icing up

[hvac01453]

I have a walk in freezer that is freezing up a big block of ice at the tube sheet end where the TXV is. The coil and pan are clear of ice except for the one end. I am suspecting the defrost termination is comming out early and considering moving it present location closer towards the compressor on the suction line. Any ideas where else I might look?

[lana]

Hi,
Try to change the defrost time. Make it longer.
Also try to defrost more frequently.
Cheers

[SteveRob]

I have a walk in freezer that is freezing up a big block of ice at the tube sheet end where the TXV is. The coil and pan are clear of ice except for the one end. I am suspecting the defrost termination is comming out early and considering moving it present location closer towards the compressor on the suction line. Any ideas where else I might look?

Before, playing with the Def term, check that the ref system is working properly, de-Ice tube sheet and TEV with hot, water, blow lamp or a forced defost with the coil wrapped in carboard, as not to raise the room temp too high.

Check out the TEV clean the orifce, check for oil cloging or blockage, reset the superheat, by calculating the spring lengthe or number of turns needed. then check with gauge and thermometer. But be sure also that the Condensing unit pack or Chiller is working correctly. Making mods should allways be last resort, be sure all aspects are correct to start with! before you take it on to re-design the system!

[chillin out]

I agree with SteveRob, check the coil gets full flooded and you don't have a massive superheat.

Also check the heaters have not 'walked' out of place as this is a very common reason for icing up at one end.

Chillin

[old gas bottle]

as above,make sure the heaters have not shifted to the other side of the coil just leaving the weather proof ends tight upto the coil block, if thats o/k i would move my termination probe or phail to the top coil run on the TEV side, set a 10 deg C, 20 min defrost, 5 min drip timer [thats very important] and watch it through its def cycle making sure the coil does not get too hot but gets enough heat in the problem area, as allready said,defrost first.

[LRAC]

Hi hvac01453

you didn't say if the coldroom was getting to temperature ok.

Regards
Lrac

[derfriguy]

Just a thought. Is the coil being pumped out prior to the defrost or is the coil full of refrigerant? Also is the suction line piped for pumpdown or nonpumpdown. This does make a difference with defrosting.

regads Steve

[setrad7791]

As above check the heater locations but also look for other factors... is the end of the evap that icing up located close to the door/entry....? if exscessive moisture is being drawn to the evap through worn door seals you will get excessive ice build up on end plate....and r they closing the door properly? I've found that most problems concerning ice up's can be customer related! Just a thought!