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emcmurray42
Limited Airflow from vent in Master Bedroom Addition
emcmurray42

My wife and I moved into a new house last summer. When we first saw the house in the spring, we did not notice that the third floor master suite had only one vent and had poor ventilation. It is very hot in the summer and cold in the winter. This is the only room in the house that has this issue. We have been using supplemental heating and cooling apparatuses to keep us comfortable and installed an attic fan to help, but nothing seems to really work all that well. Looking for a more permanent solution to this problem, but on a budget.

Dobbs
Re: Limited Airflow from vent in Master Bedroom Addition
Dobbs

In most of these "Insufficient heat in 3rd floor bedroom" cases several factors weigh against getting good heat to the 3rd floor: 1) the 3rd floor heating vent is almost always the furthest away from the furnace & thus much of the hot air is lost to the metal vent housing before it gets to the bedroom; 2) it is difficult to "zone" a forced hot air system so that the bedroom convector gets more heat during the heating furnace cycle; 3) it is somewhat difficult to ZONE a forced hot air heating duct system so that the bedroom gets more (or all) the hot air during a furnace heating cycle----however, forced hot air zoning has become a very popular project for forced hot air heating in recent years, although there's the cost of hiring a FHA heating contractor to make the needed changes---also check the 3rd floor BR RETURN vent to make sure you have good circulation of hot air coming INTO the BR & the cooled BR air being RETURNED BACK to the furnace to be reheated---hold a single thin strip piece of torn newspaper held against both vents when they are operating to see if you have a good air flow into & out of the BR---make sure there is no insulation or anything else blocking the SUPPLY and RETURN ducts in the BR.

Mild/hot weather cooling on the 3rd floor is another important issue in summer & for this you would have to explore the ceiling, as well as the exterior walls of the 3rd floor BR---is there an attic over the BR ceiling, & if so, is the BR ceiling shielded by at least a foot of insulation to minimize attic heat (and cold air in winter) from getting into the BR? Are the attic fresh air vents sealed in winter & opened in summer to control attic temperatures? Are the 3rd floor BR windows relatively new & double-pane to keep out the winter cold?? Old, drafty BR windows should be replaced; finally, are the exterior walls of the 3rd floor BR insulated with fiberglass or other insulation material?

Some of the sites below illustrate how zoning is accomplished with FHA systems; you may need the free-of-charge Adobe video insert to view the video (Adobe.com).

One concept behind zoning your forced hot air system is for a HVAC contractor to attach low-voltage switches to all of the heating vents in the house & control them by a zone switch at the furnace to open & close the vents until the thermostat in the main part of the house opens (closing the 1st floor ducts); a separate T-stat in the 3rd floor bedroom controls the amount of heat that part of the house receives---thus, if the T-stat in the main part of the house gets warm enough to shut down & close the vents in THAT part of the house, the T-stat in the 3rd floor bedroom (since that room is still cold) will continue to call for heat from the furnace until the set 3rd floor T-stat temperature is satisfied---then it too will shut down once the BR is sufficiently warm----low voltage wires have to be run thru all parts of the duct system so the ducts can be controlled by the Furnace control switches & the T-stats.

Depending on how handy you are, the basic concept to get more heat to the 3rd floor in winter is to INCREASE the air resistance on those 1st floor supply ducts that are pushing out too much heat (by inserting some simple metal/fiberglass inserts) & REDUCE the resistance on the 3rd floor duct (by making the duct slightly larger, or adding another 3rd floor supply duct) to increase the amount of heat going up there.

To find qualified HVAC contractors in your area to get estimates for the job, Google "best HVAC contractors in (your city) Illinois"; also use word of mouth by calling relatives & friends to see if they have had recent furnace servicing with someone they remember as doing a good job at a reasonable rate; if you belong to Angie's List or know a relative or friend who does, by all means use this resource before you decide to hire anyone; the Better Business Bureau (free of charge, I think) is also worth checking out; Angie's List does charge a fee for their services.

http://greenhomeguide.com/askapro/question/how-do-you-zone-a-forced-hot-air-heating-system-furnace
http://www.youtube.com/watch?v=F2EJLhZ939A

ordjen
Re: Limited Airflow from vent in Master Bedroom Addition
ordjen

I am surprised at how many homes are built without individual air returns in every bedroom. If your BR does not have a return and you sleep with the door closed, you are going to be warm in summer and cold in summer. If not, the easiest thing is to keep the bedroom door cracked open a bit, otherwise have a return added to the bedroom.

If the existing system cannot be tweaked without great effort and expense, you might look into a small split system heat pump which will service only your bedroom with suplimentary heat and cooling. Such a system might actually be economic in that it allows individual rooms to be heated/cooled while allowing the whole house system to be scaled back.

ed21
Re: Limited Airflow from vent in Master Bedroom Addition
ed21

Also make sure the room is properly insulated. If it's an older house and the room has sloping ceilings, you may be out of luck adding much insulation. Ordjen's suggestions make a lot of sence.

Mastercarpentry
Re: Limited Airflow from vent in Master Bedroom Addition
Mastercarpentry

Often a 1/2" gap is left under the door to provide a path for return air; it's usually adequate. Almost as often someone will add carpet, see the door clears it, and think that all is well when it isn't. You may have an insulation problem and you do have a HVAC problem, so what I'd suggest is to start with a HVAC inspection which may include balancing the system, adding or upgrading the duct or vent, or more. After that get an energy audit to identify insulation issues- many utility companies offer a basic audit for free. At least get a visual inspection from an Insulation contractor. And as always get several bids before starting work.

Phil

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