Archive for September, 2010

Condensate Discharge for City Multi VRV Fan Coils

Tuesday, September 28th, 2010
The City Multi fan coils have three condensate drain systems.  The primary drain is the gravity drain at the bottom of the drain pan.  The second is an optional pumped condensate outlet up high above the gravity drain.  The third is the overflow drain that operated only when the normal drains fail.  This first photo shows the lower gravity drain connected to the copper drain pipe through the patented Mitsubishi horizontal trap.  Someday I will cut one of these traps open to see how it works, but for the moment I’m just happy to say it does not require additional vertical space that a normal trap requires. 
 
 
Above shows the pumped condensate outlet.  It is a bluish color plastic. 
 
And finally, this photo shows the overflow drain connection on the opposite side of the drain pan. 
 
 
This photo shows the tailpiece connection of the condensate drain at a nearby lav.  The pipe is the black hose. 
In this photo the overflow drain outlet is shown above the shower.  If water comes out of this pipe, it is time to clean the normal drain.
 
Just a note of warning.  The City Multi fan coils come with the pumped condensate units as a standard feature and they are energized.  If you use the gravity drain and not the pumped drain, then the pump needs to be disabled.  Otherwise, the pump will come on and dump water on the floor.  (Ask me why I know this if we ever meet.:)  To give credit where credit is due, Lonny Potter, hotel engineer, was the person who discovered this issue and shared the details with me.  Lonny is seen below admiring his evaporative cooler for the kitchen make-up air unit.
 
 
 

Evaporative Cooling for Hotel Kitchen Make-up Air

Monday, September 27th, 2010

Make up air for kitchens is a big consumer of energy.  This is particularly true for the cooling side.  For locations where the humidity is low in the summer, an evaporative pre-cooler is an economical solution.  The evaporative cooler lowers the outside air temperature by evaporating water into the air stream.  The humidity of the airstream rises, but if the outside air is dry to begin, the increase in humidity is tolerable.  Palmdale, California is just such a location. 

The photo  below  shows an evaporative cooler mounted to the outside air intake of a standard gas fired make-up air unit.

 
 

This shows the wetted media which exposed the airstream to the water.    This media is constantly moistened by a water supply and a pump. 

The photo below shows the sump under the media.  In a sense, this is nothing more than a cooling tower where the airstream is pulled into the make-up air unit.

 

To see the performance, the following sequence of pictures shows the temperature starting at the outside air intake, then the air just downstream of the wetted media, and finally at the outlet grille in the kitchen.

   

Note that the temperature drops from 75 degrees outside to 58 degrees after the moisture is add and then finally back up to 66 degrees where it enters the room.  The increase from 58 to 66 degrees is due to the fan energy and the heat gain of the ductwork above the ceiling.

Mitsubishi City Multi goes into Ontario Airport

Wednesday, September 22nd, 2010

Embassy Suites, California

The new Embassy Suites hotel located at the Ontario airport in California will have guestrooms served by a VRV system by Mitsubishi.  This is following the Embassy Suites in Palmdale with the identical system completed in early 2010. 

Here are a series of photos taken during construction to showing how this system is constructed in the corridors and guestrooms.

 

This photo shows a typical guestroom fan coil unit located above the guestroom entry soffit.  The units are very compact. 

 

This shows a closer view of the fan coil unit.  The ductwork to the guestroom space is flex duct.  The two black pipes in the foreground are insulated refrigerant pipes.   The white PVC pipe is the condensate drain.  The strange grey tube with corrugations between the PVC and the fan coil is the proprietary Mitsubishi condensate trap.  It solves the problem of the P-trap which otherwise requires additional ceiling cavity height to accommodate.  Note that the electrical J-box is in the upper left corner of the photo.  All connections are on one side of the fan coil.

 

This photo shows the BC controller located in the corridor ceiling cavity.  Note the refrigerant piping connected to the left side with the brass fittings.  There are two pipes per guestroom and each pair of pipes is stacked vertically.  There are thirteen rooms connected to this BC controller.  For a typical hotel floor with about 26 guestrooms per floor, two BC controllers are provided.

 

This is another view of the BC controller with the condensate piping and main refrigerant connections shown on the end of the unit.

 

This shows the BC controller nestled amongst the other systems in the corriodor including the ventilation supply duct nearest the wall.

 

This photo shows the refrigerant piping as it splays out to the guestrooms along the corridor.  As we move further from the BC controller, the congestion becomes less and less as refrigerant pipes “drop off” to the guestrooms. 

 

This shows a small bundle of refrigerant pipes near the most remote guestrooms.  Note that the ceiling space becomes very comfortable at this point. (If we could only rent out this unused space. J)

 

This photo shows an electrical J-Box with the access panel framed in.  I have included it just so my electrical engineers do not feel left out.

Corridor Guestroom Supply Systems

Wednesday, September 22nd, 2010

Both Hilton and Marriott now require ducted ventilation air to guestrooms.  This means that outside air openings at each guestroom via PTAC or VTAC is no longer acceptable.  Likewise, operable windows are not acceptable.  In response to this requirement, designers are now providing central HVAC units to supply corridor ventilation that also includes ductwork along the corridor with branch ducts to each guestroom. 

The photo below shows the ductwork on each side of the corridor with sprinkler pipes and electrical routed in the center above the drop ceiling. 

 

This is a typical condition along most of the corridor.  However, the conditions become much more crowded where the main supply duct first enters the corridor as seen in this photo:

Here the duct must exit the vertical shaft and cross the corridor as it splits into the two branches extending the length of the corridor.

You might ask why two ducts and not just one, and the answer is that the small duct into each guestroom would have to cross over (through) the sprinkler piping in the center.  Here is a photo of the duct into a typical guestroom:

In most states there is no requirement for a fire / smoke damper.  However, California is one state where a fire/smoke damper is required at the duct penetration to each guestroom.  Here is a photo of  a typical fire/smoke damper:

Terminating the ventilation air inside the guestroom can be done in three different ways.  One approach is to run the duct to a diffuser on the other side.  The second is to connect the duct to the return side of the guestroom fan coil unit.  The third method is to terminate the duct inside the return air plenum of the ceiling space where the guestroom fan coil unit is located.

The advantage of this approach is that the return grille for the plenum can also function as the access panel for the fire/smoke damper.  This is the configuration shown in this photo as taken through the ceiling opening for the return grille.  The fire/smoke damper is seen as accessible from this opening. 

 

It should be noted that the return air plenum concept can only be used in a non-combustible building construction.  Also, any wiring routed through this plenum must comply with plenum rating requirements.  Therefore, no smurf tube in the plenum.