Isceon 59 freezer puzzler

[get the gauges]

I have been to a service call that is eluding me. A bitzer type IV (4) compressor open drive run by a 3 kw 1710rpm motor that shows 6.5A on the name plate but only pulls 3.8A including the condenser fan which is on the end of the motor shaft. 3 phase supply is correct at 440v. The system was retro fitted from R22 to the drop -in R417 isceon 59,the strangeness starts in the freezer cold room which is 4m x 3.5m x 1.9m high and has two Searle KS35/4 coolers crammed in to this small room with one of these condensing units on each cooler. The room should in my experience be able to achieve temp with one system but actually needs two comps running to achieve -15c. First i notice the lack of frosting on the coils and wind out the expansion valves as i'm confident it is not a charge problem,this achieves some frosting,but not much drop in temp, then i recharge with new gas to rule out the gas being charged in correctly, still nothing -13c with both units going like the clappers.so i check the orifices and find one of the coolers to be running a no.1 orifice in a danfoss valve ,now i've put in loads of KS35 coolers and have never put in anything as small as a no.3 and have found they nearly always run a 3hp compressor when making a freezer and have never had a problem. My suction pressure when i tried a no.3 in the valve went sky high 40-50 psi in a room already at -13c and liquid flooding back so i stopped it immediately and tried a no.2 but back pressure sky high and liquid flooding back,now i know why some one has put a no.1 on it because the back pressure needs to be lower and it's the only way of getting it down because the compressors not doing it. when running i get 10-15 psi and no more than -10c suction temp and -14c return bend temp. With R22 i should be lower in temp but i don't think this r59 is the same as R22 when at lower pressure. So i think no lets change it for R404a and change the oil, but if i put in a no.3 orifice is it going to flood back like the isceon has been doing?. I've checked the comps out and there fairly new and have good valve plates and there is no by-passing of devices such as oil seps etc. My thinking is that there needs to be a no.3 orifice in the TEV's and the present comps are too small to handle the onslaught. The staff in the kitchens say they have never seen the temperature lower than -18c and never that low for long. My boss is telling me to screw the valve in as much as possible to get the suction pressure down to a near vacuum ,i reckon a better comp is a better way of getting the pressure down. Thoughts appreciated.

[The Viking]

Personally I say we need more information.

Discharge temp and pressure.
Subcooling
Superheat
Air ON and air OFF evaporator
Air ON and air OFF condensor

To adjust TEVs and determine orifice size we need to, as a minimum, know the super heat.

[chillin out]

Any chance of using paragraphs?
It makes reading a lot easier.

Chillin

[Gary]

You "wind out the expansion valves" and then wonder why its flooding back? If you don't know how to measure superheat, then you should not be touching expansion valves. And even then, adjusting the valve is a last resort.

[Gary]

BTW, winding out the expansion valves was the wrong thing to do. Changing to a larger orifice was the right thing to do. Put the #3 back in and then adjust the superheat.

You seem to be trying to achieve some target suction pressure. That is always a mistake. Get the superheat right. The suction pressure will be whatever it needs to be. The suction pressure (by itself) is meaningless. It is what it is.

And stop listening to your boss. The blind leading the blind.

[Grizzly]

Hi Get the Gauges.
Just a thought to go with the relevant info you have already been given.
When you state the running Amps are low!
Can you confirm the Compressor is running fully loaded. Ie Is it working fully?
Grizzly

[Gary]

As I see it, the amps are low because the coil is half starved (low mass refrigerant flow = low amps), even though the TXV is running wide open. The coil is starved because the orifice is too small. It flooded back with the larger orifice because the TXV is running wide open.

[fixit4u]

Isceon 59 is probably not the best choice for your application. R417A works much better in med and high temp application.
I would recommend trying Isceon 29 (R422D) or R422B.

[get the gauges]

You "wind out the expansion valves" and then wonder why its flooding back? If you don't know how to measure superheat, then you should not be touching expansion valves. And even then, adjusting the valve is a last resort.

Yes gary, You are right ,and i do know how to measure superheat ,and that the suction pressure will be what it wants to be on the pull down. When i came to the systems they had no.1's in and when i put the usual no.3's in the systems flooded back and that is even with a new non-adjusted valve.
I'm going to start another parrotgraph now look, i only ask about the no.1 orifice in case it's something people do on 59 conversions,because someone has done it for some reason in the past, i'm assuming to get the back pressure down. I personally think the low amps are due to the comps being too small and the high pressure and liquid flood back being due to the comp not handling the job. I could fit a suction accumlulator but why should i need to every searle ks35 freezer system i've installed(and i' didn't install this one) has just worked, my whole point is has anyone ever seen a no.1 orifice on a searle 2fan ks 35/4 modern cooler because i ain't and the office at this new firm i'm at don't think it's a problem,so i'm a little unsure of any more technical advise they may offer me. Any thoughts

yours steve in the north sea.

