Heating problem

[exotiic]

Good evening again, another issue that I would appreciate advice about!

I have installed a Panasonic W18DKR 5.3kW fixed speed unit in a ground floor town house. The area is 6m*6m, the above floor is air conditioned bedroom and concrete slab, floor is concrete slab and walls are double brick construction, each side of the town houses, left and right adjoining air conditioned town houses. There is only one wall with windows facing north of 2.3m*4m and calculated heat load is 4.3kW, 3.8 heating. at the front of the home is an opening leading to the kitchen and to the stairwell upstairs, the opening is approximately 1.2m*2.7.

The issue I am having is that the system produces a 20 TD between air on and off, but the air on does not seem to increase. The air on at 20 degrees C is and air off at 40 degrees C and over time will not increase. The average room temp will sit at about 22 degrees C whilst outdoor ambient is 17 degrees C. System is R410 rated and pressures are ok. The outdoor unit condensing fan does not cycle on as much as usual and system run is 3m. Panasonic has been out and said system is working as per specs, but the room itself is not gaining any rise in temperature.

I am wondering if the opening at the front of the room is allowing excessive heat loss? Upon entry into the room there is no major sense of heat forcing through, but that doesnt mean that air flow is not being lost. I have suggested to the owner that to try and provide a temporary curtain in the opening to see if that provides any difference. He claims that his neighbour with the same layout in the apartment is running a 2.6kW toshiba inverter which is heating up the place extremely well, but I have doubts personally.

Any advice would be great?

[rude]

IM not sure if this is right but, there is a stairwell in the room going up stairs?

If so when the hot air rises could it be going up that stair well and not re circulating through the room?

[exotiic]

The stairwell is at the front of the home where the front door is. there are 4 steps going down do the room as mentioned and then the 7 steps going to the first floor. The only opening to the downstairs is the 1.2m*2.7 opening between the stairs and the room. The air con unit is at the opposite end of the room, blowing in the direction of the front door.

The possibility of escape is what I am trying to identify, as with the curtain attempt on the opening. As mentioned though I did not feel any direct heat within the stairwell on entering and did not feel any warmer than the room trying to be heated. The stairwell opening in effect is 6m away from the unit wall.

[back2space]

Outdoor ambient is 17C and indoor is 22C what temperature are you trying to achieve as that seems a reasonable temperature?

[stefs_cruiser]

I would be interested to know, what fan speed the unit is set on, and what the actual gas pressure is?

Sounds to me like it is functioning as intended though....

[Yuri B.]

How ventilation in the house works - how many air changes per hour and is the heat being recovered.

[exotiic]

I agree that the system seems to be functioning as intended especially with the temp difference and i agree that the 22 degrees is reasonable. However the client has stated that they want to feel warm and apparently 22 degrees is not warm enough for them. The 2.75kW unit placed upstairs in the bedroom achieves 54 degrees at the outlet at same ambient and they expect similar results. No matter what the client sets the system on, or if outdoor ambient increases the room remains at 22 degrees.

System is set on high speed and actual pressure on test was 660kpa in forced cooling at low ambients. On heating there is no suction pressure to take as on all splits there is no valve on suction line.

Yuri, when they tried my suggestion of closing off the room this morning with the blanket it basically sealed the room so there is very little air change at all. With the seal they stated there was no difference in performance.

As such I will be going tomorrow afternoon to examine and take some more measurements once again.

[rude]

I agree that the system seems to be functioning as intended especially with the temp difference and i agree that the 22 degrees is reasonable. However the client has stated that they want to feel warm and apparently 22 degrees is not warm enough for them. The 2.75kW unit placed upstairs in the bedroom achieves 54 degrees at the outlet at same ambient and they expect similar results. No matter what the client sets the system on, or if outdoor ambient increases the room remains at 22 degrees.

System is set on high speed and actual pressure on test was 660kpa in forced cooling at low ambients. On heating there is no suction pressure to take as on all splits there is no valve on suction line.

Yuri, when they tried my suggestion of closing off the room this morning with the blanket it basically sealed the room so there is very little air change at all. With the seal they stated there was no difference in performance.

