Frequently Asked Questions

Installer Questions

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Zehnder systems are unique. Are they difficult and time consuming to install?

While our systems are different from traditional HVAC systems, they are designed to be easy to install. Our units and distribution components fit together easily and don’t require specialized tools. For more information on the installation process, click here for our General installation Manual.

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Can a Zehnder ERV/HRV work in a retrofit?

Yes! Zehnder systems are suitable for retrofit applications. For more information, please fill out a Quote Request form and one of our salespeople will create a custom quote for your project.

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Can a Zehnder system tie into the central HVAC system?

Yes. While Zehnder systems are designed as stand-alone systems and will work more efficiently with their own distribution components, it is possible to tie into a central HVAC system if stand-alone installation cannot be achieved.

This method has a few drawbacks, including an overall lack of control over where fresh air is delivered. This can cause poor air distribution when the HVAC system is not running, especially in the bedrooms, and also stale air being drawn through the house to the HVAC return points.

When requesting a quote, please specify that existing HVAC ducting will be utilized, and your salesperson will create your quote accordingly.

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How do I determine which unit will work best for my project?

Our sales team looks at a few factors when creating your custom quote. The total square footage of the home and the number of rooms where the system will extract air (bathrooms, kitchens, laundry rooms) determine what size unit will be required to maintain an optimal air exchange rate.

Whether the project will require an ERV or HRV unit, preheater, or optional components like a ComfoWell filter casing also depends on the climate where the project is located and factors like outside air quality. Our team will work with you to ensure that your quote will include the best system and distribution components for your needs.

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How do I get a quote? Will Zehnder help with the layout of the system?

Getting your free quote is easy! When you fill out the quote request form, be sure to upload your building plans in the space provided and add any special needs. One of our expert salespeople will review the plans and create a quote that includes the most suitable unit and distribution for your project.

Your quote will include a distribution plan for each room, indicating the size and type of register and the number of tubes it will require. There is plenty of built-in flexibility within the plan to choose the placement of the registers to accommodate electrical, plumbing and aesthetic needs.

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I received my quote. How do I use it to lay out my system? What should I do before finalizing my order?

The air distribution table on your quote will indicate the distribution components needed for each room, whether it will be a supply or exhaust run, and whether it’s a ceiling or wall installation.

Before ordering, you should review each room and decide where the registers will be placed. You should also determine the final location of the unit itself and the length of runs you will need from the ComfoWell to each room as well as from the unit to both the exterior vents and the ComfoWell. The quote includes ducting from a central location, but you should verify that the amount on the quote is adequate.

Need to change a ceiling register to a wall or vice versa? Thinking of adding an optional component or possibly using insulated metal ducting for the exterior sections? Your salesperson can discuss any changes or updates needed and revise your quote accordingly.

When you’re ready to order, make sure to verify that the quantities in the highlighted sections are enough to meet your needs.

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How do I order?

To place an order for your Zehnder America quote, call our office at (603) 601-8544 ext. 0. You will pay in full at the time of order; please have the quote number and your payment information when you call. We accept credit cards over the phone. If you would like to pay by check or electronic transfer, let us know when you call, and we will verify all the order details; the order will be processed for shipping once funds are received.

If your quote came from one of our authorized distributors, you should place your order directly through them.

To order additional parts, call our office, and we can take your order and card information over the phone.

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Can I use metal ducting instead of Zehnder distribution?

Yes. If you are using metal ducting to connect the unit to the exterior, it must be insulated. You can use non-insulated metal ducting between the unit and the ComfoWell as the air is conditioned once it passes through the unit. If you plan to use metal ducting, please contact your salesperson to ensure we have the properly sized components for your project.

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The layout on my quote doesn't show the exact location of the supply and return registers. Where in the room should I put the register box?

If they are installed on the specified surface and can be accessed for commissioning and filter maintenance, registers can be placed anywhere on that surface. This gives the flexibility to work around structural, electrical and HVAC components.

It is preferable to keep the ducting runs as short as possible, so you should take that into consideration when placing your registers. Also, an 18’ square flow hood will be used during commissioning, so registers should be able to accommodate the hood.

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How long can the distribution runs be?

You should keep runs as short as possible, with a 50’ maximum length.

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How will my order be shipped to me?

Full system orders and bulky items will be palletized and shipped from our warehouse in Buffalo, New York via common carrier on a tractor-trailer. Shipping rates are determined by the size and weight of the shipment and the destination. Shipping rates fluctuate daily; the final shipping cost will be determined when the order is processed. Trucks will have a lift gate to assist with unloading, but your delivery site must be accessible for a 48-foot tractor-trailer.

If the site is on an island or otherwise not accessible by tractor-trailer, you will be responsible for having the material delivered to a safe drop-off location and for getting it from there to the job site.

Filters ordered from our website and most smaller parts orders will ship via UPS Ground. Please note that some items, such as units, silencers, ComfoTube and ComfoPipe must always ship via freight due to the bulk of the product.

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I’m in Canada. How can I order a system?

We ship directly to Ontario and Quebec. Customers in other provinces can order directly from our authorized distributors in those provinces.

Canadian customers ordering directly from Zehnder America are responsible for securing a customs broker for all palletized orders (items shipping via UPS do not require a broker) as required by Canadian Law. Please have your broker information ready when you call to place your order as we cannot process the order without this information.

We will need the name of the broker as well as their email address and telephone number. All necessary documents will be supplied to the broker when your order is packed for shipping.