[get the gauges]

You "wind out the expansion valves" and then wonder why its flooding back? If you don't know how to measure superheat, then you should not be touching expansion valves. And even then, adjusting the valve is a last resort.

Yes gary, You are right ,and i do know how to measure superheat ,and that the suction pressure will be what it wants to be on the pull down. When i came to the systems they had no.1's in and when i put the usual no.3's in the systems flooded back and that is even with a new non-adjusted valve.
I'm going to start another parrotgraph now look, i only ask about the no.1 orifice in case it's something people do on 59 conversions,because someone has done it for some reason in the past, i'm assuming to get the back pressure down. I personally think the low amps are due to the comps being too small and the high pressure and liquid flood back being due to the comp not handling the job. I could fit a suction accumlulator but why should i need to every searle ks35 freezer system i've installed(and i' didn't install this one) has just worked, my whole point is has anyone ever seen a no.1 orifice on a searle 2fan ks 35/4 modern cooler because i ain't and the office at this new firm i'm at don't think it's a problem,so i'm a little unsure of any more technical advise they may offer me. Any thoughts

yours steve in the north sea.

[monkey spanners]

Hi get the gauges

If you had a bigger condensing unit surely it would 'suck' the refrigerant out of the evaporator even quicker and increase the flood back problem.
If the compressor fitted is too small you'd have a higher suction pressure than if it was sized correctly, surley a higher suction pressure would tend to increase the run current.

As to the orifice sizing, why not phone up your wholesalers technical department and get them to size it, this is what i do if doing what i think is right doesn't bring about the desired result

If R417 has a similar viscosity, pressures and a similar required flow rate for the same duty as R22 then the same orifice should do.

Something i have seen is a distributor that is only feeding through one of its capiliaries, this gave similar symptoms, also it needs to be a external equalised valve if a distributor is used. I have also seen on another system where there distributor is just a bit of pipe with two capiliaries stuffed in, and one capiliary was above the other (rather than being side by side) this caused all the liquid to flow through only half the coil, the other half seing only vapour, this plays havoc with the superheat modulation, it was cured by turning the distributor through 90' so both outlets were on the same level.

Also i've seen a danfoss valve that was passing liquid through the equalising line straight into the suction, this caused flood back and little or no work done by the evaporator.

Jon

[get the gauges]

Hi get the gauges

If you had a bigger condensing unit surely it would 'suck' the refrigerant out of the evaporator even quicker and increase the flood back problem.
If the compressor fitted is too small you'd have a higher suction pressure than if it was sized correctly, surley a higher suction pressure would tend to increase the run current.

Jon

Sorry i think the bigger the comp the lower the suction pressure and therefore lower the cooler temp, i don't think i would be getting liquid back if i had a bigger comp.It would just evaporate in the cooler.
How did you manage to get liquid passing from your equalising line on your tev,i didn't think there was any gas exiting the tev from the equalising connection but only entering it and pressurizing the diaphram, i'll have to look up a diaphram diagram in a tev. I wish some one would come on and confirm that a no.1 orifice cannot exist in a ks 35 cooler when in a freezer situation, so far people just want to know subcooling and superheats, the liquid line is warm and the suction has ice on it but not at the compressor head in my book thats ' super - heat ' ). I'm really suprised that no one has immediatley thought straight away like i did that there is some thing wrong if someone has put a no.1 in instead of the no.3. Thanks Steve . Where's my sea sickness tablets.

[monkey spanners]

The point i was trying to make was that if you are getting liquid back at the compressor now, fitting a bigger compressor is not going to fix the problem You have got in effect and evaporator that cannot provide enough heat to boil off all the liquid, how do you see a bigger compressor helping?

The tev was faulty, it was letting by internally. By my understanding no flow takes place down the equalising line, its just used to give evaporator outlet pressure to one side of the bellows in the valve, which acts with the spring (and superheat screw) against the pressure on the other side of the bellows provided by the phial.

