A bargain and discount forum. BargainBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » BargainBanter forum » Discount and bargain forums » Frugal living
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Winter humidification wastes energy



 
 
Thread Tools Display Modes
  #1  
Old November 16th 04, 03:41 PM
external usenet poster
 
Posts: n/a
Default Winter humidification wastes energy

HvacTech2 wrote:

Z Here's a link for you to read up on...


http://lennox.com/pdfs/brochures/Len...umidifiers.pdf

it doesn't do any good to show him the truth. This guy is a legend in his
own mind and doesn't believe anything other then what he thinks.


It's surprising how little hvac installers know about physics and comfort.
You'd think they'd be curious, beyond the everyday nuts and bolts, or feel
some sense of responsibility.

We might try this in two steps:

1. The ASHRAE 55-2004 comfort standard says 69 F at 39% RH and 69.8 at 19%
are equally comfortable (PMV = -0.542.) Do you disagree with this?

2. Keeping a house 69 F at 39% RH uses more energy than keeping a house
69.8 at 19% in wintertime. Do you disagree with this?

If so, where are your calculations?


No disagreements? No calculations? :-) Let's try again, from the top:

I suspect that winter humidification wastes vs saves heating energy, and
the savings claim is an energy myth. People tend to forget that evaporating
water takes heat energy, and that heat energy has to come from somewhere,
even if something like a humidifier belt motor uses little energy by itself.

The heat saved by turning a thermostat down appears to be far less than
the extra heat used to evaporate water, in all but extremely tight houses,
eg submarines.

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf claims
that 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but the
BASIC program in the new ASHRAE 55-2004 comfort standard predicts that
69 F and 35% RH and 69.8 at 19% RH are equally comfortable (PMV = -0.542.)

If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of conductance,
turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320 Btu/h.

Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water per
pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh = 0.00617.
Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316 pounds
of water per pound of dry air. Dry air weighs about 0.075 lb per cubic foot.

With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of
air leakage, raising the indoor RH from 19 to 39% requires evaporating
720x0.00316 = 2.275 pounds of water per hour, which requires about 2275
Btu/h of heat energy.

Humid air seems healthier and may prevent furniture cracking and static
electricity, but serious air sealing seems like a better solution, with
blower door testing. Houses have natural humidity sources. Andersen says
an average family of 4 evaporates 2 gallons per day of water by breathing,
cleaning, cooking, and so on. Unlike humidification, more air sealing can
raise the RH while saving vs wasting heat energy.

Nick

Ads
  #2  
Old November 16th 04, 05:15 PM
Art Todesco
external usenet poster
 
Posts: n/a
Default

I would like to see real calculations showing one way or the other.
That said, there are health reasons to humidify and there are health
reasons not to, if you don't clean the humidifier and let mold and
bacteria grow. But, back to the original question, a house that is very
leaky will cause the humidifier to run much more than a tight house.
Before I replaced my windows the humidifer would run all winter long (in
the Chicago area). With the new windows, it might run once during a
severe cold snap. Last winter is never ran. BTW, the windows were
replaced 10 or 12 years ago, so I have had many years to monitor this.
So, any calculations must take this into account also.

wrote:

HvacTech2 wrote:


Z Here's a link for you to read up on...


http://lennox.com/pdfs/brochures/Len...umidifiers.pdf


it doesn't do any good to show him the truth. This guy is a legend in his
own mind and doesn't believe anything other then what he thinks.


It's surprising how little hvac installers know about physics and comfort.
You'd think they'd be curious, beyond the everyday nuts and bolts, or feel
some sense of responsibility.

We might try this in two steps:

1. The ASHRAE 55-2004 comfort standard says 69 F at 39% RH and 69.8 at 19%
are equally comfortable (PMV = -0.542.) Do you disagree with this?

2. Keeping a house 69 F at 39% RH uses more energy than keeping a house
69.8 at 19% in wintertime. Do you disagree with this?

If so, where are your calculations?



