VAV Diffusers | 5 Reasons why each Therma-Fuser has a Thermostat

Posted August 14, 2012 by Jim Shiminski

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Each Therma-Fuser VAV Diffuser has it’s own separate thermostat. Each acts as an individual zone of control.

Why a Thermostat is in each Therma-Fuser and not on the wall?

Acutherm Therma-Fuser
Space temperature set points can be personalized to satisfy each occupant.
Personalized temperature selections of the occupant remain set because the adjustment is out of the way from tampering by any visitor or passerby.
Average space temperature at both high and low air flow is better sensed at the Therma-Fuser location. A wall thermostat typically does a poor job sensing the average room temperature.
Open office can be zoned without creating walls on which to locate thermostats.
Decisions about who has the thermostat and who goes either hot or cold are eliminated.

Therma-Fusers are made by Acutherm, a US based company in Hayward California.

High Plume Dilution Fans for Diesel Generator Exhaust

Posted August 6, 2012 by Jim Shiminski

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High Plume Dilution Fans for Diesel Generator Exhaust:

Strobic Air - Diesel Exhaust Fan

Emergency diesel generators are necessary evils for lots of facilities. No one likes to have them around, but they must be available to provide immediate backup electrical power in case of sudden power failure.

Diesel/electric generators must also meet critical performance requirements, but they can also create problems when tested (generally weekly without load and monthly under load).

The two major problems caused by diesel generators include possibilities of re-entraining their exhaust into the building’s ventilation system (or an adjacent building’s), and unpleasant diesel exhaust odors in the neighborhood. To prevent these problems we recommend high plume dilution fans from Strobic Air.

Over the years we have done dozens of Diesel Generator Exhaust fan applications with Strobic Air Tri-Stack Fans (High Plume Dilution Fan). Strobic Air has done a really nice job creating a solution to a problem for many facility owners. A special High Temperature Tri-Stack fan is manufactured by Strobic Air. These fans are available in rigid steel construction designed specifically for high temperature applications (such as emergency diesel generator, furnace or boiler room exhaust). Tri-Stack high temperature exhaust fans are UL certified for operation at 750°F for up to 2 hours without the need for outside air dilution, and incorporate chemical resistant high temperature coatings. A brass rub ring on the inlet bell conforms to AMCA “C” spark resistance specifications.

Use the Strobic Air Online Selection Program for picking a fan. Under the System Type, choose Diluted Hi Temp for the high temperature diesel fan.

Benefits of using high plume fan for diesel exhaust:

Ideal for assisting dispersion of odors into the neighborhood
High constant volume discharge avoids re-entrainment
Aspirated dilution up to 270% within the fan
High temperature reduction in the mixing box
Maintenance-free operation

Ask Rick: Custom Air Handling Units | Recommendations on Merv Filters

Posted August 1, 2012 by Jim Shiminski

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Q. We are designing a new air handling unit for a lab. What do you typically recommend for filter ratings? We may be using energy recovery.

MERV 8 Filter

We recommend that you use a filter on either side of the energy recovery device. Typically we use a Merv-8 on the supply side and a Merv-7 on the return side. If you need final filters we would recommend Merv 14 for LEED jobs. Otherwise filter selection is application specific.

Ashrae uses Merv Ratings for all filters. Minimum Efficiency Reporting Values (MERV rate)

MERV ratings are used to rate the ability of an air filter to remove dust from the air as it passes through the filter. The MERV scale ranges from 1 to 16, and measures a filter’s ability to remove particles from .30 to 10 microns in size (100 microns is about the thickness of a human hair). Filters with higher ratings not only remove more particles from the air, they also remove smaller particles.

Contact the safety consultants of the lockout tagout experts in industrial safety guidelines and the MERV Rating Chart below for more information about the difference in performance between filters with different MERV ratings.