Jon

[Grizzly]

So i check the orifices and find one of the coolers to be running a no.1 orifice in a danfoss valve ,now I've put in loads of KS35 coolers and have never put in anything as small as a no.3 and change the oil, but if i put in a no.3 orifice is it going to flood back like the isceon has been doing?. I've checked the comps out and there fairly new and have good valve plates and there is no by-passing of devices such as oil seps etc. My thinking is that there needs to be a no.3 orifice in the TEV's and the present comps are too small to handle the onslaught.

Hi GTG.
I am slightly confused by your comment and have never put anything as small as a No3. (the larger the orifice number the larger capacity/ volume of refrigerant.) Unless you mean that you normally work on larger units?
Basically if you refer to the link below you will find that if you are using a T2 TEV for example...
2 TYPES ARE LISTED:- Range N and B.
As a Serle KS 35/4 = 5.16kw.
AND
ORIFICE 03 = 5.2KW (N) AND 2.8KW (B)
WHEREAS
ORIFICE 01 = 2.5KW (N) AND 1.0KW (B)
So given this info you are correct that a No3 Orifice is required.
But as MS AND Gary are trying to point out reading the S/H would of proved these differences.
Personally You may have experienced flood back due to the fact that the orifice capacity is slightly lager than the max output for your evap.
Therefore slight tweaking of the s/h setting would be required to compensate for age related inefficiencies!
GTG / Steve
I hope this helps and don't be offended if some of the statements made sound condescending as they are not meant that way and some of you comments do confuse / conflict!
Cheers Grizzly
http://www.danfoss.com/United_Kingdo...ductFinder.htm

[Grizzly]

So i check the orifices and find one of the coolers to be running a no.1 orifice in a danfoss valve ,now i've put in loads of KS35 coolers and have never put in anything as small as a no.3 and change the oil, but if i put in a no.3 orifice is it going to flood back like the isceon has been doing?. I've checked the comps out and there fairly new and have good valve plates and there is no by-passing of devices such as oil seps etc. My thinking is that there needs to be a no.3 orifice in the TEV's and the present comps are too small to handle the onslaught.

Hi GTG.
I am slightly confused by your comment and have never put anything as small as a No3. (the larger the orifice number the larger capacity/ volume of refrigerant.) Unless you mean that you normally work on larger units?
Basically if you refer to the link below you will find that if you are using a T2 TEV for example...
2 TYPES ARE LISTED:- Range N and B.
As a Serle KS 35/4 = 5.16kw.
AND
ORIFICE 03 = 5.2KW (N) AND 2.8KW (B)
WHEREAS
ORIFICE 01 = 2.5KW (N) AND 1.0KW (B)
So given this info you are correctthat a No3 Orifice is required.
But as MS AND Gary are trying to point out reading the S/H would of proved these differances.
Personally You may have experianced floodback due to the fact that the orifice capacity is slightly lager than the max output for your evap.
Therefore slight tweeking of the s/h setting would be required to compensate for age related inefficencies!
GTG / Steve
I hope this helps and don't be offended if some of the statements made sound condesending as they are not ment that way and some of you comments do confuse / conflict!
Cheers Grizzly
http://www.danfoss.com/United_Kingdo...ductFinder.htm

orOrifice - 0x 0,50 kW 0,50 kW 0,40 kW 0,38 kW 0,50 kW 0,38 kW068-2003Orifice - 00 1,00 kW 1,10 kW 0,90 kW 0,70 kW 0,70 kW 0,70 kW068-2006Orifice - 03 5,20 kW 5,60 kW 4,60 kW 4,20 kW 2,80 kW 3,50 kW068-2007Orifice - 04 8,00 kW 8,60 kW 6,70 kW 6,00 kW 4,20 kW 4,90 kW068-2008Orifice - 05 10,50 kW 11,30 kW 8,60 kW 7,70 kW 5,20 kW 6,00 kW068-2009Orifice - 06 15,50 kW 16,70 kW 10,50 kW 9,10 kW 7,00 kW 6,60 kW068-2010Orifice - 01 2,50 kW 2,70 kW 1,80 kW 1,60 kW 1,00 kW 1,60 kW068-2015Orifice - 02 3,50 kW 3,80 kW 2,60 kW 2,10 kW 2,10 kW 2,10 kW

[Gary]

Also i've seen a danfoss valve that was passing liquid through the equalising line straight into the suction, this caused flood back and little or no work done by the evaporator.

Jon

That's why the TXV bulb should always be mounted upstream of the equalizer connection. Leakage used to be common, but TXV's have improved over the years.