No disagreements? No calculations? :-) Let's try again, from the top:

I suspect that winter humidification wastes vs saves heating energy, and
the savings claim is an energy myth. People tend to forget that evaporating
water takes heat energy, and that heat energy has to come from somewhere,
even if something like a humidifier belt motor uses little energy by itself.

The heat saved by turning a thermostat down appears to be far less than
the extra heat used to evaporate water, in all but extremely tight houses,
eg submarines.

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf claims
that 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but the
BASIC program in the new ASHRAE 55-2004 comfort standard predicts that
69 F and 35% RH and 69.8 at 19% RH are equally comfortable (PMV = -0.542.)

If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of conductance,
turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320 Btu/h.

Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water per
pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh = 0.00617.
Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316 pounds
of water per pound of dry air. Dry air weighs about 0.075 lb per cubic foot.

With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of
air leakage, raising the indoor RH from 19 to 39% requires evaporating
720x0.00316 = 2.275 pounds of water per hour, which requires about 2275
Btu/h of heat energy.

Humid air seems healthier and may prevent furniture cracking and static
electricity, but serious air sealing seems like a better solution, with
blower door testing. Houses have natural humidity sources. Andersen says
an average family of 4 evaporates 2 gallons per day of water by breathing,
cleaning, cooking, and so on. Unlike humidification, more air sealing can
raise the RH while saving vs wasting heat energy.

Nick

  #3  
Old November 16th 04, 05:15 PM
Art Todesco
external usenet poster
 
Posts: n/a
Default

I would like to see real calculations showing one way or the other.
That said, there are health reasons to humidify and there are health
reasons not to, if you don't clean the humidifier and let mold and
bacteria grow. But, back to the original question, a house that is very
leaky will cause the humidifier to run much more than a tight house.
Before I replaced my windows the humidifer would run all winter long (in
the Chicago area). With the new windows, it might run once during a
severe cold snap. Last winter is never ran. BTW, the windows were
replaced 10 or 12 years ago, so I have had many years to monitor this.
So, any calculations must take this into account also.

wrote:

HvacTech2 wrote:


Z Here's a link for you to read up on...


http://lennox.com/pdfs/brochures/Len...umidifiers.pdf


it doesn't do any good to show him the truth. This guy is a legend in his
own mind and doesn't believe anything other then what he thinks.


It's surprising how little hvac installers know about physics and comfort.
You'd think they'd be curious, beyond the everyday nuts and bolts, or feel
some sense of responsibility.

We might try this in two steps:

1. The ASHRAE 55-2004 comfort standard says 69 F at 39% RH and 69.8 at 19%
are equally comfortable (PMV = -0.542.) Do you disagree with this?

2. Keeping a house 69 F at 39% RH uses more energy than keeping a house
69.8 at 19% in wintertime. Do you disagree with this?

If so, where are your calculations?



No disagreements? No calculations? :-) Let's try again, from the top:

I suspect that winter humidification wastes vs saves heating energy, and
the savings claim is an energy myth. People tend to forget that evaporating
water takes heat energy, and that heat energy has to come from somewhere,
even if something like a humidifier belt motor uses little energy by itself.

The heat saved by turning a thermostat down appears to be far less than
the extra heat used to evaporate water, in all but extremely tight houses,
eg submarines.

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf claims
that 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but the
BASIC program in the new ASHRAE 55-2004 comfort standard predicts that
69 F and 35% RH and 69.8 at 19% RH are equally comfortable (PMV = -0.542.)

If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of conductance,
turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320 Btu/h.

Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water per
pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh = 0.00617.
Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316 pounds
of water per pound of dry air. Dry air weighs about 0.075 lb per cubic foot.

With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of
air leakage, raising the indoor RH from 19 to 39% requires evaporating
720x0.00316 = 2.275 pounds of water per hour, which requires about 2275
Btu/h of heat energy.

Humid air seems healthier and may prevent furniture cracking and static
electricity, but serious air sealing seems like a better solution, with
blower door testing. Houses have natural humidity sources. Andersen says
an average family of 4 evaporates 2 gallons per day of water by breathing,
cleaning, cooking, and so on. Unlike humidification, more air sealing can
raise the RH while saving vs wasting heat energy.

