Air to water heat pump have a construction problem?

[nike123]

As suggested to me, I posting this question here to!

Recently (one month ago), I installed air to water heat pump, 60 KW (17 tons) on the roof off small hotel on Adriatic coast (I live and work in Croatia as HVAC service and commissioning technician). The unit is made by Galletti from Italy, model LCA60HS0. Unit has two refrigerant circuits and one water circuit. Refrigerant is R407. Compressors are Danfoss-Maneurop scroll. (http://www.galletti.it/famiglia.php?tipo=1&idfam=3 )

Few days ago I received service call from customer about high pressure alarm (H1) on Carel Microchiler controller of unit. After resetting high pressure switch witch is set to 28Bar (406 psig) I was able to start unit in cooling mode. Compressor in circuit 1 started with operation and after 20-30 seconds high pressure started to very rapidly oscillate (approximately 3-5 cycles in 1 second) between 20 and 26 Bars. In the meantime, low pressure slowly oscillates between 4 and 5 Bars (approximately 1 cycle in 1minute). After 30-40 seconds this occurrence was stopped and high pressure become stabile with slow oscillation (approximately 1 cycle in 1minute) between 19 and 22 Bars (275 and 320 psig) and low pressure also oscillates between 4.1 and 4.5 Bars (60 and 65 psig). All the time superheating was around 5-6 K (9-11°F) and changes are related to oscillation of suction pressure (with some delay). Subcooling is 6 K (11°F).
After 20 minutes of work I still noticed slight oscillations(approximately 1 cycle in 1minute) between 4.1 and 4.5 Bars (60 and 65 psig) in suction pressure and high pressure oscillates between 19 and 22 Bars (275 and 320 psig) on that circuit. Superheat also oscillates between 5 and 6 K (9-11°F). I tried to adjust TXV but I am not been able to eliminate oscillations without enlarging superheat too much. Expected superheat for this unit (according to manufacturer) is between 5 and 8 K (9-15°F). I tried to raise superheat to 8-10K (15-18°F) but oscillations remains.

This is some correspondence with manufacturer on that subject:



> > ----- Original Message ----- From: xxxxxxxxxxxxxxxx To: xxxxx Cc:
> >xxxxxxxxxxxxxxx Sent: Wednesday, August 03, 2005 4:02 PM Subject: R:
> > URGENT!
> >
> >
> >
> > Have you check if all fans turn 100% ?
> >
> >
> >
> > ----------------------------------------------------------------------------
> >
> >
> > Yes, they are!
> >
> > What is it the value of high pressure, low pressure, outdoor
> > temperature, temperature inlet/outlet water?
> >
> > Could you give me more information, please?
> >
> >
> >
> > After arriving on site H1 was on display of Micro chiller. When I
> > cancelled alarm, compressor in circuit 1 started with
> > operation and after 20-30 seconds high pressure started to very rapidly
> > oscillate (approximately 3-5 cycles in 1 second) between 20 and 26 Bars.
> > In the meantime, low pressure slowly oscillates between 4 and 5 Bars
> > (approximately 1 cycle in 1minute). After 30-40 seconds this occurrence
> > was stopped and high pressure become stabile with slow oscillation
> > (approximately 1 cycle in 1minute) between 19 and 22 Bars and low
> > pressure also oscillates between 4.1 and 4.5 Bars. All the time
> > superheating was around 5-6 K and changes are related to oscillation of
> > suction pressure (with some delay). Sub cooling is also 6 K. This
> > indicates that too much of refrigerant is feed by expansion valve to
> > compressor in some moment after starting of compressor, so that liquid
> > hammering on high side triggers high pressure switch, and that this is
> > mostly happening after power failure or after short power disconnecting
> > (by service technician or owner) when 4 way valve changes position.
> > Also, when I try to heighten superheating this problem
> > still remains. My assumption is that placing off sensing bulb off
> > expansion valve near objects of high mass slowing reaction
> > off expansion valve so overfeed and oscillation is occurring! Also lack
> > off suction accumulator contributing to this problem!
> >
> > Readings after 15 min that unit is working!
> >
> > Outdoor temp. 29°C (84°F)
> >
> > Water temp. inlet 14°C (57°F)
> >
> > Water temp. outlet 8°C (46°F)
> >
> > Evaporation pressure 4.1-4.5 Bar(60 and 65 psig) (oscillate)
> >
> > Condensation pressure 19-22 Bar (275 and 320 psig) (oscillate)
> >
> > Subcooling 5-6K (oscillate)
> >
> > Superheating 5-6K (oscillate)
> >
> >
> >
> >
> >
> > I think that condensation pressure is slightly higher
> > than normal but I could not find any restriction in refrigerant
> > circuit!
> >
> >
> >
> >
> >
> > We need urgent answer because that is hotel full of guests.

