Help - My Air Conditioner Won't Keep Up

[maxwelhse]

I'm probably repeating myself but anyway... Its going to be HOT out this week... Make sure your outdoor unit for your AC is clean and all obstructions are cleared. Take a few minutes to hose it out and trim back the grass around it. Its going to work extra hard this week.

Your AC will thank you and so will your SO.

Can confirm... Just did what I suspect to be the first cleaning ever on my landlord's 10 year old unit... and did it about 2 days late. She's dead and CM confirms it's likely fatal.

Fun times! Glad it's not coming out of my pocket...

 

[ChristianPatriot]

Mine runs constantly once we go over 90 outside. Though the t-stat is set at 78, the temps go up to about 80 or so by the t-stat. Product of a vaulted ceiling with not enough insulation.

To be fair, Indiana stuff is only designed for 95 degree days, and that’s with a perfectly sized brand new unit. They start to lose efficiency after day one. Compound that with a bunch of consecutive 90 degree days. It’s not hard to see why units can sometimes have a hard time keeping up. Only maintaining 78-80 might be a whole other story though.

 

[gregkl]

To be fair, Indiana stuff is only designed for 95 degree days, and that’s with a perfectly sized brand new unit. They start to lose efficiency after day one. Compound that with a bunch of consecutive 90 degree days. It’s not hard to see why units can sometimes have a hard time keeping up. Only maintaining 78-80 might be a whole other story though.

That makes me feel better...I think.

Unfortunately my house that was built in 1962 has T&G 2" thick SYP boards to form the vaulted ceiling, 2" of foam insulation, felt paper and shingles for my roof system.

I believe this is what is causing my heat loss/gain. Over the past 5 years I have insulated the walls, sealed the doors and windows which has helped. But those ceilings are providing a huge loss for me.

And I have 36 large windows in my home!

On another note, is that your truck in your avatar? I'd love to have something like that!

 

[maxwelhse]

That makes me feel better...I think.

Unfortunately my house that was built in 1962 has T&G 2" thick SYP boards to form the vaulted ceiling, 2" of foam insulation, felt paper and shingles for my roof system.

I believe this is what is causing my heat loss/gain. Over the past 5 years I have insulated the walls, sealed the doors and windows which has helped. But those ceilings are providing a huge loss for me.

You probably don't want to hear this, but you can always at least partially "unvault" that ceiling if you want. Back when my A/C was working, this house would pull about a 40F delta T, so 105 outside and 65 inside (though I wouldn't normally keep it that cold) and I have vaulted ceilings, just with modern insulation. Frankly I'm super impressed with how well insulated this house is for just being a cheap, purpose built, rental house. Beats the pants off of the 1970s house I owned before moving here.

A hot air return right at the peak may help too if that's at all possible, or even a ceiling fan. If you just have hot air trapped up there then the AC can only do so much. Frankly, a 10-12 degree delta T would leave me so uncomfortable that I'd pay a pretty penny to improve it... even with an army of window ACs.

 

[HoughMade]

Loving my new A/C (I'd better). Sitting at 74 all the time and the unit even shuts off during the hottest midday. I've never actually seen the indicated temp above 74.

 

[churchmouse]

Mine runs constantly once we go over 90 outside. Though the t-stat is set at 78, the temps go up to about 80 or so by the t-stat. Product of a vaulted ceiling with not enough insulation.

Uh actually a process of being short on capacity.

 

[BiscuitsandGravy]

Just finished walking about with the vac and cleaned out the cold air return vents. Thermostat is on 75 and it finally shut off.

 

[gregkl]

You probably don't want to hear this, but you can always at least partially "unvault" that ceiling if you want. Back when my A/C was working, this house would pull about a 40F delta T, so 105 outside and 65 inside (though I wouldn't normally keep it that cold) and I have vaulted ceilings, just with modern insulation. Frankly I'm super impressed with how well insulated this house is for just being a cheap, purpose built, rental house. Beats the pants off of the 1970s house I owned before moving here.

A hot air return right at the peak may help too if that's at all possible, or even a ceiling fan. If you just have hot air trapped up there then the AC can only do so much. Frankly, a 10-12 degree delta T would leave me so uncomfortable that I'd pay a pretty penny to improve it... even with an army of window ACs.