Nick

  #4  
Old November 16th 04, 07:02 PM
Ace
external usenet poster
 
Posts: n/a
Default

You can say what you want about humidifiers, but I had an Aprilaire 600
installed on my new Carrier furnace return air duct and (my new ranch style
home is 2,880 sq feet) since I did my throat is not dry and sore every
morning I get up and I don't have hock my socks off to clear out my throat.
Also, static electricity has been eliminated in my home. I also think that
my gas bill will be cheaper with proper humidification. I disagree with you
who say home humidification is a farce. Of course one should not over
humidify and have their windows all steamed up and their walls dripping with
condensation. Common sense comes into play.


"Art Todesco" wrote in message
news[email protected]_s53...
I would like to see real calculations showing one way or the other.
That said, there are health reasons to humidify and there are health
reasons not to, if you don't clean the humidifier and let mold and
bacteria grow. But, back to the original question, a house that is very
leaky will cause the humidifier to run much more than a tight house.
Before I replaced my windows the humidifer would run all winter long (in
the Chicago area). With the new windows, it might run once during a
severe cold snap. Last winter is never ran. BTW, the windows were
replaced 10 or 12 years ago, so I have had many years to monitor this.
So, any calculations must take this into account also.

wrote:

HvacTech2 wrote:


Z Here's a link for you to read up on...

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf


it doesn't do any good to show him the truth. This guy is a legend in

his
own mind and doesn't believe anything other then what he thinks.

It's surprising how little hvac installers know about physics and

comfort.
You'd think they'd be curious, beyond the everyday nuts and bolts, or

feel
some sense of responsibility.

We might try this in two steps:

1. The ASHRAE 55-2004 comfort standard says 69 F at 39% RH and 69.8 at

19%
are equally comfortable (PMV = -0.542.) Do you disagree with this?

2. Keeping a house 69 F at 39% RH uses more energy than keeping a house
69.8 at 19% in wintertime. Do you disagree with this?

If so, where are your calculations?



No disagreements? No calculations? :-) Let's try again, from the top:

I suspect that winter humidification wastes vs saves heating energy, and
the savings claim is an energy myth. People tend to forget that

evaporating
water takes heat energy, and that heat energy has to come from

somewhere,
even if something like a humidifier belt motor uses little energy by

itself.

The heat saved by turning a thermostat down appears to be far less than
the extra heat used to evaporate water, in all but extremely tight

houses,
eg submarines.

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf

claims
that 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but the
BASIC program in the new ASHRAE 55-2004 comfort standard predicts that
69 F and 35% RH and 69.8 at 19% RH are equally comfortable (PMV

= -0.542.)

If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of

conductance,
turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320

Btu/h.

Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water

per
pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh =

0.00617.
Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316

pounds
of water per pound of dry air. Dry air weighs about 0.075 lb per cubic

foot.

With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of
air leakage, raising the indoor RH from 19 to 39% requires evaporating
720x0.00316 = 2.275 pounds of water per hour, which requires about 2275
Btu/h of heat energy.

Humid air seems healthier and may prevent furniture cracking and static
electricity, but serious air sealing seems like a better solution, with
blower door testing. Houses have natural humidity sources. Andersen says
an average family of 4 evaporates 2 gallons per day of water by

breathing,
cleaning, cooking, and so on. Unlike humidification, more air sealing

can
raise the RH while saving vs wasting heat energy.

Nick



  #5  
Old November 16th 04, 07:02 PM
Ace
external usenet poster
 
Posts: n/a
Default

You can say what you want about humidifiers, but I had an Aprilaire 600
installed on my new Carrier furnace return air duct and (my new ranch style
home is 2,880 sq feet) since I did my throat is not dry and sore every
morning I get up and I don't have hock my socks off to clear out my throat.
Also, static electricity has been eliminated in my home. I also think that
my gas bill will be cheaper with proper humidification. I disagree with you
who say home humidification is a farce. Of course one should not over
humidify and have their windows all steamed up and their walls dripping with
condensation. Common sense comes into play.


