Ohmwork

[News]

Yeah, that's why I said 'can get'

Those very well insulated houses arent ideal where it gets
very hot in summer and you want an outside inside effect.

Insulation also keeps heat out as well as in. They are generally cool in
summer too. Just draw cooler air in from the north side, preferably from
under vegetation, and a well insulated house can be very comfortable.

 

[William W. Plummer]

Insulation also keeps heat out as well as in. They are generally cool in
summer too. Just draw cooler air in from the north side, preferably from
under vegetation, and a well insulated house can be very comfortable.

In the summer, you have the option of variable insulation -- open the
windows and doors. Use fans.

 

[Rod Speed]

Insulation also keeps heat out as well as in.

Sure, but one thing that makes a house very livable in the
weather thats not extreme at either end is that outside
inside situation where you can have the comfort thats
usual inside, the chairs and entertainment etc while still
having the house very open to the outside as well.

Hard to do that with a very well insulated house.

They are generally cool in summer too.

Depends on the area. We have summers with 10 days
in a row with the temperature over 40C and nothing
you do can keep the house 'cool' in that situation.

Just draw cooler air in from the north side, preferably from under
vegetation, and a well insulated house can be very comfortable.

Yes, but not with the extremes of hot weather.
You have to have active cooling then.

And I find that in that situation, its very pleasant to have that
outside inside effect thru the morning until the temperature
gets too hot, then close the house down and turn on the active
cooling. And do the reverse in the evening, when its cooled
down enough, turn the active cooling off and open everything up.

Good insulation has real downsides in that situation.

Get the same effect in winter too with huge amounts
of glass on the equator side of the house, with no
heating at all required on sunny days. Not cheap to
have good insulation for the night or overcast days.

We get enough sunny days here that I choose
to just pay for the heat on the overcast days.

 

[News]

Sure, but one thing that makes a house very livable in the
weather thats not extreme at either end is that outside
inside situation where you can have the comfort thats
usual inside, the chairs and entertainment etc while still
having the house very open to the outside as well.

Hard to do that with a very well insulated house.


Depends on the area. We have summers with 10 days
in a row with the temperature over 40C and nothing
you do can keep the house 'cool' in that situation.

Your a/c bills will be much smaller in a superinsulated house.

Yes, but not with the extremes of hot weather.
You have to have active cooling then.

In situations were a/c would be normally be used, a superinsulated house
drawing in, via ducting, outside air on the north face under vegetation can
keep the house comfortable.

And I find that in that situation, its very pleasant to have that
outside inside effect thru the morning until the temperature
gets too hot, then close the house down and turn on the active
cooling. And do the reverse in the evening, when its cooled
down enough, turn the active cooling off and open everything up.

Good insulation has real downsides in that situation.

It does not.

 

[Rod Speed]

In the summer, you have the option of variable
insulation -- open the windows and doors.

Yes, but its that situation, with quite a bit of that 'variable
insulation' where heating just thru the floor can have its
downsides unless the variable insulation is expensive.

Use fans.

No use in the most extreme conditions, you need active cooling.

 

[Rod Speed]

Your a/c bills will be much smaller in a superinsulated house.

Nope, I use evaporative cooling.

In situations were a/c would be normally be used, a superinsulated
house drawing in, via ducting, outside air on the north face under
vegetation can keep the house comfortable.

Nope, not when its 40C outside, and that's in the shade.

Nothing but active cooling will produce
anything like a comfortable house.

It does not.

Corse it does. That insulation prevents the house taking
advantage of the outside temp when its comfortable.

 

[Fred B. McGalliard]

....

other hand I have to wonder if this is straight plagairism
of copyrighted material; a jailable offense.

I thought you had to be sued? And of course, there is fair use. All the
republican comments about Moor's movie may quote elements of it in order to
comment on it.

 

[Fred B. McGalliard]

....

More sections. The more you keep the greywater segregated into separate
regions, the better.

I have been thinking on a stratified storage method. There are two ways I
can think of to do this. One is to let the warm water enter near the tank
bottom and flow up an insulated column with downward pointing vanes, so the
hot water will rise till it reaches the level of water at that temperature
plus a small delta, then it will flow out, adding to the strata at that
temperature. The other method would use a temperature sensor and a moveable
drain tube/orifice to achieve the same stratification. This would work to
capture and store solar warm, solar hot, ambient (when you have a hot day),
and grey water heat, all in the same tank.