> ----- Original Message ----- From: xxxxxxxxxx To: xxxxx Cc: xxxxxxxxxxxxSent: Thursday, August 04, 2005 3:21 PM Subject: R: REMINDER Fw:
> URGENT!
>
>
>
> About your problem, it's necessary that you check if the power supply is
> stable, in addition have you enough capacity of power supply? The alarm
> H1 take even when there is a little black out of power supply
>

> The power supply voltage is stable (within +/- 5%) as noted in startup
> report and capacity of power supply fairly dimensioned because this is
> new building (voltage drop on unit is less than 2%) so the problem is
> not on power supply. Sometimes, during bad weather conditions, black out
> of power supply occurs and I got call from user about H1.
>
> As I described in yesterday report, that’s happening after 4 way valve
> change position (because of power interruption) and after that,
> refrigerant flooding of compressor crankcase take place! In my opinion
> this happens because of lack of suction accumulator!
>
> So I need solution for this problem from You because it appears to me
> that this is construction problem and customer is quite upset with fact
> that after every power interruption he needs to clime up too roof and
> resets high pressure switch.
>
> Also, if this is happening now in summer mode, possibility that this
> happens in winter mode is even greater because off frequent 4 way valve
> changes during defrosting, like we have case with that MCA037 unit this
> winter!
>
> Also, You didn’t react on oscillating pressures and high condensation
> pressure issues in my yesterday report so I expecting that this is going
> to be considered in Your additional <correspondences with me on this
> matter.


Because they are on collective vacation named "feragosto" I cannot expect any meaningful answer until it is over by 1.of September.
I'd like to see Yours opinions on this mater!
Thanks!

P.S. My native language is not English so if something is senseless, please don’t kill me! :-)

[Edited by nike123 on 08-14-2005 at 03:30 AM]

[txvsrule]

Let's start at the top. Is the high pressure switch cutting out in the cooling mode or in the heating mode?

Have you seen the unit cut off on high pressure? What were the load conditions then?

Is the expansion valve bulb securely mounted and in an appropriate place and insulated?

What are the evap water temps when the unit starts up? Is there a reason that they would be very cold? Maybe you are migrating liquid refrigerant into the compressor during the off cycle.

Are the first and second circuits turning on and off in the correct sequence?

You've said that you see oscillations in the pressures, during this time, what is the evap entering and leaving water temps? Are you sure the condensor fans are running all the time and at the correct speed(I think this unit has variable speed condensor fans)?

Does the same thing happen to the second compressor circuit?

I know it is a new unit and you shouldn't have to, but do you have the ability to pump down and recharge the unit if need be? You never know it might be slightly overcharged, though I doubt it.

Rob



[Edited by txvsrule on 08-13-2005 at 09:01 AM]

[txvsrule]

Also, do you have a water tank on the chilled water loop of this unit or is the loop volume sufficient to eliminate swings?

Does the loop water temperature have wide swings?

Rob

[jacob perkins]

Originally posted by nike123
Refrigerant is R407.


Replace it... with R-22.

Always good to see hard questions.

