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Should I be concerned about a hot garage?
- Thread starter daniel
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SageBrush
REJECT Fascism
It takes about 0.5 kWh to heat a gallon of water 50C
It would not surprise me if Daniel uses 30 gallons of hot water a day, so ~ 15 kWh of heat transfer
Dan203
Active Member
What's that work out to with regard to cooling a two car garage that's 90+? How much heat transfer would be required to cool that much space to even say 80 degrees?
groovidad
Living the Dream!
Brah, crack your garage door about a foot. If you have a free wall space, you can have an exhaust fan installed for a couple hundred dollars. I'm in the same outrigger as you. I also have a side access door I leave cracked open about 2 feet. It does help keep the temp below 90. Though, overheat protection is on, I don't want the car sapping juice to keep it cool.
Typical spec is 500 sqft per ton A/C (North Texas) but that is for the house so you can keep it in the 0's if desired. If your garage is insulated, even 1/2 ton (6,000 Btu) will do wonders and probably maintain under 90 deg. It will also improve comfort by removing humidity. Esp true in HI.
Mine is insulated but still gets really hot in the summer.
Mine is insulated but still gets really hot in the summer.
I’ve seen my internal cabin temp get in the 160’s regularly. It’s really hot here and I refuse to run my AC 12 hours a day when the car is outside the garage. I’ve also asked a lot of different Tesla owners what they do and most don’t run cabin protection.
Time will tell if it’s a bad idea but I will deal with the issues if/when they come up.
Time will tell if it’s a bad idea but I will deal with the issues if/when they come up.
SageBrush
REJECT Fascism
I am neither an engineer or an HVAC person so I can only give a general answer you should treat with some amount of skepticism:
You don't really want to cool the garage, you want to cool the air in the garage. If you run the heat pump 10 hours a day you have the equivalent of about a 0.5 kW AC running at a COP of 3.
1.5 kW = ~ 5,000 btu/hour
SageBrush
REJECT Fascism
Ouch.
I see up to 105F in New Mexico. Some of the difference:
- I seek shade
- If no shade I park facing the sun and put up sun-shields
- I always crack open the windows for ventilation. If dust was a problem I would run the fan
At first I thought this was a joke because I can't imagine what car company would design a car that can't stand more heat than a human. But I see it seems a serious question. I'd think that if you can take 90 F degrees, then so can your car. Where I grew up, this was a cooling trend
The question was serious because I don't know beans about batteries. The first two or three replies put my concerns to rest, but the thread seems to have wings.
I cannot imagine what gave you the idea I would use 30 gallons of hot water a day. I take a quick shower once or twice a day, wash dishes for one person every day, and run a load of laundry in a front-loader once every week or ten days. I cannot imagine that I'd use more than ten gallons in a day, and maybe only five.
But of course, the whole heat-pump discussion is moot because my hot water is solar.
I'm not going to do anything about the garage now that I know (thanks to all you smart folks here on TMC) that 90° is not an issue. (But I'm reminded of why I never wanted to live in Texas or Phoenix. At least here, if my A/C failed, I could walk 4 minutes and jump in the ocean.)
ETA: The heat for my water is free, but I still try to conserve water.
SageBrush
REJECT Fascism
I stand corrected.
This study says 60 gallons/day for a household of 4. A single person would use more than 15 since consumption is non-linear as the household size increases.
roblab
Active Member
120 here in Phoenix, 118 so far the high in garage, down to only 110 this week. I'll be glad to get back to "sunny" California where our temps are barely up to 90. Garage is never "hot" as it cools down at night and holds it.
I see. You assumed a two-person household. Sadly, I'm only me. Here's another factor: I suspect that the average woman washes clothes far more often than I do. Thus, being a single man, my water use for laundry is probably far below the average. And being in Hawai'i, I probably use fewer clothes, and the national average includes some percentage of people with top-loaders, which use a lot more water than a front-loader.
Thus my estimate of 5 to 10 gallons per day.
And since this came up in the context of using a heat pump to cool the garage while heating the water, note that here in Kihei, the temperature of the incoming "cold" water is actually lukewarm. The water from my cold tap is too warm to drink comfortably. I have to mix in some refrigerated water to make it drinkable. Thus heating my hot water requires far less energy than it did, say, in Spokane, where I used to live, or North Dakota, where I lived before that. So a heat pump would cool my garage even less.
So it's a good thing I don't need to cool my garage after all.
SageBrush
REJECT Fascism
I remembered that you are a single person household. Mostly I was thinking that a snow-bird constitution would shower a lot in a hot and sticky (humid) climate.I see. You assumed a two-person household. Sadly, I'm only me. Here's another factor: I suspect that the average woman washes clothes far more often than I do. Thus, being a single man, my water use for laundry is probably far below the average. And being in Hawai'i, I probably use fewer clothes, and the national average includes some percentage of people with top-loaders, which use a lot more water than a front-loader.
Thus my estimate of 5 to 10 gallons per day.
And since this came up in the context of using a heat pump to cool the garage while heating the water, note that here in Kihei, the temperature of the incoming "cold" water is actually lukewarm. The water from my cold tap is too warm to drink comfortably. I have to mix in some refrigerated water to make it drinkable. Thus heating my hot water requires far less energy than it did, say, in Spokane, where I used to live, or North Dakota, where I lived before that. So a heat pump would cool my garage even less.
So it's a good thing I don't need to cool my garage after all.
I remembered that you are a single person household. Mostly I was thinking that a snow-bird constitution would shower a lot in a hot and sticky (humid) climate.
Without A/C that would probably be true. With free (solar-powered) A/C my house is always a comfortable 78 to 79 F. and my showers are brief (to conserve water, not energy). Most of my outdoor time, and all my exertion activities, are in the morning, followed by a quick shower. And that's mostly to rinse off the salt, since after swimming I'm pretty much clean. If I have chores later in the day, I take another quick shower when I get home. Sometimes I use the elliptical exerciser before paddling, so my legs get a workout, and then a quick rinse shower before going down to the canoe club. I've never taken long showers. And my hair is so short that washing it takes no longer than any other equal area of me. I can't believe I use more than three gallons of shower water in a day, and that's probably 4 parts cold to 1 part hot, since I use it lukewarm and the "cold" water is almost warm enough to use straight.
This time of year it's really too hot in the afternoon for me to spend much time out of doors. Occasionally I go for a walk on the beach in the late morning or early afternoon. So I'm mostly in my nice cool house after my morning paddle.
fajitamondays
Member
SageBrush
REJECT Fascism
IIRC most shower heads are in the 2-3 gallons a minute range. You can buy more frugal varieties
Dmagyar
Member
Here’s my set up just outside Sacramento, Ca. Hot here also, fan makes a bit of noise, so don’t run it very long, but does adjust to come on when it hits pre determined heat...also shuts itself off by the same thermostat control...
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