More than custom designer range hoods

http://www.customrangehoods.ca/In addition to designing unique designer range hoods we also supply standard range hoods similar to those found in appliance stores - the big difference between our range hoods and those in the appliance stores is our range hoods use the finest materials, have variable speed blowers that are included in the canopy and matched to your cooking equipment based on the cooking equipments power, dimmable halogen lights and a choice of stainless steel baffle filters or mesh filters.

We also supply inserts for canopies - stock sizes or custom sizes.

Range Hoods and Make Up Air Systems

Why does your range hood need a make up air system


What is make up air for range hoods

High cfm range hoods take out large volumes of air from the building space. If this air is not replaced at the same rate that it is expelled, the building will experience a negative pressure (the air pressure outside the building is greater than the air pressure inside the building).

A few common indicators of a negative air pressure problem are:

•Exterior doors are hard to open

•Drafts around doors and windows

•Range hood may not be drawing vapours properly

•Smoke from a wood burning fireplace is pulled into the room

Custom Island Range Hood - Claret Red with polished brass trim

A make-up air system replaces the air that is expelled by a building's exhaust system, maintaining the proper balance between inside and outside air pressures while also providing many other benefits:

•Provides conditioned air back into the home - cooled in summer, warmed in winter, de-humidified

•Aids the proper functioning of range hood exhaust fans

•Improves air quality

•Stops backdrafting of fireplaces, natural gas fired furnace and hot water tank exhausts

In the colder northern hemisphere where the windows and doors are closed through the winter and where the homes have become increasingly air tight building inspectors are paying more attention to the need for make up air where high powered range hoods (some areas as little as 600cfm) are installed.

Interesting consumer discussion and experiences on magic lung vs baffle filters

Follow this link to read unbiased consumer discussions on the magic lung filter system vs the baffle filter system - we run into this issue all the time with range hood filters - people are sold on the "magic lung koolaid" as someone put it, the less expensive hood and don't appreciate that baffle filters are by far the best form of filtering a range hood:


- Easy to clean

- 96% efficient

- Best fire spread retarder

- Realtively quiet



http://ths.gardenweb.com/forums/load/appl/msg0208411027007.html?22




Baffle filters - capture 96% of solid material



What you need to know to install range hood ducting

Firstly we need to understand a critical element in range hood ducting – static pressure in the kitchen hood duct configuration

Follow this link to the author for additional useful range hood installation information

Static Pressure:
Inside every duct, there is a constant pressure being exerted at any point from all directions. When a range hood fan moves air through the duct, the air counters resistance from this pressure which is known as static pressure. Thus, kitchen venthood fan has to have the ability to overcome the static pressure in a duct so as to effectively duct stale air to the outside of your home. This can be done by calculating the equivalent duct length of any duct for the range hood ducting.

Calculating Equivalent Duct Length (EDL):
Simply measuring the length of a duct is not enough to know how much static pressure an exhaust fan has to overcome. Ducts may have one or more elbows, turns, or wall caps which add to the static pressure in a duct. Thus, you have to calculate the equivalent duct run and not the actual duct run so as to size an exhaust fan properly.

The static pressure in any duct run differs according to the material of the duct, number of elbows and turns, exterior wall cap and wall jacks etc. Listed below are the standard values for different duct components.

• Smooth metal duct:
• Actual duct length x 1 (eg. 3ft of duct = 3EDL

• Flex aluminum duct: Actual duct length x 1.25 (for 4”diameter duct)
• Actual duct length x 1.50 (for 6”diameter duct)

• Insulated flex duct: Actual duct length x 1.50 (for 4”diameter duct)
• Actual duct length x 2.00 (for 6”diameter duct)

• Wall caps/roof caps/back draft dampers: 30 feet for each cap (for 4”diameter duct)
• 40 feet for each cap (for 6”diameter duct)

      

• Elbows and turns: 15 feet for each (for 4”diameter duct)
• 20 feet for each (for 6”diameter duct)

For example assuming 6” ducting for the kitchen range hood:

 A rule of thumb is that a duct run for a range hood should not exceed 100EDL


Using the above values, you can calculate the equivalent straight duct length that an exhaust fan has to overcome so as to push stale air outside your home and counter static pressure effectively.

Ventless or Vented range hoods - sometimes you have no option

A ventless hood is the last resort if you cannot find a way to get the fumes from cooking on the range to the outside. While such a hood will trap grease and will kill odors (while the charcoal in the filter is still active - very important - charcoal filters have a limited lifespan) it will not reduce the condensation and smoke caused by cooking. This is especially a problem if you cook with gas that generates a lot of condensation. Depending on how much you cook you may need to replace the carbon filters every 2 - 6 months to deal with the cooking smells.

While it may cost a little extra, over the years you will benefit enormously from a properly vented range hood - you will also save money by not having replace the carbon filters. http://www.customrangehoods.ca/

Make-Up Air Systems

Why do we need Make-Up Systems


1. Our homes have become extremely air tight with the result that fresh air replacement from outside via air seepage, can no longer be relied upon to bring in clean air. The result is that the air quality on our homes becomes very unhealthy. So in order to improve this air quality we need to find a way to bring in fresh clean air and evacuate or clean the stale air. This is achieved with make up air systems. You can liken the situation to living inside of a sealed plastic bag - without make up air - particularly in winter the air quality becomes very poor and unhealthy.