[nike123]

Originally posted by txvsrule
Let's start at the top. Is the high pressure switch cutting out in the cooling mode or in the heating mode?

In the cooling mode!


Have you seen the unit cut off on high pressure? What were the load conditions then?

Yes! That day when I came on call, first what I done was canceling high pressure switch and unit was worked about 30 min. after that without interruption. I didn't put gauges on unit yet and I only monitored high pressure thru Carel Microchiller condensing pressure sensors after few minutes (it was 22 Bar) . Then it was again high pressure alarm (I was just leaving site assuming that alarm is transient event) and everything latter is described above! Load conditions are:
water outlet 8°C (46°F)
water inlet 14°C (57°F)
outdoor temperature 29°C (84°F)


Is the expansion valve bulb securely mounted and in an appropriate place and insulated?

Yes!


What are the evap water temps when the unit starts up?
Is there a reason that they would be very cold? Maybe you are migrating liquid refrigerant into the evaporator.


14°C (57°F) ???


Are the first and second circuits turning on and off in the correct sequence?

During testing I was turned off second circuit in order to get constant work of compressor so I could be able to adjust superheat on expansion valve. And after that, I turned on both circuits, and they are turning on and off in correct sequence.


You've said that you see oscillations in the pressures, during this time, what is the evap entering and leaving water temps? Are you sure the condensor fans are running all the time and at the correct speed(I think this unit has variable speed condensor fans)?

Temperatures of water are 14/8 °C (57/46°F)! Fans are always on max speed because this particular unit hasn't got condensation control and fans are operated by contactor.


Does the same thing happen to the second compressor circuit?

Partially! High pressure switch did not occur but smaller oscillations on pressures are also evident on second circuit.


I know it is a new unit and you shouldn't have to, but do you have the ability to pump down and recharge the unit if need be? You never know it might be slightly overcharged, though I doubt it.

I have the ability to pump down and recharge the unit if needed, but I also think that overcharge isn't the case here!

[nike123]

Originally posted by txvsrule
Also, do you have a water tank on the chilled water loop of this unit or is the loop volume sufficient to eliminate swings?
Yes I have water tank off 315 litres (83 gallons)in the unit!
http://www.imagewiz.net/usr/hvac1/nike123/15671_LCA_water_circuit.jpg


Does the loop water temperature have wide swings?

No, termostat setings are 2°C (3,6°F) diferential, set temperature is 12°C (54°F)and lowest water temperature (water outlet)is 5°C (41°F)

[nike123]

Originally posted by jacob perkins

Originally posted by nike123
Refrigerant is R407.


Replace it... with R-22.

Always good to see hard questions.



I wish I could! :-)

[txvsrule]

That is odd.
Does this unit have a liquid receiver?
Is there a way for you to see if the expansion valve is getting a constant flow of liquid (a sight glass)?
Did you check the condensor temperature drop?

Rob

[nike123]

Originally posted by txvsrule
That is odd. Does this unit have a liquid receiver?

Yes, it does!


Is there a way for you to see if the expansion valve is getting a constant flow of liquid (a sight glass)?

Yes, after filter dryer and near the TXV, I have sight glass. First few minutes after starting off compressor, sight glass have occasional flow of bubbles, whose appearance and absence correspond with oscillation of suction pressure, and after that few minutes they disappear but oscillation remain.
On the other hand, in second circuit, I have constant flow of bubbles and significantly lover oscillation of suction pressure.


Did you check the condensor temperature drop?

Yes, it's 14°C (25°F)!

[nike123]

I forgot to mention that second circuit has smaller compressor than first and that everything else is the same in both circuits.
1st. compressor is Danfoss-Maneurop SZ161T4VC and 2nd. is Danfoss-Maneurop SZ120S4VC.

[txvsrule]

It seems that your TXV is hunting, even on a stable load. I know this is a new unit, but did you check the TXV for size and the correct powerhead for the refrigerant? (Maybe the machine was built in July and they couldn't wait to take August off.):)

Is the temperature of the line where the TXV bulb is attached stable or does it oscillate as well?