"Art Todesco" wrote in message
news[email protected]_s53...
I would like to see real calculations showing one way or the other.
That said, there are health reasons to humidify and there are health
reasons not to, if you don't clean the humidifier and let mold and
bacteria grow. But, back to the original question, a house that is very
leaky will cause the humidifier to run much more than a tight house.
Before I replaced my windows the humidifer would run all winter long (in
the Chicago area). With the new windows, it might run once during a
severe cold snap. Last winter is never ran. BTW, the windows were
replaced 10 or 12 years ago, so I have had many years to monitor this.
So, any calculations must take this into account also.

wrote:

HvacTech2 wrote:


Z Here's a link for you to read up on...

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf


it doesn't do any good to show him the truth. This guy is a legend in

his
own mind and doesn't believe anything other then what he thinks.

It's surprising how little hvac installers know about physics and

comfort.
You'd think they'd be curious, beyond the everyday nuts and bolts, or

feel
some sense of responsibility.

We might try this in two steps:

1. The ASHRAE 55-2004 comfort standard says 69 F at 39% RH and 69.8 at

19%
are equally comfortable (PMV = -0.542.) Do you disagree with this?

2. Keeping a house 69 F at 39% RH uses more energy than keeping a house
69.8 at 19% in wintertime. Do you disagree with this?

If so, where are your calculations?



No disagreements? No calculations? :-) Let's try again, from the top:

I suspect that winter humidification wastes vs saves heating energy, and
the savings claim is an energy myth. People tend to forget that

evaporating
water takes heat energy, and that heat energy has to come from

somewhere,
even if something like a humidifier belt motor uses little energy by

itself.

The heat saved by turning a thermostat down appears to be far less than
the extra heat used to evaporate water, in all but extremely tight

houses,
eg submarines.

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf

claims
that 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but the
BASIC program in the new ASHRAE 55-2004 comfort standard predicts that
69 F and 35% RH and 69.8 at 19% RH are equally comfortable (PMV

= -0.542.)

If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of

conductance,
turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320

Btu/h.

Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water

per
pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh =

0.00617.
Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316

pounds
of water per pound of dry air. Dry air weighs about 0.075 lb per cubic

foot.

With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of
air leakage, raising the indoor RH from 19 to 39% requires evaporating
720x0.00316 = 2.275 pounds of water per hour, which requires about 2275
Btu/h of heat energy.

Humid air seems healthier and may prevent furniture cracking and static
electricity, but serious air sealing seems like a better solution, with
blower door testing. Houses have natural humidity sources. Andersen says
an average family of 4 evaporates 2 gallons per day of water by

breathing,
cleaning, cooking, and so on. Unlike humidification, more air sealing

can
raise the RH while saving vs wasting heat energy.

Nick



  #6  
Old November 16th 04, 08:40 PM
[email protected]
external usenet poster
 
Posts: n/a
Default

wrote:

You can say what you want about humidifiers...


Thanks Ace. They waste energy.

I also think that my gas bill will be cheaper with proper humidification.


I disagree. Perhaps you have no understanding of physics.

I disagree with you who say home humidification is a farce.


I never said that. Perhaps you have no understanding of English :-)

Have a nice day.

Nick

  #7  
Old November 16th 04, 08:40 PM
[email protected]
external usenet poster
 
Posts: n/a
Default

wrote:

You can say what you want about humidifiers...


Thanks Ace. They waste energy.

I also think that my gas bill will be cheaper with proper humidification.


I disagree. Perhaps you have no understanding of physics.

I disagree with you who say home humidification is a farce.


I never said that. Perhaps you have no understanding of English :-)

Have a nice day.

Nick

  #8  
Old November 17th 04, 09:59 AM
Gary R. Lloyd
external usenet poster
 
Posts: n/a
Default

On 16 Nov 2004 09:41:34 -0500, wrote:

HvacTech2 wrote:

Z Here's a link for you to read up on...


http://lennox.com/pdfs/brochures/Len...umidifiers.pdf

it doesn't do any good to show him the truth. This guy is a legend in his
own mind and doesn't believe anything other then what he thinks.


