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nova
24-02-2005, 09:01 PM
SL-400e:
- Very cold ambient, let's say -35°C
- Setpoint: around +10°C
- unit is on high speed heat

- suddenly unit shifts to cool and closes its defrost damper door

- why?

:)


EDIT: Forgot the unit model..

Latte
25-02-2005, 02:13 AM
Hi Nova,

Being in mind i left the industry while the SL300 was in nappies so havn't worked on a 400 but for a guess it is some kind of defrost system to de-ice the condenser which would probably be iced up due to he low ambient and the damper door closes to protect the load as it is on cool mode. Have TK gone majorly high tec and have sensors in the condensor for defrosting that at low anbients.

Regards

Fatboy

Reeferjon
25-02-2005, 10:58 AM
Is that SRII

nova
26-02-2005, 09:06 PM
Hi Nova,

Being in mind i left the industry while the SL300 was in nappies so havn't worked on a 400 but for a guess it is some kind of defrost system to de-ice the condenser which would probably be iced up due to he low ambient and the damper door closes to protect the load as it is on cool mode. Have TK gone majorly high tec and have sensors in the condensor for defrosting that at low anbients.

Regards

Fatboy

Very nice quess, but not the answer. :)

nova
26-02-2005, 09:10 PM
Is that SRII

I'd say that this is implemented to SR-2 too, but this feature was introduced to uP-VI 3036 (or 4040) software.

More to the case:
- 2 minutes after the unit shifted to cool and closed the damper door it shifts to heat again and opens the damper door.

This feature is called "Improved heating capacity". So what's happening? :)

Latte
27-02-2005, 01:45 AM
Hi Nova,

Running out of idea's. Does the unit go onto a kind of defrost mode instead of going onto cool at setpoint so instead of cycling it just goes heat/defrost/heat ect but keeps the unit running to prevent battery going flat/engine getting cold although i am fairly sure the SR's had a battery level restart setting. Wheres Colin Lacey when you need him :confused:

On another subject: John are you going to the CV show in april

Does my PDL key in my toolbox start any of these units anymore :D

Regards

Fatboy

Latte
27-02-2005, 01:50 AM
John,

Just having a sort out of a load of old rubbish and just found all my old certificates signed by Mark Balentyne and Malcolm Miles.
Worth anything any more. :rolleyes: :D

Going to PM Principle engineer on this one, all out of idea's

Regards

Fatboy

MRW
27-02-2005, 12:38 PM
hi nova,
if the unit is in heat and the ambient is that low,you will lose discharge pressure,losing heat capacity.
so when the discharge transducer sees a low discharge pressure and the unit is calling for heat/defrost it will momentarily de-energise the pilot solenoid allowing the unit to cool ,this will then build the discharge pressure up giving better heat performance in low ambients.
This is my theory but i have never seen it happen as it doesnt get that cold here

nova
27-02-2005, 02:22 PM
John,

Just having a sort out of a load of old rubbish and just found all my old certificates signed by Mark Balentyne and Malcolm Miles.
Worth anything any more. :rolleyes: :D

Going to PM Principle engineer on this one, all out of idea's

Regards

Fatboy

Ah, Malcolm Miles :) When I was at Bruessels in MT training, Malcolm conducted the course. That was one fantastic course. One of the best trainings I've ever been.
Say best regards to Malcolm from "Talking pushy" :D

EDIT: Who am I kidding: it was the best training I've ever been

nova
27-02-2005, 02:38 PM
hi nova,
if the unit is in heat and the ambient is that low,you will lose discharge pressure,losing heat capacity.
so when the discharge transducer sees a low discharge pressure and the unit is calling for heat/defrost it will momentarily de-energise the pilot solenoid allowing the unit to cool ,this will then build the discharge pressure up giving better heat performance in low ambients.
This is my theory but i have never seen it happen as it doesnt get that cold here

Hi MRW,

I've never seen this IRL and I doubt I'll never see it due the big heating capacity of SL-400's. IIRC this was implemented for Canada.

This feature kicks in due the too low delta T in heating. It's not pressure driven (although these two of course relates).

But do we actually see any pressure rise by shifting to cool?
Our damper door is closed while in cool and this prevents the heat absorbation from compartment to the refrigerant, which will affect to the discharge pressure.

:)

nova
27-02-2005, 03:05 PM
We could put this in this way:
How would we affect to the refrigerant if we close the damper door while on cool and how would that affect to the heating capacity? :)

Latte
27-02-2005, 04:51 PM
Hi Nova,

closing the damper door on cool is going to cause liquid feedback to the compressor as there is no heat transfer in the evap, now whether this would case higher discharge pressure as the pot is trying to push liquid through or in fact it would lower it becuase you are taking more heat out of the compressor which is my guess then i cannot see how this will help the heating capacity. As MRW said you need to try and raise discharge temps to make the sysem work better.

Regards

Fatboy

Reeferjon
27-02-2005, 05:04 PM
At first I thought you were discribing 'Bucking Heat' a mode on SB400's.
But then I remembered this.

During operation under extremely low ambient temperatures the refrigerant charge may migrate to the condenser coil.
If the uP detects low heating capacity with low ambient temperatures, this function will act to flush refrigerant from the condenser.

nova
27-02-2005, 05:07 PM
Hi Nova,

closing the damper door on cool is going to cause liquid feedback to the compressor as there is no heat transfer in the evap, now whether this would case higher discharge pressure as the pot is trying to push liquid through or in fact it would lower it i am not sure :confused:

Regards

Fatboy

Now we're getting close. Indeed the idea is to pass refrigerant in liquid state through the evap. :)

EDIT: But not to the compressor

Latte
27-02-2005, 05:09 PM
Hi John,

Hadn't even thought of this, i have of cause come accross oil migration to the evaps at low temp, had not thought about it working the opposite way on long term heat mode.