MERV Rating Chart

ASHRAE Standard 52.2				ASHRAE Standard 52.1	Application Guidelines
MERV Rating	Particle Size Removal Efficiency			Dust-Spot Efficiency Percent	Particle Size and Typical Contaminant	Typical Applications	Typical Air Filter Type
MERV Rating	0.3 to 1	0.3 to 1	0.3 to 1	Dust-Spot Efficiency Percent	Particle Size and Typical Contaminant	Typical Applications	Typical Air Filter Type
20	≥ 99.999	in 0.1 – 0.2 μm particle size		–	< 0.3 μm Virus (un attached) Carbon Dust Sea Salt All combustion smoke	Electronics manufacturing Pharmaceutical manufacturing Carcinogenic materials	HEPA/ULPA Filters
19	≥ 99.999	in 0.3 μm particle size		–
18	≥ 99.99	in 0.3 μm particle size		–
17	≥ 99.97	in 0.3 μm particle size		–
16	> 95	> 95	> 95	–	0.3-1 μm All bacteria Droplet nuclei (sneeze) Cooking oil Most smoke Insecticide dust Most face powder Most paint pigments	Superior commercial buildings Hospital inpatient care General surgery	Bag Filters – Non supported (flexible) microfine fiberglass or synthetic media, 12 to 36 inches deep. Box filters – Rigid style cartridge, 6 to 12 inches deep.
15	85-95	> 90	> 90	> 95
14	75-85	> 90	> 90	90-95
13	< 75	> 90	> 90	80-90
12	–	> 80	> 90	70-75	1-3 μm Legionella Humidifier dust Lead dust Milled Flour Auto emission particles Nebulizer drops	Superior residential Better commercial buildings Hospital laboratories	Pleated filters – Extended surface with cotton or polyester media or both, 1 to 6 inches thick. Box Filters – Rigid style cartridge, 6 to 12 inches deep.
11	–	65-80	> 85	60-65
10	–	50-65	> 85	50-55
9	–	< 50	> 85	40-45
8	–	–	> 70	30-35	3-10 μm Mold Spores Dust mite body parts and droppings Cat and dog dander Hair spray Fabric protector Dusting aids Pudding mix	Better residential Commercial buildings Industrial workspaces	Pleated filters – Extended surface with cotton or polyester media or both, 1 to 6 inches thick Cartridge filters – Viscous cube or pocket filters Throwaway – Synthetic media panel filters
7	–	–	50-70	25-30
6	–	–	35-50	< 20
5	–	–	20-35	< 20
4	–	–	< 20	< 20	> 10 μm Pollen Dust mites Cockroach body parts and droppings Spanish moss Sanding dust Spray paint dust Textile fibers Carpet fibers	Minimum filtration Residential window air conditioners	Throwaway – Fiberglass or synthetic media panel, 1 inch thick Washable – Aluminum mesh, foam rubber panel Electrostatic – Self-charging (passive) woven polycarbonate panel
						Minimum filtration Residential window air conditioners

(Table Data Source – United States Environmental Protection Agency)

Related Blog Categories:
Air Handling Units
Energy Recovery

Does Coil Cleaning Save Energy?

Posted July 30, 2012 by Jim Shiminski

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Does coil cleaning save energy? This was the first question that we asked before agreeing to promote Steril-Aire as a manufacturer. We knew that the technology worked; that you could clean a coil to a nearly new condition by using UVC lights. That we knew. We also new that a clean coil would save energy. But we didn’t know whether you could save enough to make it worthwhile.

Dirty Cooling Coil Fins

The short answer is yes, coil cleaning does save energy and it is worthwhile. I have included an article published in the November 2006 ASHRAE Journal; “Coil Cleaning Saves Energy”. This study looked at air handling units (AHUs) before and after coil cleaning to see what impacts coil cleaning had on energy savings.

Three key variables that added credibility to the study:

The AHUs were large enough to provide substantial data (both units over 30,000 CFM).
The AHUs were constant volume (not easy to find these days). It would have been difficult to quantify energy savings on Variable Air Volume (VAV) units.
The weather data was constant during reporting periods.

The study looked at a huge building in downtown NYC. See the following results and conclusions:

Cleaning the AHU SF-9 coil resulted in a decrease in the pressure drop across the coil, of approximately 14%. This resulted in a corresponding increase in airflow.

Cleaning the cooling coil in AHU SF-9 resulted in an increase of 25.3% tons of cooling (on prior 81 tons of cooling). They estimated that 100 tons (352 kW) of cooling capacity would be added to the building once all four AHUs coils were cleaned. (Building had a total of 1,800 [6330 kW] tons available capacity.)

Cleaning the cooling coil increased the thermal efficiency of the cooling coil 25% with respect to its ability to transfer its energy to its sensible loads (10% with respect to latent loads).

Cleaning the cooling coil would continue to save energy by decreasing the load on the chiller plant, and making the heat transfer of this loading more efficient. It reduced the time of multiple chiller operation and its associated pumps, cooling towers, chemical costs, wear and tear, etc.

It is worthwhile to note that the coils in these units were 30 years old and its last cleaning was nearly a year before the study.

Conclusion: Good maintenance practices, including coil cleaning, can significantly improve energy efficiency (by as much as 10% to 15% as in this case).

Related Blog Posts:
Ask Rick: What is UVC?

Ask Rick: High Plume Dilution Fans | Adding VFDs to Existing System

Posted July 23, 2012 by Jim Shiminski

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Q. We are considering conversion of constant speed Strobic fans (six fans on a common mixing plenum) into variable speed fans by adding VFD’s to satisfy the the plenum static pressure set point. What do you recommend to ensure that we do not run them below the required minimum plume height.

