Condensate Discharge for City Multi VRV Fan Coils

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

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

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

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.

Lime Build Up in Hotel Tankless Water Heaters

December 1st, 2009

Summary: Lime build up is an issue for tankless water heaters in residential installations. In a hotel, this should not be an issue if a water softener is installed.

Mullinax Solutions posted an interesting article on the differences between tank-type and tankless water heaters. In the article they noted that lime build up in a tankless water heater from hard water is a significant problem compared to a tank type water heater. This is counter to manufacturer claims, but the research cited pointed out what most engineers, including myself, would intuitively expect. The Mullinax article explained that the elevated temperatures and the slower flow rates through a tankless water heater contribute to lime build up.

But does this concern for residential installations translate to hotels? I believe not. Hotels located where hard water is an issue generally have water softeners for the hot water system. As noted in the research, a water softener mitigates this concern about tankless water heaters. Therefore, this disadvantage of tankless water heaters should not be a problem in a hotel.

Of course, the challenge in a hotel is to identify any application for a tankless water heater. But applications in hotels do exist. My two favorite applications are for the hot water recirc lines in water zones separated by pressure reducing valves, and for spot water loads such as remote kitchens. But the fact remains that the high demand of a hotel is best served by a system with large storage capacity.

Rain City Solar is Hope for Seattle

September 25th, 2009

Summary:  After years of waiting for solar power to come of age, we have finally begun installing solar PV systems in the Seattle and Puget Sound area.

The favorite comparison for solar power in Seattle is Germany.  Germany has a similar solar exposure as Seattle and Germany has been on a rampage to install PV solar.  Germany has an historical need to become energy independent from the world.  Even during WWII when oil was cut off from Germany, the country still produced synthetic gasoline.   And now the Germans see the value of solar power.

For me, I see solar power as a gift to my children and their children.  It is a gift that never stops giving.  It is better than stock certificates.  It is like having a family farm that stays in the family for generations.

Some people still think in terms of rate of return (ROI) or payback.  I find this analysis silly when compared to the ROI of buying a Lexis or some other expensive car.  Does anyone every consider the ROI of a luxury car?  Does anyone ever think, “I’m buying this $50,000 car for my children and their children?”  Of course not, yet the price tag is seldom an issue.  So rather than buy luxury cars, I am installing solar on my home and all the homes of my children.

Check out Rain City Solar if you live in the Seattle or Puget Sound area.  We know what we are doing and will make sure you get a system that will make your grandchildren look at the roof and say thanks to you long after you have left them on their own.

The New Look of Green for Hotels

March 28th, 2009

Summary: I am embarking on a personal campaign to make the new wall mounted VRV air conditioning units for guestrooms the new “look of green” for hotels.

Studies show that green conscious buyers of electric cars want their cars to look green as well as be green.

So why not apply that same marketing strategy to hotel guestroom air conditioning units?

What is the chance that the VRV wall mounted unit below could become the desirable “look of green” of the modern hotel guestroom? If that could be accomplished, hotel developers would have an economic solution to costly, high-end HVAC systems. These VRV systems are low cost, energy efficient, and exhibit “five star” comfort and quiet to guests.

So I challenge hotel designers to make this look the “look of green” in hotel design.


As seen in the photo above, use of these systems is not completely original for hotels.  However, I am not aware of any major brand prototypes that include this as an option.  Concealed VRV units are being installed, but the construction cost savings are not being fully realized.  The challenge is to incorporate the exposed unit into designs that look good.

Please contact me if you wish to discuss ideas for incorporating this concept into your hotel projects.

Check out this website for more information on VRV systems:
Mitsubishi City-Multi

Hotel Hot Water System Legionella Remedies Still Elusive

March 21st, 2009

Summary:  Legionella in hotel hot water systems remains a potential risk for hotel owners and designers.  This article summarizes the status of the progress toward dealing with Legionella in hotels.

Janet Stout, PHD and her colleague Dr. Victor Yu, MD are leading the research in Legionella in buildings in general.  In my efforts to find the best solution to this problem in hotels, I have begun conversations with Dr. Stout to see what we as designers can do to make sure our buildings are not at risk for a Legionella incident.  Here is some of what I have learned so far.  Please note that this subject is still under study and there are few conclusive statements that can be presented at this time.  I will be following this article with updates as my investigation progresses.  Anyone is welcome to call and discuss.

Matthew R. Freije is another expert I have discovered from his article “10 Ways Plumbing Engineers Can Prevent Legionnaires’ Disease” in the March 2009 issue of PME magazine.  He is teaching a seminar on “Performing High Quality Legionella Assessments” in May 19-21, 2009.  I will be attending to learn more and will share what I learn.

