On Oct 30, 7:50*am, RickH wrote:
On Oct 29, 8:51*pm, DD_BobK wrote:
On Oct 29, 11:05*am, RickH wrote:
On Oct 29, 10:36*am, "SteveB" wrote:
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. *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.
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