Air flow/hall thermostat problem

11 years ago

We recently bought a 1960's ranch house, built on a slab in a southern community. The Hvac is a heat pump that works well except for one poblem. The thermostat is in a hall which has no heat vents but two large return vents. If all the doors off the hall are clsoed, it becomes a closed room with no heat vents so the system runs a long ti e to reach the set temp so that the rooms of the house are either too hot (if heater is running) or too cold (if a/c is running). We can get around this by playing with leaving a door open or patially open which lets some heat get to the thermostat so it gets to temp soon after the rooms are warm. Sometimes however, when it turns on and sucks air through the return vents in the hall, the open door will slam shut.

We are thinking there must be some kind of adjustable door vent we could place in one of the doors to regulate this a little more precisely and to avoid the door slamming.

Anyone have the right product or solution? Thanks.

Sort by:Oldest

Comments (8)

geoffrey_b
11 years ago
Relocate the thermostat. It's not that difficult.
ionized_gw
11 years ago
You have one air handler/heat pump that is served with two returns in the same hallway?

It seems like your base problem is that you have inadequate return air flow. With supplies elsewhere and the returns in the hall, you need to have air flow from ALL the rooms into the hallway where the returns are. The typical low cost way too do this is undercutting the doors. Alternative methods are to install jump ducts (transfer grilles, transfer grills, transfer grates,...) in the walls or through the attic space. Ideally, you have a return in each room, but that is costly. The door undercutting is often subverted by later carpet or flooring installation.

If you have pressure differentials like you describe, opening one door is not going to work very well. You pressurize the rooms with the doors closed and depressurize the hallway or what ever room the returns are in. What happens then? Air blows right out of your house from the pressurized rooms, into the attic, past leaks around the windows and wherever there is a little crack or hole. In the room where there is negative pressure, outside air gets sucked in, from the attic,.... The sucking air in from a hot/humid outdoors sometimes results in condensation and wood rot.

For now, leave all your doors open. Maybe later undercut them to an area equal to the supply grill size in that room or install grills, jump ducts or transfer ducts.
Related Professionals
California General Contractors · Grand Rapids General Contractors · Fresno General Contractors · Jackson General Contractors · Daytona Beach Home Remodeling · Panama City Home Remodeling · Chattanooga Home Remodeling · Augusta Home Remodeling · Wilmington Bathroom Remodelers · Fort Myers Bathroom Remodelers · Oklahoma City Bathroom Remodelers · Danbury Bathroom Remodelers · Dubuque Bathroom Remodelers · Mansfield Bathroom Remodelers · Orange County Bathroom Remodelers
myrtle_59
Original Author
11 years ago
Thanks for the explanation, ionized.
myrtle_59
Original Author
11 years ago
Thanks geoffrey, we considered moving the thermostat but i think ionized has pinpointed the issue.

Btw, i think somewhat recent carpet in the bedrooms may have caused or exacerbated the problem.
energy_rater_la
11 years ago
good post Ionized!

the rooms off the hallway need return air pathways.
doors undercut up to 1" will allow air from
one supply to return.
but if you've just carpeted, then the carpet
blocks the air flow.

in a year or two you'll see ghosting under
the doors where the dirt filters through
the carpet on its way to the hallway return.

you could add transfer grills in the walls
above the doors, or to the side of the doors.
don't line them up though, make one higher
and one lower. this will eliminate light transfer
and help with noise transfer. if you put
them back to back, you'll have both noise & light
issues.

or you could do a jump duct from each room
into the hall.
supply boxes, duct, supply grills. the duct
"jumps" the air from bedroom to hall.
this would be an attic install, and the least
intrusive solution.

best of luck.
ionized_gw
11 years ago
Energy, with transfer through the walls, do you recommend duct between the grills or do you just use the stud space?
JamesMcKImm
11 years ago
Best and cheapest option would be to re-locate room stat/thermostat. You can get it wireless option and easily control the temperature with your smart phone or ipad

Here is a link that might be useful: London Plumber
energy_rater_la
11 years ago
just use the stud space.

if you have space you could locate
the grills over the door.

if you have more than one supply grill
in the master suite, you may need to
increase size or add two sets of transfer grills

see if solving the return air problem
makes the tstat issues better.

best of luck.