frequency of defrosts.the only reason i set my controllers to 32 mins is that most fridgies will work in blocks of 5 mins this way i know if someone else has had a go at one of my systems,oops the secrets out now.

anybody from darwin like to make a comment?

[Grizzly]

Hey!
Lowcool.
Good point about the reason for the odd defrost times.
AND NO offence was taken. I meant as I said.
I am still learning!!!
Cheers Grizzly

[old gas bottle]

i too run cold rooms at 1deg C without heaters and have done for years with no problems to speak of all though thats right on the limit,,the iceing up you are getting could also happen with heaters. its all down to system design and product type,usage etc, as nike says,extend the diff to 3 deg,i would set the defrost to every 4 hrs and 20 mins as a base setting for a single system and 30mins for multiples as the box temperature will not rise as fast or at all, next thing to look at is high moisture content either in the product or entering the box.

[georgedvf]

Thanks to all! I talked to the owner to get more information about the product and operation; the problem appears to be that they open the door very often and as consecuence a lot of moisture from the exterior goes in, I will set defrost as you said and also I'll try to convince the owner to modify the operation so the door open less time.

[old gas bottle]

or get a air curtian,some nice ones on the market now.

[Grizzly]

Or if they don't want to spend the money.
Fit a strip curtain, anything will be better than nothing!
The energy savings will pay for themselves.
Grizzly

[lowcool]

strip curtains are a good idea especially given target temperature and room usage,however if you increase defrost frequency and shorten time you may still hold a reasonable temperature.
definitely push for a strip curtain!