Over the years we have installed lot’s of Strobic Air Tri-Stack Fan systems without Variable Frequency Drives (VFD’s). Most were installed on variable air volume lab applications. Bypass dampers were incorporated to balance system load. We are now looking to convert many to variable speed systems.

First check to make sure that the motors are inverter duty. Strobic Air has provided mostly Toshiba EQP III Premium Efficiency motors for the past ten years. If the motor is not inverter duty then it will need to be replaced.

Smart Fan System Screen

Our first choice for controlling an existing system is the new Tri-Stack® Smart System. We now design these into nearly all new multi-fan systems. They provide several key advantages.

Controls fan speed to meet building demand while maintaining a minimum outlet velocity and stack height
Reduces sound levels at off-peak loading
Stages fan operation and rotates redundant fan
Can be retro-fit onto existing systems
Easy to use touch screen controls
Communicates with most building systems
Detects failures and activates backup fan
Controls isolation and bypass damper positions
Optional wind speed optimizer to adjust minimum outlet velocity based on wind speed and direction

The Tri-Stack® Smart System calculates the fan output from the Tri-Stack fan curve. The direct drive motor makes this possible. That allows for the use of static pressure sensing only. Air flow sensing with pitot tubes in the hazardous air stream are not necessary.

In lieu of the Smart System you can design your own control system. You will need to measure duct static pressure and modulate the VFD’s to control for the system static pressure set-point. The system will also need to measure airflow and maintain a minimum discharge velocity of 3000 fpm by staging fans on and off . The VFD minimum speed should be set during system start-up. Minimum fan flow can be determined from fan curves. The sequence can get a little complicated as you need to control VFD’s, fan staging and bypass dampers. Another reason to choose the factory supplied package.

Further questions on controlling High Plume Dilution Fans; askRick?

UVC Emitters | Fast Install Tower makes trial easy

Posted July 18, 2012 by Jim Shiminski

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Steril-Aire FIT – Fast Install Tower

This is an easy, economical way to try UVC Emitters on cooling coils. We have a lot of customers that still aren’t convinced that UVC Emitters are viable. We suggest that they try them. Take a old dirty cooling coil, install the Steril-Aire FIT and wait a couple of months. Bio-film and associated crud will be cleaned away. Seeing is believing.

More questions on UVC Emitters; askRick?

Related Blog Posts:
Ask Rick: What is UVC?

Ask Rick: Bearing Life | What is L10?

Posted July 13, 2012 by Jim Shiminski

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Bearing Life

Wheel Bearing from Thermotech

Bearings are a critical component in all HVAC equipment. Bearing life is usually expressed as the number of hours an individual bearing will operate before the first evidence of metal fatigue develops. The usual life rating for industrial applications is called “L-10” life. Simply put the L-10 life is the number of hours in service that 90% of bearings will survive. Or, conversely, 10% of bearings will have failed in the L-10 number of service hours.

L10 life: is the preferred term in specifying bearing life and is defined by The American Bearing Manufacturers Association (ABMA).

L50 or average life: is accepted as the bearing life associated with a 50% reliability, i.e., after a stated amount of time, only 50% of a group of identical bearings will not yet have developed metal fatigue.

L50 life equals five times the L10 life. The following chart shows a comparison of L10 to L50 equivalents.

Required L10 – Life Hours	Equivalent L50 (avg) Life Hours
20,000	100,000
40,000	200,000
80,000	400,000
100,000	500,000
200,000	1,000,000

No Guarantee

Failed Wheel Bearing

The bearing life rating is theoretical and based on statistics. Specifying a L10 life does not guarantee that the bearings will have a 90% reliability when installed in real world applications. The calculation for Basic Rating Life assumes proper lubrication, no shock or vibration, perfect alignment, debris free environment and temperatures that are not extreme. In the real world, none of these conditions are realistic and the “installed life” of the bearing will depend on the application and maintenance.

Further questions on Bearing Life; askRick?

Energy Recovery Heat Pipes | 5 Advantages of using Heat Pipes for Air-To-Air Energy Recovery

Posted July 9, 2012 by Jim Shiminski

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We have choices in equipment that we can select for air to air energy recovery applications, we even have the best options for Geothermal Heating and Air systems. Here are 5 advantages that Heat Pipes offer;

Energy Recovery Heat Pipes Features

1. Passive Operation
No energy input is required to operate the Heat Pipes. There are no moving parts. When two air streams pass through the Heat Pipes, one air stream on the supply side and the other on exhaust side, the temperature difference between the two air streams heats and cools refrigerant. The phase change of the refrigerant, from a liquid to a vapor and back again, transfers energy from one side to the other. It’s simple.