Just as a test you could try to stabilize the TXV bulb temperature by placing it in a bucket of ice water with the unit running to see if the oscillations go away.

If they still don't then I would pump down the system, do a thorough evacuation and recharge it. Maybe it has some non-condensibles (although if the sight glass clears completely, it doesn't seem likely).

Is the high pressure switch located directly on the liquid line or is it placed remotely using a capillary? As a last resort you could remote the high pressure switch using an appropriately sized capillary tube. The length and small diameter of the tube will act as a sort of a time delay device slowing down the reaction time of the switch, making it immune to the startup oscillations. Obviously, you can't choke off the switch too much as it won't sense anything.

Rob

[drivewizard]

I would take a real close look at the TXV bulb mounting. Pull it completely off and clean/sand line and bulb. Check contact area of bulb and line for absolute 100% contact and also position on line, horizontal run, vertical, 12:00. 6:00 etc. Make sure it is tightly secured also. Have seen unit come out of our factory with bulbs tie strapped to suction line, and causes the same problem you are seeing.

also what brand /type of TXV is used?

[nike123]

Originally posted by txvsrule
It seems that your TXV is hunting, even on a stable load. I know this is a new unit, but did you check the TXV for size and the correct powerhead for the refrigerant? (Maybe the machine was built in July and they couldn't wait to take August off.):)

It seems to me that You are on right track here!
After examination of factory data for Compressor and TXV valve it is obvious that this is bit small TXV for that compressor.
Compressor (SZ161T4VC) has capacity under measured pressures off 37 KW and TXV (Danfoss TRE10-10) has capacity off 33 KW.
And yes, powerhead is corect!



Is the temperature of the line where the TXV bulb is attached stable or does it oscillate as well?

I don't now, I need to examine that!



Just as a test you could try to stabilize the TXV bulb temperature by placing it in a bucket of ice water with the unit running to see if the oscillations go away.

If they still don't then I would pump down the system, do a thorough evacuation and recharge it. Maybe it has some non-condensibles (although if the sight glass clears completely, it doesn't seem likely).

I will try with ice water to see proper functioning of TXV!



Is the high pressure switch located directly on the liquid line or is it placed remotely using a capillary? As a last resort you could remote the high pressure switch using an appropriately sized capillary tube. The length and small diameter of the tube will act as a sort of a time delay device slowing down the reaction time of the switch, making it immune to the startup oscillations. Obviously, you can't choke off the switch too much as it won't sense anything.

High pressure switch is located directly on liquid line, very close to compressor, and this solution with capillary tube could solve this problem.

Thank You, for your kind contribution on this mater!

[nike123]

Originally posted by drivewizard
I would take a real close look at the TXV bulb mounting. Pull it completely off and clean/sand line and bulb. Check contact area of bulb and line for absolute 100% contact and also position on line, horizontal run, vertical, 12:00. 6:00 etc. Make sure it is tightly secured also. Have seen unit come out of our factory with bulbs tie strapped to suction line, and causes the same problem you are seeing.

also what brand /type of TXV is used?

Danfoss TRE10-10Z Code no. 067L2015 (range K)

[txvsrule]

Good Luck!

Rob

[john dalton]

Good Afternoon Gentlemen,

First and foremost Nike123 let me welcome you to this forum of your colleagues and peers here in America. It’s always nice to chat with a fellow colleague working in Europe.

I’d like to start by asking several background questions if I may:

1. When you were recording your 6°K (11°F) delta T across the evaporator was just the first stage compressor on, or were both compressors operating?

2. When you reset the first stage TXV to operate at 8-10K (15-18°F) did you record your subcooling at that time?

3. Exactly where, and at what position (clockwise) is the TXV’s sensing bulb located at? Is it insulated, and what area of the air cooled heatpump chiller is the sensing bulb located in?