 

[News]

Nope, I use evaporative cooling.



Nope, not when its 40C outside, and that's in the shade.

There is a level where it will not work. The threshold will be higher with
superinsulation..

 

[Rod Speed]

There is a level where it will not work.

Yep, and that is quite common.

The threshold will be higher with superinsulation..

Nope, what matters with that particular question
is whether the 'outside air on the north face under
vegetation' is actually a comfortable temperature.

Super insulation isnt even particularly relevant
on that, compared with normal insulation.

 

[daestrom]

More time steps might help. It takes 6/1.25 = 4.8 minutes to fill
half the tubing, which is comparable to its time constant.

Would give you a smoother curve, but would not change the end point.

I hope that isn't required, because it might add to clogging problems.
Greywater will enter the top of the drum via a horizontal part of a
1.5" elbow and leave from the bottom via a 1.5" elbow on a dip tube.
I'm hoping it will stratify, between bouyancy forces and poor downward
heatflow. With no bouyancy and 0.00554 ft^2/h thermal diffusivity, 60 F
water with a 100 F surface might warm to 80 F 1' below in 180x1^2 hours.

Yes. The ideal case is each layer does not mix with another, nor is any
heat conducted between sucessive 'grey' 'layers'. Since water doesn't
really behave perfectly in a large tank, we break it up into several small
ones with insulation between them.

I thought about that, but the outer tubing becomes more expensive, and
there's the clogging problem.

Save cost of drum, that helps alleviate the extra cost. Yes, there is the
clogging problem. But even with the large drum, there would be a
sedimentation problem. The bottom would fill with 'silt' and such. Just
could operate longer before needing to clean it out.

This kind of tubing will bend to a 20D radius without kinking...


Hmmm. Hair, soap, food particles. Some septic tanks use nylon stocking
output filters. Input filters... yuck. Tiny crud particles might still
agglomerate inside the heat exchanger.

Well, a wye strainer would be a lot easier to flush out once a month or
whatever. And so the amount of 'crud' that enters into the heat-exchanger
would be less and *it* would last longer before needing a thorough cleaning.
Either a high-pressure/high-flow flush, or disassembly. If expect to
disassemble often, could take that into account with the fittings/design.
Empty, disconnect, take outside, pull inner tube from outer,
scrub/brush/rinse, reassemble, reinstall. If it's only once a year or less,
might be a not-bad summer weekend project.

Of course, the commercial version of GFX heat exchanger doesn't require this
maintenance, but is more expensive ;-)

daestrom

 

[RamRod Sword of Baal]

We do have these new fangled ideas called windows, and you can open them and
let the cool breeze in............

In fact my new air conditioning system actually will start to bring in large
quantities of fresh air when it is cool enuff to cool down the house, rather
than run the cooling (Compressor), as an energy saving feature.

 

[daestrom]

...

I have been thinking on a stratified storage method. There are two ways I
can think of to do this. One is to let the warm water enter near the tank
bottom and flow up an insulated column with downward pointing vanes, so the
hot water will rise till it reaches the level of water at that temperature
plus a small delta, then it will flow out, adding to the strata at that
temperature.

Interesting idea. Just have to make the vanes large enough and/or keep the
flow low enough that the inflow rate doesn't disrupt the stratification too
much. Keep the Reynolds number down below the turbulent point and it could
work.

The other thing you would need is that the bouyancy/rising force be able to
move the water up the column as fast as the incoming water. Otherwise, the
extra flow of incoming warm water would 'overflow' the downward pointing
vanes and spill out in a region colder than you want.

The other method would use a temperature sensor and a moveable
drain tube/orifice to achieve the same stratification. This would work to
capture and store solar warm, solar hot, ambient (when you have a hot day),
and grey water heat, all in the same tank.

Active motion control of the tube may be difficult to attain. But perhaps
some sort of 'bulb' on the end that would change bouyancy with the flowing
water's temperature? Then it would rise/fall automatically with the
temperature changes (with some slight delay for the bulb to adjust).

daestrom

 

[daestrom]

Exactly. Kachadorian has insulation under the blocks, although not that
much. He is attempting to extract heat from the ground, that will circulate
in the house to prevent freezing when unoccupied.

Ah... Now *that* was a feature I didn't notice. If the air outlets on one
end of the blocks are higher than the opposite inlet, a natural chimney
should do the trick.

have

Even when insulating properly under the floor, some heat is lost. This can
be minimised by using Kachadorians hollow blocks. Less thermal bridging to
the ground beneath.

