Delfield HELP

[coldsnap]

3 door prep table...404a. Left side evap. freezes after 30 min of operation. Check evap. superheat and it's all over the place ( from 10 to 25 ). Suction ruuning 58 head at 265 at temp.

Replaced expansion valve, filter, evac. and charge w/ 32 oz. as listed. Unit ran 1 hour perfectly....40 deg. box temp. 14deg. evap. super heat on new valve...23 deg comp. superheat. Cust calls 6 hours later evap. freezing over again. Gaskets are good...both fans running strong...now what?

[mmmdave]

Infiltration through condensate drain line?

Recheck SH?

[james122964]

Tstat is bad, get a A12-701 constant cut in 41 adjustable cut out 15 - 31.
Weave some of the cap tube from the control in the evap fins, it will push all the way up through, then back down 1 time each way should be good.

This control will cut the coil(s) out when the evap freezes and and bring it back on after it is defrosted.

Jim

forgot to ask, is this a model with a top rail?

[icemeister]

I have only run across a very few Delfield prep tables but in the process noticed a problem with their vertically mounted evaporator between the door sections.

The problem I've seen is the condensate often won't drip off the coil. It hangs there by surface tension (or something like that) and blocks the naormal airflow, the condensate then freezes in place and then the whole coil starts to freeze up.

The first solution I found (rather unscientifically) was to spray the coil with Pam...because it was real handy there in the kitchen.

I also found that a food grade silicon spray worked good too. Actually, I think anything that has some solvent like alcohol in it will clear off the buildup on the coil that is causing this problem.

This may not work in every case, but I've had pretty good luck at it. ;)

[coldsnap]

Tstat is bad, get a A12-701 constant cut in 41 adjustable cut out 15 - 31.
Weave some of the cap tube from the control in the evap fins, it will push all the way up through, then back down 1 time each way should be good.

This control will cut the coil(s) out when the evap freezes and and bring it back on after it is defrosted.

Jim

forgot to ask, is this a model with a top rail?

This is a top rail. T-stat is located on evap that is NOT freezing. If T-stat was shooting low, wouldn't both evaps. freeze?

[james122964]

This is a top rail. T-stat is located on evap that is NOT freezing. If T-stat was shooting low, wouldn't both evaps. freeze?

I just had one today, but it was the evap that had the tstat that was the problem. I would check the tstat to make sure it opens and closes, the one today would not. I do not think it would matter because if it is not shutting off on temp which ever coil freezes first will hold your refrigerant robbing the rest of the system and freezing more, never ending cycle.

Make sure the fans on both side(s) are running at speed, then get sh*t built up on the fans that slows them down, and cloggs the fan cover.

Its a tight fit in there, make sure the liquid line is not touching the TXV sensing bulb.

Hope that helps,

Oh, make sure that both evap discharge lines are the same temp you may have to adjust the valve to feed more on the one that is not freezing** this is high a high probability.

Jim


jim

[coldsnap]

[QUOTE=james122964;7570982]I just had one today, but it was the evap that had the tstat that was the problem. I would check the tstat to make sure it opens and closes, the one today would not. I do not think it would matter because if it is not shutting off on temp which ever coil freezes first will hold your refrigerant robbing the rest of the system and freezing more, never ending cycle.

Make sure the fans on both side(s) are running at speed, then get sh*t built up on the fans that slows them down, and cloggs the fan cover.

Its a tight fit in there, make sure the liquid line is not touching the TXV sensing bulb.

Hope that helps,

Oh, make sure that both evap discharge lines are the same temp you may have to adjust the valve to feed more on the one that is not freezing** this is high a high probability.

Jim


jim[/QUOTE. I understand adjusting super heat slightly to avoid freezing, but sure would like to figure this thing out.

Shouldn't saturation temp. remain above or near freezing and deice on off cycle?

[james122964]

jim[/QUOTE. I understand adjusting super heat slightly to avoid freezing, but sure would like to figure this thing out.

Shouldn't saturation temp. remain above or near freezing and deice on off cycle?[/QUOTE]

I go for a 20 degree coil on these and that is were I try to adjust the cut out on the control, this will give them a product temp in the 32 range, I do the rough and have them fine tune based on result.

Go for a 20 degree coil, make sure you have the sides on and wait 15 min between adjustments, it will be difficult if you are not there early before they start opening and closing and climbing over you.

Dial both coils into this suction line temp.

Jim

Edit, Your coil will freeze as the box temp drops, that is why the cut in is constant at 41 degrees, all ice will be melted away and the product will not be out of temp for health department. This makes your coil temp the controlling point when it is 20 the box will be about 25 when it is 41 the box will be about 46 the product will be between 33 and 37.

Jim

[coldsnap]

20 degree at coil exit.....superheat will be what it may?

[james122964]

20 degree at coil exit.....superheat will be what it may?

You will have a hard time getting super heat since the suction access point is near the compressor or on the compressor and you have a top rail that is running and messing with the suction pressure you read.

The top rail is usually on a LP control and cuts off when the box is statisfied and the suction pressure drops, this should be cut in at 45 psi and with a 25 differential.

So yes, feed the coils to the same temp, most likely the one that is not freezing is starving.

Jim

[james122964]

20 degree at coil exit.....superheat will be what it may?

remember when the coil actually reaches 20 degrees, it will statisfied and cut off the solenoid.

Jim

Main point is to get the suction lines the same temp. coil should be about 20 degrees.

[coldsnap]

I'll give it a try.

[270wsm]

I have only run across a very few Delfield prep tables but in the process noticed a problem with their vertically mounted evaporator between the door sections.

The problem I've seen is the condensate often won't drip off the coil. It hangs there by surface tension (or something like that) and blocks the naormal airflow, the condensate then freezes in place and then the whole coil starts to freeze up.

The first solution I found (rather unscientifically) was to spray the coil with Pam...because it was real handy there in the kitchen.

I also found that a food grade silicon spray worked good too. Actually, I think anything that has some solvent like alcohol in it will clear off the buildup on the coil that is causing this problem.

This may not work in every case, but I've had pretty good luck at it. ;)

I have seen this way too many times. The ones i have worked on are upflow with the fans on top blowing upwards. It seems that would help keep the water from draining down properly. I'm not sure if it was a design change or the wrong evaporator, but i had to replace one the other day. I ordered the whole evaporator asembly from delfield. The new one is identicle except now the fans blow down, bringing air in from the top and out the bottom.

[VTP99]

I see a lot of these tables in pizza shops.

[trippintl0]

I know you said both fans running strong, but make sure the correct fan blade & motor is on there. Delfield has several different style fans and blades. I believe on that style, the fans are supposed to suck in air at bottom (where fans are mounted) and push it through coil and out the top. Also, sometimes one fan blows good and causes the other to spin but the other fan isn't running full speed.