Unit Heaters

Frequently Asked Questions

Features and options:

How quickly can I get units?

Zehnder Rittling has a quick ship from stock program available. These units ship in 24-48 hours from receipt of order. They ship via the method of choice at the time of order. Availability based on current stock.

Can motor voltages be changed in the field?

Changing from a standard 120v motor to a 230v can easily be accomplished in the field. However changing from a 120 or 230v motor to a 460/3 motor requires an additional motor mounting bracket.

Also all accessories must be reviewed as they may not be compatible with the change in voltage.

Changing a unit to explosion proof requires the additional motor mount along with a change in the fan. Also standard accessories are not compatible with explosion proof applications.

Why are accessories limited on explosion proof units?

Explosion proof units are specialized units require a different class of components and wiring to ensure their compliance as explosion proof. These accessories are typically provided on site by a qualified electrical. Zehnder Rittling chooses to not provide these items and is not ETL certified to provide them.

What about custom material or color?

Cabinets are made from cold rolled steel and finish in a standard grey powder coat finish. However there are alternate finishes available:

Standard Colors

All stock units are finished in a standard grey finish. If a standard color from the Zehnder Rittling color chart is requested that can be provided. There is an upcharge for these units and the unit will need to be made to order.


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.
  • Orders can be placed for standard US made product with custom color selections or other standard Zehnder Rittling colors by choosing the required product and adding a comment to the order referencing the color. Stock units are not available in custom colors. 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.


Stainless steel or alternate materials

Zehnder Rittling does not offer unit heaters in alternate materials, including stainless steel or galvanized as it does other products. In most cases these materials are requested for specific environments. In these cases we recommend coatings, which you can find details on below.

What if the unit heaters need to be coated?

Under specific circumstances there may be a situation where the entire unit (cabinet and coil) or just the coil itself may need to be coated. Depending on the requirements of the situation there are a couple of available options.

If the unit heater needs to have protective coating then heresite or e-coat finishes are available. These finishes use a dip process to apply the coating, resulting more complete coverage and are designed to add protective properties to the product. These coatings are typically used for corrosive environments and are commonly applied to unit heaters.

E-coat has the advantage of allowing a powder coat finish applied, as an option. The standard e-coat finish is black. With heresite a finish coat cannot be applied and is an opaque orange color.

Please contact customer service or applications engineering for more information on these coatings, including pricing and lead time.

Can units be re-painted in the field?

With the standard finishes the process is the same as any other field painting procedure. The surface should be scuffed/roughed up to ensure adhesion of the liquid paint. An oil based enamel paint (alkyd, acrylic, urethane, epoxy) should be used. Latex or lacquer paints should not be used. Spray the paint to achieve an even coating and let dry completely before using the product. Take care to not cover or damage the serial label on the rear of the unit.

What additional controls are available?

In cases where the standard offering of basic or thermostatic controls does not meet the needs of the project we can provide any number of custom options, however space is limited on the rear of the unit.

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.

Can additional valve packages be provided?

While valve are not typically supplied with unit heaters we do have a limited availability of standard valves used with cabinet heaters or fan coils that can be used with these units. These valves can provided loose for field install. They are limited to ½” or ¾”. Thread by sweat adapters will be needed.

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