4. Do both compressors have crankcase heaters, and if so, what is their wattage (KW), and have you verified that they are operating?

5. Are all six (6) of your condensing fans running? If so, have you checked each and every one to determine if the rotation is correct? Have you checked to make sure that the condensing fan blades are positioned correctly in the fan housings?

6. I realize that this system is only one (1) month old, but have you inspected the condensing coil top verify that it is clean?

7. Have you inspected the temperature and/or pressure drop of the liquid line filter/drier to determine if there is a slight restriction?

I’ll stop here for now and give my fellow colleagues a chance to ask their own individual diagnostic questions.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Nike123,

The correct mounting orientation of this TXV’s sensing bulb is on a horizontal section of the suction line at either the 4:00 or 8:00 o’clock position [since the suction line is > ¾” inch (12.7 mm)].

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Drivewizard,

Regarding your previously posted comment:

"…Check contact area of bulb and line for absolute 100% contact and also position on line, horizontal run, vertical, 12:00. 6:00 etc…”

I’m not sure if the above comments were “check points” or “suggestions” so I’ll post the following. Please disregard should they be “check points”….thank you.

Since the suction line we are working with is larger than ¾” inch, then the correct sensing bulb orientation would be either 4:00 or 8:00 o’clock in a horizontal section of the suction line. Under no circumstances should the sensing bulb be located at the 6:00 o’clock position, and installation on a vertical line, although possible, is not recommended if at all possible.

Respectfully Submitted,
John J. Dalton

[drivewizard]

John, I agree the bulb should be at 4 or 8, I did not know what size line he had as I am not familiar with those units. I was just mentioning 12 and 6 as examples of what it might be, not where it should be. Also definittely should be on horizontal run. I assumed he knew the correct locations for his line size, as he appears to be experienced. I know, I shouldn't assume anything.

Nike: I am not familiar with Danfoss TXV's, I am very predjudiced towards Sporlan. Have not had good luck with Alco valves. But just my opinion. Good luck.

[john dalton]

Dear Drivewizard,

Although Nike123 did not post the suction line size, he did post that this 17 ton system had duel compressors, hence the “assumption” on my part that the first stage compressor’s suction line should be >3/4”. Nike123 has since updated his original post and supplied us with the actual model numbers. After reviewing the model numbers I determined that the compressors are rated at 13.0 and 10.0 tons respectfully.

Based on the fact that this equipment was manufactured in Italy and apparently has no UL or ARI ratings, I think the vast majority, if not all, of the service technicians at this forum are unfamiliar with this product.

As far as being unfamiliar with Danfoss TXV’s, just remember that Sporlan, Alco, and even Danfoss TXV’s all operate under the same basic principles.

Let’s see what Nike123 is up to shall we………………………

Respectfully Submitted,
John J. Dalton

[nike123]

Originally posted by john dalton
Good Afternoon Gentlemen,

First and foremost Nike123 let me welcome you to this forum of your colleagues and peers here in America. It’s always nice to chat with a fellow colleague working in Europe.

I’d like to start by asking several background questions if I may:

1. When you were recording your 6°K (11°F) delta T across the evaporator was just the first stage compressor on, or were both compressors operating?

2. When you reset the first stage TXV to operate at 8-10K (15-18°F) did you record your subcooling at that time?

3. Exactly where, and at what position (clockwise) is the TXV’s sensing bulb located at? Is it insulated, and what area of the air cooled heatpump chiller is the sensing bulb located in?

4. Do both compressors have crankcase heaters, and if so, what is their wattage (KW), and have you verified that they are operating?

5. Are all six (6) of your condensing fans running? If so, have you checked each and every one to determine if the rotation is correct? Have you checked to make sure that the condensing fan blades are positioned correctly in the fan housings?

6. I realize that this system is only one (1) month old, but have you inspected the condensing coil top verify that it is clean?

7. Have you inspected the temperature and/or pressure drop of the liquid line filter/drier to determine if there is a slight restriction?


