All posts by Robert Eddy

Residential Mechanical Ventilation – The Minnesota Solution

Minnesota-Residential-Code-2015

The state of MN has been at the forefront of adopting residential building codes that incorporate energy efficiency designs for residential mechanical ventilation. These codes have additional provisions which address some of the serious side effects such designs can have on the home’s inhabitants and structural integrity.

Back in the early 1980’s, these energy efficient building designs introduced highly insulated air tight homes. These designs significantly reduce a home’s energy consumption but created adverse consequences that could not go ignored. Extensive research conducted over the past 30+ years was the driving force behind the current 2015 Minnesota Energy Code. Considered controversial by the builders and realtors, primarily due to the code’s cost impact on a home’s sale price, this code is also viewed as a showcase for all the advocates of the advancement of building science.

The 2015 MN Mechanical Ventilation Code

In the past, many residential ventilation systems were either unbalanced or exhaust only; typically, exhausting more air than was brought into a home. This approach was generally considered “easier” and” less costly.” The state of MN however, decided that the benefits of a balanced ventilation system far outweighed any cost concerns.

The 2015 MN Residential Energy Code requires a total ventilation rate based on the total square footage and the number of bedrooms there are in a home. A minimum of 50% of the total ventilation rate must be met by a continuous and balanced whole-house mechanical ventilation system. Kitchen and bath fans can be a part of the overall ventilation system, but an HRV/ERV system alone can meet both the total and continuous requirements of the current code. Such multi-purpose systems use minimal amounts of energy, are energy efficient (many models are Energy Star rated) and improve the indoor air quality of a home.

New homes already adhere to the 2015 MN Residential Energy Code. Builders are now required to install these ventilation systems during construction, but homeowners can retrofit older homes with an HRV/ERV system also. Though it is not required to add a balanced system to homes built before February 14, 2015, it is a relatively simple modification that connects to a home’s furnace ductwork to simultaneously exhaust indoor air and bring in outdoor air.

The Drawbacks of Unbalanced Mechanical Ventilation and Negative Pressure in Homes

An unbalanced mechanical ventilation system involves fans exhausting and/or supplying air in unequal amounts into a home. When the supply air exceeds exhaust air, it creates positive pressure in a home. When exhaust air exceeds supply air, it creates negative pressure. Homes operating under positive and negative pressures can affect the safe operation of fossil fuel appliances and expose a home’s inhabitants to serious health risks over time; toxic gasses and airborne contaminants such as radon, mold, allergens, bacteria and viruses. A balanced ventilation system in homes negates pressure differential consequences and helps minimizes the impact of such health risks by effectively diluting their concentrations in an efficient manner.

Negative pressure can cause back drafting, a likely reason why your fireplace doesn’t draft very well. Large exhaust devices such as kitchen range hoods (generally over 300 cfm) pull significant amounts of air out of a house, your fireplace chimney (when open) will be trying to bring air back into the structure to reach a point of pressure equilibrium. To remedy such situations, a make-up air device can be installed which is capable of mechanically bringing back into a home the same amount of air that’s being exhausted by the range hood. Make-up air requirements are also a part of the 2015 MN Energy Code.

The Air in Our Homes

The movement and types of air within a home is not a simple matter. The 2015 MN Residential Energy Code is very specific in its requirements. It outlines not only the need for ventilation in homes but also addresses combustion air (air needed for fossil fuel appliances), make-up air (air that deals with sources of significant negative pressure) and provisions to protect homeowners from radon (a soil gas commonly found in MN that contains carcinogenic particles). Most homeowners are unfamiliar with building codes so finding a competent builder and HVAC contractor is highly recommended.

It’s good to see that most new single family homes in MN today are implementing HRV/ERV balanced ventilation systems to meet the total ventilation requirements of the MN Energy Code. Homeowners of older homes need not despair, for retrofitting an existing home with a balanced HRV/ERV ventilation system is not overly complicated or expensive.

Using Supplemental Electric Duct Heaters in Heat Pump Systems

supplemental-heaters-in-heat-pump-systems

Homeowners are increasingly relying on VRF heat pumps and ductless mini-splits to keep their families warm during the heating season. At the same time, commercial property managers are relying more and more on these devices as well, thanks to the ease of installation, simple controls and unparalleled flexibility that they offer.

VRF and ductless mini-splits represent some of the most efficient kinds of heaters on the market. Whereas propane and oil heating systems rely on expensive fuels to operate, these heat pumps produce indoor warmth in a cost-effective, environmentally friendly way.

However, heat pump mini-splits can be overtasked when dealing with subzero temperatures. These conditions cause HP’s to eliminate the efficiency that makes them so desirable and to produce less heat affecting the comfort of the living space.