2. Now if you add a kitchen range hood that evacuates large amounts of air, the situation actually becomes far worse - we are exhausting the air from our sealed plastic bag example above and without any make up air bringing air back into the "plastic bag", the environment actually becomes depressurized - the pressure inside the bag rapidly becomes less than the pressure outside - the results can be catastrophic as our heating equipment such as fireplaces, hot water tanks and furnaces rely on balanced air pressure to exhaust the poisonous gases to the outside. When a home becomes depressurized these gases actually get drawn back into the environment with the lowest pressure - the "plastic bag" - our home.

So what do make-up air systems do. Very simply they are linked via pressure switches or electronic switching to suck air back into the home as it is exhausted and to constantly bring in a supply of fresh air. By way of example, when we use our range hood that is say exhausting 600cfm (cfm = cubic feet per minute - visualize a block of air that is 12"x12"x12" - that's 1cfm), now with a 600cfm range hood that is 600 of these blocks of air every minute leaving our "plastic bag" type home - under this situation the average home would attain a negative air pressure situation very very quickly and the dangerous gases from our appliances would invade the home and its occupants.

The make-up air system would be activated before this negative air situation has had chance to develop and would pull air back into the home to replace the exhausted air - make-up air system must of course also heat this air before bringing it back into the home in winter and cool it in summer.

So that very simply is how make-up air systems work and why we need them.

Below please find copy from the Uniongas website on make-up air:

http://www.uniongas.com/business/gastechnology/productsservices/iaq/iaqMakeupAir.asp

In most cases, the need for ventilation air is achieved by the addition of a make-up air unit(s). These units are essential to a building's mechanical operation and to the health and comfort of its occupants. By providing a controlled quantity of clean, conditioned ventilation air to common areas of the building, they:

•Reduce drafts, dust and dirt entering the building;

•Replace air exhausted by equipment such as kitchen or bathroom fans or process or industrial exhaust fans;

•Reduce odours.

A make-up air unit consists of a fan and a heat-exchanger component as well as filters and dampers. Gas-fired units are available in many sizes to meet building ventilation needs and are supplemented by a variety of control components (both temperature and air quality) and operating strategies. Control systems are important as they can be designed to handle 100% outdoor air or to mix outdoor air with re-circulated indoor air. Mixed air systems can be electronically controlled. Heating can be provided at fixed or variable heating rates and control strategies for these systems can also vary from simple manual systems to computerized options.

Depending on the application, make-up air units can be installed either on rooftops or indoors. High-rise buildings generally install their units on rooftops, where they are mounted on either a curb or metal roof frame, then connected with the building's electrical and duct work system. In walk-up apartments, units are often installed in utility or attic rooms and conventionally ducted to feed air to the corridors and common areas.

A variety of features are available that will enhance the performance of make-up air units, including:

•Heat reclaim coils or heat wheels, to recover waste heat;

•High efficiency filtration to maintain air quality and automated controls governing both temperature and air quality to minimize energy consumption - including capacity control utilizing two-stage or modulating gas valves that will match the unit's output with your building's needs.

Electric make-up air heaters can also be converted to natural gas by installing a heating coil in the duct, which is heated by hot water that is supplied by a gas-fired boiler.

Baffle or Mesh Filters

The question is often asked what is the difference between baffle and mesh filters. Apart from the appearance baffle filters are more efficient than mesh filters because they permit the easier flow of air through the filter. When air passes through a baffle filter it must make 2 x180 degree turns and in so doing must speed up to make that turn - when the air speeds up it deposits the grease and moisture onto the bend in the filters. Baffle filters are also better at eliminating the posibility of a fire running up into the ductwork.

Baffle filter










Mesh filters on the other hand consist of anywhere from 3 to 6 layers of fine mesh laid one upon the other - so the air is forced to pass through tiny holes creating more noise and typically less efficient than baffle filters.

A Modern Aire Mesh Filter













Baffle and mesh filters are normally dishwasher safe and it is very important to wash them both on a regular basis to avoid not only a fire in the filter but also to ensure grease is not sucked through to the blower and inside of the hood.

Not all mesh filters are created equally - Modern Aire uses high quality stainless steel that has holes punched on the outside - this protects the finer mesh from damage. Most of the mesh filters on the market do not have this protective layer of stainlees steel and the finer aluminium mesh gets easily damaged when placing in the dishwasher.

Re-Circulating Range Hood Venting

Recently i have come across a fair number of people doing kitchen Reno's' who have no way of venting the hood externally - i therefore decided to write a few sentences on the topic to try and help them out.

No way of venting or not allowed to vent
I guess the first question on most peoples minds is - Why should i vent the hood in the first place - this article will help you with that question. Typically folks with this kind of problem are in condo environments where they are not allowed to punch a hole into the external wall or even go up through the roof. They really only have one option - they must re-circulate the air. This entails sucking in the air via a range hood that firstly captures the grease and moisture with the grease filter, it then ideally passes the filtered air through a carbon filter and then returns the cleansed air back into the kitchen. So as you can see this is a two stage process of removing the grease and moisture from the air and then the carbon filter removes the odors. So when planning or purchasing your range hood ensure that the hood has at least 5 layers of fine mesh grease filter to collect the grease and moisture and an optional carbon filter - I am sure you have seen those grease filters that have big gaps in them - this will not do the job and is typically found on the lower end of the range hood scale. The grease filter must be washable - i recommend placing the grease filter (which is typically layers of aluminum mesh with a stainless steel frame) in a dishwasher weekly depending on cooking style. The carbon filter is a replacement item that should be replaced after a month or two depending on cooking style. The most important thing in the grease/carbon filter relationship is washing the grease filter otherwise the grease ends up getting sucked into the carbon filter and negating its value.

If anyone has questions or needs advise please feel free to visit me at:

http://www.customrangehoods.ca/

go to the Contacts Page, send me a question or just post a response to this blog.