HVAC - school me please

bowtieman55

bowtieman55

Well-Known Member
Joined
Jan 25, 2006
Location
Edenton, NC
So I just bought this house back in October. It's a two-story home, built in the '50s. It's got what I consider "central air". My issue is this. I turn the heat/air off when I leave for work in the morning. I turned it on yesterday when I got home at 5:50ish (to 70 degrees) and it ran ALL night NON-STOP. When I looked at the thermostat before I went to bed, it was sitting on 68* (or so). The living room couch is situated on the wall against the "heater" (which is in the kitchen), where the vent is on the wall (pictured). The floor registers put out warm air, but cool air is escaping from the wall vent and I feel it as I'm sitting on the couch. I could go on with this, but first I'd like some input on what type of system I've got, what I should expect from it, and what I can do to make it more efficient. TIA>:beer:

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Looks like you have a heat pump. What was the outside temp there last night? What was the temp inside when you got home? It may actually cost you less to leave the heat running all day. Heat pumps need some kind of backup/emergency heat to run when it is below 20 or 25 degrees outside because it is not efficient at all at this temperature. Some use electric heat strips. I have an oil furnace as backup in my house. The thermostat has an outside temp sensor and automatically turns the furnace on when it gets below whatever temp I set it at. I have it set at 20 degrees. It is not as hard for the heat pump to maintain a certain temperature as it is to raise the temperature in the house.
 
^ I just posted these pics as well. Forgot to mention that once and a while, while the heat is running, I hear what sounds like a "blow off" from the heat unit inside. Sounds similar to a blow off valve on a turbo or something. Is this common?
 
The cool air that you feel getting drawn back into the heater is the return air. It's getting pulled into the air handler (metal box in the photos), is warmed/cooled, then sent out in ducts to registers around the house.

Keep an eye on those lights on the bottom side of the thermostat -- one says Aux Heat, the other says Emergency Heat. AFAIK, both should mean that the heat pump is relying (at least partly) on a separate heat strip or furnace for supplemental heat. Basically what a heat pump does is reject heat. In the summer, it takes heat from inside, and releases it outside. In the winter, it collects heat from the outside and distributes it inside.

When it's too cold outside, the condenser (the big box outside) can freeze up. Mine is all automatic. So it'll run the heat pump as much as possible. Then sometimes it will turn the furnace on (while the blower motor is still running the whole time), and switch back over to A/C mode to warm the condenser. Basically taking some of the furnace heat to keep heating the house, while also taking some of it outside to thaw out the condenser. "Emergency" mode is a manual override that says it's too cold outside to mess with the heat pump, just use the heat strips or furnace all the time. That uses more electricity (generally speaking), but it's your only choice when it's really cold out.
 
The temp outside was in the VERY low 30s with a very strong wind, making it feel like the high teens. I assume that had alot to do with the unit having to over work to keep up with the cold/wind. I think I'm going to start leaving it on during the day (maybe around 65 or so?) that way it won't have to start fresh from a 50* inside temp.
 
Shawn, the "room" that the heat unit is in has a louvered door. I guess that would mean the unit is drawing air from both the living room and kitchen. What I was getting at it that I feel the cool air from the heater/return vent. There is a return in the floor upstairs as well. Those rooms don't warm as well because the ducting runs up into the attic space and then exit the registers that are placed in the ceilings of the upstairs rooms.
 
With the louvered door, you could experiment with blocking off all or part of the return vent on the living room side. It might keep it from feeling drafty.

I also edited my post above... added a bunch of other info. Hopefully that makes sense.
 
I was thinking of adding a black (fine) mesh screen behind the return cover. Would that help any? I'm not HVAC expert, but I would think the louvered door would be sufficient enough to eliminate the return vent in the living room...once we put up drywall of course.
 
Shawn said:
The cool air that you feel getting drawn back into the heater is the return air. It's getting pulled into the air handler (metal box in the photos), is warmed/cooled, then sent out in ducts to registers around the house.

Keep an eye on those lights on the bottom side of the thermostat -- one says Aux Heat, the other says Emergency Heat. AFAIK, both should mean that the heat pump is relying (at least partly) on a separate heat strip or furnace for supplemental heat. Basically what a heat pump does is reject heat. In the summer, it takes heat from inside, and releases it outside. In the winter, it collects heat from the outside and distributes it inside.

When it's too cold outside, the condenser (the big box outside) can freeze up. Mine is all automatic. So it'll run the heat pump as much as possible. Then sometimes it will turn the furnace on (while the blower motor is still running the whole time), and switch back over to A/C mode to warm the condenser. Basically taking some of the furnace heat to keep heating the house, while also taking some of it outside to thaw out the condenser. "Emergency" mode is a manual override that says it's too cold outside to mess with the heat pump, just use the heat strips or furnace all the time. That uses more electricity (generally speaking), but it's your only choice when it's really cold out.
Click to expand...


