R404A Beer Cooler

[NwBurbs]

Looking for some feedback on the following.

Came acroos a beer cooler in a hotel that is runing 404A

Cooler had a frozen coil, low on gas.

Thawed coil and since the unit was at 2psi on the low side, added 404. Was dialing in the unit into superheat after the hot pull down and the unit started going off on high head. The condenser and compressor are located on top of cooler in ceiling that has little air movement.

I was not able to have the unit obtain the needed superheat due to high head and not able to add needed gas.

1) Thoughts on the high head problem. Since the unit is positive pressure is it possbile non-condensible got in the system other than on startup if a proper vacuum was not done? I don't think so. Also, I have seen condensers on top of units, but believe that due to limited airflow this unit is going to run higher head due to where it is located and lack of proper air movement with this aircooled unit.

2) Normal operating pressures of 404A box in a medium temp application? Right now I am at 60/380...not right for sure....where should I be at? I would think 70/ and maybe 225?

Thanks in advance.

[taz24]

Looking for some feedback on the following.

Came acroos a beer cooler in a hotel that is runing 404A

Cooler had a frozen coil, low on gas.

Thawed coil and since the unit was at 2psi on the low side, added 404. Was dialing in the unit into superheat after the hot pull down and the unit started going off on high head. The condenser and compressor are located on top of cooler in ceiling that has little air movement.

I was not able to have the unit obtain the needed superheat due to high head and not able to add needed gas.

1) Thoughts on the high head problem. Since the unit is positive pressure is it possbile non-condensible got in the system other than on startup if a proper vacuum was not done? I don't think so. Also, I have seen condensers on top of units, but believe that due to limited airflow this unit is going to run higher head due to where it is located and lack of proper air movement with this aircooled unit.

2) Normal operating pressures of 404A box in a medium temp application? Right now I am at 60/380...not right for sure....where should I be at? I would think 70/ and maybe 225?

Thanks in advance.

You would have broken the law if you had done that in the UK.
In the UK it is iligal to just top up a system that is short of gas.

404a is a zeotropic blend so if you lose part of the mix and then top it up you are then left with a charge that is not pure 404a and may give you different running pressures. Check that the condenser is clean, pull all the gas do a proper leak test, repair leak and then weigh in the correct amount of refrigerant as per the makers plate.

Ps are you sure you have not over charged it. How do you know how much gas was in the system and how do you know that you put the right amount in, I bet you did not weigh it in.

Do the job properly and if the compressor is not faulty it will be fine.

taz.

.

[NwBurbs]

You would have broken the law if you had done that in the UK.
In the UK it is iligal to just top up a system that is short of gas.

404a is a zeotropic blend so if you lose part of the mix and then top it up you are then left with a charge that is not pure 404a and may give you different running pressures. Check that the condenser is clean, pull all the gas do a proper leak test, repair leak and then weigh in the correct amount of refrigerant as per the makers plate.

Ps are you sure you have not over charged it. How do you know how much gas was in the system and how do you know that you put the right amount in, I bet you did not weigh it in.

Do the job properly and if the compressor is not faulty it will be fine.

taz.

.

Wow!!!! Tight regs in the UK.

Thanks for the tip on the 404A reaction....was not aware of that bit of into.

After the coil was thawed and clear and the pressure was 2psi.....the entire was not full of ice....just like two inches of it on the very first pass of coil after the TXV....which was covered solid in ice.

Condenser is nice and clean as I have blowen it out with nitrogen.

I did not weight in the charge as their is a sight glass and the superheat was like 50 whent he unit was started back up. After the hot pull down, the superheat was twenty.

Thanks again for the tip on the 404A properties, as this is the problem.

Compresser has to have the gaskets changed as their are leaks on the discharge side and head of the compressor.

[Brian_UK]

If the 2psi was with the system OFF then it is possible for the system to have gone to negative pressures when the compressor ran.

So it is possible for air to have gotten into the system; a good vac out when the repairs are done should resolve it.

[NwBurbs]

If the 2psi was with the system OFF then it is possible for the system to have gone to negative pressures when the compressor ran.

So it is possible for air to have gotten into the system; a good vac out when the repairs are done should resolve it.

One other thing that I noticed on this one was that they had the cut out pressure set at 0?????, so it could have sucked in some air when it was pulling down after the cycle.

[icecube51]

is a beercooler not an evaporator in a water tank???? so if he had a vacuum,and the small leak is in there.......did he not pull a small amount of Ho² (water) in the succion line...?? just thinking out loud here.

Ice