It's surprising how little hvac installers know about physics and comfort.
You'd think they'd be curious, beyond the everyday nuts and bolts, or feel
some sense of responsibility.

We might try this in two steps:

1. The ASHRAE 55-2004 comfort standard says 69 F at 39% RH and 69.8 at 19%
are equally comfortable (PMV = -0.542.) Do you disagree with this?

2. Keeping a house 69 F at 39% RH uses more energy than keeping a house
69.8 at 19% in wintertime. Do you disagree with this?

If so, where are your calculations?


No disagreements? No calculations? :-) Let's try again, from the top:

I suspect that winter humidification wastes vs saves heating energy, and
the savings claim is an energy myth. People tend to forget that evaporating
water takes heat energy, and that heat energy has to come from somewhere,
even if something like a humidifier belt motor uses little energy by itself.

The heat saved by turning a thermostat down appears to be far less than
the extra heat used to evaporate water, in all but extremely tight houses,
eg submarines.

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf claims
that 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but the
BASIC program in the new ASHRAE 55-2004 comfort standard predicts that
69 F and 35% RH and 69.8 at 19% RH are equally comfortable (PMV = -0.542.)

If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of conductance,
turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320 Btu/h.

Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water per
pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh = 0.00617.
Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316 pounds
of water per pound of dry air. Dry air weighs about 0.075 lb per cubic foot.

With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of
air leakage, raising the indoor RH from 19 to 39% requires evaporating
720x0.00316 = 2.275 pounds of water per hour, which requires about 2275
Btu/h of heat energy.

Humid air seems healthier and may prevent furniture cracking and static
electricity, but serious air sealing seems like a better solution, with
blower door testing. Houses have natural humidity sources. Andersen says
an average family of 4 evaporates 2 gallons per day of water by breathing,
cleaning, cooking, and so on. Unlike humidification, more air sealing can
raise the RH while saving vs wasting heat energy.

Nick


Since you seem to love math (I can do it but I hate it), let's give
you a little challenge:

Let's assume the same house. The indoor conditions are to be
maintained at 70F and 40% RH (because the homeowner likes it that
way). This translates to an indoor dewpoint temperature of about 44F.
When the outdoor dewpoint drops below 44F, that 160CFM of infiltration
air will need to be humidified, right?

But wait, we have our family of four providing 2 gallons per day of
humidity. Thus we can drop to a lower outdoor dewpoint before extra
humidification is needed for the infiltration air.

So here is the mission, should you choose to accept it:

At what outdoor dewpoint temperature do we need to start adding
moisture in order to maintain our 70F and 40% RH?

What if the house were half the square footage (1200 sq ft)?

Gary R. Lloyd CMS
HVACR Troubleshooting Books/Software
http://www.techmethod.com

  #9  
Old November 17th 04, 09:59 AM
Gary R. Lloyd
external usenet poster
 
Posts: n/a
Default

On 16 Nov 2004 09:41:34 -0500, wrote:

HvacTech2 wrote:

Z Here's a link for you to read up on...


http://lennox.com/pdfs/brochures/Len...umidifiers.pdf

it doesn't do any good to show him the truth. This guy is a legend in his
own mind and doesn't believe anything other then what he thinks.


It's surprising how little hvac installers know about physics and comfort.
You'd think they'd be curious, beyond the everyday nuts and bolts, or feel
some sense of responsibility.

We might try this in two steps:

1. The ASHRAE 55-2004 comfort standard says 69 F at 39% RH and 69.8 at 19%
are equally comfortable (PMV = -0.542.) Do you disagree with this?

2. Keeping a house 69 F at 39% RH uses more energy than keeping a house
69.8 at 19% in wintertime. Do you disagree with this?

If so, where are your calculations?