WOW...you been here or something? :lol: That sounds exactly like what this unit does. The thermostat is set on the "normal" side, though the "aux" light does sometime light up. You REALLY explained this well, and I REALLY appreciate it.
 
bowtieman55 said:
^ I just posted these pics as well. Forgot to mention that once and a while, while the heat is running, I hear what sounds like a "blow off" from the heat unit inside. Sounds similar to a blow off valve on a turbo or something. Is this common?
Click to expand...

what you are hearing is the system going into and running in "Defrost" mode, where it will super( sorta) heat the outside coil to melt any ice/frost that has built up.

if you watch it you may se a puff of steam when the fan comes on

The noise you may hear when it shuts down is the compressor relieving pressure by being forced to run backward by built up pressure in the system ( back pedaling )

normal, and is designed to do this.

when we first moved into our house, I had never been around a heat pump, no clue how they worked.

woke up one morning to it doing it's defrost thing, growling and throbbing , raising hell ( right under bedroom window )

looked out the window just as the fan kicked out the steam made from the defrost cycle. Scared the hell out of me, thought it was burning up...

shut it down and called someone who had a clue.

cost me $50 to get laughed at.......

another thing I learned,

when it is real cold out, keep an eye on the outside of the unit, especially if it's snowing or freezing rain. they can build up and ice covering that the DEfrost mode won't melt off.

if you see this, switch it to AC for about 10-15min. it'll melt off the ice and start working normally once switched back to heat.
 
Shawn, Kevin, thank you guys so much. You've both explained it very well; well enough for even me to understand and that's saying alot. :beer:
 
The dang unit is installed upside down. (newbie installer):rolleyes:

You are better off leaving the heat on when you are away. Maybe a few degrees colder than what you like it when you are at home. It has already been said, when the extreme cold temps come the heat pump will only maintain current temp in the house and will run all the time.
 
The other thing to do is to get a programmable thermostat. When set up properly it will automatically lower the temp when you're gone and asleep and raise it when you are there and awake. Mine cost me $30 and saved me $90 the first month I had it. The louvered door is generally for intake air for a gas fired furnace or water heater. Because it has to vent the fumes outside, it has to get air from somewhere to burn or the flame will go out. All else said above is correct. You might also go up into the attic and insulate the duct work so you get all the heat into the house instead of heating up freezing cold ducts.
 
All Above Advice Is Good & True!

Looks like most questions have been addressed. I'm confused on the Louvered thing; might want to investigate, & see just what it is Really for. Few more tidbits!= That unit is OLD, but like my 30 yr oldee, long as it runs, I can't afford to replace it. They are not very efficient! Your return/s, are usually where the filter/s go, also. Top floor; harder to blow heat down, that up. [ceiling fans] Your home may be poorly insulated. Wall insulation generally began in the 60s. Can be blown in. Attics,seldom have enough, & window & door casings, none! I don't have floor insulation, but with a full basement, I prefer the small leakage, to help heat/cool it. As for turning heat off, or down, remember, everything in the house, walls, furniture, ect, has to regain whatever temp., your trying for. I usually lower mine 5-10 degrees, when leaving. Looked at the program thermostats once; for our older units, cost is higher. I just use my finger! On the heat exchange; a proper unit will give you 12-15 degrees difference, between the output registers, & the intake, whether Heat or AC. My units heat, tops about 90drgrees; if it exceeds that, say 110-120, that means the aux. heat strips are ON. 1 more, = check ALL duct work & joints. Make sure it's properly sealed! And "DUCT" tape, is not made for ducts! Hope this helps!
 
Just something to add. I looked in my attic when I first bought my house (built in 1964) and it still had the original wool insulation. During the first winter the ceiling was cold to the touch. It had settled so much I could see the 2x's. I looked into insulating it myself and compared it to having it done. Found a guy that blows in white glass. He charged me $475 for 1370 sq ft 8 inches thick. It ended up being over a foot thick at the lowest point and it is guaranteed not to settle. It more than paid for itself the first year. My furnace went from running every 10 minutes or more often to every 30-45 minutes.
 
BACK TO IT! SUMMER EDITION! :D..........:confused:

Just noticed tonight that the house was warm...and it had been cool during the day. The "vent fan" was running, blowing ambient air through the vents...but the outside unit wasn't running. At all...o_O



dammit.....
 
Mine is sucking hind tit as well.

I think it's time to toss this one to the tweakers and upgrade.

It's been running all day inside temp is currently 81 that is down from 83, t-stat is set @ 78, was 75 before I left for the weekend and ran the stat up.

Guess we'll see if it does catch up.
 
78, wow. I set mine to 70, and with the kids running in and out all day it keeps it to around 72, any higher than that and I'd be sweating. If I can keep the doors closed it'll keep up and maintain 70.

bowtieman55 said:
BACK TO IT! SUMMER EDITION! :D..........:confused:

Just noticed tonight that the house was warm...and it had been cool during the day. The "vent fan" was running, blowing ambient air through the vents...but the outside unit wasn't running. At all...o_O



dammit.....
Click to expand...

T-stat crapped out?
 
OOH OOH OOH!!! I just figured it out. LOL


I turned the unit on (I had turned it off a little while ago because it wasn't acting right (cooling)...) and went outside. While it was running inside, the outside unit was not, but I could hear the fan motor trying to run. :(

So my fiance turned the unit off while I was outside, and I heard the fan motor switch off...no more electrical "buzz" from the motor. Also, the panel where the fan motor attaches was very warm. Calling the Home Warranty folks tomorrow...
 
So do you all suggest I call the Home Warranty people (which should have a service charge of $65..."Trade Service Fee") or call the local A/C repair shop?
 
See how much the fan costs. It's mounted by the four screws you have circled in your pic. If you can change an alternator on a small block chevy you can change that fan. There is a name plate (sticker) on it with the model number and info you'll need to buy another one. If that part of the unit is getting hot it's most likely because the fan is trying to run but is locked up or a bearing is seized and it can't turn, so it builds heat.
 
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