As such I will be going tomorrow afternoon to examine and take some more measurements once again.
Thats too low for R410a

i suspect a gas leak. Weigh in a new charge and see how that goes. If you can't spot a leak it will be on your flares somewhere.

Whats the pressure of the suction line in heat mode?

[back2space]

Is the upstairs unit an inverter?

[exotiic]

Thats too low for R410a

i suspect a gas leak. Weigh in a new charge and see how that goes. If you can't spot a leak it will be on your flares somewhere.

Whats the pressure of the suction line in heat mode?

I dont think its a gas leak, remembering that the ambient is low at 17 degrees and forced cooling for it to run. Tomorrow is supposed to be warmer so I will get figures tomorrow on inspection.

The upstairs unit is a conventional fixed speed also back2space

[exotiic]

Just a question - IF there is a refrigerant shortage, I couldn't expect such a temperature difference from air on to air off indoor coil could I?

[rude]

Depends is the 40 degrees air off constant along the whole fan area. or are some readings a bit lower?

another question. Was the unit working properly previously, now its just stopped working properly?

[Gary]

No matter what the client sets the system on, or if outdoor ambient increases the room remains at 22 degrees.


Given a higher setpoint:

If the compressor runs non-stop without reaching the setpoint, it is a system problem.

If the compressor cycles off before reaching setpoint, it is a control problem.

[acnerd]

Good evening again, another issue that I would appreciate advice about!

I have installed a Panasonic W18DKR 5.3kW fixed speed unit in a ground floor town house. The area is 6m*6m, the above floor is air conditioned bedroom and concrete slab, floor is concrete slab and walls are double brick construction, each side of the town houses, left and right adjoining air conditioned town houses. There is only one wall with windows facing north of 2.3m*4m and calculated heat load is 4.3kW, 3.8 heating. at the front of the home is an opening leading to the kitchen and to the stairwell upstairs, the opening is approximately 1.2m*2.7.

The issue I am having is that the system produces a 20 TD between air on and off, but the air on does not seem to increase. The air on at 20 degrees C is and air off at 40 degrees C and over time will not increase. The average room temp will sit at about 22 degrees C whilst outdoor ambient is 17 degrees C. System is R410 rated and pressures are ok. The outdoor unit condensing fan does not cycle on as much as usual and system run is 3m. Panasonic has been out and said system is working as per specs, but the room itself is not gaining any rise in temperature.

I am wondering if the opening at the front of the room is allowing excessive heat loss? Upon entry into the room there is no major sense of heat forcing through, but that doesnt mean that air flow is not being lost. I have suggested to the owner that to try and provide a temporary curtain in the opening to see if that provides any difference. He claims that his neighbour with the same layout in the apartment is running a 2.6kW toshiba inverter which is heating up the place extremely well, but I have doubts personally.

Any advice would be great?

Just curious, but is it a wall-mounted unit? How high is the ceiling? Do the directional louvres point down when in heating mode? Just wondering if with high ceilings you don't have all the hot air higher up. Also, if it's a floor mounted unit, all the heat will remain above and you won't necessarily have increased return air flow temp.

[Yuri B.]

The feeling the upstaires A/C might be going into the cooling mode by some times, and the both units are "wrestling".

Maybe the isolation of the concrete floor is weak and it is too cold.

[exotiic]

Thank you all for helping and I will provide my readings taken again today and answer your questions.

Based on outdoor ambient of 18 deg C, system is working perfectly on cooling. Suction pressure running at 700kpa. Air on internal is 16 deg C, air off is 3.4 deg C. External air on is 21.1 deg C and air off is 29 deg C.

On heating cycle, I noticed condenser fan will operate immediately. Pressure will reach 3000+ KPa (off the gauges) and fan will turn off. Pressure will drop to 2640kPa and fan will return to operate. Within 15 seconds the pressure will rise again and cut off, and will operate in this nature for the complete cycle. To me it seems abnormally quick to raise such in pressure but Panasonic seems to think it is normal?

Internal air on temp is 21.1 deg C and air off is 39.4 deg C. External Air on is 18 degC and air off is 14 deg C. Room ambient is steady at 21.5 deg C.