[Grizzly]

That's why the TXV bulb should always be mounted upstream of the equalizer connection. Leakage used to be common, but TXV's have improved over the years.

Being thick here Gary, by upstream do you mean that the phial is fitted on evap suction outlet BUT before the equalising line? Which makes sence actually.
Grizzly

[Gary]

A bitzer type IV (4) compressor open drive run by a 3 kw 1710rpm motor that shows 6.5A on the name plate but only pulls 3.8A including the condenser fan which is on the end of the motor shaft.

Is this direct drive or does it have belts and pulleys? If so, I'm wondering if the pulleys are sized correctly.

[Gary]

Being thick here Gary, by upstream do you mean that the phial is fitted on evap suction outlet BUT before the equalising line? Which makes sence actually.
Grizzly

Yes, the phial is before the line. If the equalizer leaks, the TXV will not be affected, and it would take a very substantial leak to flood back to the compressor.

[Gary]

By my understanding no flow takes place down the equalising line, its just used to give evaporator outlet pressure to one side of the bellows in the valve, which acts with the spring (and superheat screw) against the pressure on the other side of the bellows provided by the phial.

Jon

As you say, the equalizer pressure balances against the phial pressure, with the diaphram in between them. The resulting pressure is transferred to the valve by a shaft on the equalized side.

The shaft has a seal where it goes through the valve wall. Those seals sometimes leak. This was common on older valves, but shaft seal materials are much better nowadays.

[Grizzly]

GTG.
Further to my last post I have had another look at the Searle Website again and they state that a KS 35/4 ON R22 is only 4.89KW.
So the plot thickens, it would definitely seem that the TEV SIZING IS EVEN MORE RELEVANT.
Plus there is also info on sizing the distributor orifice plate etc to give minimum back pressure.
This may relate to your problem to?
Gary thanks for your helpful advise.
Grizzly

[get the gauges]

That's why the TXV bulb should always be mounted upstream of the equalizer connection. Leakage used to be common, but TXV's have improved over the years.

Thanks gary, i think we've all learned something here about leaky tev's and the relevance of where the phial sits in relation to the equalizing line.
The open drive bitzer type IV is belts and pulleys and yes i thought that too,but i didn't want to start messing about with something thats been in 13 years and never worked too good on R22 let alone R417( isceon 59)
It has foxed me and i have left it unresolved because a 3 Orifice wouldn't exist without flooding back, may be an tex2 valve can't work with 59 at low temps because it is looking at the R22 temp/pressure relationship.

[get the gauges]

GTG.
Further to my last post I have had another look at the Searle Website again and they state that a KS 35/4 ON R22 is only 4.89KW.
So the plot thickens, it would definitely seem that the TEV SIZING IS EVEN MORE RELEVANT.
Plus there is also info on sizing the distributor orifice plate etc to give minimum back pressure.
This may relate to your problem to?
Gary thanks for your helpful advise.
Grizzly

It's technically the wrong cooler i believe as it has 6 fins to the inch and not the usual 4 to the inch for frost reasons. people have obviously had probs with this one in the past as they have the no.1 in the cooler.


I will post if there are any developments in the saga,and don't worry i don't take offence at any one on here as i'm greatful of any advise.

Steve. In the northsea, i can see that platform they evacuated today from here.

[get the gauges]

The point i was trying to make was that if you are getting liquid back at the compressor now, fitting a bigger compressor is not going to fix the problem You have got in effect and evaporator that cannot provide enough heat to boil off all the liquid, how do you see a bigger compressor helping?

The tev was faulty, it was letting by internally. By my understanding no flow takes place down the equalising line, its just used to give evaporator outlet pressure to one side of the bellows in the valve, which acts with the spring (and superheat screw) against the pressure on the other side of the bellows provided by the phial.

Jon

Ah, i thought thats what you must have mean't but i had never come across it before. Thanks. The thing about this room is there is very little load and a 2hp unit and a ks25/6 would kill it, there is very little load to evaporate the liquid especially if the big cooler fills up a bit with liquid.

[Electrocoolman]

Hi GTG,
Reading your original post, you mention that the motor spec is 1710rpm...suggesting it is designed for 60Hz operation. Understand that you are on N. sea rig....was it built in the states? What is your power supply on board...50 or 60 Hz? Have they changed the power spec as its now working in Europe...just a thought.
The lower current draw could be due to wrong voltage supply, but more relevant is that the motor and compressor will be running some 18% slower than possible design speed, effecting capacity, etc. Something worth checking?