Installing an electric duct heater for supplemental heating is one of the best ways to address this dilemma. The result is a far more efficiency in terms of the overall system’s Heating Seasonal Performance Factor (HSPF).

Choosing Electric Duct Heaters for Supplemental Heating

There are several ways to mount and install your electric duct heater in a mini-split system. One of the most popular methods is to install the electric duct heater on the discharge duct of the air handling unit, effectively keeping the duct heater unit out of sight.

By choosing a device correctly sized to fit inside the discharge duct and handle the needed additional BTU load, supplemental heating is available when it is needed and not used when the outside temperature isn’t cold enough to need it. In order to maximize efficiency, you’ll need to choose an electric duct heater that offers modulation, such as Thermolec electric duct heaters.

Modulation allows the duct heater to rapidly switch on and off in response to the difference in temperature inside and outside the building it is installed in. Using a duct temperature sensor and an SCR control, the supplemental heater can provide just the right amount of thermal energy to satisfy the need for additional heat.

On extremely cold days, the heat pump outdoor unit shuts off while the indoor air handling unit continues to run. The air handling unit provides the air flow and the electric duct heater provides the right amount of BTUs needed to satisfy the heating requirements.

Heat pump systems are growing in popularity in today’s marketplace because of their impressive performance/efficiency ratings.  With many brands and types toting efficiencies of 400+ %, the energy savings is difficult to ignore.  Unlike the original heat pumps of years’ past (introduced in the 1970’s), today’s heat pump technology produces BTU outputs capable of providing full heating comfort for residential and commercial structures located in environments with outdoor design temperatures down to zero degrees Fahrenheit.   Incorporate supplemental heat, such as a Thermolec modulating electric duct heaters, and the result is a heat pump system with no outside cold temperature restrictions.

How Do Ductless Air Conditioners Stack Up Against Traditional Units?

ductless-air-conditioning

When it comes to residential and light commercial heating, ventilation and air conditioning, a fast-growing market segment is quickly developing into an industry-leading trend. Ductless air conditioners, also called mini-splits, are increasingly replacing the large, bulky window-mounted systems of yesteryear. Is this a passing fad, or are there real benefits to be enjoyed by installing one of these systems in your home or workplace? Read on to find out.

 Ductless Heating and Cooling: Advantages and Disadvantages

 The main difference between these new systems and traditional window air conditioners is that they are smaller, more efficient and more flexible when it comes to mounting and placement. Mini-splits allow homeowners to selectively heat and cool individual rooms according to their occupants’ desires by connecting a single outdoor unit to multiple indoor air controllers.

EMI-Air-handler-three-qrt-view

If you’re considering installing a mini-split air conditioner, you can expect to enjoy the following advantages:

 • Increased Efficiency—According to Energy.gov, up to 30 percent of air conditioning energy loss is due to air seeping through imperfect ductwork. This ductless air conditioners bypass ducts entirely, there is no subsequent energy loss, making these devices robust energy savers.

 • Easy Installation—Although ductless mini-split systems may seem complex to install, they are actually simpler than most packaged air conditioner systems. For example, installing the EMI Iverter by ECR International requires only a single three-inch hole be drilled into the wall. Since air conduits can be easily extended, the outdoor unit can be mounted anywhere for convenience.

EMI-presents I-verter

  • Better Aesthetics—Since the mini-split system does not rely on the location of windows, homeowners enjoy a much wider degree of options when it comes to interior design. A sleek indoor unit placed near a room’s ceiling is far less distracting than a heavy, noise-producing unit occupying an entire window.

Ductless air conditioners come with remote controls so that tenants and guests can adjust air flow and temperature without having to physically access the device. This means that both the indoor and outdoor units can be effectively hidden from view, which is very valuable and comfortable from a design perspective.

  • Quiet Operation—The ability to place the noise-producing outdoor half of the unit a safe distance away from the room being conditioned makes the entire process almost silent.
  • Greater Security—Window-mounted air conditioners are prime targets for intruders and trespassers. Although they are set in place rigorously, a properly equipped burglar can remove the unit and gain direct access to the inside of the building through the window. Ductless air conditioners offer no such entry point.
  • Increased Property Value—Appraisers consider mini-split air conditioners to be valuable assets to most homes and commercial structures. The presence of a robust and well-maintained ductless air unit translates into increased equity.

Four-way Cassette Indoor Unit Hang type view

Disadvantages to Ductless Air Cooling and Heating

Although this technology offers sufficient benefits to merit investment on any homeowner’s behalf, the units themselves can be more expensive than window units or evaporative coolers. In structures that don’t already have extensive ductwork installed, however, they are a much cheaper and more reliable option than installing a central air unit.

