There is a time in the last few days of summer when the ripeness of autumn fills the air. IP address: 54.189.37.104Time: 2016-09-24T13:18:44ZURL: http://www.youtube.be/watch%3Fv%3DAiQMUqdEBdI%26feature%3DrelatedImage 1 of 2 This limestone-covered range hood looks pretty — but does it actually work? Last month at ACI in Baltimore I attended an interesting session about range hoods. It was chock-full of useful information and very well presented (often a hit-or-miss proposition at many conferences). I was planning on waiting until the slides were available online, but I’m anxious to share this information. I will update this post when I have a link available. I thought I knew what range hoods do, and I had the basics down, but it was interesting to find out all the nasty stuff that ranges, particularly gas ranges, create when in use. There’s moisture from whatever we are cooking, as well as from the fuel as it burns. I get that carbon monoxide (CO) is produced as the burners start.

What I didn’t know about was the nitrogen dioxide (NO2), ultrafine and fine particles, and most surprisingly, formaldehydeChemical found in many building products; most binders used for manufactured wood products are formaldehyde compounds. Reclassified by the United Nations International Agency for Research on Cancer (IARC) in 2004 as a “known human carcinogen.", a byproduct of heated oil. Clogged holes on greasy burners change the air/fuel mixture, leading to incomplete combustion and more CO. Then we get to the oven. More CO is produced as burners cycle on an off in gas ovens. Any food residue on the oven walls turns into tiny particles when heated that are released into the air and breathed in by a home’s occupants. The hotter the oven, the more particles are released. The very high heat of self-cleaning ovens creates even more of these nasty particles. Using a well-functioning range hood, vented to the outside, helps keep some these nasty things out of our lungs. And staying out of the house when your oven is on self-clean mode is a good move.

Makeup Air for Range Hoods The Hazards of Cooking With Gas Q&A Spotlight: Dealing with a High-Capacity Range Hood Q&A: Cooktop ventilation in a Passivhaus home Fine Homebuilding video: Makeup Air For Commercial Exhaust Fans in Homes Fine Homebuilding Q&A: Range hood sucks smoke from the fireplace The air in homes with gas stoves don’t meet EPA standards for outdoor air quality (yes, I said outdoor) much of the time. alive air purifier instructionsAbout 40% of these homes exceed standards for NO2, 20% for formaldehyde, and 5% for CO. Apparently the EPA thinks it is OK to have poor indoor air quality inside a house, but not outside.homedics air purifier and humidifier OK, so now that we are terrified to even turn on our stoves, what should we do? .20 air rifle cleaning kit

We still need to eat. Well, start by using a range hood. The study that this presentation was based on evaluated a variety of range hoods both in homes and in a lab where they could adjust heights and depths, and switch out different hood types. The conclusion was that most of them don’t work very well, and the ones that do work are so big that they are probably backdraftingIndoor air quality problem in which potentially dangerous combustion gases escape into the house instead of going up the chimney. something in the house. (For more information on this problem, see Makeup Air for Range Hoods.) The things that make a range hood work are a large capture area – the bigger and lower the better – and a minimum of 200 cfm of air flow. Unfortunately, most hoods aren’t deep enough to cover the front of the cooktop and most of them are placed higher than they should be so people don’t bang their heads on them. (I’ve done it plenty of times.) And we haven’t even talked about those recirculating hoods that are just noisemakers.

One interesting, but rather obvious, solution is to use the back burners, as that is where the range hoods draw the best. Also, it is a good practice to start the hood before you turn on the burners to exhaust CO. High-volume hoods should be used at their lowest settings, and if they don’t have a makeup air system (and how many do?) in a tight house, opening a window helps avoid backdrafting. Like many things we learn about how homes work, range hoods seem to not work properly more often than not. If we can convince homeowners to buy (and manufacturers to offer) large, low-volume range hoods, install them low enough to work effectively, and convince homeowners to operate them properly, then we might make some progress on improving the air quality in our kitchens and homes.Looking to find HVAC contractors in your area? Get free quotes » Plenty of people who run central air conditioning systems in Houston (and other cities where hot weather dominates the calendar) complain about how their air conditioning doesn’t do a good job keeping their home comfortable, and, in most cases, they are probably right. 

There are so many things that can and do go wrong with central HVAC systems that it’s tough to know where to start, but I’ll give it a shot. 1. Leaky ductsProbably the single biggest cause of poor A/C performance is leaky ducts.  Ducts are kind of like pipes – they move air through them and deliver it at the end.  We notice when our water pipes leak because we see the damage immediately, but we rarely see the effects of leaky ducts directly; rather it sneaks up on us over a long period of time, and many people never figure it out.  When ducts leak, they let cool air out into whatever space they are in, often the attic, which, in case you haven’t noticed, can get pretty hot in the summer.  Ducts need to be sealed at all the metal-to-metal and metal-to-flex connections – not at the insulation.  Have someone pull back all the insulation and put a nice thick layer of goopy mastic at all the joints, then replace the insulation.  Don’t use duct tape. It won’t work, and the metal tape designed for ducts doesn’t do a whole lot better.2.

Too much or too little refrigerant chargeSomething else that can make your AC inefficient is the refrigerant charge.  Traditional A/C uses a refrigerant that transfers the heat between the inside and the outside.  Every system is designed to work efficiently with a specific amount of refrigerant, and too often there is either too much or too little in the system.  A good HVAC contractor can check the charge and either add or remove some to make sure it is set correctly.  A wrong charge can decrease the efficiency by 20-30%, so checking and fixing this can make a big difference.3. Installing the wrong filterMake sure you have the right filter installed.  Most HVAC systems were designed to use one of those cheap fiberglass filters to clean the air.  Unfortunately, they don’t do a very good job at it, so many people go to their local hardware or big-box store and buy a super-duper high efficiency pleated paper filter GUARANTEED to keep their air cleaner.  It might actually keep the air cleaner, but it also cuts down on the air flow, making the whole system less efficient. 

They can make the cooling coils freeze, creating even bigger problems.  If you really need a good filter, first seal the ducts to keep the air in and the nasty stuff out, then get a 6 inch thick pleated filter which fits into a special cabinet which your HVAC contractor can install for you. They do a good job filtering the air and don’t cause the same problems with the air flow.4. Not enough return ductsThe last thing I’m going to talk about is return ducts.  Lots of HVAC systems are installed with a single, large return somewhere in the middle of the house.  Each room has its own supply, but the air is supposed to, sort of magically, slide under the door and get back to the big return duct to be cooled again.  The problem is that the space under the door usually isn’t big enough, so the air doesn’t flow through the whole house well enough to keep things evenly cooled.  Some rooms are hot, some are cold, and none are just right.  Consider having an HVAC contractor add some extra return ducts in bedrooms and other rooms with doors (except for bathrooms) to give you better air flow and increased comfort.