What thermal bridging are you thinking of? I'm talking about large slabs of
foam insulation with no 'bridging' and then the cement poured over that. If
anything, the block provides bridging from above the air-core to below by
way of the concrete webbing.

daestrom

 

[Rod Speed]

We do have these new fangled ideas called windows,
and you can open them and let the cool breeze in............

Pity they are pretty lousy insulation wise whatever
you do unless you spend heaps on them.

In fact my new air conditioning system actually will start to bring in large
quantities of fresh air when it is cool enuff to cool down the house, rather
than run the cooling (Compressor), as an energy saving feature.

Sure, but thats nothing like the pleasant environment you get with big
glass doors you can open when the outside is pleasant temp wise.

I have those on both the N and S side of the main room, in fact every
room except the smallest rooms have them, and its very pleasant indeed.

The main downside is that super insulating them is quite expensive and
they are quite expensive themselves compared with the walls they replace.

 

[News]

Ah... Now *that* was a feature I didn't notice. If the air outlets on one
end of the blocks are higher than the opposite inlet, a natural chimney
should do the trick.
just

What thermal bridging are you thinking of? I'm talking about large slabs of
foam insulation with no 'bridging' and then the cement poured over that. If
anything, the block provides bridging from above the air-core to below by
way of the concrete webbing.

Insulation only slows heat when travelling through, it does not prevent heat
movement. Having a conventional concrete slab with insulation under does not
totally prevent heat from entering the ground. The higher the slab
temperature the more heat is lost to the ground. Hollow concrete blocks
with insulation below, and a heated screed above, give less of an area for
heat to travel down to the insulation below. You have a semi suspended
floor.

The space under the floor would be heated when having hydronic pipes in the
screed above. This would create circulation of air into the rooms above,
making an underfloor system more responsive, eliminating, or vastly
reducing, one of it disadvantages.

I don't think Kachadorian ever thought of this application for his hollow
floor. It is certainly better than charging the slab up with purchased heat
as that is what he does some of the time.

 

[[email protected]]

Would give you a smoother curve, but would not change the end point.

I disagree. Seems to me more time steps would show more stratification.

Yes. The ideal case is each layer does not mix with another, nor is any
heat conducted between sucessive 'grey' 'layers'.

Can't get much better than 1' in 180 hours, ignoring bouyancy...

Since water doesn't really behave perfectly in a large tank,
Oh?

we break it up into several small ones with insulation between them.

How will the water behave without insulation?

Save cost of drum...

I've collected about 300 free drums. Floorspace is also an issue.

....ie a 2x20x1.5 = 60" diameter.

Well, a wye strainer would be a lot easier to flush out once a month or
whatever. And so the amount of 'crud' that enters into the heat-exchanger
would be less and *it* would last longer before needing a thorough cleaning.
Either a high-pressure/high-flow flush, or disassembly. If expect to
disassemble often, could take that into account with the fittings/design.
Empty, disconnect, take outside, pull inner tube from outer,
scrub/brush/rinse, reassemble, reinstall. If it's only once a year or less,
might be a not-bad summer weekend project.

Yuck.

Nick

 

[daestrom]

may slabs

Insulation only slows heat when travelling through, it does not prevent heat
movement. Having a conventional concrete slab with insulation under does not
totally prevent heat from entering the ground. The higher the slab
temperature the more heat is lost to the ground.

Thanks, but heat-transfer 101 isn't really necessary.
Hollow concrete blocks

with insulation below, and a heated screed above, give less of an area for
heat to travel down to the insulation below. You have a semi suspended
floor.

The concreate webbing will bridge down through the block. Yes, that is a
smaller area, but higher conductivity. The air pockets in the cores are
*not* perfect insulators. As you said, the air would 'only slow heat
travelling through, it does not prevent heat movement'. Foam insulation has
a higher R-value than still air, so an equal thickness of foam would be
better at limiting heat loss.

But this air isn't 'still'. If it is circulating (naturally, or forced) as
you suggest, then there is heat transfer between the air flowing through the
core (presumably this air is as warm or warmer than the room itself) and the
*bottom* half of the concreate block. Full floor surface area, and
concrete. So the only significant insulation is what you place *below* the
block. With air circulation, I would think the block provides little
insulating value at all.

