Cabinet Unit Heaters

Frequently Asked Questions

Features and options:

What if I need dimensional changes to the unit?

There are times that the unit size does not match up with the existing space. In those cases we can look at making adjustments to the unit to fit the space.

While the standard units are sized for optimal space usage, including valves and controls, we can make some changes to the overall unit size. However there are limitations for changing these sizes. There are a number of changes that can be made, see below for specific details.


What if the existing opening is larger than the standard unit size?

There are two options when trying to fill a space larger than the unit. The wall seal kit can be made with larger flanges. This is the simpler and less expensive option. The other option would be increase the cabinet size. This is more complicated and a more limited option. However the overall appearance will be superior.

Custom lead time will apply in either case, contact the factory for pricing.


How about making the unit size larger?

Increasing the overall size of the unit has few limitations in most cases. Whether it is to fill an existing space or to allow for the mounting of components inside the cabinet we can modify most dimensions.


How about a larger depth?

The unit depth is the most difficult to change, as it will have the biggest impact on airflow and coil location. However some adjustments are available, if required.

Typically making the unit deeper is only requested for floor mounted units, to fit into an existing space. The easiest way to do that is to provide what is typically referred to as a false back. This is actually an extension of the two sides and the top. This is accomplished using additional pieces that are field installed. This allows the most flexibility as the added depth can be 1 – 10” and does not change the base cabinet construction.

Adding this depth does affect the mounting of the unit as the wall brackets are moved away from the mounting surface. This requires supports to be run from the wall to the unit to secure it or additional mounting through the legs of the unit.


How about a longer length?

As a standard a 6” extension to the base 8” end pocket is available, making the end pocket 14” total. This can be done to both end pockets for a total of 12” of extended length, as standard length. If additional length or end pocket space is required that can be quoted, up to a total unit length of 94” in most cases, 115” in the most extreme.


How about a larger height?

With wall and ceiling units making the unit as tall as 30” is not an issue. The cabinet itself will be changed to accommodate the additional height (from the standard 24”). Increasing the cabinet size requires significant changes to the cabinet construction, both internal and external.

With floor mounted units the height can be changed in one of two ways, the cabinet height can be increased or the leg base height can be increased. Increasing the leg base height is a simpler change and allows for more flexibility than adjusting the cabinet size. In extreme circumstances both heights can be adjusted.


How about making the unit size smaller?

Shrinking the overall size of the unit has the more limitations than making the unit larger as the internal component sizes drive most of the overall dimensions. This means that there are hard limits to what can be modified.


How about a smaller length?

The unit depth is unable to be changed based coil and blower sizes and locations.


How about a smaller depth?

In general this is the easiest dimension to change when trying to reduce a unit size, due to the unit design having two equal end pockets, 8” wide. The electrical end pocket can be reduced to 4”, removing 4 3/16” of length from any standard unit size. This will require remote mounting of the thermostat or speed switch, if required, as well as limit the available electrical options. This is the minimum size to allow for the mounting of a junction box and allow for construction of the cabinet.

We can also reduce the piping end pocket by 4” as well. However this will severely impact the space available for valve packages and limit the selection to ball valves. Any additional valves will need to be remote mounted.

Either of these options will reduce the available space for installation of incoming power or water connections.


How about a shorter unit?

The overall height of most units can be reduced 2” by reducing the plenum size of the blower area. Floor units offer an additional height modification, through the leg base. The base of the units can be reduced by about 1” for further reduction.


How about a custom size wall seal kit?

Custom wall seal kits can be used for recessed units in lieu of changing the cabinet size. The standard trim frame is 1 ½” on all 4 sides (adding a total of 3” to both the height and length of the standard cabinet size). This additional size overlaps the opening. By increasing the flange size larger spaces can be covered up. Wall seal flanges have been made as large as 12” in some cases.

Can I use a wall unit in the ceiling? Ceiling unit on the wall?

From a performance and mounting perspective there is no issue using a ceiling unit on the wall or vice versa. There are two differences that need to be kept in mind when doing this.

First is that wall units come with access doors and have optional unit mounted thermostats available, ceiling units do not. This is due to the fact that most ceiling units are not accessible and thermostats are remote mounted.

Second is ceiling units come with hinged front panels equipped with safety chains. This restricts the front panel from coming away from the unit and requires the operator to disconnect the safety latch before the panel will fully open. The wall unit does not come with these features. Kits can be purchased to install these items in the field should they be required.

Why don’t units with factory mounted thermostats come with remote temperature sensors?

While it is strongly suggested that any unit with a unit mounted thermostat utilize a remote temperature sensor it is not included with the unit or the thermostat price. This is due to the fact that many installations do not use them or do not want them. Adding them to the base price and forcing their use could put the units at a competitive price disadvantage. Sensors are available as a ship loose option as standard.

If factory mounted temperature sensors are required please contact the factory for availability and pricing.

Can I get a unit with perforated inlets and outlets?

Units have louvered or open/ducted inlets and outlets as standard, with bar grill or double deflection grilles as options. However we can provide units with perforated inlets and outlets for security applications. In these cases airflow may be restricted, so out inlet and outlet sizes will need to be adjusted to account for the additional restriction.

Can the coil handing be adjusted in the field?

Should the need arise to change the coil handing in the field the unit can be adjusted. Since the unit has end pockets on either side the water and electrical connections can be flipped.

The electrical components will need to be removed first. Then the fan deck removed and then the coil. Re-insert the coil in the new position; be sure to cover the original knockouts for the coil on the end panel. Once the coil is back in place re-install the fan deck, locate the electrical components in the new electrical end pocket and rewire. Take care when removing all components.