What we know about Legionella:

  1. Legionella is prevalent to some degree in almost all hot water systems.
  2. Most people have adequate immunity to low levels of Legionella bacteria, otherwise it would be a more serious problem.
  3. Immune compromised people are at higher risk to Legionella in situations that would not otherwise be a concern for the average person.
  4. Our practice of keeping hot water at 120 degrees creates a breeding ground for Legionella.
  5. Raising the temperature of hot water to above 140 degrees is helpful, but not the full answer.  Legionella is not fully killed at higher temperatures and no hot water system has a homogeneous temperature throughout.  For example, the bottom of a hot water storage tank may seldom reach the average tank temperature, especially near the cold water inlet.
  6. There are recognized methods of reducing the presence of Legionella, but none are 100 percent effective.  The common methods include:
    • Thermal Eradication: Boil the suckers!
    • Superchlorination: Kill them with chlorine like in a swimming pool.
    • Copper-silver ionization: Copper ions break down the skin of the Legionella, and the silver ions mess up the DNA.  (or something sinister like that)
    • Filtration with 0.2 micron filters.  At least the critters are fat enough to capture.

Testing for Legionella is the first step to knowing if your hotel has a problem.  The testing costs about $150 per sample, and it is recommended that a typical hotel be tested at about 5 places.

See Legionella Sample Collection for how to do this at your hotel.

ASHRAE is funding research into the issue of Legionella in cooling towers.  This is another breeding ground for Legionella that concerns many full service hotels.

Since I am just beginning to understand the subtleties of this topic, I will conclude this article for fear of continuing on and spreading untrue information.  However, it is my intention to continue learning about this subject and sharing what I learn along the way.

Update April 3, 2009: Here is a link to the best article I have found so far encompassing the full range of Legionella issues:  Legionella 2003 by the Association of Water Technologies.

Marriott Mid-Rise vs. Code High-Rise

February 23rd, 2009

Summary: Comparison of a Marriott mid-rise smoke control and building construction requirements compared to a Marriott under full IBC code high-rise smoke control and building construction requirements.

Marriott construction guidelines define a mid-rise hotel as any hotel more than six stories and less than 75 feet tall.  For this mid-rise classification, Marriott requires certain aspects of a high-rise building to be included in the design.  The following is a comparison of the these requirements relative to what is required by the IBC for a fully  classified high rise hotel.

As is often the case, when a local jurisdiction is informed that a mid-rise hotel is going to be designed per the Marriott criteria, full high-rise criteria is imposed.  Check with your local jurisdiction regarding this issue at the start of your project to avoid surprises.

Emergency Generator Stair Fans Only All Fans
Smoke Report and
Rationale Analysis
Third Party Testing of
Smoke Control
Fire-Fighter’s Control
Fire Command Center X X
Exit Stair Pressurization X X
Mechanical Smoke Exhaust
for Corridors
Mechanical Smoke Exhaust
for Public
Elevator Pressurization X
Full Smoke Control
System per Section
Fire Alarm Speaker
System for Zoned
Secondary Water Supply
for Sprinkler
Emergency voice/alarm
Automatic Fire Detection
Two hour protection for
control and
power wiring (907.2.12.1)
Fire Department
Communication System
Vestibule at Exit Stairs
on Each Floor
Exhaust Fans Rated for

Hotel CPVC Expansion Joints

February 18th, 2009

Summary: No sooner had I published the article on the double standard of CPVC pipe vs Copper pipe, a leak developed at one of my hotels with CPVC domestic water pipe.  Here is the story.

In my article “CPVC vs Copper in Hotels: Is there Still a Double Standard?” I shared my observation that the double standard for CPVC and Copper pipe was behind us with regard to pipe failures.  But within hours of publishing that article, I awoke to see the email trail of a hotel in Bellevue, Washington experiencing leaks in the piping.  Here is the story.

The mains of this 7 story hotel are a brand of CPVC called Coristan, which is a high grade of CPVC suited for larger diameter pipes.  As it turns out, there was no problem with the pipe.  However, we all know that CPVC has a higher coefficient of expansion than copper.  Thus, it is mandatory to use expansion joints to compensate for pipe expansion as the water in the pipe rises from 50 degrees to 120 degrees.  In a long hotel, this can be a significant expansion and without the expansion joints, the risers would be stressed and possibly sheared off.

What happened in this instance was a failure of the expansion joint.  Fortunately, the leak was small and the amount of water involved was limited.  Of course, even a small amount of water on ceiling tiles and carpet can cause significant monetary loss, but consider that other extreme of a 6 inch main water pipe flowing at full pressure.  That would be enough water to fill the hotel basement before someone could find the valve.  But, again, that is not what happened.

Below are pictures of the failed expansion joints.  Note the cracks in the bellows.  At one point it was thought that the flexing of the expansion joint had caused the failure, but the final analysis determined that the bellows failed from lengthwise stress caused by the water pressure, not the temperature fluctuations.   Be aware that there is a continuous stress on the pipes from the water pressure.  For a six inch pipe, the stress at 80 psi is about a ton of force.  It is less for smaller pipe diameters and is stricktly proportional to the area of the inside of the pipe cross section.

What was missing were extension limiting rods that keep the expansion joint from extending too far.   If you use this type of expansion joint, specify the joint expansion rods.




A more traditional means to control expansion is a “U-loop” as shown in the two photos below.  This is fool-proof, but requires extra space that may not be available.



Below is a response from the manufacturer regarding the failure mode of the bellows expansion joints in the previous photos.  You be the judge of whether this is an accurate assessment.

PROCO PRODUCTIONS, INC response to failure