We keep our AC at 78 during the day and 72 at night. That is comfortable for the two of us. We try to stay as close to outside temps as reasonable year round. We are warm in the summer but without the humidity and cool in the winter(think long pants and sweatshirts/sweaters). Winter has the biggest delta between indoors and outdoors with as much as a 40 degree differential but the rest of the year we try to keep it around 10 degrees.

I do have a ceiling fan going which has helped with the comfort but has probably caused the AC to work harder to condition the hot air it pulls down from the peak.

Window units won't fit as I have uniquely shaped awning style windows.

 

[maxwelhse]

Window units won't fit as I have uniquely shaped awning style windows.

A portable AC will. You may even find that maybe 2 portable units do a better job where you actually spend your time and may actually reduce your cooling bills since your central AC never shuts off. Many various varieties of casement windows (no matter side or top open) you can also just remove the entire pane without much effort and make a plywood slug to go in its place to hold the AC. Given the choice, a window unit will work better.

Still, with only a 10-12 degree delta I'm thinking something may just be "wrong", as CM is saying. My old house was like yours and I discovered it was because the "renovators" I bought it from had 100% blocked off the return air ducts by literally capping them off with plywood and dry walling over them. The only thing I could do was open the return air up in the basement and make sure to leave the basement door open at all times. It helped, but obviously wasn't ideal.

The long-term fix to that would have involved me building a plenum where the duct USED to be where a pantry USED to stand. Glad I sold the house before I bothered with that nightmare...

 

[gregkl]

Uh actually a process of being short on capacity.

I'm sure this is correct and could be corrected with a larger unit. If my unit wasn't so new (less than 10 years old), I would think about up sizing it. And I might once I recover from this 5 year reno I'm finally wrapping up.

Right now it will keep up if the outdoor temps stay below 90.

When the roof is ready to be replaced, I'm going to look into building up the roof to be able to add more insulation. I think that would help with the heating bills in the winter too. At least the heat can keep up!

 

[gregkl]

A portable AC will. You may even find that maybe 2 portable units do a better job where you actually spend your time and may actually reduce your cooling bills since your central AC never shuts off. Many various varieties of casement windows (no matter side or top open) you can also just remove the entire pane without much effort and make a plywood slug to go in its place to hold the AC. Given the choice, a window unit will work better.

Still, with only a 10-12 degree delta I'm thinking something may just be "wrong", as CM is saying. My old house was like yours and I discovered it was because the "renovators" I bought it from had 100% blocked off the return air ducts by literally capping them off with plywood and dry walling over them. The only thing I could do was open the return air up in the basement and make sure to leave the basement door open at all times. It helped, but obviously wasn't ideal.

The long-term fix to that would have involved me building a plenum where the duct USED to be where a pantry USED to stand. Glad I sold the house before I bothered with that nightmare...

Good point. I could remove a section and block it out and fit a window unit. After restoring all 36 windows I'm really good at removing the sections.

I'll think about that if this heat continues this summer. Usually we don't get that many 90+ degree days here.

I do have cold air returns in all the rooms.

 

[maxwelhse]

Good point. I could remove a section and block it out and fit a window unit. After restoring all 36 windows I'm really good at removing the sections.

That's what we did with the house I grew up in as it was electric radiant heat with no duct work. We popped the lower window assembly out of the double hung, cut plexi to fit the profile of the AC to the storm window, made custom fit nylon "shelves" to sit the units on (with the proper slope so they'd drain the water outside, and not back into the room), and filled the space between the plexi and the accordion fillers on the window units with urethane foam (aka, "sponge rubber"). It worked awesome for the little guys. For the one big one in the house we also had to install support chains and eyelets on the outside of the house through the trim to mold it up (and also control the angle).

You couldn't exactly do this with casements, since you don't have conventional storm windows with those, but you could build a box to mimic the result. I will tell you that doing it out of wood is a complete waste of time as all of that stuff is wet 100% of the time and even the best woods will only hold up for a few years. I did the last one in a fit of rage, with the materials I had on hand, in an extra hot summer to put one in my bedroom and used plywood coated in fiberglass resin and trimmed the edges with aluminum channel. That lasted about 8 years. The all plastic ones were going on 20+ years and were sold with the house 10 years ago now.

