zanotti bgm11702f/abr mono bloc system icing up

[doormaster2008]

Has anyone had problems with these systems.i have been looking after this one for 3 years now with very little problem. It's on a walk in freezer.it keeps building up ice between the fan and coil stopping the airflow.i have checked the defrost settings and can't fault it.it works for a couple of weeks then it's a sheet of ice from top of blower to drip tray about 5mm thick. Has anyone any ideas.it defrosts every 3 hours.thanks.

[Andy AC]

If the evap fans have a capacitor, they are high speed fans and should really roar and give good airflow through coil, if the cap has failed they will run slowly.
On the freezers, the cranckase pressure regulators leak gas.
Check the evap probe is still attached to the coil.
I had one the other day where the evap probe had failed and wouldn't go into defrost because the probe was reading high all the time.

[charlie patt]

Also had same as above only thing would say if building ice between coil and fan it could be more to do with moisture in room ie leak in insulation because ice is not on coil perhaps the Df is not the issue I have had this happen twice on a zanottie once because of badly build room and one because the side panel on evap was not screwed in correctly and unit pulled air out the side rather than through the coil

[doormaster2008]

Also had same as above only thing would say if building ice between coil and fan it could be more to do with moisture in room ie leak in insulation because ice is not on coil perhaps the Df is not the issue I have had this happen twice on a zanottie once because of badly build room and one because the side panel on evap was not screwed in correctly and unit pulled air out the side rather than through the coil
Hi guys. I have checked panels , fan speed, probe, settings, and everything else I could think of.i run it through manual defrost and it clears the coil.i even upped the term temp to 20c from 15c and it seemed to take longer to build up but it has done it again.it lasted 2 weeks this time.

[chemi-cool]

What refrigerant? HG I presume.

ice buildup has to do with moisture [physics], what left for you to find out is whether the moisture is coming from the outside or lack of removing moisture.
I am sure you have checked the water tray outlet for a free flow.
something is not functioning well there, some pictures and more details might wake up some of the gray stuff...:D

[doormaster2008]

Hi Chemi-cool. Refrigerant is R404a.drain is clear, door is open a lot but it has been for 3 years with no problem.even thought of changing control panel but at nearly £300 unless it defiantly is faulty don't want to risk it.unfortunately the site isn't local so I can't keep too close a check on it to see if it is something they are doing.

[chemi-cool]

One more thing that comes to mind is the refrigerant, 404 tends sometimes to "burn" as starts to behave funny. You can replace all the charge or [my recommendation] replace it with 507A. Always works better.

[cadwaladr]

Nothing has been sucked into the evaporator causing an obstruction does it blow well when it's defrosted?

[Tayters]

If the evap fans have a capacitor, they are high speed fans and should really roar and give good airflow through coil, if the cap has failed they will run slowly.
On the freezers, the cranckase pressure regulators leak gas.
Check the evap probe is still attached to the coil.
I had one the other day where the evap probe had failed and wouldn't go into defrost because the probe was reading high all the time.

Some good info. Have seen a couple where the CPR has failed and it looks like the system is short of charge initially. Suction pressure is low, room about -12 but ice on suction pipe from CPR to compressor. This is caused by the CPR staying shut / only just open. Either fit new valve or cut out CPR and fit loop of 5/8 pipe if customer a bit squeaky. Bit of a giveaway can be is if you undo the CPR adjusting cap you get a quick hiss of gas which shows you the seal is goosed. Don't think this causes coil icing up though.

If you suspect the probe you could try upping the termination to as high as it will go and set defrost time to 15 mins or so it will only terminate on time. Might prove a point if you can't keep going back to site to check.

Happy Easter!
Andy.

[Magoo]

Hi
After 3 years heavy usage check door seals for damage. Particularly the floor seal.

[monkey spanners]

I've had customers putting steaming hot food in to chill it which soon iced up the evaporator, I'd also check the condenser is clean, maybe give it a blow through with some nitrogen.

[doormaster2008]

Hi guys.have checked door seal, airflow, etc.condenser okay. Fitted remote condenser 18 months ago due to heat.only frozen pies going in to room.until it suddenly ices the room temp is -18c. The coil itself does not ice up in the front or middle only at the back closest to the fan. Thought they might have been blocking inlet with pies but they say not and it is always clear when I check it.

[redroge]

Do the fans switch off when on defrost
Is there a drain down period after defrost termination
Should it not be defrosting every six hours
Is it solid ice on the evap or snow?

[doormaster2008]

Do the fans switch off when on defrost
Is there a drain down period after defrost termination
Should it not be defrosting every six hours
Is it solid ice on the evap or snow?
Hi red roger. It's set up as recommended by zanotti. Defrost every 3 hrs ,2 min fan delay and drain time.solid ice not snow.

[redroge]

Have you tried moving the termination sensor to where the ice build up is

[chemi-cool]

You have mentioned that the ice is between the coil and the fans, could there be any problem with the fans? do they turn continually during cooling cycle or from any internal problem or control they stop once in a while?

[doormaster2008]

You have mentioned that the ice is between the coil and the fans, could there be any problem with the fans? do they turn continually during cooling cycle or from any internal problem or control they stop once in a while?
It has always worked okay when ever we have been on site.it runs continuously in cooling cycle.

[doormaster2008]

Have you tried moving the termination sensor to where the ice build up is
I thought about trying to resite it but the ice is just touching the coil so it would be difficult to fix it

[doormaster2008]

Have you tried moving the termination sensor to where the ice build up is
Hi.have thought about it but the ice is just touching the coil making it difficult to position it properly

[redroge]

Is there a two minute drain down time then a fan delay while the compressor brings the coil temp down after defrost

[chemi-cool]

After you have ruled out all the possible problems, all I can say is that the unit works fine:D

The only thing that left to do is spending 24 hours watching the unit at work, get a warm coat....

[doormaster2008]

Afterhave ruled out all the possible problems, all I can say is that the unit works fine:D

The only thing that left to do is spending 24 hours watching the unit at work, get a warm coat....
Ha ha.thanks chemi.do you recommend any particular coat.cheers

[doormaster2008]

Is there a two minute drain down time then a fan delay while the compressor brings the coil temp down after defrost
Yes.2min drain then 3 min fan delay

[redroge]

Is there a lot of snow on the cold room ceiling

[chemi-cool]

Ha ha.thanks chemi.do you recommend any particular coat.cheers

I think that will do the trick.


http://www.backcountry.com/canada-goose-polar-bears-international-expedition-down-parka-mens?CMP_SKU=CDG0053&MER=0406&utm_source=CJ&utm_source=Affiliate&mr:trackingCode=448F5E4&AID=10279061&PID=905846&SID=men_down

[doormaster2008]

Is there a lot of snow on the cold room ceiling
None at all

[redroge]

Is it possible that moisture is forming on the top panel during defrost and dripping down when the fan starts, is the drip pan heater working, it's a long time since I worked on freezer cold rooms but I thought the defrosts should be every six hours.
Like Chemi says you will probably have to invest in a big coat.

[mattym]

I had a one s couple of month ago where there was a small gap from top of evap housing to ceiling it conensated on the top cover and froze so every time it defrosted the condensation would het bigger forming a bigger ice build up and eventually it would track its way to the evap coil and start freezing one top corner and eventually do the whole coil not much but its something