Coping with heat

Creekside said:
Thermal energy is thermal energy.
Click to expand...

I know, but I was talking about temperature perception. That is a very different thing, as people who've been through the menopause will tell you. Possibly in more detail and at greater length than seems necessary.

Besides which, even non-menopausal humans aren't great at sensing tiny temperature changes, so even if the fridge/freezer raised the temperature in the whole kitchen by a third of a degree (which it doesn't), it'd make no difference to my comfort.

The small patch of air warmed by the fridge/freezer isn't the cause of the uncomfortable temperature in the kitchen anyway, as evidenced by the drop in the thermometer reading as soon as the real problem dips below the horizon.

So it does make sense to freeze ice packs if heat from the sun's making me feel unwell and overheated. The net gain in comfort is substantial, and that's without taking into account that 90% of the time I'm not even in the same room as the freezer.

If you were talking about the problem of superfluous heat generated by cats, I'd be with you all the way. They're ridiculously hot and they keep trying to sit on you.
 
Kitty said:
I know, but I was talking about temperature perception.
Click to expand...
Yes, but the thermal energy added to a room adds to the perception. Localized cooling (ice pack on your skin) definitely overrides a fractional degree of room temperature. However, without that localized cooling, half a degree might make the difference between feeling too hot or too cold. My 60W miniPC does noticeably raise the temperature in my (small) room. Refrigerators use a few hundred watts for roughly 8 hrs a day, so if I had a fridge in my room, it would significantly reduce my comfort level in the warm season.

For the previous example, putting ice in front of a fan does increase comfort level if the fan is blowing the cooled air directly on the person. For cooling the house, it fails miserably, since it adds heat.
 
Creekside said:
Yes, but the thermal energy added to a room adds to the perception. Localized cooling (ice pack on your skin) definitely overrides a fractional degree of room temperature. However, without that localized cooling, half a degree might make the difference between feeling too hot or too cold. My 60W miniPC does noticeably raise the temperature in my (small) room. Refrigerators use a few hundred watts for roughly 8 hrs a day, so if I had a fridge in my room, it would significantly reduce my comfort level in the warm season.

For the previous example, putting ice in front of a fan does increase comfort level if the fan is blowing the cooled air directly on the person. For cooling the house, it fails miserably, since it adds heat.
Click to expand...
I don’t think that freezing water bottles is contributing that much to the heat of the house considering that most people are keeping the freezer running anyways on account of the food inside of it.
 
Utsikt said:
How does this work?
Click to expand...
The refrigeration device is a heat pump: it pumps thermal energy from the water to the air in the room (unless it has condenser coils outside the house). It takes energy to pump heat from one material to another, and isn't 100% efficient, so moving a kw of heat from some water would add probably much more than a kw of additional heat to the house.

jnmaciuch said:
I don’t think that freezing water bottles is contributing that much to the heat of the house considering that most people are keeping the freezer running anyways on account of the food inside of it.
Click to expand...
True, it depends on the size of the house. If you're living in a 6000 sq ft house with lots of south-facing windows, a large inefficient upright fridge and freezer, lots of lights and entertainment system and computer always on, etc, freezing a jug of water for personal cooling won't make a difference. If you live in a small home or just one room, it might be noticeable.

Personality matters too. Some people are oblivious to everyday physics. My mindset does pay attention to those details, so knowing that some web page's video ad that I can't block is adding tens of watts of heat to my already hot room annoys me.
 
Creekside said:
The refrigeration device is a heat pump: it pumps thermal energy from the water to the air in the room (unless it has condenser coils outside the house). It takes energy to pump heat from one material to another, and isn't 100% efficient, so moving a kw of heat from some water would add probably much more than a kw of additional heat to the house.
Click to expand...
Oh, I was thinking of a freezer in a different room. The room with the freezer can be as hot as it wants, as long as the room with me in gets cooler.
 
Utsikt said:
Oh, I was thinking of a freezer in a different room.
Click to expand...

I was thinking one one in a different room, that has massive heatsinks on three sides of it, that already contains at least a dozen ice packs (I only freeze stuff overnight so I know it's renewable energy), and will never be able to produce enough heat to make me feel too warm...unless it was on fire, I suppose.

The only appliance here that makes me overheated is the sun. :D
 
Utsikt said:
The room with the freezer can be as hot as it wants, as long as the room with me in gets cooler.
Click to expand...
Most houses don't have insulation in interior walls. If your freezer room has well-insulated outer walls, the heat will transfer into other rooms.

I had a friend who wanted to make a walk-in freezer in his house. His original plan was to put a couple of regular chest freezers in there with the lids open. I explained that he would just heat the room, rather than cool it, since those freezers pump heat from the interior walls to the exterior walls. A walk-in freezer has the condenser coils and the compressor outside the house, so that it pumps heat from the evaporator coils in the freezer to the outside air. Likewise with heat pumps for HVAC, except that they are reversible, pumping outdoor heat from low temperatures into the house at a higher temperature.
 
