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Posted by RickH on October 30, 2009, 10:50 am
> > > >> No, it takes too long to re-heat the boiler and all the water in t=
he
> > > >> pipes, radiators, and floor tubing. =A0It is always best to set it=
once
> > > >> and leave it there all winter. =A0Too much energy is lost when all=
that
> > > >> water is asked to re-heat all the surfaces again. =A0For example w=
hen I
> > > >> feel the return manifold from the coils under my concrete slab aft=
er
> > > >> the slab was allowed to cool, the return water is ice cold, all th=
at
> > > >> energy to reheat the slab. =A0No, bad asvice, best to keep it warm=
and
> > > >> leave it there, saves tons of energy.
> > > We use warm water here to shower. =A0I'd say that a higher % of peopl=
e use
> > > heat pumps or gas to heat rather than water. =A0In your case, MAYBE i=
t is
> > > cheaper to leave it on, but I think you are only quoting yourself, an=
d no
> > > analytic studies by any testing agency. =A0Can you find any said stud=
ies? =A0I
> > > don't doubt that you believe what you say is true, I just think that =
it is
> > > not.
> > > Steve
> > Boiler installers never put daily "set back" thermostats on boilers,
> > only forced air systems get those, and they tell you to set the
> > thermostat once and leave it there.
> > The rules are completely different for radiant heated buidings vs air
> > heated buildings.
> > In an air heated building you heat the air, in a radiant heated
> > building you heat the building materials and that in turn heats the
> > people. =A0When you lose all that stored energy it costs a fortune to
> > recover it back in boiler usage. =A0There is nothing quite like the
> > warmth of a radiant-heated house.
> So the laws of themodynamics are different from system to system?
> Heat its lost to the environment based on the difference in
> temperature between the heated space & the unheated space. =A0 As the
> temperature of the heated space falls, the heat loss also fails. =A0When
> the temperature of the heated space falls to that of the unheated
> space, heat loss stops.
> I believe you are confusing the "time" it takes to recover with "huge
> amounts of energy are required to re-heat everything".
> If you were correct in your thinking (& oyu are not) the whole concept
> of temperature setback would not work (& it does).
> cheers
> Bob- Hide quoted text -
> - Show quoted text -
If left alone the boiler kicks on maybe once every 4-6 hours for only
a short 5-10 minute period (maybe 4 or 5 recyclings of the entire
water load).
If you let the house cool for 10 hours while at work, the boiler will
have to run several hours to get all the floors (and house contents)
heated again. This run is more than the sum amount of time the boiler
would have been fired if you had just left it alone. You've never
lived with a boiler have you? Air is low mass, it heats up very
quickly, radiant heating of the building mass itself takes longer from
the same starting temp as the air entering a forced-air system.
Yes, the "rules" are different for forced-air vs under-floor radiant
heat, in practice, but not the laws of thermodynamics are not.
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Posted by DD_BobK on October 30, 2009, 1:17 pm
> > > > >> No, it takes too long to re-heat the boiler and all the water in=
the
> > > > >> pipes, radiators, and floor tubing. =A0It is always best to set =
it once
> > > > >> and leave it there all winter. =A0Too much energy is lost when a=
ll that
> > > > >> water is asked to re-heat all the surfaces again. =A0For example=
when I
> > > > >> feel the return manifold from the coils under my concrete slab a=
fter
> > > > >> the slab was allowed to cool, the return water is ice cold, all =
that
> > > > >> energy to reheat the slab. =A0No, bad asvice, best to keep it wa=
rm and
> > > > >> leave it there, saves tons of energy.
> > > > We use warm water here to shower. =A0I'd say that a higher % of peo=
ple use
> > > > heat pumps or gas to heat rather than water. =A0In your case, MAYBE=
it is
> > > > cheaper to leave it on, but I think you are only quoting yourself, =
and no
> > > > analytic studies by any testing agency. =A0Can you find any said st=
udies? =A0I
> > > > don't doubt that you believe what you say is true, I just think tha=
t it is
> > > > not.