If this isn't the reason that nova is thinking of it is certainly a good reason for the units to do this

Regards

Raymond

Edit: Poss reason to stop oil getting too hot in evap when on heat constantly, liquid going through on cool flushes is out

nova
27-02-2005, 05:17 PM
At first I thought you were discribing 'Bucking Heat' a mode on SB400's.
But then I remembered this.

During operation under extremely low ambient temperatures the refrigerant charge may migrate to the condenser coil.
If the uP detects low heating capacity with low ambient temperatures, this function will act to flush refrigerant from the condenser.

Correct!
The idea of this "TherMax" -system is to pass refrigerant in a liquid form through the evaporator and gather it into accumulator. This will evacuate the condenser from liquid refrigerant and we have more refrigerant in use which means increased heating capacity.
:)

Latte
27-02-2005, 05:21 PM
Well Done John,

Go to top of the class, Oh You are already there.


Sorry don't have an answer to your'e PM will keep an eye out.

regards

Fatboy

MRW
27-02-2005, 06:22 PM
by shifting to cool,you should get vapour comming back to the compressor,allowing the comp to warm.
If it is on heat for a long while,liquid would come back to the comp & possibly the comp might ice up cooling it too much to get any heat capacity giving poor heat in low ambients

nova
27-02-2005, 08:05 PM
by shifting to cool,you should get vapour comming back to the compressor,allowing the comp to warm.
No vapour due the closed damper door.


If it is on heat for a long while,liquid would come back to the comp & possibly the comp might ice up cooling it too much to get any heat capacity giving poor heat in low ambients
Having accumulator in suction line, you'd hardly get any liquid to the compressor.

:)

-nova

absolute-zero
02-02-2008, 12:04 AM
Correct!
The idea of this "TherMax" -system is to pass refrigerant in a liquid form through the evaporator and gather it into accumulator. This will evacuate the condenser from liquid refrigerant and we have more refrigerant in use which means increased heating capacity.
:)

Here is another phonix that rises from the ashes, as Grizz would put it.

I wish i was a member when these were posted, "TK Trivias"

I understand all the special modes of operations as it pertains to the 400, but where in the heck is the accumulator tank in a TK unit that utilize the screw compressor?

Perhaps the SB 400 is differnt here than the SL 400 is there?

A-Z

absolute-zero
02-02-2008, 12:40 AM
SL-400e:
- Very cold ambient, let's say -35°C
- Setpoint: around +10°C
- unit is on high speed heat

- suddenly unit shifts to cool and closes its defrost damper door

- why?

:)


EDIT: Forgot the unit model..

Nova, I know this is an old thread but would like to shed a little light on it as I find it an interesting thread.

The unit is running in mode called "Heat Mode Charge Migration Cycle" found in S/W 4310 or higher. It is used to increase the unit’s heating capacity under certain conditions.


If the TPDF in heat is lower than expected for the
current return air temperature and ambient temperature, the controller places the unit in low
speed cool and closes the defrost damper for 2
minutes. This forces refrigerant into the heating
circuit. After 2 minutes the unit goes back into
heat and the defrost damper is opened. The
additional refrigerant that was forced into the
heating circuit increases the heating capacity.


The Heat Mode Charge Migration Cycle usually
happens when the return air temperature and the
ambient temperature are both low. If you notice
the unit going into low speed cool and closing the
defrost damper for 2 minutes when the setpoint is
well above the return air temperature, the unit is
running through a Heat Mode Charge Migration
Cycle.

I think you should bring back "TK Trivia" as it will help many think and learn. Great education and or training tool. Good job with thinking up that approach. ;)

If interested in bringing back, I would entertain in assiting topics and trivia.:D

Latte
06-02-2008, 09:43 PM
Nova/A-Z/Reeferjon

Cant someone come up with more questions ? i like to keep my brain ticking over. Anyone been on a TK course recently and remember any of the questions.

regards

Fatboy

absolute-zero
06-02-2008, 09:51 PM
I agree, I proposed this to Nova, since he is the guy that started it.

I dont want to steal the guys thunder for his creation and idea.

It doesnt have to be just TK trivia, it can be trivia for CTC as well. :)

A-Z

absolute-zero
06-02-2008, 10:19 PM
I agree, I proposed this to Nova, since he is the guy that started it.

I dont want to steal the guys thunder for his creation and idea.

It doesnt have to be just TK trivia, it can be trivia for CTC as well. :)

A-Z

Also on that note... There are technicans here at different skill levels, and trivial questions should be ranged from simple basics thru Advanced master levels.... Just a suggestion....:)

A-Z

Latte
06-02-2008, 10:24 PM
Thanks AZ

Anything newer than an SL400 and im lost although i suppose they have not reinvented the wheel and the refrigeration side should be the same, just the control circuits

regards

fatboy

absolute-zero
06-02-2008, 10:34 PM
Thanks AZ

Anything newer than an SL400 and im lost although i suppose they have not reinvented the wheel and the refrigeration side should be the same, just the control circuits

regards

fatboy

Not alot has chaged, other than the SR2 and SR2 mutitemp, the mutitemp SR2 has a couple added components for Z configuration, and suction press transducer to accomodate Discharge transducer, the refrig flow still works the same.

Better not leave out the new SLX 100, 200, and 400 series, two condensor fan squirell cages, for optimum subcooling, designed for high ambient conditons.

This was just introduced to european market, but hope to see something similiar in a SB unit here in the future.

A-Z