This price difference can be covered through energy savings over the estimated 12-15 years of an air conditioner’s service life, however, since even the best ductwork still produces energy loss. In some conditions, the fact that the outdoor unit produces water through condensation can be troublesome, but proper installation and placement takes care of that issue conveniently.

For more information on comparing mini-split ductless air conditioners with central air units, window units and evaporators, consult this useful infographic made by Energy.gov.

How to Use a Makeup Air Heater to Prevent Residential Backdrafting

Makeup Air Heater for Residential range hoods

It’s no secret that U.S. homeowners are becoming increasingly attracted to the idea of installing high-powered, commercial-quality kitchen equipment in their homes. The widespread availability and increasing affordability of these devices makes them a common sight in American kitchens.

At the same time, residential building contractors are designing homes that are more airtight than ever before. As a result, house depressurization and its associated risks are on the rise, making reliable makeup air solutions a necessity for many households.

Introducing House Depressurization and Makeup Air

House depressurization occurs when the air pressure inside the house is lower than that of the atmosphere outside. This creates a system of negative pressure. According to the EPA, this can cause exhaust gases, such as those produced by combustion-based kitchen appliances, to backdraft into the home. This accumulation is dangerous for residents and can promote the growth of mold, placing the integrity of the structure itself in peril.

In order to create an indoor pressure system that pushes exhaust gases out, home contractors typically install either engineered openings or mechanical ventilators. However, this approach does not provide adequate air infiltration for larger kitchen ranges.

According to the Pennsylvania Housing Research Center, exhaust hood systems capable of exhausting in excess of 400 cubic feet-per-minute (CFM) require the installation of a complementary makeup air system. The system must be automatically controlled to start and operate simultaneously with the exhaust system, in accordance with International Residential Code M1503.4.

Since the unit needs to both push air inside the home and heat the air to a temperature that does not negatively impact the home, an appropriately powered unit is necessary.

Calculating Power Requirements

Although simply choosing a makeup air unit with the same CFM-rating as the kitchen exhaust seems like a logical idea, actually choosing the right unit is a little more complex than that. This is mostly due to the difference in temperature the unit has to compensate for. In order to determine how powerful a makeup ventilation system is needed for a particular kitchen appliance, we need a few figures:

  • The exhaust rate of the device
  • The desired temperature rise
  • The heating capacity of the makeup air heater
  • The electrical power available(voltage/phase)

High-powered commercial cooking ranges generally include information about their exhaust rates, given in CFM. If that information is not immediately available from the appliance manufacturer, it may be necessary to arrive at an estimate based on the type and power consumption of the unit. The American Society of Heating, Refrigerating and Air Conditioning Engineers sells a handbook that contains the information needed to make this estimate.

Arrive at the desired temperature rise by subtracting the coldest likely design temperature from the home’s desired room temperature. This number will be multiplied by the CFM of the appliance and then divided by the number of BTUs-per kilowatt the makeup air system uses, arriving at the desired kilowatt performance of the heater.

HVAC manufacturers like Thermolec typically include BTU-per-kilowatt figures in their product specification sheets. So if a homeowner needs to displace 400 CFM even when the outside temperature is 20°F and the ambient room temperature is 70°F, using a Thermolec Makeup Air Model FER-8-6-240, the equation would look like this:

(70-20) x 400 ÷ 3.412 = 5.86 Kw

How do we know that this is the appropriate figure for that particular model? Going back to the specification sheet, we can see that the FER-8-6-240/1 has an 8-inch collar size and delivers a maximum of 6 Kw—meaning that it’s the correct model for this example even though it has a reported CFM of 300.

This is typical of the Upper Midwest, where state regulations explicitly require units be powerful enough to compensate for large differences in temperature. As a result, people who live in colder climates will need to adjust accordingly by calculating the actual CFM using the above equation.

 

ECR Announces the MAC/DCB Self-Commissioning Condensing Boiler

We are very excited to announce ECR’s new line of self-commissioning, condensing gas boilers.  The Utica MAC and the Dunkirk DCB are both 95% AFUE and use [AI] Control Technology. The [AI] Control self-commissions and continuously calibrates to ensure maximum efficiency at all times. It measures water temperature, flue gas temperature, flame signal and pressure – conditions that can impact the boiler operation and CO levels. The [AI] control will automatically shut down operation should these values exceed normal operating levels. This provides added protection for you and your customer.

Available in both a heating only model (125mbh input) or a combi (153mbh domestic input, 125mbh heating input), the MAC/DCB offers excellent turndown in both heating (5.7:1) and DHW (7:1).

The MAC/DCB offers an intelligent condensing approach to today’s residential heating and domestic hot water needs.  Give us a call for a live fire demo of this exciting new product from ECR.

EP Sales maintains a large inventory of Thermolec and Summeraire products and parts to service the needs of our customers.