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fridg
27-01-2012, 12:52 PM
Just had a call out 11 pm , meat cases hi temp. Receiver was bone dry , all floats bottom out + level is way below sensor , but no liquid alarm going off on rack. :mad:

Find a few fans not running , replace fans , can hear 8 or more LLS modulating , over & over (Starving issue ?) monitor temps
still a tad to high for my liking. :eek:
Receiver still dry

Sporlan heat reclaim valve whistling at me , valve was pinching refrigerant from the cases , close valve down & wallah , liquid levels come back & cases back to temp.

First time i have had to deal with a heat reclaim problem with these systems.

Any tips & hints or different methods of dealing with such problems or others that may present themselves ?

cold.man
27-01-2012, 05:23 PM
hi fridg

sounds as your pack is running onn minimum charge.
what is being used from the heat reclaim is it store heating or hot water or even both?
by rights the heat reclaim should come second fiddle to the cases on the shop floor if cases begin to struggle the heat reclaim valve should close down.
what pack controller do you have?
is there a relay in the control circuit for the heat reclaim faulty?
is the controller for the AHU or water faulty?
it is not unusual to have erratic liquid reciever levels with a pack with heat reclaim, its down to the way the heat reclaim is controlled.
alot of engineers don't like it and just switch it off instead of trying to solve the problem.
Myself personally i think if there is heat you are able to use it should be taken advantage of and used.
the most efficient set up for heat reclaim ive seen myself is plate heat exchangers direct from the compressor discharge for water especially.
take sainsburys for instance they use PHE for the water and also use secondary condensor coils for the AHUs for store heating.

fridg
27-01-2012, 11:05 PM
I agree on the minium charge , or at very least it is a little low.
The reclaim in this specific store is just for store comfort heating.

I agree that the AC comes second fiddle to refrigeration , i was told this when i done a walkthrough to familarize myself with the plant. The main contracting company said to me " Don't worry about the heat reclaim you will rarely have a problem with that & it will shut itself down if there are refrigeration issues"

We only look after the refrigeration in the store , another company has the AC.

Controller for the rack is a Danfoss AK2 SC-255 , i steer clear on the AC side of things as it is not our primary concern while on site , the ac is controlled by a seperate Emerson E2 Facility Management System.

You could be right , maybe a board point relay has gone or a water sensor fault keeping the valve open , but as stated Refrigeration should override the AC.

cold.man
28-01-2012, 01:42 AM
This is the problem with facilities managment companies, don't know if this is the sort of company you work for yourself ( facilities managment ).
any problems with the heat reclaim gets back heeled between the fridge mechanics and a/c mechanics and it somtimes can become even more of an issue when there is a sub contractor involved.
ive had a call out before with cases struggling and the discharge pressure was low so obviously there was a liquid problem onto the shop floor.
i found the problem due to the heat reclaim valve had the sv removed and a magnet put in its place. the problem was the coil on the valve was faulty that was it.
checked the signing in book and a subbie had been out, the store was complaining the store was to cold so the muppet just replaced the sv coil for a magnet but obviously he was an a/c engineer and didnt realise it would affect the refrigeration.
not sure what part of oz your from but do have city taken over all the coles stores now throughout australia?

mikeref
28-01-2012, 10:05 AM
Hmmm, heat reclaim for instore butcher shop hot water or store heating should only have minimal effect on liquid levels in the refrigeration reciever. Point being, discharge gas is diverted only, as in superheat and sensible heat is transferred to air or water and the amount removed, if sized correctly, cannot allow the gas to condense as it must continue on to the condenser.

Condenser fans will cycle off as discharge pressure reduces to prevent, ah.... lowering the high pressure gas from condensing..too... soon... and causing a pressure drop before liquid is returned to reciever. A/c heat and heating water should not be on at the same time, nor should heat reclaim be activated when compressors are unloaded..;) Mike.

fridg
29-01-2012, 07:26 AM
Mmmm a magnet sure would solve the problem of a burnt out coil.

Not sure if City has taken over all stores oz wide , but they look after them all in my region.
We only do their work when they are busy or off call , we work well together , the issue was temporarily resolved on the night to keep product at correct temp , even though we were 3hrs apart.

Thanks for all the input.