did /do i have moisture problem

march 2010 fitted two frasscold/ kobul 15 hp on a freezer room just a holding room standard foods no fish etc etc installed and commisioned by a good engineer 3 day hp test and 2 day vac to a excellent torr/ 305 driers dry sight glases 15m piperun minus 18 temp p traps oil traps suc accum/oil sep crank heater hp lp pump down on danfoss sol valve/fan sp control on condensor kobul evap controlled by dixell with 4 hr df temp term 8 dc on 30 min term each unit is capable of doing the room on its own, loaded twice a day with 30 ish pallets room cap 249 pallets coils on stainless rods, ran for two weeks done oil samples all ok change 305 driers as we always do no debris all good, 4 months later we had a pourous evap/ it was leaking on the loop just like a pinprick on a loop/ repaired it drier change new ref oh its 404 to/ hp test it and vac overnight all good/ until it struck another leak 4 leaks in three months then the other coil started it/ i have ended up removeing them but kobul and the wholesaler aint totally cooperating the wholesaler is good to be fair but kobul are blameing moisture/ the room was installed in a dry enviroment in a excellent manner and we never had any tev freezing its a alco power valve too/ if we did have moisture my question is would it pinprick the loops of evap/ they pinprick the coil like a pourous ten year old foster /we had no freezing tevs and good driers good vac with a torr gauge with a oil change halve way through/ i even checked the drains to check for amonia through drains any guidance guys

My only thought on tubing going porous is the velocity and state of the tubes to start with.through the tubes.

My knowledge is only on evidence that I've seen on copper tubing with water running through it; any impurities in the tubing, possibly from manufacture, create solid nodules on the inside of the tubing. Oil and refrigerant flowing over the nodules create eddies and start to erode the tube wall. A bit like a wave moving around a pebble on the beach washes the sand away from under the pebble.

Also if any flux was used, during manufacture or even install, that wasn't cleaned out then that can also start erosion.

Good luck with it.

take an oil sample send it off anything in yr system will be in the oil otherwise its down to poor manufacturing on evaps as yr install is pretty flawless have had the pin pricks occure myself on R22 system but that was very old and crappy system i do alot of foster work on older 404A freezers and now if theres even a hint of it being short i change evap cappillary drier and do full strength pressure test and when i inspect evap there is always a tell tale spot but they are all over 5 yrs old at least kobal is hussmann i think worked for them and they manufacture i think in poland and its not the best to be honest had some ropey protocol packs from there with a strange sealing paste or flux blocking suction pressure stage controller caused no end of probs oh thats my opinion lol

Can't see it being a moisture problem if it reached a good vac level (unless it was in the refrigerant), would a refrigerant sample test be able to prove sytem has acceptable moisture levels?

The few evaps i have seen fail due to moisture have made blisters that eventually burst in the u bends sockets, not pin holes.

I have also seen a few u bends fail due to particles in the refrigerant not making the turn and punching a hole, i suspect this was due to a monkey using a holesaw to make tee's as had been told, had voiced opinion but it wasn't wanted so just did as was instructed...:o

Jon :)

we done oil samples at 4 months and all was well i think i am being bluffed we will sea many thanks guys for your assistance ta charlie

You have to contact the manufacturer, the tube they have used is too thin and when they bend the U part, the out side is much thinner then the rest of the tube.

sounds very much like a bad product but at the prices of copper today, every manufacturer try to save money and this time, its on your back!

Charlie

If the wholesaler is covering warranty then Kobul are probably looking after them and just not admitting it? Would it be worth your while to see if others have had similar problems maybe by opening another thread on it?

Alec