When recessing a unit can the wall seal kit be installed at any depth?

Yes, the wall seal is a kit that shipped loose for field installation. This includes locating the flanges at the required depth. The unit can be recessed from 2” – 10”.

What if I ordered an exposed unit and it needs to be recessed?

If a wall mounted or ceiling mounted unit is ordered as exposed but needs to be recessed you can order a trim kit. This will allow you to apply the unit in a recessed application. In the case where the inlet or outlet are in the top or bottom panels you will need to order new cabinet pieces to accommodate the new airflow pattern as well. This will mean field disassembly and reassembly of the cabinet. Contact the factory for pricing.

Floor units cannot typically be recessed as there is no standard wall seal kit and the outlet is usually in the top panel. However a custom wall seal kit and a front outlet would allow for the unit to be recessed. Slope top units cannot be recessed.

What if the back needs to be finished?

There are applications with some floor units where the back side of the unit maybe visible. While the unit is designed for attachment to the wall, even with the floor units a painted back panel can be provided. These panels will cover the entire back and be one solid color. This will require additional mounting through the leg base to ensure stability of the install.

Can key locks be provided?

Standard fasteners are slot head on access doors and Allen head on front panels. Access doors have an option to be upgraded to Allen head and both the doors and fronts can be upgraded to a Torx fastener with center pin for limiting access. If more secure access is required either or both fasteners can up changed to key lock. For access doors one or both doors can be upgraded and for fronts one to three fasteners can be upgraded, depending on the unit. There is a charge per fastener, contact the factory for more details.

What about custom material or color?

Cabinets are typically made from cold rolled steel and finish in one of our six standard powder coat finishes or the standard Zehnder Rittling prime coat. However we can make them from alternate materials or custom color:


Stainless Steel

  • Unpainted 304-4B finish is typical, though alternate finishes are available (polish/mirror finish not recommended).
  • For the price add see Custom pricing page in the price book. Comments should be added to the order denoting what items are to be stainless.
  • Custom lead times apply.
  • Entire cabinet and wall seal kit must be stainless as all cabinet pieces are visible when installed and in contact with each other.
  • Use stainless steel in applications where aluminum enclosures are requested.


Galvanized Steel

  • Unpainted for field finish. 18, 16, 14 gauge available.
  • Price and lead time add, must be quoted by Zehnder Rittling.
  • Custom lead times apply


Custom Color

  • Zehnder Rittling is able to match existing or special colors. Color chip must be provided for match (manufactures part number alone is not recommended due to potential variations in charts/chips). Chips are typically not returned and may be cut for match by the vendor. Finished goods should not be sent for paint match.
  • Price and lead time match, see Custom pricing sheet. Price is dependent on total amount of units at time of order.
  • Orders can be placed for standard product with custom color selections by choosing the required product and adding a comment to the order referencing the color. Customer service will make the necessary adjustments to the order.
  • Chips should be sent to Zehnder Rittling customer service immediately to reduce lead time/delays.
  • Two processes are available for custom color orders, depending on required approval, that will affect lead time. If the chip is provided for match only the order can be entered and released once the chip is received by Zehnder Rittling.
  • If color match approval is required once the chip is provided it will be sent to our vendor for match. Chips will then be sent out to you for approval. Once the color is approved the order can be released for production.
  • Metallic matches are not available. However we are able to provide two metallic colors, Silversmith and Bright Argent. These are the only two approved metallic colors.
  • Contact customer service for samples.

What additional controls are available?

In cases where the standard offering of thermostatic controls does not meet the needs of the project we can provide any number of custom options. From programmable thermostats to additional control components, such as air or current sensors, we have experience with a wide range of controls.

Provide the details of the custom control request and we can provide a price or an alternative. If a specific controls component or manufacturer is requested that detail should be included, with the relevant cut sheet and part number.

In extreme cases of custom controls the specification can be provided for Zehnder Rittling to review.

Another available option is for factory mounting of customer supplied DDC controls. This option is available as a standard. It requires a cut sheet and wiring diagram provided, as well as a completed customer supplied parts information sheet.

Please contact applications engineering for more details.

Can additional valve packages be provided?

While most basic valve package applications are covered by our standard offering, it is not all inclusive. There are plenty of configurations or alternate component packages that can be thought up. So for those situations we are able to offer custom valve packages.

There are many alternatives available when it comes to custom valve packages, starting with modifying our own available packages to suit a need, either by adding in or removing a standard component. We can source an alternative part to meet a specification or by brand name.

We can accept customer supplied items.

We can add in items we do not offer as standard.

All of these options will require review to determine availability and options. The request should be forwarded to applications engineering for further details.

Can valve packages be factory mounted?

Valve packages as standard are factory assembled and shipped loose for field install. They are not factory installed on the coils due to the possibility of damage due to shipping and handling during install of the unit. Factory mounted valve packages can be provided as a custom, with additional supports provided to minimize potential damage, but additional care must be taken during installation. Additional charges will apply.

An alternate solution is to order the units with factory mounted unions. This will minimize the site install and remove the risk of additional damage. This is a standard option available through the configurator.

How do I order replacement parts?

If the need arises for replacement parts the simplest way to handle this request is to provide the unit serial number to customer service along with the part(s) request. This will allow them to ensure that the correct part for your unit is available or provide you with an alternate. If the serial number is not available you will be provided with a quote for the current version of the item requested.

Once customer service has the information they will provide you with a quote for the item, including price and availability

Performance ratings:

How do I get performance data for my cabinet unit heaters?

It is recommended that you use for all performance rating and product capacity, including all cabinet unit heaters.

Base performance data can be found in the catalogs.