Balancing Valves in a Fan Coil Application

Linear Diffuser Plenums

Displacement Calculations - Part 1

SSR Electric Heat vs Staged Heat

ECM Retrofit - Things to Consider

As most people in our industry are well aware – a newer fan motor technology can provide huge energy savings and extended service life. There are many existing buildings full of older permanent split capacitor (PSC) motors that typically last for 10-12 years in a series fan-powered unit. These motors are 20-60% efficient and service life may suffer if operating at lower speeds. As soon as these motors start showing an increasing pattern of failures, building owners who are aware of electronically-commuted motors (ECMs) may express an interest in upgrading to this newer technology. ECMs have a minimum efficiency of 80% and a service life of 25-30 years. It is possible to attempt this type of retrofit, but there are a few things to be aware of.

Were the unit models in question ever available with ECM?

If a particular unit model has been available with an ECM option, all the parts and pieces should be readily available. Of course the most important part is the motor itself and it must be programmed for a given blower cabinet. Although it may be possible to assemble parts and pieces that will fit into an existing unit, motor programming could be an issue if the unit was never developed for an ECM option. Depending on the number of units involved, it may be cost prohibitive to develop custom ECM programming for each cabinet size. One possible solution would be to factory program the ECMs for constant torque rather than pressure independent control. This could limit or eliminate the need for any development work.

Will the existing electrical service handle the ECM?

The ECM replacement will likely be rated for a different horsepower and full load current. Although the resulting operating current draw should be less than the PSC motor it replaced, motor nameplate ratings may require upsizing the supply circuit in order to provide the necessary electrical safety. Obviously, this could greatly complicate the retrofit process and add a lot of cost.

Did you know that the UL/ETL listing will be voided?

Any field modifications to a UL/ETL-listed product that results in a change of electrical characteristics such as current draw or motor horsepower will void the listing. This is true even if factory parts are field installed by factory personnel. Once a UL/ETL-labeled product leaves the factory, any changes that do not match the data found on the unit label will void the listing. The only way to reinstate the label would involve having a UL/ETL inspector visit the jobsite and field label the units. This could be very costly but may be unnecessary if local inspectors will not be involved in the retrofit process.

Have you considered the total amount of parts that will be required?

ECM retrofit doesn’t just mean replacing the motor. It generally means replacing the motor, the speed control, and blower assembly. It will likely also require additional components like power cables, communication cables, and a power filter. It could even require changing internal options like line and/or motor fuses.

Have you considered the cost of field labor required?

All of these modifications will have a field labor cost. It could easily take an hour to access each unit and swap out the various parts. It may take longer depending on the accessibility of a given unit. In an occupied building this work may need to be carried out at night or on weekends. Additional hours of electrician time would be required for any modifications to the supply circuit.

In summary

Although the temptation to upgrade from PSC motors to ECM is strong, remember that the process is not as simple as just changing motors. It involves many more parts and could require electrical work too. That doesn’t necessarily rule out the possibility on an ECM retrofit. Many building owners have contacted their local Titus representative to investigate the possibilities. ECM technology is quickly taking over this industry and it’s important to understand exactly what a retrofit may entail so that you can provide the right answers to your customers.

For information on this topic, please contact Randy Zimmerman at rzimmerman@titus-hvac.com or Titus Communications at communications@titus-hvac.com.

Thermal Displacement Diffusers

Options for Surface Mounting Ceiling Diffusers

One of the more frequently asked questions we receive in application engineering is in regards to surface mounting Titus diffusers. When a ceiling grid is not present, surface mounting is specified and the installation questions arise. Linear diffusers are available with concealed mounting, square and rectangular diffusers with square or round inlets are not.

The most important thing to know about surface mounting is that it normally requires additional framing to which the units will be secured. We often receive calls for mounting instructions after the sheet rock has been installed which is too late to provide framing without removing the installed surface. 

Framing requirements will vary from one job to the next, but there are some general guidelines and terminology we use.

Obviously installing screws in the face of a diffuser will work as it does for grilles but the duct return flanges behind diffuser edges are generally not available to provide a secure mounting base for screws. Also, many surface mount frames do not have a flat surface nor is there a screw hole fastening option available. Furthermore, screw fastening certainly does not enhance the aesthetics of the installed diffuser. 

The TRM mounting frame makes installation of grilles, diffusers and other ceiling components in plaster and sheetrock ceilings as simple as inserting them in a standard T-bar type ceiling

All sheetrock is mounted to ceiling joists. Joists are usually parallel to each other and spaced at two to three feet apart depending on local building codes, and in most cases, the framing for the diffuser can be mounted to the top of, and perpendicular to the joists. Screws are then used to mount the back pan to the framing. Framing members should be centered on the diffuser location to allow sufficient clearance for the diffuser inlet and associated duct. Additional care must be taken so as to avoid any protrusions or features that will occupy the space necessary for the framing on the rear side of the diffuser. Framing should also be at a depth that will allow the diffuser to firmly seat against the sheet rock. Most diffuser back pan heights are less than the depth of the joist. The sheet rock or ceiling surface is installed into an opening provided for the diffuser.

The diffuser core should be removed prior to installation to allow for screws to be installed in the top of the back pan transition; this is the flat portion on the rear of the back pan. Screws are then used to secure the back pan to the framing. It is helpful to use washers to prevent the screw heads from being driven through the back pan if the framing is not flush to the rear of the pan. In most cases the screws can be placed in a manner to not be visible from the occupied space after the diffuser core or face is re-installed.

The illustration above shows how the TMS diffuser would be mounted in sheetrock  

As an alternative to the framing process, and one that we suggest if the ceiling surface has been installed without prior framing for the diffuser mounting, is to use our rapid mount frame. The TRM frame can be installed in the space between the joists following the installation of the ceiling. 

The TRM replicates a standard ceiling grid module and a lay-in (type 3) frame diffuser. The diffuser can then be laid in the TRM frame. The TRM frame does add a border to the finished appearance of the diffuser, but also can be utilized as an access port to the space above the ceiling by simply pushing the diffuser up and out of the opening. 

While the TRM does represent additional diffuser cost, the reduced labor requirement and flexibility of the installation sequence offers a distinct advantage.

The TRM is available in steel and aluminum and is ordered as a separate line item. Remember, when using the TRM frame, the (type 3) diffuser frame must be used instead of the (type 1) diffuser frame.

For information on this topic, please contact Mark Costello at mcostello@titus-hvac.com or Titus Communications at communications@titus-hvac.com.