> > > > Steve
> > > Boiler installers never put daily "set back" thermostats on boilers,
> > > only forced air systems get those, and they tell you to set the
> > > thermostat once and leave it there.
> > > The rules are completely different for radiant heated buidings vs air
> > > heated buildings.
> > > In an air heated building you heat the air, in a radiant heated
> > > building you heat the building materials and that in turn heats the
> > > people. =A0When you lose all that stored energy it costs a fortune to
> > > recover it back in boiler usage. =A0There is nothing quite like the
> > > warmth of a radiant-heated house.
> > So the laws of themodynamics are different from system to system?
> > Heat its lost to the environment based on the difference in
> > temperature between the heated space & the unheated space. =A0 As the
> > temperature of the heated space falls, the heat loss also fails. =A0Whe=
n
> > the temperature of the heated space falls to that of the unheated
> > space, heat loss stops.
> > I believe you are confusing the "time" it takes to recover with "huge
> > amounts of energy are required to re-heat everything".
> > If you were correct in your thinking (& oyu are not) the whole concept
> > of temperature setback would not work (& it does).
> > cheers
> > Bob- Hide quoted text -
> > - Show quoted text -
> If left alone the boiler kicks on maybe once every 4-6 hours for only
> a short 5-10 minute period (maybe 4 or 5 recyclings of the entire
> water load).
> If you let the house cool for 10 hours while at work, the boiler will
> have to run several hours to get all the floors (and house contents)
> heated again. =A0This run is more than the sum amount of time the boiler
> would have been fired if you had just left it alone. =A0You've never
> lived with a boiler have you? =A0Air is low mass, it heats up very
> quickly, radiant heating of the building mass itself takes longer from
> the same starting temp as the air entering a forced-air system.
> Yes, the "rules" are different for forced-air vs under-floor radiant
> heat, in practice, but not the laws of thermodynamics are not.
Sorry Rick, you're mistaken...setback always saves energy, you're
confusing recovery time, inconvenience & comfort with energy use.
Run the numbers, I'll give you a starting point.
Are we talking CI radiators, baseboard units or in floor radiant
heat? Tube material? Estimate or determine the total amount the
water in the system. Estimate the weight of the radiators & delivery
system. Calc the thermal capacity of the water & the delivery
system. Hint: The specific heat of water is 1 btu/lbm degF .... it
is left as an exercise for the reader to determine Cp of the other
materials in the system.
I think you'll be surprised how little heat is "contained" in the
system.
So by your logic I should leave my mountain home heater thermostat set
at 68F ALL the time? Day, night and when unoccupied because re-
heating all the insulated mass of the house; drywall, flooring, floor
framing and furnishings would take a "bunch of energy" ?
I don't think so...my fuel bill is high enough with the set back
technique is play.
btw I have lived with boiler / steam heat :)
cheers
Bob
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Posted by mm on October 30, 2009, 8:35 pm
On Fri, 30 Oct 2009 07:50:56 -0700 (PDT), RickH
>> > > >> No, it takes too long to re-heat the boiler and all the water in the
>> > > >> pipes, radiators, and floor tubing. It is always best to set it once
>> > > >> and leave it there all winter. Too much energy is lost when all that
>> > > >> water is asked to re-heat all the surfaces again. For example when I
>> > > >> feel the return manifold from the coils under my concrete slab after
>> > > >> the slab was allowed to cool, the return water is ice cold, all that
>> > > >> energy to reheat the slab. No, bad asvice, best to keep it warm and
>> > > >> leave it there, saves tons of energy.
>> > > We use warm water here to shower. I'd say that a higher % of people use
>> > > heat pumps or gas to heat rather than water. In your case, MAYBE it is
>> > > cheaper to leave it on, but I think you are only quoting yourself, and no
>> > > analytic studies by any testing agency. Can you find any said studies? I
>> > > don't doubt that you believe what you say is true, I just think that it is
>> > > not.