Kitty said:
and will never be able to produce enough heat to make me feel too warm
Click to expand...
As I said, it depends on the size of the rooms, exterior temperature, insulation, etc. Running my 60W computer for a few hours does raise the temperature in my well-insulated 8'x8' room by several degrees if the exterior temperature is near my initial interior temperature. Running a 1 kW toaster oven for a few minutes would have the same effect.
 
Creekside said:
Most houses don't have insulation in interior walls. If your freezer room has well-insulated outer walls, the heat will transfer into other rooms.
Click to expand...
I think you’re over-estimating the heat transfer into non-adjacent rooms in terms of how many degrees the temp realistically will change, compared to the change in temp in the person’s immediate surroundings if they put ice in front of a fan.
 
I don't understand this whole discussion on fridges and freezers. I don't think we're going to start getting rid of them. I have three, by the way. We rent and they provide a fridge that is tiny that I am stuck with. I have a proper fridge/freezer in the garage and an under counter deep freeze in the living room as I didn't have a space and plug anywhere else.

Other than I can feel a tinge of heat at the back, they don't seem to be pumping out significant heat.
 
PrairieLights said:
I don't understand this whole discussion on fridges and freezers. I don't think we're going to start getting rid of them. I have three, by the way. We rent and they provide a fridge that is tiny that I am stuck with. I have a proper fridge/freezer in the garage and an under counter deep freeze in the living room as I didn't have a space and plug anywhere else.

Other than I can feel a tinge of heat at the back, they don't seem to be pumping out significant heat.
Click to expand...
It’s basically due to physics. Heat is energy, and energy can’t be destroyed, only transformed or transferred.

If you want to lower the temperature of something, you have to transfer the energy from the item into something else. In a freezer, the energy goes into the surroundings of the freezer, which means that the surroundings heat up by as much as the insides of the freezer cools down.

But because the surroundings of the freezer has a much larger volume than the inside of the freezer, the temperature in the room will not increase as many degrees as the temperature inside the freezer decreases. You can think of it as if the heat is diluted in a pool compared to in a bathtub. Pouring a boiling kettle into the bathtub will raise the temperature in the bathtub by more than if you pour the same kettle into a pool.

There are a few more things to account for with a freezer, but this will be the main reason for why freezers produce heat into the rooms they are placed in.

Nobody are suggesting to get rid of the freezers. Just to not be in the same room as it if possible if you’re trying to avoid the heat yourself.
 
Creekside said:
Most houses don't have insulation in interior walls. If your freezer room has well-insulated outer walls, the heat will transfer into other rooms.

I had a friend who wanted to make a walk-in freezer in his house. His original plan was to put a couple of regular chest freezers in there with the lids open. I explained that he would just heat the room, rather than cool it, since those freezers pump heat from the interior walls to the exterior walls. A walk-in freezer has the condenser coils and the compressor outside the house, so that it pumps heat from the evaporator coils in the freezer to the outside air. Likewise with heat pumps for HVAC, except that they are reversible, pumping outdoor heat from low temperatures into the house at a higher temperature.
Click to expand...
Had to google chest freezer, because could not imagine a big-boobed freezer.

These are not very efficient.

I have a simple fridge freezer with drawers. Also a high efficiency one. So it will probably excude a little bit of warmth but very little. My tv gives off more heat.

But as @Kitty said, it is about perception as well, and I have not measured it.

What is adding a lot of heat are my windows that are south facing.
 
PrairieLights said:
I don't understand this whole discussion on fridges and freezers.
Click to expand...

You're not alone. :D

I'm baffled by the thought of the 0.3º C of heat produced by a fridge/freezer in a one room having any meaningful impact, given that the sun can raise the temperature in the whole house by up to 20º C.

And the idea that you shouldn't take the ice packs out of the freezer to cool yourself, because re-freezing them might increase the kitchen temperature by another fraction of a degree for a few hours.

The house has never been made uncomfortably warm by the heat from any appliance, including the central heating boiler. On average it feels overheated about 20 days a year, and the cause is always the sun.

Chestnut tree said:
Had to google chest freezer, because could not imagine a big-boobed freezer.
Click to expand...

:rofl::rofl:

I have one in the shed. From this day forth it will be known as Big Busty Brenda.
 
Kitty said:
You're not alone. :D

I'm baffled by the thought of the 0.3º C of heat produced by a fridge/freezer in a one room having any meaningful impact, given that the sun can raise the temperature in the whole house by up to 20º C.

And the idea that you shouldn't take the ice packs out of the freezer to cool yourself, because re-freezing them might increase the kitchen temperature by another fraction of a degree for a few hours.

The house has never been made uncomfortably warm by the heat from any appliance, including the central heating boiler. On average it feels overheated about 20 days a year, and the cause is always the sun.



:rofl::rofl:

I have one in the shed. From this day forth it will be known as Big Busty Brenda.
Click to expand...
Haha love Brenda
 
You must log in or register to reply here.
Back
Top