I’ll stop here for now and give my fellow colleagues a chance to ask their own individual diagnostic questions.

Respectfully Submitted,
John J. Dalton



These are my answers to Your questions!

1. Just the one compressor is on.
2. No.
3. I don’t know for this particular unit (it is hidden behind electric box and hard to reach and see), but from similar units of this manufacturer I know that they are positioned near 4 way valve (8-15 inches) on suction pipe. This is refrigerant circuit schematic diagram for this unit. The full arrow representing cooling direction.
Position of sensing bulbs of summer and winter TXV (again from similar units of this manufacturer) is at 3 and 9 hour of clock.

http://www.imagewiz.net/usr/hvac1/nike123/15691_rwefrigerant_diagram2.jpg

4. Yes they are, 100W, they operate OK.
5. Yes. They are all working fine, at top speed, all in same (right) direction.
6. Yes, it's clean as new.
7. Yes, and there is no restriction on filter dryer. This was my first assumption because I have few problems with filters on different series (smaller units) of this manufacturer, but here, this is not the case.

Thank You for your questions!

[nike123]

This is legend for above shematic!

1 CHILLED WATER INLET
2 CHILLED WATER OUTLET
3 DE-SUPERHEATER WATER INLET
4 DE-SUPERHEATER WATER OUTLET
5 CHARGE CONNECTION
6 HIGH PRESSURE SWITCH
7 LOW PRESSURE SWITCH
8 COMPRESSOR
9 CONDENSER
10 DE-SUPERHEATER
11 BUFFER TANK
12 EVAPORATOR
13 FILTER DRYER
14 FLOW SWITCH
15 HIGH PRESSURE MANOM.
16 LOW PRESSURE MANOM
17 FAN MOTOR
18 CHILLED WATER PUMP
19 GATE VALVE
20 CRANK CASE HEATER
21 ENERGY - SAVING COIL
22 SIGHT GLASS
23 SHUT-OFF VALVE
24 EVAPORATING PRESSURE PROBE
25 CONDENSING PRESSURE PROBE
26 EXPANSION TANK
27 WATER INLET TEMPERATURE SENSOR
28 WATER OUTLET TEMPERATURE SENSOR
29 EXTERNAL AIR TEMPERATURE SENSOR
30 CHECK VALVE
31 SAFETY VALVE
32 WATER SAFETY VALVE
33 THERMOSTATIC VALVE
31 FREE-COOLING VALVES
35 SOLENOID VALVE
36 PARTIALIZATION SOLENOID VALVE
37 CONDENSING WATER INLET
38 CONDENSING WATER OUTLET
39 4-WAY-VALVE
40 LIQUID RECEIVERS
41 EXPANSION VALVE

[nike123]

Originally posted by john dalton
Dear Nike123,

The correct mounting orientation of this TXV’s sensing bulb is on a horizontal section of the suction line at either the 4:00 or 8:00 o’clock position [since the suction line is > ¾” inch (12.7 mm)].

Respectfully Submitted,
John J. Dalton



This is from technical manulal of TXV!
http://www.imagewiz.net/usr/hvac1/nike123/15692_mounting.jpg

Suction line is 35 mm!

[nike123]

Originally posted by drivewizard
John, I agree the bulb should be at 4 or 8, I did not know what size line he had as I am not familiar with those units. I was just mentioning 12 and 6 as examples of what it might be, not where it should be. Also definittely should be on horizontal run. I assumed he knew the correct locations for his line size, as he appears to be experienced. I know, I shouldn't assume anything.

Nike: I am not familiar with Danfoss TXV's, I am very predjudiced towards Sporlan. Have not had good luck with Alco valves. But just my opinion. Good luck.

As I said, I don't now exact position of sensing bulbs, but I would check after my vacation. :-)

What I know from my experience (10 years in refrigeration and air-conditioning), and from my senior colleagues, Danfoss is good quality brand.