If I removed the indoor sensor and placed in cold water output internally would achieve up to 43 degrees. If I disconnected the internal coil sensor, internal output would reach 48 degrees and the outdoor unit would cut off on high pressure as the internal fan would run on very low speed. Condenser fan kept running until compressor cut off.

Yuri, the upstairs unit is not on at the same time as we have used this system, even in testing. The unit upstairs is only usually at bed time but this unit has been operating even in testing today during the day without achieving higher conditions.

Acnerd, it is a high wall mounted unit, room heigh is 2.4m and the unit is mounted 150mm below the ceiling (60mm below cornice to allow for hanging on installation). The directional louvres have been pointing downwards to push the air lower that is correct.

Gary, except for the compressor high pressure cut off, the compressor does not cycle off and does not reach the set point.

Rude, the air temp is an average across the whole fan, with sides reaching 38-39 and centre reaching 40-41 Deg C. The system has performed this way following the night of installation.

Thank you for all taking the time and effort to provide your input and help, it is really appreciated. To me the symptoms seem to offer the explanation that it is undersized for the space, given that the 20 deg temp difference is high but the air intake does not increase, to thus increase the air out over time. However, I did another heat calc today whilst on the job to confirm my original calcs and confirmed max cooling requirement is 4.5kW and max heating calc based on 4.12kW achieving 23 deg indoors. The next door neighbour has a 4.3kW inverter (so would ramp up to 5kW at max approx) and conditons the room without issue.

I offered to replace the unit with the 5.3kW inverter model and I would test the model at my workshop. The Panasonic tech is quite adament there is nothing wrong with the system which I would believe if it were able to increase the room temperature inside to a comfortable temp.

[back2space]

How does the system behave in cooling?

[exotiic]

In cooling the system appears to work extremely well, though ambient is only 18 degrees. Suction pressure running at 700kpa. Air on internal is 16 deg C, air off is 3.4 deg C. External air on is 21.1 deg C and air off is 29 deg C.

[Gary]

Just a question - IF there is a refrigerant shortage, I couldn't expect such a temperature difference from air on to air off indoor coil could I?

That would depend on indoor fan speed. Does the indoor fan stay at high speed throughout the heating cycle? Is the airflow restricted and/or recirculating?

[Gary]

In cooling the system appears to work extremely well, though ambient is only 18 degrees. Suction pressure running at 700kpa. Air on internal is 16 deg C, air off is 3.4 deg C. External air on is 21.1 deg C and air off is 29 deg C.

I would not say it is working "extremely well".

The outdoor (cond) dT is 7.9K indicating a very light load. This means it is not picking up a good heat load on the indoor coil.

The indoor (evap) dT is 12.6K indicating that the airflow is borderline sufficient for that very light load.

I would say the indoor fan is running on low speed.... or airflow restricted.

[Gary]

On heating cycle, I noticed condenser fan will operate immediately. Pressure will reach 3000+ KPa (off the gauges) and fan will turn off. Pressure will drop to 2640kPa and fan will return to operate. Within 15 seconds the pressure will rise again and cut off, and will operate in this nature for the complete cycle. To me it seems abnormally quick to raise such in pressure but Panasonic seems to think it is normal?


If I understand this correctly:

If the indoor (cond) airflow is insufficient, the outdoor (evap) fan cycles to reduce the load.

Assuming I am reading your remarks correctly, this is looking like an indoor airflow problem.

[Gary]

What we in the industry think of as multi-speed fan motors are usually in fact multi-horsepower motors. (True multi-speed motors are very expensive)

With no load on the shaft a multi-hp motor will turn at the same speed on all settings. It is only when a load is added that the hp determines the speed. The low speed (low hp) setting runs the fan blade slower simply because it doesn't have enough muscle to run it at high speed.

Anything which adds to the load (tight bearings, dirt on the fan blades, restricted airflow, etc.) will slow the motor.

This may or may not be the case here, but it warrants close inspection.

[rude]

after reading what gary has said. Is the indoor temp sensor connected into its holder? it hasnt fallen out has it? That would stop the fan increasing its speed in heating.

