evap pressure regulator

[paul_h]

I've got a new cabinet that has an ice cream well and a 4 door bench display fridge.
The static coil for the ice cream freezer normally has it's own condensing unit and it's temp is only controlled by an EPR.
However in this install, they had no room for the condensing unit, so it's connected to the same condensing unit as the fridge cabinets.
Would that work? I always thought the fridge would need an epr if it's connected to a freezer circuit? Wouldn't the higher suction line pressure from the fridge stuff the settings for the freezer EPR?
No matter what you set the freezer EPR to, as soon as the solenoids for the fridge open up, the pressure in the freezer evap goes up, so how can you keep a constant pressure in the freezer?

(I didn't install it and I don't know who did.)

[Peter_1]

They count on the fact that the fridges will shut down after some time where the pressure then can drop enough to freeze the freezer evap.
If you ask me, a very bad designed control.
I should control it this way: if freezer asks for freezing, then shut down temporarily the fridges or some, enough to drop the pressure +/- 10K below desired cabinet temperature. But again, it still remains a lousy control.

[paul_h]

So the best bet is to shut down the fridges to set the epr on the freezer, and then hope for the best?
The thing is, I shut down one fridge, and was happily setting the epr and then left.
I got a call back afterwards saying the freezer wasn't cold enough, I then found out there was a second fridge which is why the freezer pressure was high enough/right the first time.
After I shut that one down too, the epr didn't seem to do much.
I was aiming for 250kpa (r404a), but no matter how I set the valve it wouldn't get that high in the freezer evap. It seemed to be 140kpa or not enough flow to keep the freezer below -10C

[Gary]

The EPR should be on the fridge, not the freezer... or EPR's on both.

[paul_h]

That's my problem. The epr on the freezer on it's own condensing unit as a temperature control, fine, fair enough that's how their system runs.
But putting their freezer with epr as a temp control on the same condensing unit as medium temp refrig? That means epr for all I thought myself.
There's more than one fridge as I worked out too on the circuit.
But the other problem was even when I switched the fridge off, not much reponse from this EPR. I thought it was respomding to my settings before, then I found out about the second fridge on this circuit must have been cutting in. So I turned that fridge off too, but the epr then doesn't seem to do much
What's the odds of a faulty epr and how to test?

[lowcool]

put the eprs on the fridges,cycle all systems with controller and solenoids,fit correct rated condensing unit with accumulator and cpr valve then you will find that some sort of capacity control will be required for compressor when freezer or fridges cycle.peter has got it right is a lousy instal

[Gary]

That's my problem. The epr on the freezer on it's own condensing unit as a temperature control, fine, fair enough that's how their system runs.
But putting their freezer with epr as a temp control on the same condensing unit as medium temp refrig? That means epr for all I thought myself.
There's more than one fridge as I worked out too on the circuit.
But the other problem was even when I switched the fridge off, not much reponse from this EPR. I thought it was respomding to my settings before, then I found out about the second fridge on this circuit must have been cutting in. So I turned that fridge off too, but the epr then doesn't seem to do much
What's the odds of a faulty epr and how to test?

Keep in mind that an EPR sets a minimum pressure in the evap. The pressure can't go lower than the setting, but it can go anywhere above the setting and above the setting it will generally reflect the temp of the freezer. Until the freezer temp is below design, you won't be able to bring it back up with the EPR.

[paul_h]

Keep in mind that an EPR sets a minimum pressure in the evap. The pressure can't go lower than the setting, but it can go anywhere above the setting and above the setting it will generally reflect the temp of the freezer. Until the freezer temp is below design, you won't be able to bring it back up with the EPR.

Yes , that's what I want. I want to set the EPR to 250kPa on r404a (-15C). I've found all the fridges on this condensing unit and switched them off and wound back the EPR. At this stage the suction presure is 140kPa with the icecream freezer actual storage temp at -15C as I ran it for a while to get down to temp.
I was trying to increase the pressure to 200 - 250kPa but it didn't seem to increase the SST.
At the moment I'm trying to see if the system works at all, even with the fridges turned off. So I want to be able to dial in a SST for the freezer using the EPR and with the fridges off, but I didn't seem to be able to do much with the EPR, and two other contractors couldn't either. When I wound the EPR is, the presure didn't change on my gauges)
But once I can stabilise a temp in the freezer using the EPR, then if it goes awry with the fridges back on, then I can tell the manufacturer to supply parts and labour to adjust the system. I just need to prove the fault isn't with me or the freezer EPR first. (manufacturer isn't local, they're eastern states, I'm west. Plus I'm trying to build a business not upset people)

[lowcool]

you had it right in the first post,it wont work,get your heat load capacity from the evaps or expansion valves and see if it matches condensing unit capacity if so you will have some luck in trying to make it work,are tevs correct for refrigerant being used,maybe epr is not suited for that high a temp -15 might be ok for gelati but not for ice cream,as you said it performs without cabs on but not brilliantly why increase your setting to 200-250 as it will only warm the evap up.your only wasting your time if you dont go back to the manufacturer with related facts,the client wont pay,you and the client should be upset.screw the maker who sold the crap as nothing is its correct application,or go one step further and get the australian refrigeration council onto them,pretty sure it says something about design and trade quality,thats part of the purpose of arc KEEP THE DINGOS OUT!

[paul_h]

I was just going to use -15C as a starting point as the complaint was the ice cream is too hard/cold. The shop owner wants the ice cream to be -15C as the warmest temp, colder is fine as long as it isn't too cold/hard.
Once I got the valve to hold that pressure with the cabinets off I was going to drop the pressure if needed.

I'l have a look at everything else when I go back later this week.

[frozo]

Paul, i used to work on similar system to the 1 your describing back in the late70's, first get rid of those epr, use thermosat and solonid control on your cabinets,place a check valve on the suction line of your ice cream well after the txv bulb,then i recommend using the old fashion way of using the L.P control to cycle the unit of and on as temperature controller for your ice cream well.As i said this was back in the 70s when those cabinets where on the good old r12 gas. We used to use the epr on the milk well.I am presuming that those cabinets are fdc, not static plates.This should work as long as that system is balanced.