[Edited by nike123 on 08-14-2005 at 03:58 AM]

[john dalton]

Dear Nike123,

Thank you for answering my questions, but of course your answers just generates additional questions in the process, such as:

1. Are the “assumed” fan coil units being serviced by this air cooled heatpump unit equipment with two way water shut off valves or three way diverter valves?

2. The first stage compressor operating with a 6°K (11°F) delta T across the evaporator would suggest that the delta T across the evaporator with both first and second stage compressors operating would approach 10.2°K (18.7°F), this seems a bit high in that normal systems in the US are 56% lower. The factory rated water flow for this unit is approximately 11,990 l/h (35.4 GPM), a quick calculation of your water flow based on the first stage compressor operating (10.0 tons) with a 6°K (11°F) delta T would suggest that your operating water flow was 7,418 l/h (21.9 GPM), how does this chilled water flow sound to you?

3. If I’m reading the refrigerant circuit schematic diagram correctly, the liquid line receivers (item #40) are only in the refrigeration circuit fully in the heating cycle, in the cooling cycle they are only “T”d into the liquid line, and therefore cannot obtain a typical seal plug as in normal systems, is this correct?

4. You posted that the TXV’s sensing bulb is located on the suction line approximately 8 to 15 inches away from the reversing valve (four way valve). What is the length of the entire suction line (in the cooling cycle) from the outlet of the heat exchanger to the inlet of the reversing valve? Can you visually verify that the sensing bulb is insulated properly?

Again, I’ll stop and wait for your answers my friend.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Nike123,

Thank you for the additional information. Interesting that the liquid line receiver is used only in the heating cycle, even more interesting is the fact that the TXV’s sensing bulb is located on the suction line next to the compressor(downstream of the reversing valve) instead of the outlet of the evaporator where you would normally see it.

I have to say, that as the information becomes more available, the oscillating operating readings you are observing sounds more and more like a hunting TXV. But we will see my friend. The discharge pressure is too high as well though.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Nike123,

Regarding your previously posted comments:

“…after my vacation…”

Are you working on your vacation friend?

Respectfully Submitted,
John J. Dalton

[simpleman]

I'm thinking non condensible.

[john dalton]

Dear Simpleman,

Given the limited information, it could be.

We could ask for the following information:

Discharge line temperature

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Nike123

I’ve “assumed” these refrigeration systems have not been opened up, but would like to confirm that at this time.

You’ve done a great job of posting information about your system so far, so I “assumed” you didn’t open either refrigeration circuit since you neglected to post anything about that.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Nike123

Have to leave the office at this time. I get to go home and take my wife and six children out to dinner as makeup for working on a Saturday (something I usually do anyway).

“I’ll be back….”

As our famous governor has said on more than one occasion. Have a great weekend and talk to you Monday morning(California time here) and Nike123…..try to enjoy your vacation friend.

Respectfully Submitted,
John J. Dalton

[nike123]

Originally posted by john dalton
Dear Nike123,

Thank you for answering my questions, but of course your answers just generates additional questions in the process, such as:

1. Are the “assumed” fan coil units being serviced by this air cooled heatpump unit equipment with two way water shut off valves or three way diverter valves?

2. The first stage compressor operating with a 6°K (11°F) delta T across the evaporator would suggest that the delta T across the evaporator with both first and second stage compressors operating would approach 10.2°K (18.7°F), this seems a bit high in that normal systems in the US are 56% lower. The factory rated water flow for this unit is approximately 11,990 l/h (35.4 GPM), a quick calculation of your water flow based on the first stage compressor operating (10.0 tons) with a 6°K (11°F) delta T would suggest that your operating water flow was 7,418 l/h (21.9 GPM), how does this chilled water flow sound to you?

3. If I’m reading the refrigerant circuit schematic diagram correctly, the liquid line receivers (item #40) are only in the refrigeration circuit fully in the heating cycle, in the cooling cycle they are only “T”d into the liquid line, and therefore cannot obtain a typical seal plug as in normal systems, is this correct?

