Posted by Solar Flare on October 29, 2005, 12:15 pm
Controllable thermal mass would be in order in some climates.
> >daestrom wrote:
> >
> >> If you have a superinsulated house, so good that when you turn the furnace
> >> off overnight for 10 hours, the temperature only drops 2 degrees, then a
> >> set-back thermostat won't save you much more energy. Even if you set it
> >> to 45F or lower, the house is only dropping 2 degrees so the energy lost
> >> to the environment is not much less than when you keep temperature
> >> constant.
> >>
> >> On the other hand, a drafty, poorly insulated house that cools down 15 to
> >> 20 degrees in just six hours, then for those six hours the difference
> >> between the inside temperature and the outside temperature is less than if
> >> you had kept the temperature up all night. So the house lost less energy
> >> to the environment. In other words, setting down the thermostat saves
money.
> >
> >I can just picture someone opening his windows to save energy :-)
> I can picture someone minimizing the mass in a superinsulated house and
> air conditioning it at dusk in wintertime, pumping the little heat stored
> in the building mass into a well-insulated warm water storage tank for
> recovery at dawn.
> Or doing something similar with a stratified heat storage tank and fin-tube
> pipes near the ceiling, pumping enough cool water up from the tank bottom
> during the day to keep a room near a sunspace from exceeding 70 F, then
> pumping more up at dusk to cool the room to 50, then pumping warm water up
> (or letting it thermosyphon) from the top of the tank the next morning to
> heat the room to 70, with the help of a slow ceiling fan.
> Nick
Posted by Mel on November 2, 2005, 11:06 am
A question that's been bugging me for a while... is air-circulated
central heating more or less efficient than water-circulated central
heating?
I seem to remember reading that heating by convection requires higher
temperatures to reach the same "confort feeling", so wouldn't it make
sense to have water based central heating?
And would this have an impact on the best amount/duration of set-back
for a specific house?
Sorry about the question a little of-topic....
Mel
Solar Flare a écrit :
> Controllable thermal mass would be in order in some climates.
>
>
>>
>>
>>>daestrom wrote:
>>>
>>>
>>>>If you have a superinsulated house, so good that when you turn the furnace
>>>>off overnight for 10 hours, the temperature only drops 2 degrees, then a
>>>>set-back thermostat won't save you much more energy. Even if you set it
>>>>to 45F or lower, the house is only dropping 2 degrees so the energy lost
>>>>to the environment is not much less than when you keep temperature
>>>>constant.
>>>>
>>>>On the other hand, a drafty, poorly insulated house that cools down 15 to
>>>>20 degrees in just six hours, then for those six hours the difference
>>>>between the inside temperature and the outside temperature is less than if
>>>>you had kept the temperature up all night. So the house lost less energy
>>>>to the environment. In other words, setting down the thermostat saves
>
> money.
>
>>>I can just picture someone opening his windows to save energy :-)
>>
>>I can picture someone minimizing the mass in a superinsulated house and
>>air conditioning it at dusk in wintertime, pumping the little heat stored
>>in the building mass into a well-insulated warm water storage tank for
>>recovery at dawn.
>>
>>Or doing something similar with a stratified heat storage tank and fin-tube
>>pipes near the ceiling, pumping enough cool water up from the tank bottom
>>during the day to keep a room near a sunspace from exceeding 70 F, then
>>pumping more up at dusk to cool the room to 50, then pumping warm water up
>>(or letting it thermosyphon) from the top of the tank the next morning to
>>heat the room to 70, with the help of a slow ceiling fan.
>>
>>Nick
>>
>
>
>
Posted by Solar Flare on November 2, 2005, 6:32 pm
Many claim hydronic heating to be more efficient because of many reasons.
- you can put more heat where you want it.
- warmer floors can lend to cooler air with more human comfort.
- alternative heat sources can be integrated easily
Temp setback is almost useless though ,due to the large thermal masses of the
radiators usually involved. The response may be too slow.
A question that's been bugging me for a while... is air-circulated
central heating more or less efficient than water-circulated central
heating?
I seem to remember reading that heating by convection requires higher
temperatures to reach the same "confort feeling", so wouldn't it make
sense to have water based central heating?
