Is the activent really going to save me 30% $$$ per year on energy bills?

[rollandelliott]

http://www.theactivent.com/save.html

The above product claims "up to" 30% energy savings per year. Their test data is based on ONE home. Has anyone used it? Do you recommend it?

My home has ONE big central air supply and one return, that cools the central great room very well, but the 3 peripheral bedrooms tend to be a little warmer. I probably need to undercut the doors to get some more cooling. My home has 10 vents. At fifty bucks a vent, it adds up. But theoretically I'd only need vents in the Great Room. Once that reaches say 75 degrees F, then the activents would close and then the peripheral rooms would be cooled more.

Here's why I dont' believe the hype. My thermostat is in the Great Room. Right now it cuts OFF early because the Great room cools down quickly while other rooms remain warmer. If I install the activent, wouldn't it make the HVAC system run longer since the peripheral rooms would receive the balanced of the air, thus making it run a bit longer?

[westbranch]

Rolland we don't have A/C, just heat where we manually set all our duct vents specifically to get the desired temp in each room. took a while to get it right but ... it works.
House temp is controlled by a programmable thermostat.
Don't see why A/C would not work the same or may need slight seasonal adjustment.

hth

[solar_dave]

AC can be trickier in that heat gain changes over the course of the day. I know properly placed thermostat and open doors on the west face rooms helps a lot to keep temps balanced.

[waynefromnscanada]

If there's an outlet for either heating or cooling in a room and the door is shut, and if there's no return duct for the air being pumped into the room, then the circulation stops, except for whatever leakage can escape around ill-fitting doors, windows etc.
Solution? Install return air ducts, or cut the bottoms off the doors, or leave the doors open. Otherwise it's like blowing into a balloon, only a little goes in, then everything stops until you make a hole in the balloon.

[techntrek]

I have another solution. I had a similar problem when we moved into our house. The upstairs thermostat was located in the large, open hallway. However, the two rooms with the greatest heating and cooling loads (west/southwest side of the house, and most walls/ceilings are externally exposed) were always... too cold or too hot. Like your great room I had to make the hallway either a fridge or sauna to be comfortable elsewhere. Add on the use of a wood stove in the winter which prevented the hall thermostat from ever triggering because it was nice and toasty, plus we sleep with the bedroom doors closed for fire safety. A bad situation in every direction.

Easy solution, I moved the thermostat into our bedroom. During the day when the door is open it triggers normally for A/C, or not at all in the winter most of the time since the heat from the stove will drift in. At night it ensures the bedroom (and the other bedrooms) stay properly warm or cool while letting the hallway stay mostly unregulated. In the winter the hallway acts as a large heat reserve so when the heat pump kicks on it doesn't have to work as hard (the return vent is right there in the hallway.

So, you could try moving your thermostat into one of your back rooms.

[rollandelliott]

I think I will move the thermostat to the bed room. My next crazy idea is to buy some zone control dampers and hook them up to a leviton programmable timer switch. I'll program it so the dampers close the vents at night from 10pm to 6am and then are open during the day. Together with a programmable thermostat it should save some money. It will cost about the same as the activents but there wont' be any batteries involved and thus no human that forgets to replace them.

[inetdog]

I think I will move the thermostat to the bed room. My next crazy idea is to buy some zone control dampers and hook them up to a leviton programmable timer switch. I'll program it so the dampers close the vents at night from 10pm to 6am and then are open during the day. Together with a programmable thermostat it should save some money. It will cost about the same as the activents but there wont' be any batteries involved and thus no human that forgets to replace them.

I also have some experience with a zone control system (and the design idiocy of putting the bedroom wing thermostat in the hallway where it gets none of the heat or cooling information from the bedrooms themselves.) Never did move it though.
The one thing I would caution you on is to make sure that there is enough open vent area with the bedroom vents closed to still allow sufficient airflow through the furnace or A/C. Too much restriction can cause problems or require you to increase the blower speed to allow proper operation.

[rollandelliott]

I guess I'll have to get the idiot guide to air flow through ducts to figgure this out.

[inetdog]

I guess I'll have to get the idiot guide to air flow through ducts to figgure this out.

The well informed hobbyist's guide would be more useful, I am sure.

The heater and or A/C unit installation documents should have some information about required airflow (with the purpose of guiding the installer to select the right fan speed tap), so all you may need to do is measure some static pressures under operation with a simple water tube manometer.