[exotiic]

Rude, The indoor temp sensor is firmly in its holder on the evap. I took it out out to test it in water to cool temp and testing increase temps and when cooled allowed for slightly higher output.

Gary, the internal fan speed, when manually set on the remote stayed on high speed for the duration of the test. I can not see any visible air flow restrictions internally or externally.

When we removed the evap COIL sensor from its position, the fan slowed down and the indoor output produced up to 47-48 Deg C but cut the compressor on high pressure due to the restricted air flow.

I understand your point Gary about the outdoor fan cycling to reduce the load but internally there does not seem to be any restriction in air flow or seem to be running on low speed.

[Gary]

Whem you had it in cooling mode, did you check the superheat?

If the superheat is low, then the indoor airflow is probably insufficient.

If the superheat is high, then the system is probably undercharged.

[Magoo]

Could it be that the concrete slad floor and double brick exterior walls are too much of a heat sink lose with ambient at +17 and probable ground temp 5'C lower ,add, all the heat added is going upstairs.
During NSW summer and ambient rockets to 35+, and ground temp rises plus upstairs heats up, the cooling cycle will probably struggle as well. magoo

[hvaclover]

Whem you had it in cooling mode, did you check the superheat?

If the superheat is low, then the indoor airflow is probably insufficient.

If the superheat is high, then the system is probably undercharged.



Hello Gary.

Guess who?

[Gary]

Hello Gary.

Guess who?

I'm guessing Count Dracula... Am I close?

[nike123]

I would say that possibility is that you have some control problem.
Reason could be because of high outdoor temperature and low indoor load. That conditions causing fix speed control of unit to work on its edge or beyond edge and various protection functions to operate and prevent continuous production of heat.

First, I would recover and weigh refrigerant (if short than you have leak), evacuate to 500 microns and than charge new refrigerant by weight to exclude refrigerant problem. Than I would wait that outdoor temperature drop below 15°C for further observation and evaluation on system performance.

[hvaclover]

I'm guessing Count Dracula... Am I close?


Liberfraumilch and Michelob. Ramp room. The Dutchess.
The Booby Trap. Polish Century club.

Chapter 150

Sorry to the others, but I have no PM available to me.:off topic:


Taco Bell. Limo ride to Jason's.


Ringing any bells yet?

[Gary]

Liberfraumilch and Michelob. Ramp room. The Dutchess.
The Booby Trap. Polish Century club.

Chapter 150

Sorry to the others, but I have no PM available to me.:off topic:


Taco Bell. Limo ride to Jason's.


Ringing any bells yet?

:off topic: That narrows it down to my drinking days, but keep in mind that those were my drinking days... the memories may be a little fuzzy... lol

I'll try to take this to PM.

[nike123]

Sorry to the others, but I have no PM available to me.:off topic:


You have visitor message (http://www.refrigeration-engineer.com/forums/faq.php?s=&do=search&q=visitor+message&match=all&titlesonly=0#faq_vb3_public_profile) availiable.

[hvaclover]

:off topic: That narrows it down to my drinking days, but keep in mind that those were my drinking days... lol

I'll try to take this to PM.

I don't have PM. Post count is too low.

[nike123]

..................................................................

[nike123]

I don't have PM. Post count is too low.

Just click to Gary name and then "view public profile"

[hvaclover]

Just click to Gary name and then "view public profile"
Ef hardi sto!

[Gary]

I don't have PM. Post count is too low.

I'm guessing, John?... I sent you a visitor message.

[exotiic]

Just an update - Replaced the unit this morning with the inverter model E18HKR and after running for 20 minutes started taking measurements of the conditions.

External ambient air temperature was 16.3C. Temperature in at indoor was 23.6C and temp out was 46C.

Externally, temp in was 15.6C and temp out 8.8C. Liquid Line pressure constant at 3100kPa and stable, with evap fan constantly running. Immediately upon running we could feel the difference in the room. I will now set up the unit in my workshop and test again with comparison to other models.

[back2space]

I think the unit was undersized causing the room temp not to increase.

[exotiic]

The heat load calcs required a max of 4.5kW cooling based on outdoor ambient of 36K and 4.12kW heating to achieve 23 degrees indoors.