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What is commissioning? What will the agent do?

Commissioning is the quality assurance process of thoroughly verifying and proving that building systems are installed and operating according to the criteria in the original design and engineering documentation. The agent will measure the airflow at each register adjust, if needed, to keep the airflow within 10% of the design flow, which is the Passive House Standard.

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My installation is complete, and I paid for commissioning. How do I make an appointment?

Once the system is fully installed and ready to turn on, you will need to visit our website and fill out the Commissioning Request Form. You must be able to answer “yes” to all questions (with the exception of certifications if that doesn’t apply) before the system can be commissioned. Once the form is received, our Commissioning Manager will assign an agent to complete the commissioning, and the agent will contact you to schedule a mutually acceptable date and time. Please note that if the checklist is inaccurate and/or if the system is not ready for commissioning, you will be charged a $165 Not-Ready fee.

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I’m not installing in an area where commissioning is available. How do I make sure the system is balanced?

If you are installing a Q350, Q450 or Q600, the unit is self-balancing upon startup. If your system uses a CA unit, we have the flow hood available to rent for self-commissioning. Please call our office for more information.

Homeowner/General Questions

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What’s the difference between an Energy Recovery Ventilator (ERV) and a Heat Recovery Ventilator HRV?

A Heat Recovery Ventilator (HRV) exchanges the air and preserves 80%-92% of the heat from the extracted air, returning it to the incoming air via the unit core. Incoming and exhaust air never mix in a Zehnder system. HRVs are slightly more efficient at preserving heat than ERVs but are not the best option in every climate. HRVs are better suited to areas with a relatively dry climate.

An Enthalpy, or Energy Recovery Ventilator (ERV), also preserves heat at a rate of up to 90% via the unit core, but it also exchanges some moisture from the wetter airstream to the drier one, helping to preserve optimum humidity in the home.

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How does an ERV/HRV system recover heat? Does it put exhaust air back into the home?

Our systems recover up to 90% of the heat already in the home without mixing the fresh air with the exhaust. As the two airstreams pass through the unit’s core, the heat is transferred through the core into the incoming air.

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Who can install a Zehnder system in my home?

Most homeowners choose a trusted HVAC or general contractor to perform the installation. The system is designed so that all the pieces fit together easily to save time and money on installation. Our General Installation Manual gives an overview of how our systems fit together, and manuals and specifications for individual units and peripherals are available on our website as well. We also offer videos for many of the steps and offer phone support through our office to help ensure your project goes smoothly.

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When should I replace my filters?

There are three types of filters associated with a Zehnder system:

  • Unit Filters – These filters are located in the ventilation unit. Units will have 2 filters – a supply air filter and a return air filter. The Supply-side filter, which has a red frame or writing, is typically a MERV 13-rated filter and will filter the air from the outside. The return side filter, with a black frame or black writing, is typically a MERV 7/8 rated filter and is used to filter the air from the home before it passes through the core. These filters typically should be replaced every 6 months. We recommend a monthly check for any excess buildup of dirt and debris and vacuuming lightly to remove any buildup if the filter is less than six months old.
  • Return Register Filters – Zehnder recommends all return registers be fitted with a return filter. For our round registers, a cone filter is provided to catch debris before it enters the distribution system. These are washable filters and typically last about a year before they need to be replaced. The Rome register filters are rectangular in shape. These filters are not washable and should be replaced yearly.
  • Comfowell Filters – Some customers are looking for extra filtering capabilities. Zehnder offers a ComfoWell filter option for our systems. These filter casings can have either a MERV 15-rated filter or an activated carbon filter option.
    • The MERV 15-rated filter should be changed every 6 months.
    • The Carbon Activated filter should be changed when outside smells are detected in the home. The life expectancy of the carbon filter will vary based on your outside conditions.
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Why do I need extract filters? Isn’t the air already filtered?

The intake filters keep the intake air clean, but extract filters keep particles that are already inside the home (like pet dander or dust, for example) from getting back into the ductwork and the unit core.

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How do I order replacement filters?

You can order filters online by visiting our Filter Store. Choose US or Canada (based on your billing address) and then select the filter(s) you need for your unit, ComfoWell and return registers. They will be shipped directly to your door.

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Do I need to do any other maintenance?

Once a year the unit should be opened, and the core removed to allow for a full cleaning. A full cleaning should consist of:

  • Vacuuming of the unit’s interior
  • Wiping out of the interior of the unit with mild soap and a damp sponge or cloth.
  • Inspection of the fans, including gentle wiping of the impellers with a damp cloth
  • Cleaning of the core in accordance with the core cleaning manual, which can be found here. Some older cores cannot be cleaned, they will have a label indicating not to get them wet.
  • Inspection of the exterior grilles should also be done on an annual basis if not more often. If the Grille is dirty, it also should be removed and cleaned. Exterior grilles should also be checked periodically in winter for snow or ice buildup.
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I’m getting an error code on my control panel. What should I do?

There are several reasons for error codes. If you see one on your control panel, call our office and we’ll get you in touch with a service technician who can assist you.

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My system has a preheater. Will that heat the air in my home?

The preheater on your system is designed to heat incoming air enough to keep the unit from shutting down in sub-freezing temperatures. It will turn on when outside temperatures drop below 32°F (HRV) / 24°F (ERV) in order to keep the unit core from freezing.

The preheater does not heat incoming air to the point where it will affect the home's temperature, and it does not affect heat recovery efficiency.