And would this have an impact on the best amount/duration of set-back
for a specific house?
Sorry about the question a little of-topic....
Mel
Solar Flare a écrit :
> Controllable thermal mass would be in order in some climates.
>>
>>
>>>daestrom wrote:
>>>
>>>
>>>>If you have a superinsulated house, so good that when you turn the furnace
>>>>off overnight for 10 hours, the temperature only drops 2 degrees, then a
>>>>set-back thermostat won't save you much more energy. Even if you set it
>>>>to 45F or lower, the house is only dropping 2 degrees so the energy lost
>>>>to the environment is not much less than when you keep temperature
>>>>constant.
>>>>
>>>>On the other hand, a drafty, poorly insulated house that cools down 15 to
>>>>20 degrees in just six hours, then for those six hours the difference
>>>>between the inside temperature and the outside temperature is less than if
>>>>you had kept the temperature up all night. So the house lost less energy
>>>>to the environment. In other words, setting down the thermostat saves
> money.
>>>I can just picture someone opening his windows to save energy :-)
>>
>>I can picture someone minimizing the mass in a superinsulated house and
>>air conditioning it at dusk in wintertime, pumping the little heat stored
>>in the building mass into a well-insulated warm water storage tank for
>>recovery at dawn.
>>
>>Or doing something similar with a stratified heat storage tank and fin-tube
>>pipes near the ceiling, pumping enough cool water up from the tank bottom
>>during the day to keep a room near a sunspace from exceeding 70 F, then
>>pumping more up at dusk to cool the room to 50, then pumping warm water up
>>(or letting it thermosyphon) from the top of the tank the next morning to
>>heat the room to 70, with the help of a slow ceiling fan.
>>
>>Nick
>>
Posted by nicksanspam on November 3, 2005, 3:10 am
>... is air-circulated central heating more or less efficient than
>water-circulated central heating?
I'd say they are about the same, in principle. For solar heating,
air can be a lot simpler than water.
>I seem to remember reading that heating by convection requires higher
>temperatures to reach the same "confort feeling", so wouldn't it make
>sense to have water based central heating?
Moving air makes people feel cooler, although slow-moving air makes little
difference, and most people prefer a little airflow for comfort. Radiators
usually contain higher temp water than air system temps. Lower temp furnaces
can be more efficient, with less heat going up the chimney.
>And would this have an impact on the best amount/duration of set-back
>for a specific house?
It seems to me that air is better for setbacks. Less thermal mass, so
the setback begins sooner, and after a setback, some clever (Honeywell)
thermostats average air and wall temps and initially overheat the room
air to make up for cold walls until the walls catch up. This allows
delaying the end of a setback, which saves energy.
Nick
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> >
> >> If you have a superinsulated house, so good that when you turn the furnace
> >> off overnight for 10 hours, the temperature only drops 2 degrees, then a
> >> set-back thermostat won't save you much more energy. Even if you set it
> >> to 45F or lower, the house is only dropping 2 degrees so the energy lost
> >> to the environment is not much less than when you keep temperature
> >> constant.
> >>
> >> On the other hand, a drafty, poorly insulated house that cools down 15 to
> >> 20 degrees in just six hours, then for those six hours the difference
> >> between the inside temperature and the outside temperature is less than if
> >> you had kept the temperature up all night. So the house lost less energy
> >> to the environment. In other words, setting down the thermostat saves
money.
> >
> >I can just picture someone opening his windows to save energy :-)
> I can picture someone minimizing the mass in a superinsulated house and
> air conditioning it at dusk in wintertime, pumping the little heat stored
> in the building mass into a well-insulated warm water storage tank for
> recovery at dawn.
> Or doing something similar with a stratified heat storage tank and fin-tube
> pipes near the ceiling, pumping enough cool water up from the tank bottom
> during the day to keep a room near a sunspace from exceeding 70 F, then
> pumping more up at dusk to cool the room to 50, then pumping warm water up
> (or letting it thermosyphon) from the top of the tank the next morning to
> heat the room to 70, with the help of a slow ceiling fan.
> Nick