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Installing Jumper Ducts to Make Bedrooms More Comfortable

 

Climate control and comfort in a home depends on much more than the size, power and efficiency of the heating and cooling system. It depends on proper insulation, air sealing and, above all, it depends on the air duct's distribution and adequate balance between return and supply ducts. Larry Janesky, founder of Dr. Energy Saver, was recently in Central Florida helping a homeowner with a high cooling bills, and uneven temperatures around the house.


Jumper Ducts

Jumper Ducts

 

One of the big problems with heating and air conditioning systems in any climate is that they are not pressure balanced throughout the house, with an even distribution of supply air to each room and return air to each room. In this case it is very common around here. We have our air handler, so this is our air conditioning and we have our return coming in the bottom and our supply duct going out the top. Now the supply trunk line runs through the attic and supplies are branched off to each room. Let's take a look what the return air duct is doing.


Air Outside The House

Air Outside The House

That is not a good thing; we are pushing conditioned air outside the house. Let's measure and quantify this difference in pressure. When this bedroom door is open the door opening itself serves as the return because the central area is where we are drawing air back to the HVAC system; so this really is our return. The air can come out of the supply duct into the bedroom and run out through the hallway, but the problem is when we close the door we no longer have a return into that bedroom and this could be a problem.


Read Full Transcript:

Hey, I'm Larry Janesky from Dr. Energy Saver. You know, we have Dr. Energy Savers all over the United States; we have so many different climates. We have coastal climates. We have mountain climates. We have dry hot climates like in the southwest. We have cold climates. We have mixed humid climates and we have hot humid climates, as represented by where we are today in Central Florida. You know the purpose of a home is to create comfort for the homeowners, for the occupants and what do we as far as comfort? Well, we like it between 70 and 75 degress. We like low relative humidity and in any of the climates we always have challenges. We want to keep heat out of the building in some climates, or some seasons, and other seasons, when we keep heat in the building, we want to control humidity. Well Florida homes here in the South East have lots of problems.

Let's take a look. One of the big problems with heating and air conditioning systems in any climate is that they are not pressure balanced throughout the house, with an even distribution of supply air to each room and return air to each room. In this case it is very common around here. We have our air handler, so this is our air conditioning and we have our return coming in the bottom and our supply duct going out the top. Now the supply trunk line runs through the attic and supplies are branched off to each room. Let's take a look what the return air duct is doing. Here we are just outside the utility room, and we see a return grill here and a return grill here. Well, there are no other returns anywhere else in the house. This means that we are drawing all our return air from these common areas, from the kitchen, from the living room, from the dining room and from the central hallway. When bedroom doors are closed we have no return air coming back from the bedrooms. Let's see what happens. Here we are in one of the three bedrooms of this house. In here, we see a supply duct, so from the duct system, the condition there comes out of this duct, but there is no return duct in this bedroom. What will happen is the supply air will blow up the bedroom so we will have positive pressure in this bedroom and force more air out through the sliding glass door, through any windows, through the walls, through the ceiling into the attic. That is not a good thing; we are pushing conditioned air outside the house. Let's measure and quantify this difference in pressure.

When this bedroom door is open the door opening itself serves as the return because the central area is where we are drawing air back to the HVAC system; so this really is our return. The air can come out of the supply duct into the bedroom and run out through the hallway, but the problem is when we close the door we no longer have a return into that bedroom and this could be a problem. Let's measure it. I have a device here that quantify the pressure difference across the door and if I close this door that I have 5.4 Pascals of negative pressure. 2-1/2 Pascals is acceptable we have the air handler running supply duct is pumping air into this bedroom, but no return air is coming out because the door is closed. 5.3 Pascals is a negative pressure that means that side has more pressure, this side has less pressure that means, and that side is going to push air out of the house and on this side, the main area, the living area, the kitchen and so forth, was de-pressurizing it. We are taking more air from it than we are putting back into it. We are putting disproportionate amount of air into the bedrooms that cannot get back.

So, what we are doing in the main kitchen and living area is sucking air in through the walls, through the windows and doors from the attic and from any air holes that lead to the outside to make up for it. Having unbalanced air pressure in the house, because the duct system is not designed properly, is going to increase the amount of air leakage in the house, the exchange of air between inside and outside. It is going to make our home feel draftier. It is going to draw hot humid air form the outside into the house that we then have to pay electricity to run our air conditioning system, to remove that moisture, to cool that air. It is just a not good situation; so what we are going to do is fix this problem. Now, many homes north, south, east, west will have a central return from the HVAC system in a central hallway and we still have the same problem here. There are supply ducts in various rooms and no return ducts in those rooms. When we close those doors, our pressures are way off. So what we are going to do to fix this problem is add a return grill in each of these three bedrooms so that supply air can get in and return air can get out and we balance the pressures, not only in those bedrooms when the doors are closed, but also in the main body living area of the house. So, we have less air exchange from inside to outside one way or the other. Okay so now we have added our return grills as you can see in here. We put that return in this room and we put returns in these other two bedrooms three extra returns and now let's see before we had 5 Pascals of negative pressure in here or 5 Pascals of positive pressure we should say in the bedroom with the air handler running.

Now we have added the returns, let's see what happens now. Look at that under 2 Pascals of pressure, 2 Pascals before we are about 5. So what is happening is the new return that we put in, you can see it in here, is now allowing air to get out of this room back the air handler so that we don't blow up the room with pressure. When we blow up the room with pressure because we don't have a return and only a supply what happens is there is less air comes out of the supply because it has got positive pressure against it backing it up against the supply ducts so less air will come out. Now we have less positive pressure, more air will come out of the supply duct and the air could get back out of our return duct so now if we look at this room and this room was about 5 Pascals before. We have 1-1/2, less than 2 Pascals of positive pressure in this room; so the return ducts that we put in there were jumper ducts. They did the trick. We hope this video has really helped you get an understanding of what we do here. We hope your home is the next one we have the opportunity to work on. Give us a call today.

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