On Fri, 2006-09-22 at 08:36 -0300, Gerhard Fiedler wrote:
> hgraf wrote:
> 
> > But that's why I have a programmable thermostat, the furnace is basically
> > off all day, turns on when I get home, and turns down to 19 degrees C
> > again a few hours before I go to sleep so by the time I go to sleep my
> > room is nice and cool. A few hours before I wake up the thermostat goes
> > back up to 23C and the bathroom is nice and warm by the time I wake up.
> 
> You seem to live alone, right? 

Nope, it's my brother and myself, but we have similar schedules.

> Take a typical weekday from my childhood: We
> get all up. At that time, all room thermostats except the kitchen are on
> lower temperatures, so the only room that is warm then is the kitchen. It
> gets warm because the central control of the warm water is set to heat it
> up higher a bit before we get up. The room thermostats all stay that way
> when we all go our way (work and school). The central warm water control
> goes down a bit at that time, because comfort heating is not required.
> Around noon, a bit before I come home from school, it goes up again.
> Kitchen is warm. I turn up the thermostat in my room. (I may have done so
> in the morning, or not...) In the afternoon, the only one who is in the
> house is me, and the only rooms heated are my bedroom and the kitchen. Late
> afternoon my mom comes home, with my sister. Her room gets now also heated,
> and maybe also the laundry room if my mom's going down there (in the
> basement) to do something. Only in the evening the living room gets also
> heated. At that time, it's still not everything heated equally: my parents'
> bedroom is only at sleeping temperature, most or all rooms in the basement
> are only at maintenance temperature, bathrooms (except for the main
> bathroom) are at a lower than comfort temperature. 

Perhaps it's a house size thing? My house is simply too small to "shut
off" certain rooms at certain times. Most rooms in the house are "multi
purpose", and due to the open concept there are certain rooms that are
so open to other rooms it wouldn't make sense to heat one and not the
other. My bedroom functions as my entertainment room and office, my
brother's bedroom functions as his office as well. There are only two
rooms we aren't regularly using in the course of each day: the spare
bedroom and the laundary. In both cases those registers have been shut
off.

> This is a lot less heating than with only one central control. Before the
> individual room thermostats, up to the 60ies, there were only manual valves
> at the radiators in Germany, similar to the shutters (louvres? is that the
> same thing?) in the air outlets. But when the radiator thermostats became
> reasonably available, people soon realized that a few bucks more for the
> radiator thermostat are easily made up for with energy savings due to less
> overheating and increased comfort due to less overheating and less
> underheating. So from the 70ies on, most people added these to their older
> installations, and new installations are since then pretty much all
> equipped with individual thermostats.

What are the savings to individual control compared to the way I do
things (programmable thermostat) for a WELL insulated home? Considering
how long it takes my home to drop just a degree I'm not convinced the
savings are that great.

> > My "problem" with individual controls is that it can take quite a while
> > to warm up a room, so if your plans change one evening you are stuck in
> > a cold room for a few hours (admittedly if I get home from work early
> > for some reason I'm in the same boat).
> 
> Well... it seems that it's just as easy to heat up one room when plans
> change than it is to heat up a whole house. 

Exactly, which is why my whole house starts getting heated before I come
home.

> > It becomes quite difficult with forced air to dynamically change things.
> > The reason being any setting change in one vent will affect many other
> > vents. It's very common that turn off one room results in another room
> > going 3 degrees above the rest of the house. 
> 
> We are here in a high-tech discussion group where many people deal with
> complex control issues, right? Come on... controlling something like this
> can't be /that/ difficult :)  You seem to forget that the "other room" also
> has now a controlled inlet, so if it gets warmer, the inlet closes down
> more, automatically -- so it wouldn't get warmer. 

Actually, it can be impossible, in the case of my brothers rooms. As a
test we closed down ALL the outlets in the house except his room. The
result? His room STILL was colder then the rest of the house, and my
room (two outlets and right above the furnace) was still a few degrees
above the rest of the house. Room to room control of more then a few
degrees simply isn't a good idea with forced air. That is one benefit of
a radiator type system, individual control is "guaranteed" to work.

> Your argument is based on
> your current experience with a system without individual room control, and
> is in fact an argument for using individual room controls rather than
> against it. You can also control the pressure of the air flow in the main
> duct, so you have always the same pressure. Closing one vent then won't
> affect the others (or at least not that much), because the duct pressure
> won't change as a consequence of this. This of course presumes that the
> ducts are wide enough so that there are no significant pressure changes
> along the individual branches due to shutters opening or closing. Or you
> work with controlling the temperature of the air flow into each room with
> local, controlled air mixers (like the high-end cars do it). All kinds of
> ways to tackle something like this... where there is a will there is a way,
> or so the saying goes. 

Actually my system IS designed with some individual control, it's just
that forced air isn't that great for individual control.

In my case, where basically every room is used in my house is used when
I'm home, individual control just doesn't make much sense. Aside from
this, more of the house you cut off, the less air flow there is through
the cold air returns, I'm sure this will affect how well the furnace can
heat the home.

> > I'm not saying it's impossible, but with a well insulated house I don't
> > think it's worth the effort. 
> 
> Here we come back to the differences in energy consumption between
> different cultures. If heating is a major energy consumer (as you stated
> earlier, in another thread), and heating energy consumption is proportional
> to the difference in temperature between inside and outside (no matter how
> good the insulation is, this is more or less the case), keeping as many
> parts of the house as cool as possible definitely reduces the amount of
> energy needed for heating -- and since this is a major contributor, it
> reduces the overall amount of energy needed per person. Whether this is
> worth it or not is a subjective judgment, and it seems that different
> people and different cultures (being an average of the individual people)
> come to different conclusions. (Maybe as a function of energy prices,
> average infection with NIH syndrome and other factors :)

I'm not debating that SOME savings might be had, what I'm debating is
the savings aren't worth the annoyances of walking into a frigid room
when plans change (damn, didn't plan to do the laundry today but I gotta
take the car in). Of course, my utility costs are about half of the
average utility cost (as I've seen) so "worth" is certainly relative. I
am curious though, does anybody have info on the following: same size
house, one with forced air, the other with radiators, which is more
efficient and by how much?

Personally I've lived with radiators and after buying a house with
forced air I'll NEVER go back. With radiators there was always areas in
the room that were warmer then others, and the smell of that metal
heating always annoyed me. I'm VERY sensitive to smells (I can tell the
model of subway car in my transit system based purely on the smell of
the air conditioning) and that was one thing I always hated about
radiators.

TTYL

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