The only thing that sucked about it was security. If I had to go that way today, I'd probably bite the bullet, pull the interior window moldings, install some deep thread inserts in the 2x4s framing the windows out, try to trim it out as neatly as possible after the fact, and bolt on straight up steel bars in front of the AC. It's not like window ACs are particularly attractive anyhow, so, the prison look may actually add some "cool" factor (pun intended). You could always used barbed wire to double up on coolness...

Anyhow... If your central air is running that hard, you may actually find it to be an overall cost savings to just condition the places you spend most of your time, like living room and bedroom, and forget the central entirely.

 

[Hoosierdood]

I'm probably repeating myself but anyway... Its going to be HOT out this week... Make sure your outdoor unit for your AC is clean and all obstructions are cleared. Take a few minutes to hose it out and trim back the grass around it. Its going to work extra hard this week.

Your AC will thank you and so will your SO.

Thanks for the reminder. I just went out yesterday to check it and it had a bunch of dust and cottonwood boogered up in it. I hosed it off and cleaned it up since I knew it was going to be a hot week.

 

[Sigblitz]

Is your roof clean when the neighbor's have snow on theirs? Your heat loss is coming through, and your hot attic will warm the house in the summer. It's really too hot to fix it now.

 

[Mark-DuCo]

My uncle runs an Hvac/plumbing business, and he was telling us about a customer this weekend.

She called him up and said that her outside unit was making a terrible racket and he needed to come check it out right away. He said he would get there but the end of the day. She called back about an hour later and said he needed to come now before the outside unit walked away from the house.
When he got there it wasn't running so he went and turned the thermostat down and heard it. He walked outside and saw the outer unit moving back and forth about 4 inches, so he through breaker. He looked inside of it and found about a 6ft black snake had been curled up on the fan and had been taken for a ride.
Luckily the snake didn't do much damage other than flattening the fins a bit. He said it's the first time he has ever seen that.

 

[gregkl]

Is your roof clean when the neighbor's have snow on theirs? Your heat loss is coming through, and your hot attic will warm the house in the summer. It's really too hot to fix it now.

If you mean me, my roof over the vaulted part is always clean in the winter. It will take several inches of snow to stick and it won't stay up there long. Being vaulted, there is no attic.

 

[churchmouse]

If you mean me, my roof over the vaulted part is always clean in the winter. It will take several inches of snow to stick and it won't stay up there long. Being vaulted, there is no attic.

When we did the add on to the front of the house and vaulted the ceiling we did a 2' air space between the ceiling and the roof. Well insulated and properly vented.
Man that was fun to build.....

 

[gregkl]

When we did the add on to the front of the house and vaulted the ceiling we did a 2' air space between the ceiling and the roof. Well insulated and properly vented.
Man that was fun to build.....

I wish they would have done something like that. Even back in the early 60's I would have thought they knew enough to make the roof system able to me insulated.

But then again, the walls didn't have any insulation in them either. An option back then?

 

[maxwelhse]

If you mean me, my roof over the vaulted part is always clean in the winter. It will take several inches of snow to stick and it won't stay up there long. Being vaulted, there is no attic.

Ya know, it would be the most ghetto thing ever, but you could just VHB tape more pinkboard to the drywall to hold you over. If you paint it before you stick it up there it might not even look "that" terrible. I think the expensive corning stuff is something like R5 per inch. The cheap Menards stuff is R3 or 4.

I mean... This is technically the same technology they used on the space shuttle for the re-entry tiles... so... you can sell the idea as you're building a rocket and you are now, by definition, a practicing rocket scientist.

 

[churchmouse]

I wish they would have done something like that. Even back in the early 60's I would have thought they knew enough to make the roof system able to me insulated.

But then again, the walls didn't have any insulation in them either. An option back then?

Energy was stupid cheap. No real push for this until heat pumps became the norm. If a house was heat pump ready it was pretty well insulated. Now it is the norm with energy being a huge expense.