ECM

[get the gauges]

Hi GTG,
Reading your original post, you mention that the motor spec is 1710rpm...suggesting it is designed for 60Hz operation. Understand that you are on N. sea rig....was it built in the states? What is your power supply on board...50 or 60 Hz? Have they changed the power spec as its now working in Europe...just a thought.
The lower current draw could be due to wrong voltage supply, but more relevant is that the motor and compressor will be running some 18% slower than possible design speed, effecting capacity, etc. Something worth checking?

ECM

I'll look into that there are frequency and voltage issues on these things, and this ones in the irish sea.

[Electrocoolman]

Another thought.....what type of defrost does the evaporator use? Its not 'stuck' on per chance?

Hot gas if not shutting off fully, could give liquid floodback could it not? and high suction pressure.

[Gary]

Okay... let's rethink this:

I can't see it from here, so I have to rely on the incomplete information given and make some basic assumptions.

We know the TXV orifice is undersized for the coil, but the compressor is unable to handle the increased refrigerant flow of a larger orifice.

With the smaller orifice we seem to have a full load with a low to normal TD. IOW, we have a full load (perhaps even a heavy load), yet we have low amps on the compressor drive motor, all of which suggests that the speed of the compressor could be increased.

Let's imagine that somewhere along the line someone replaced the drive pulley with a smaller diameter pulley. That would account for the low amps.

Let's further imagine that when they did so, they encountered the same floodback conditions you did, at which time they downsized the orifice.

IOW, they downsized the refrigerant flow (coil output) to match the slower moving compressor, in effect downsizing the entire system.

Hmmm... how could we confirm this?

[Gary]

Perhaps the original intent was to have two complete systems, either of which could handle the entire load, with one acting as back-up. Then someone came along and decided that each system should be downsized to handle half of the load... I have seen stranger things... LOL

[Grizzly]

Woke up early thinking about your dilemma, sad I know!
Anyway just to add to the comment electrocoolman made about 50hz and 60hz. If at 60hz the evap fans would also run slower wouldn't they?
I think you are starting to see the wood for the trees GTG. Your comments about evap sizing coupled with Gary's thoughts about system sizes. Seem to make sense.
Could you not shut down one system then another to see which copes better. I suspect Gary was suggesting this at one stage.
If it is any consolation I get more issues that are difficult to resolve due to systems being over sized, than the other way round.
These are also much harder to resolve, but boy do you feel good when you do.
Grizzly.

[Gary]

Undersizing the drive pulley on a belt drive compressor would have the same symptoms as an inefficient compressor, i.e. low evaporator and condenser TD's, low subcooling and superheat, hunting and possible floodback.

Undersizing the orifice would then resolve the superheat, hunting and floodback problems, but (assuming proper superheat adjustment) the low TD's would remain, because of the relative compressor vs condenser and compressor vs evaporator sizing mismatches.

[get the gauges]

Woke up early thinking about your dilemma, sad I know!
Anyway just to add to the comment electrocoolman made about 50hz and 60hz. If at 60hz the evap fans would also run slower wouldn't they?
I think you are starting to see the wood for the trees GTG. Your comments about evap sizing coupled with Gary's thoughts about system sizes. Seem to make sense.
Could you not shut down one system then another to see which copes better. I suspect Gary was suggesting this at one stage.
If it is any consolation I get more issues that are difficult to resolve due to systems being over sized, than the other way round.
These are also much harder to resolve, but boy do you feel good when you do.
Grizzly.

Undersizing the drive pulley on a belt drive compressor would have the same symptoms as an inefficient compressor, i.e. low evaporator and condenser TD's, low subcooling and superheat, hunting and possible floodback.

Undersizing the orifice would then resolve the superheat, hunting and floodback problems, but (assuming proper superheat adjustment) the low TD's would remain, because of the relative compressor vs condenser and compressor vs evaporator sizing mismatches.

Grizzly. I have actually run both systems individually and can acheive -14'c which tells me if one system could have a bigger orrifice it could get to -21'c.

Gary. I'm thinking that pulleys are the way forward, the motors can take it as they are rated 6.5A/ phase, Both comps have been replaced in the past and one of them is nearly new, or maybe the pulley's were never sized correctly and it just perfomed enough when on R22.

When i fix the job i'm on now i'm sure i'm going to have to go back to this one to get it sorted so at least i've got some new ideas .Thanks Steve.