4. You posted that the TXV’s sensing bulb is located on the suction line approximately 8 to 15 inches away from the reversing valve (four way valve). What is the length of the entire suction line (in the cooling cycle) from the outlet of the heat exchanger to the inlet of the reversing valve? Can you visually verify that the sensing bulb is insulated properly?

Again, I’ll stop and wait for your answers my friend.

Respectfully Submitted,
John J. Dalton




Again, these are the answers to Yours questions!

1. Neither. The fan coil units don’t have valves at all. They simply turn on and of their fans by room thermostat.
2. I don’t now much on this subject except measured data, so I am going to give You rated technical data for this unit! This unit also has control valve for attenuation of water flow!

http://www.imagewiz.net/usr/hvac1/nike123/15713_Rated_data.jpg
THE RIGHT MODEL IS LCA60HS0!!!!
3. Yes! Could you explain me this seal plug because I am not familiar with that?
4. The length of the entire suction line (in the cooling cycle) from the outlet of the heat exchanger to the inlet of the reversing valve is approximately 1m (3 foot). Back then, when I was making inspection of this unit, I was visually checked all internal insulation and parts so I think that bulbs are insulated properly.

Again, thank You for Your questions my friend.

[Edited by nike123 on 08-14-2005 at 03:33 AM]

[nike123]

Originally posted by john dalton
Dear Nike123,

Regarding your previously posted comments:

“…after my vacation…”

Are you working on your vacation friend?

Respectfully Submitted,
John J. Dalton


Not physically, but mentally I am always on my work, if I am not with some girls or good beer crew! :-)

[nike123]

Originally posted by john dalton
Dear Simpleman,

Given the limited information, it could be.

We could ask for the following information:

Discharge line temperature

Respectfully Submitted,
John J. Dalton



On this ocasion, it is not measured!

[nike123]

Originally posted by john dalton
Dear Nike123

I’ve “assumed” these refrigeration systems have not been opened up, but would like to confirm that at this time.

You’ve done a great job of posting information about your system so far, so I “assumed” you didn’t open either refrigeration circuit since you neglected to post anything about that.

Respectfully Submitted,
John J. Dalton

That's right! I didn't open this system yet, because I expect answers from manufacturer of equipment, and because system cools object (it is slightly oversized), and weather conditions are mild, and I am on vacation till 1st. of September. ;-)

[nike123]

Originally posted by john dalton
Dear Nike123

Have to leave the office at this time. I get to go home and take my wife and six children out to dinner as makeup for working on a Saturday (something I usually do anyway).

“I’ll be back….”

As our famous governor has said on more than one occasion. Have a great weekend and talk to you Monday morning(California time here) and Nike123…..try to enjoy your vacation friend.

Respectfully Submitted,
John J. Dalton



Thank You, and enjoy Your weekend with Your big family my friend.

[jacob perkins]

Originally posted by nike123
Also lack
off suction accumulator contributing to this problem!



Why is there no accumulator?

[nike123]

Originally posted by jacob perkins

Originally posted by nike123
Also lack
off suction accumulator contributing to this problem!



Why is there no accumulator?

This is because constructors of this unit didn't thought that is necessary! According to Danfoss-Maneurop, SZ 161 compressor has 12 kg of refrigerant limit before is mandatory to install suction accumulator, and SZ 120 has 10 kg of that limit. According to nameplate of unit, both circuits have same amount of refrigerant (9,5kg). And because they are Italaians and they are not Germans. :-))

[jacob perkins]

That is interesting.

did you charge this unit ,or do you have records of what has been put in since start up,ect...?

[nike123]

Originally posted by jacob perkins
That is interesting.

did you charge this unit ,or do you have records of what has been put in since start up,ect...?

Nope, as I stated before, unit is, as it is from factory, and nobody has opened her, or on any other way messed around with her! (Did I messing with pronouns here?)
Allegedly, they are testing every unit in factory prior shipment (that is what I saw when I was in factory)!