VRV indoor unit may use the built-in temp sensor at each indoor unit to control room temperature. AHU may use return air temp sensor to control average room temp.

@@aircondlounge Got it..thank you very much sir❤

Anytime

Will put this on my list.

No problem.

Thanks

Divert the oily kitchen exhaust upward I guess. Then collect the oil at the elbow there with a piece of metal, plus some rainwater =D

I think in this case should recalibrate the VAV airflow in those rooms. The big room needs more airflow while reducing the airflow in the small room.

@@aircondloungeso that means each duct that connects each room must have a VAV?

@alexekwueme7477 It depends. If each room needs about 1500 CFM, then it is likely that every room needs a VAV box. Otherwise, 2-4 rooms can share one VAV box. Each room will then rely on the radial or OBD on their diffuser to adjust to their required airflow (eg: 150, 250, 700, etc.). If multiple rooms are sharing one VAV box and each room diffuser doesn’t have volume control damper, then small room will indeed be overcooled since majority of the temperature control comes from the big room because the big room contributes more airflow for the control.

And the thermostat used to control the VAV is likely located in the big room as well.

@@aircondlounge I think each room should have VAV and it's damper plus thermostat for full control of the air in the rooms.

For VAV AHU, you should apply a diversity factor to the total sensible heat you mean?

@@aircondlounge you should calculate total sensible load of all zones hourly to find the worst scenario with highest load, not just add the load of each zones together. because they can not occur at the same time to add them together

For load calculation yes. However, if those zones are serve by one AHU, adding the max load at each zone at different hour will lead to oversizing because when one zone is at max load, it doesn’t necessarily means the other zones are at max load as well. So, sum up the load by the same hour and choose the highest one should be the optimal approach.

@@aircondlounge yes thats what I mean. So you select the hour with highest load?

Because this video is about coil sizing, the sensible loads are just an example. In load calculation, I do calculate by hourly and pick the highest load hour.

Thanks.

It’s nice to meet you!

I have not seen such a VAV damper, mostly are very basic ones. Designing <1700 CFM per VAV box can help with the noise.

Thank you

Great!

Thanks. Will do that.

Got it

Thanks. Other than noise, pushing the FPM higher will lead to higher pressure drop which is the air resistance that could slow down the AC fan speed (which reduces the overall airflow). However, we’re talking about prolonged length like a duct. One or two grilles that increases from 500 to 800 FPM wouldn’t have a noticeable difference.

@@aircondlounge what about if the decorative grill is used to replace the air return grill cover? Am I going to starve the furnace from pulling in enough air? What are the risks I run here?

@@whitefalcon017 ​​⁠ it’s best to check with the grille supplier about the free area and then calculate the required grille size in order not to affect the system

Sure. Some other differences are cost, VRF is higher, then the control, VRF has centralized thermostat, also the capacity, VRF offer much higher capacity than multi-split.

@@aircondlounge thanks! Can we set different temperatures in different rooms for both multi-split and VRF? If yes, can we set different modes (heating or cooling) in different rooms also for these two systems? Again, truly appreciate your knowledge sharing and guidance. 🙏🙏👍👍

@HL34908 different temperature yeah, both systems can make it. But running cooling and heating simultaneously is usually VRF only and it needs to be the “3 pipes” system.

No…is to warn the viewers that I’m going to press the remote control and a loud beep is coming. Cause people may tune up their speaker volume to listen to the noise the unit produces.

Thanks. Sure will post more about load calculation.

Morning, I yet to publish a video on that topic. Will upload in the future. Thanks.

Anytime

It is extracted from the ASHRAE Handbook. You may try google it though.

@@aircondlounge ok thanks a lot. :)

Basically you subscribe to the service. You don’t own the equipment. The HVAC company will ensure the performance and efficiency to be met.

@@aircondlounge nowadays do they use this model now?

@5331011204 it’s a relatively new model. So, the respective companies are expanding.

The most leading company ever all over the world

Probably continue on December. Now preparing to launch a new course.

Always visit your channel if there's a new upload.

It’s an audiosample

Some ppl need to know if their machines are working or not which comes with the db noise level on packages so this helps to know if a machine is broken or not

For residential aircons, many countries have their own rating system and that’s the best one. For example, in the US, SEER for cooling efficiency and HSPF for heating efficiency. COP usually reflects the efficiency on the product design level. For actual efficiency, SEER HSPF are better indicators.

It’s Mitsubishi Electric, US