>> > > Steve
>> > Boiler installers never put daily "set back" thermostats on boilers,
>> > only forced air systems get those, and they tell you to set the
>> > thermostat once and leave it there.
>> > The rules are completely different for radiant heated buidings vs air
>> > heated buildings.
>> > In an air heated building you heat the air, in a radiant heated
>> > building you heat the building materials and that in turn heats the
>> > people. When you lose all that stored energy it costs a fortune to
>> > recover it back in boiler usage. There is nothing quite like the
>> > warmth of a radiant-heated house.
>> So the laws of themodynamics are different from system to system?
>> Heat its lost to the environment based on the difference in
>> temperature between the heated space & the unheated space. As the
>> temperature of the heated space falls, the heat loss also fails. When
>> the temperature of the heated space falls to that of the unheated
>> space, heat loss stops.
>> I believe you are confusing the "time" it takes to recover with "huge
>> amounts of energy are required to re-heat everything".
>> If you were correct in your thinking (& oyu are not) the whole concept
>> of temperature setback would not work (& it does).
>> cheers
>> Bob- Hide quoted text -
>> - Show quoted text -
>If left alone the boiler kicks on maybe once every 4-6 hours for only
>a short 5-10 minute period (maybe 4 or 5 recyclings of the entire
>water load).
>If you let the house cool for 10 hours while at work, the boiler will
>have to run several hours to get all the floors (and house contents)
>heated again.
Are you sure. You just said that the boiler it runs 5-10 minutes
every 4 to 6 hours. So if you are gone for 10 hours, the maximum
that the boiler wouldn't run would be 20 minutes.) Yet now you say it
would take several hours to get the house heated again. Plainly it
would take 20 minutes or less to get the boiler heated to it's normal
temp, instead of just pretty hot for lack of 20 minutes of heating.
I don't have a boilerIs there more to the cycle that you think would
delay heating the house?
>This run is more than the sum amount of time the boiler
>would have been fired if you had just left it alone.
No, it's not. You just assume that it is. Or it seems like it.
> You've never
>lived with a boiler have you? Air is low mass, it heats up very
>quickly, radiant heating of the building mass itself takes longer from
>the same starting temp as the air entering a forced-air system.
Of course it takes longer to heat up. It also takes longer to cool
off, so it isn't as cold as the air is when you get home.
>Yes, the "rules" are different for forced-air vs under-floor radiant
>heat, in practice, but not the laws of thermodynamics are not.
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Posted by DD_BobK on October 31, 2009, 11:19 pm
> > > > >> No, it takes too long to re-heat the boiler and all the water in=
the
> > > > >> pipes, radiators, and floor tubing. =A0It is always best to set =
it once
> > > > >> and leave it there all winter. =A0Too much energy is lost when a=
ll that
> > > > >> water is asked to re-heat all the surfaces again. =A0For example=
when I
> > > > >> feel the return manifold from the coils under my concrete slab a=
fter
> > > > >> the slab was allowed to cool, the return water is ice cold, all =
that
> > > > >> energy to reheat the slab. =A0No, bad asvice, best to keep it wa=
rm and
> > > > >> leave it there, saves tons of energy.
> > > > We use warm water here to shower. =A0I'd say that a higher % of peo=
ple use
> > > > heat pumps or gas to heat rather than water. =A0In your case, MAYBE=
it is
> > > > cheaper to leave it on, but I think you are only quoting yourself, =
and no
> > > > analytic studies by any testing agency. =A0Can you find any said st=
udies? =A0I
> > > > don't doubt that you believe what you say is true, I just think tha=
t it is
> > > > not.
> > > > Steve
> > > Boiler installers never put daily "set back" thermostats on boilers,
> > > only forced air systems get those, and they tell you to set the
> > > thermostat once and leave it there.
> > > The rules are completely different for radiant heated buidings vs air
> > > heated buildings.