No disagreements? No calculations? :-) Let's try again, from the top:

I suspect that winter humidification wastes vs saves heating energy, and
the savings claim is an energy myth. People tend to forget that evaporating
water takes heat energy, and that heat energy has to come from somewhere,
even if something like a humidifier belt motor uses little energy by itself.

The heat saved by turning a thermostat down appears to be far less than
the extra heat used to evaporate water, in all but extremely tight houses,
eg submarines.

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf claims
that 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but the
BASIC program in the new ASHRAE 55-2004 comfort standard predicts that
69 F and 35% RH and 69.8 at 19% RH are equally comfortable (PMV = -0.542.)

If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of conductance,
turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320 Btu/h.

Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water per
pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh = 0.00617.
Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316 pounds
of water per pound of dry air. Dry air weighs about 0.075 lb per cubic foot.

With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of
air leakage, raising the indoor RH from 19 to 39% requires evaporating
720x0.00316 = 2.275 pounds of water per hour, which requires about 2275
Btu/h of heat energy.

Humid air seems healthier and may prevent furniture cracking and static
electricity, but serious air sealing seems like a better solution, with
blower door testing. Houses have natural humidity sources. Andersen says
an average family of 4 evaporates 2 gallons per day of water by breathing,
cleaning, cooking, and so on. Unlike humidification, more air sealing can
raise the RH while saving vs wasting heat energy.

Nick


Since you seem to love math (I can do it but I hate it), let's give
you a little challenge:

Let's assume the same house. The indoor conditions are to be
maintained at 70F and 40% RH (because the homeowner likes it that
way). This translates to an indoor dewpoint temperature of about 44F.
When the outdoor dewpoint drops below 44F, that 160CFM of infiltration
air will need to be humidified, right?

But wait, we have our family of four providing 2 gallons per day of
humidity. Thus we can drop to a lower outdoor dewpoint before extra
humidification is needed for the infiltration air.

So here is the mission, should you choose to accept it:

At what outdoor dewpoint temperature do we need to start adding
moisture in order to maintain our 70F and 40% RH?

What if the house were half the square footage (1200 sq ft)?

Gary R. Lloyd CMS
HVACR Troubleshooting Books/Software
http://www.techmethod.com

  #10  
Old November 17th 04, 05:10 PM
[email protected]
external usenet poster
 
Posts: n/a
Default

Gary R. Lloyd wrote:

Let's assume the same house. The indoor conditions are to be
maintained at 70F and 40% RH (because the homeowner likes it that
way). This translates to an indoor dewpoint temperature of about 44F.


Td = 530/(1-530ln(0.4)/9621)-460 = 44.5. Pi =0.4e^(17.863-9621/530)
= 0.2994 "Hg... wi = 0.62198/(29.921/Pi-1) = 0.006286 pounds of water
per pound of dry air.

When the outdoor dewpoint drops below 44F, that 160CFM of infiltration
air will need to be humidified, right?


Somehow...

But wait, we have our family of four providing 2 gallons per day...


2x8.33/24/60 = 0.0116 lb/min.

Thus we can drop to a lower outdoor dewpoint before extra
humidification is needed for the infiltration air.


Sure.

At what outdoor dewpoint temperature do we need to start adding
moisture in order to maintain our 70F and 40% RH?


When 160x0.075(wi-wo) 0.0116, ie wo wi - 0.000966 = 0.005319 and Po
= 29.921/(0.62198/wo+1) = 0.2357 "Hg and Td = 9621/(17.863-ln(Pi))-460
= 40.2 F.

What if the house were half the square footage (1200 sq ft)?


When 80x0.075(wi-wo) 0.0116, ie wo wi - 0.001933 = 0.004353 and Po
= 29.921/(0.62198/wo+1) = 0.2079 "Hg and Td = 9621/(17.863-ln(Pi))-460
= 35.1 F, if it has half the air leakage.

Nick

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Ohmwork News Frugal living 71 July 24th 04 01:22 AM


All times are GMT +1. The time now is 09:21 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2004-2018 BargainBanter.
The comments are property of their posters.