2. Long Life
There is nothing in the Heat Pipes to wear out! The Heat Pipes are passive. They have no moving parts. To guard against corrosion, the Heat Pipes can be ordered with a protective coating. The Heat Pipes are fabricated with a multitude of charged circuits. Under normal operations, there is no reason for these ever to leak. If one of the many circuits did leak there would be little impact on performance as other circuits would still function.

3. Isolated Air Streams
Dividing partitions to separate the two air streams can be easily added to Heat Recovery Heat Pipes. The copper tubes carrying the Heat Pipe working fluid are expanded into the mating holes in the dividing plates assuring an excellent seal to prevent cross contamination. This divider makes heat pipes a good choice in laboratory type applications, where cross contamination is a concern.

4. Minimum Maintenance
Since the Heat Pipes have no moving parts, the only maintenance recommended is periodic cleaning. A coil cleaner may be applied for this purpose just as for any cooling coil.

5. Flexible Size
Heat Recovery Heat Pipes from can take up less space than other heat recovery schemes. They can also be manufactured in custom sizes to fit nearly any application. Heat pipes can also be compact in depth. A six-row heat recovery heat pipe can be fabricated with a thickness of as little as 8 inches.

Further questions on heat pipes; askRick?

Visit Heat Pipe Technology for further information.

Ask Rick: Labratory Exhaust Fans | When should you manifold laboratory exhausts?

Posted July 7, 2012 by Jim Shiminski

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Q. When should you manifold laboratory exhausts?

Typical Individual Lab Exhaust Fan Set

We have been asked this questions countless times through the years. In the past, public opinion held that you don’t know what lab chemicals are being work with so you don’t combine any lab exhaust. All laboratory hoods were serviced by individual exhaust fans. This was extremely expensive both in first cost and in operational costs. Maintenance costs were very high.

When Strobic Air first introduced the Tri-Stack fan in 1986 nearly all systems were single fan systems. Now nearly all systems are manifolded systems.

Manifolding fume hood exhausts is recommended for all types of hoods with the exception of radioisotopes and perchloric exhaust. By combining the exhaust hoods, sufficient mass can be achieved to create sufficient momentum to break through the recirculation zone on the roof. This creates a safer roof environment and significantly reduces re-entrainment.

Manifolding systems also offers the following advantages over single fan sets:

First Cost Savings

Strobic Air Manifolded Fan System

Lower Equipment Cost
Lower Install Cost

Operation Cost Savings

Lower Energy Costs
Lower Maintenance Cost

Energy Recovery is significantly easier to design and more cost effective
Increased System Flexibility
Added System Redundancy

More questions on Manifolding Lab Exhaust Fans; askRick?

Air Handling Units | Split Replacement Coils

Posted July 2, 2012 by Jim Shiminski

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Split Replacement Coils

“I didn’t know these were available.”
“Wish I had known about these sooner.”
“What a great idea., this will save a lot of pain”

Split-Fit Coil from Aerofin

All comments that we have heard from building owners after showing them split coils.

Replacing large water coils in air handling units is never easy. It’s even more difficult and expensive when equipment space is restricted (most of the time). These Split-Fit coils from Aerofin are slick. Long coils can be divided into smaller sections for field joining in the unit. They are factory assembled and tested to ensure leak tight service in the field.

Split-Fit coils are available for both heating and cooling coils that have a maximum operating pressure of 100 psig and a maximum operating temperature of 160F. The following ranges are available:

Fin Height: 12 to 54 inches
Fin Length: as required to match existing coil
Rows: 2 to 8
Circuit: identical to original coil
Special Apps: higher pressure/temperature designs are available

Split replacement coils offer a big advantage over having to create additional access space for coil replacements. It also allows us to design tighter units knowing this is available for future coil pulls.

Questions on Split Replacement Coils; askRick?

VAV Diffusers | 5 Reasons why each Therma-Fuser has a Thermostat

High Plume Dilution Fans for Diesel Generator Exhaust

High Plume Dilution Fans for Diesel Generator Exhaust:

Ask Rick: Custom Air Handling Units | Recommendations on Merv Filters

Q. We are designing a new air handling unit for a lab. What do you typically recommend for filter ratings? We may be using energy recovery.

Does Coil Cleaning Save Energy?

Ask Rick: High Plume Dilution Fans | Adding VFDs to Existing System

Q. We are considering conversion of constant speed Strobic fans (six fans on a common mixing plenum) into variable speed fans by adding VFD’s to satisfy the the plenum static pressure set point. What do you recommend to ensure that we do not run them below the required minimum plume height.