> > > In an air heated building you heat the air, in a radiant heated
> > > building you heat the building materials and that in turn heats the
> > > people. =A0When you lose all that stored energy it costs a fortune to
> > > recover it back in boiler usage. =A0There is nothing quite like the
> > > warmth of a radiant-heated house.
> > So the laws of themodynamics are different from system to system?
> > Heat its lost to the environment based on the difference in
> > temperature between the heated space & the unheated space. =A0 As the
> > temperature of the heated space falls, the heat loss also fails. =A0Whe=
n
> > the temperature of the heated space falls to that of the unheated
> > space, heat loss stops.
> > I believe you are confusing the "time" it takes to recover with "huge
> > amounts of energy are required to re-heat everything".
> > If you were correct in your thinking (& oyu are not) the whole concept
> > of temperature setback would not work (& it does).
> > cheers
> > Bob- Hide quoted text -
> > - Show quoted text -
> If left alone the boiler kicks on maybe once every 4-6 hours for only
> a short 5-10 minute period (maybe 4 or 5 recyclings of the entire
> water load).
> If you let the house cool for 10 hours while at work, the boiler will
> have to run several hours to get all the floors (and house contents)
> heated again. =A0This run is more than the sum amount of time the boiler
> would have been fired if you had just left it alone. =A0You've never
> lived with a boiler have you? =A0Air is low mass, it heats up very
> quickly, radiant heating of the building mass itself takes longer from
> the same starting temp as the air entering a forced-air system.
> Yes, the "rules" are different for forced-air vs under-floor radiant
> heat, in practice, but not the laws of thermodynamics are not.
If left alone the boiler kicks on maybe once every 4-6 hours for only
a short 5-10 minute period (maybe 4 or 5 recyclings of the entire
water load).
If you let the house cool for 10 hours while at work, the boiler will
have to run several hours to get all the floors (and house contents)
heated again.
<<<<<
Your numbers cannot be correct.....
"left alone" it runs 10 minutes in 5 hours but "setback" for 10 hours
("let the house cool") and "the boiler will have to run several
hours"
nonsense
cheers
Bob
btw did you do those thermal mass / heat capacity calcs?
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Posted by on October 31, 2009, 4:44 pm
On Thu, 29 Oct 2009 11:05:16 -0700 (PDT), RickH
>> >> No, it takes too long to re-heat the boiler and all the water in the
>> >> pipes, radiators, and floor tubing. It is always best to set it once
>> >> and leave it there all winter. Too much energy is lost when all that
>> >> water is asked to re-heat all the surfaces again. For example when I
>> >> feel the return manifold from the coils under my concrete slab after
>> >> the slab was allowed to cool, the return water is ice cold, all that
>> >> energy to reheat the slab. No, bad asvice, best to keep it warm and
>> >> leave it there, saves tons of energy.
>> We use warm water here to shower. I'd say that a higher % of people use
>> heat pumps or gas to heat rather than water. In your case, MAYBE it is
>> cheaper to leave it on, but I think you are only quoting yourself, and no
>> analytic studies by any testing agency. Can you find any said studies? I
>> don't doubt that you believe what you say is true, I just think that it is
>> not.
>> Steve
>Boiler installers never put daily "set back" thermostats on boilers,
>only forced air systems get those, and they tell you to set the
>thermostat once and leave it there.
>The rules are completely different for radiant heated buidings vs air
>heated buildings.
>In an air heated building you heat the air, in a radiant heated
>building you heat the building materials and that in turn heats the
>people. When you lose all that stored energy it costs a fortune to
>recover it back in boiler usage. There is nothing quite like the
>warmth of a radiant-heated house.
Sorry, but no matter what you do, if you lower the AVERAGE temperature
over a long period, you save energy. That's the beginning, middle, and
end of the facts. Your average temp over the entire heating season is
what counts. Lowering the temp for a period each day results in a
lower average temp over the course of a heating season.
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