The space under the floor would be heated when having hydronic pipes in the
screed above. This would create circulation of air into the rooms above,
making an underfloor system more responsive, eliminating, or vastly
reducing, one of it disadvantages.

This I can understand. But as far as limiting heat loss, I think you'd be
better off just doubling the thickness of the under-floor/block insulation.

daestrom

 

[daestrom]

I disagree. Seems to me more time steps would show more stratification.

If you model with only an 'upper grey water' and a 'lower grey water', then
the stratification is limited to two layers. More time steps won't make
more layers. Why do you think it would? Try it.

Can't get much better than 1' in 180 hours, ignoring bouyancy...


How will the water behave without insulation?

The time between 'bursts' will be a factor here. Even with perfectly
stratified water 'layers', heat will be conducted between each 'layer'. If
the time between 'bursts' is really long compared to the time-constant for
the layers, the tank will reach a uniform temperature throughout before the
next 'burst'. You don't want that. You want the grey water in the upper
layers to remain hot and not conduct its heat to the cooler layers
underneath it. You want the bottom grey-water layer to be as cold as the
incoming freshwater. That way, when it is pushed out by the next 'burst', i
t won't be taking much energy with it. On the other hand, if the entire
tank equalizes, then the next 'burst' will push warmer water out the
grey-water outlet, wasting energy.

In the case of tube-within-a-tube, the same problem will occur if the
sucessive coils of the outer tube are in direct contact.

I've collected about 300 free drums. Floorspace is also an issue.

Well, you mentioned the price of a drum in your earlier calcs, so I
*assumed* you had to pay for the drum.

...ie a 2x20x1.5 = 60" diameter.

Of course, a more expensive setup might be made with several straight
sections of copper pipe. Two different sizes, and reducing 'Tee's on each
end with the smaller tube 'crossing the top of the tee' while the outer
tube's water comes out the base of the 'tee'. But that's a lot of joints to
'sweat' and you couldn't disassemble it for cleaning. But with copper, you
might get away with much shorter total length (owing its higher
conductivity). And put the grey water through the smaller central tube with
just the 90 degree elbows on the ends. Could probably flush it easier than
the outer tube, and with just a straight-thru shot and elbows, it might not
foul as much.

Yuck.

Oh? And emptying out a 55 gal drum with this 'gunk' in the bottom of it is
any better? Oh wait, you might just replace it with one of those free drums
you have. Sorry, we're not all that lucky.

daestrom

 

[[email protected]]

If you model with only an 'upper grey water' and a 'lower grey water', then
the stratification is limited to two layers...

We might simultaneously increase the number of layers and the number of
time steps. If half the tubing fills in 4.8 minutes, we might consider
at least 2 layers... with at least 4 layers for 2.4 minutes, and so on.

When x = 1 and erf(x/sqrt(4at)) = erf(0.5) = 0.5... from page 89 of the
1998 Shaum's Outline on Heat Transfer. Section 4.4 on "One-dimensional
systems: fixed surface temperature, semi-infinite body."

This could be close to ideal stratification. Bouyancy would help even more.
How do we combine the bouyancy and diffusivity effects?

The time between 'bursts' will be a factor here. Even with perfectly
stratified water 'layers', heat will be conducted between each 'layer'.

It looks to me that very little heat will conduct downward between layers...
180 hours is very long compared to the time between bursts. Altho the drum
walls are steel, about 1/16" thick.

If the time between 'bursts' is really long compared to the time-constant for
the layers,

Which it isn't...

the tank will reach a uniform temperature throughout before the next 'burst'.

You don't want that. You want the grey water in the upper layers to remain
hot and not conduct its heat to the cooler layers underneath it. You want
the bottom grey-water layer to be as cold as the incoming freshwater.

Sure. That's what we want.

That way, when it is pushed out by the next 'burst', it won't be taking
much energy with it. On the other hand, if the entire tank equalizes,
then the next 'burst' will push warmer water out the grey-water outlet,
wasting energy.

We don't want that.

Well, you mentioned the price of a drum in your earlier calcs, so I
*assumed* you had to pay for the drum.

Rarely. You can probably find used drums where you live as well.
Bakeries tend to buy syrups and honey in these kinds of drums.

And emptying out a 55 gal drum with this 'gunk' in the bottom of it is
any better?

I'd hope to avoid that with natural flow, but it might have a bulkhead
boiler valve near the bottom for backflushing into the septic system.

Nick