anyone know when to use 2 way or 3 way valve for ahu?

[cheesecake]

As far as I know, Yunos was finally assigned as regional sale director.
Leow led Trane retrofitting and chiller installation team, aligned with Mr Lee EL's energy efficiency team.
There was another guy, called Liew (Malaysian), who might still be working at Trane.

Yunos and Leow left Trane and Liew took over Leow. After that I lost touch. Yunos joined another group set up by some former York guys while Leow was on his own.

 

[greenies]

Yunos and Leow left Trane and Liew took over Leow. After that I lost touch. Yunos joined another group set up by some former York guys while Leow was on his own.

Thanks for update, and have a nice Sunday.

 

[ykhuser]

Supply air means cool air from AHU or FCU, which is treated and clean.
Supply air is toward occupant areas.

Fresh air means outside/ outdoor air which is not treated yet.
Fresh air is commonly supplied for kitchen and machine rooms.
5-10% fresh air and 90-95% return air are to be treated by FCU or AHU and then supplied to occupant rooms.

Hope the above clarification is quite ok.
Cheers,

not really.
i been to many sites.all got different config.
this case is supply air is generated by supply air fan(motor) , not by ahu motor and fcu motor.
but some sites did label as what you explain.they label supply air duct connecting to ahu output.which explain the existence of supply air temperature
1 of the site is like this
huge supply air duct connected to outside environment.when fan off, the damper will also fully shut.
from the huge fresh air duct...many small fresh air duct are tapped to supply fresh air into many small partition room.
site 2 config:
huge frsh air duct is used.many smaller fesh air duct is tapped into smaller room.
huge supply air fan is used in loading/unloading bay plus enclosed basement carpark.the fan speed are interlocked to CO2 sensor.
huge exhaust air fan with vsd are interlock to CO sensor (oxygen to dilute co2 )

the duct are all labels ...FAD, SAD, FAF, SAF, EAD, EAF clearly
so which is correct?

 

[ykhuser]

Work with Trane or York?

O ok I googled and he is Trane. So you know Pay?

isnt this 2 famous chiller brand?
i got 1 site with 12 chillers (150 tonn each )
now only 7 years...3 chillers are grounded.compressors shorted to ground.
the owner still cannot get a proper answer.

 

[greenies]

not really.
i been to many sites.all got different config.
this case is supply air is generated by supply air fan(motor) , not by ahu motor and fcu motor.
but some sites did label as what you explain.they label supply air duct connecting to ahu output.which explain the existence of supply air temperature
1 of the site is like this
huge supply air duct connected to outside environment.when fan off, the damper will also fully shut.
from the huge fresh air duct...many small fresh air duct are tapped to supply fresh air into many small partition room.
site 2 config:
huge frsh air duct is used.many smaller fesh air duct is tapped into smaller room.
huge supply air fan is used in loading/unloading bay plus enclosed basement carpark.the fan speed are interlocked to CO2 sensor.
huge exhaust air fan with vsd are interlock to CO sensor (oxygen to dilute co2 )

the duct are all labels ...FAD, SAD, FAF, SAF, EAD, EAF clearly
so which is correct?

You might have seen carpark ventilation system, where fresh air (FA) is sometimes conveniently designated as supply air (SA) because the outdoor air is not treated and directly supply to carpark areas.

When you look at air handling unit (AHU), FA and SA are differentiated.

 

[greenies]

isnt this 2 famous chiller brand?
i got 1 site with 12 chillers (150 tonn each )
now only 7 years...3 chillers are grounded.compressors shorted to ground.
the owner still cannot get a proper answer.

If there is short-circuit in chiller, there are only two root causes; one at chiller starter panel and the other at motor.
Usually, chiller supplier and electrical contractor have to work closely, and resolve the problem.
As the chillers are 7-years old, the key party is the chiller maintenance contractor.

 

[cheesecake]

isnt this 2 famous chiller brand?
i got 1 site with 12 chillers (150 tonn each )
now only 7 years...3 chillers are grounded.compressors shorted to ground.
the owner still cannot get a proper answer.

I know these 3, Trane, York and Carrier as the largest players here while brands like Hitachi are not well-known.

150 tons are small compared to the 2000 tons used by chilled water district cooling system like Changi.

 

[cheesecake]

If there is short-circuit in chiller, there are only two root causes; one at chiller starter panel and the other at motor.
Usually, chiller supplier and electrical contractor have to work closely, and resolve the problem.
As the chillers are 7-years old, the key party is the chiller maintenance contractor.

Air-cooled are not as robust as the water-cooled chillers.

 

[ykhuser]

I know these 3, Trane, York and Carrier as the largest players here while brands like Hitachi are not well-known.

150 tons are small compared to the 2000 tons used by chilled water district cooling system like Changi.

nex has 8 nos of 800tonn chillers..
anyone know RWS?i saw the powerful giant cooling towers

 

[ykhuser]

Air-cooled are not as robust as the water-cooled chillers.

they are all water cool.all got monthly servicing

 

[greenies]

​

they are all water cool.all got monthly servicing

If those chillers are from Trane, the motor is hermetic and cooled by chilled water loop and it needs heater for motor assembly.
The chiller room with Trane chillers is ok with simple ventilation.

If it is York, the motor is open type, air-cooled.
The chiller room is quite hot and needs proper ventilation system, sometimes the room is air-conditioned.

 

[greenies]

Air-cooled are not as robust as the water-cooled chillers.

Water-cooled chillers are more efficient than air-cooled.

 

[cheesecake]

they are all water cool.all got monthly servicing

Give us the brand and who are your maintenance contractors and perhaps we can assist. There are a few good companies that will be able to resolve the problems.