Fridge Quiz!

[Simon Butler]

During a recent service call to a six month old multi deck chiller I found the following evaporator arrangment. If from the following description you can picture these coils, then see if you can guess the symptoms the cabinet was suffering from.

After the externally equalised TEV the evaporator feed tee's into the bottom of two sections of single pass evaporator coil. The return is connected to the top of the coil and from the coils tee's back into a common suction which has the TEV bulb attached. The coils are arranged in two equal sized sections one placed directly in front of the other so that the air on, passes through the first section then through the second.

No faults were found with the condensing units.

The cabinet is made up of two equal multiplexed sections and built into a restaurant as part of a £750,000 refit.

[Simon Butler]

Marc,

I have recommended that we repipe the evaporators so that the feed enters the rear evaporator at the top of the coil, leave’s at the bottom of the coil and onto the top of the front coil exiting at the bottom of this coil then returning to the condensing unit. This configuration would allow the TEV to operate correctly and prevent the refrigerant logging in the bottom passes of the coils.

What do you think?

[Dan]

I am guessing that the front coil has a wider fin spacing and its intent is to dehumidify the air before it enters the second coil. Piping the coils the way you suggest would be the correct way to pipe them. If you have gas defrost, you may want to stick with the bottom feed, otherwise I agree with your solution.

[Simon Butler]

Dan,

The coils are identical and it only has ambient defrost, it just amazes me that even a small manufacturer can produce a cabinet like this. At the moment the TEV is closing right down, the lower passes of the coil are flooded with liquid and probably oil and the cabinet is only managing 13-14C , I have already had to change the condensate trays because they were too small. Also the air is allowed to pass by the coils at both ends and the condensers are recycling hot air and you have to be a contortionist to get gauges on to it.

Thanks for confirming my thoughts on what to do, the only problem I have now is that I can't guarantee the customer that any modifications will gain the desired temperature of 3-5C. I have made that clear to them though and I don't think they will ask this manufacturer to make any more cabinets for them.

[Dan]

For beverage duty you will be able to make it work. Keep in mind, the customer bought a display case, not a refrigerator. I am surprised the manufacturer has not been contacted to make the repair. Regardless, Marc's observation and your solution both make sense.

[frank]

Is the cabinet made by "Storer Refrigeration" ?

[Jasper]

FRANK
I can see why you think this may be a Storer cabinet, but they never manufactured a cabinet with that many flaws, they also always piped from the top of the first evap into the bottom of the next.
see you later

Jasper

[Simon Butler]

Frank/Dan,

The cabinet was custom made by Excel refrigeration for a shopfitting firm who asked me to look at it. The cabinet is required to run below 5C by the customer and normally holds sandwiches etc, although I can not be sure what specs were given to Excel. The shopfitting firm has told me that Excel are not being at all helpful as far as warranty repairs are concerned and have asked me to compile a report on the cabinet for them so that they can recover the repair costs.
I'll take some pics with the digital camera before I make any alterations and post them on the site.