Heat?

[David P. Valley]

I just found some great deals HERE.

I'm going to go above and beyond and start to do these tests on HVAC.

[David P. Valley]

Charley,

If I were to purchase this one, what readings should I be obtaining (approximately) on HVAC registers?

[Brian A. MacNeish]

I bought a whack of equipment through these folks in 1990. They had some of the best prices around then. haven't checked today's prices though.

http://www.davis.com/

[David P. Valley]

Originally Posted by Brian A. MacNeish

I bought a whack of equipment through these folks in 1990. They had some of the best prices around then. haven't checked today's prices though.

http://www.davis.com/

I just did the research for ya. They are not as cheap as the link I posted.

[Brian E. Kelly]

Originally Posted by Brian A. MacNeish

Brian:
Not too many people would know of Alnor (or Shortridge, for that matter). What background do you have to know of this company?

Busboy at a Lobster house.

[Brian E. Kelly]

Originally Posted by dvalley

Charley,

If I were to purchase this one, what readings should I be obtaining (approximately) on HVAC registers?

If you know what cubic/ft/minute or cubic/liters/min you want it is a simple math problem to convert David.

Lets see what Charley comes up with.

[David P. Valley]

Originally Posted by bkelly2

If you know what cubic/ft/minute or cubic/liters/min you want it is a simple math problem to convert David.

Lets see what Charley comes up with.

He did mention that he like to see his installs at 300-400 CFM's......the meter will not convert for me?

[Brian E. Kelly]

Measure the register.

Say the register measures 1 square foot, and the velocity is 1 foot a minute.

That equals 1 cfm.

Eventually you will have a chart of the normal register sizes you come across with the proper conversions.

[David P. Valley]

Originally Posted by bkelly2

Measure the register.

Say the register measures 1 square foot, and the velocity is 1 foot a minute.

That equals 1 cfm.

Eventually you will have a chart of the normal register sizes you come across with the proper conversions.

Damn, I hate math.

[Charley L. Bottger]

Originally Posted by Brian A. MacNeish

Brian:
Not too many people would know of Alnor (or Shortridge, for that matter). What background do you have to know of this company?

Alnor is the Hvac industry standard test equipment used that brand it seems like a hundred years ago. We had vent hoods with sash type glass doors that were connected to pneumatic/electronic controlled Bladder VAV's that increased or decreased CFM according to the position of the door a OSHA requirement for laboratory use in R&D. These doors were required Preventive maint checks

[Charley L. Bottger]

Originally Posted by dvalley

I just found some great deals HERE.

I'm going to go above and beyond and start to do these tests on HVAC.

David let me give you an example of why you don't want to go there. To many variables you will not be able to take an anemometer around to the registers and simply say this is correct or this is wrong. I am sticking my neck out further than I like to do as I normally do not quote Stats and or formulas on this board to many guys take it as chiseled in stone. You Stated you do not like math well if you decide on this path you better get to like it.

If The heated air is furnishing all of the heat for a room, 3 things must be known to be able calculate the air volume.
1. Heat Load
2.Room Temp
3. Duct temp
The heat load must be determined, The room temp is decided by the designer. Normally it is 72 degrees F. dry bulb. The duct air temp is more difficult to decide. If a low duct temp is used large air volumes will be necessary to carry enough heat. If high duct temps are used, the furnace will have to operate with a higher (Stack) temp.

Engineers recommend that a grille Temp be at least 125 degrees and that duct temps be near 140 degrees. The lowest temp needed to obtain these result depend on the duct lengths. Knowing that the specific heat of air is .24 BTU/LB the weight of air needed is found by the specific heat equation

Room heat load = .24 X wt, of air X the temp difference.


To obtain the volume you must first find the volume of one pound of air at the duct temp. This value is obtained from a psychrometric chart.

One pound of air = 17.1 Cu.Ft.



David I have a book with all of these formulas but I think I have made my point don't go there, not a good Idea for the HI, I do not use a meter to check air volume and do not state so in my reports. My statement is generally System appears to be performing or system appears not to be performing. Let the Hvac's make the determination.

[Brian A. MacNeish]

Originally Posted by bkelly2

Busboy at a Lobster house.

Obviously not using all your brain/skills at that point in your life!

[Brian E. Kelly]

Originally Posted by Brian A. MacNeish

Obviously not using all your brain/skills at that point in your life!

I have been on a Brain Rationing program from an early age, as you may have noticed on other threads, some people have run out.

[David P. Valley]

Originally Posted by cbottger

David let me give you an example of why you don't want to go there. To many variables you will not be able to take an anemometer around to the registers and simply say this is correct or this is wrong. I am sticking my neck out further than I like to do as I normally do not quote Stats and or formulas on this board to many guys take it as chiseled in stone. You Stated you do not like math well if you decide on this path you better get to like it.

If The heated air is furnishing all of the heat for a room, 3 things must be known to be able calculate the air volume.
1. Heat Load
2.Room Temp
3. Duct temp
The heat load must be determined, The room temp is decided by the designer. Normally it is 72 degrees F. dry bulb. The duct air temp is more difficult to decide. If a low duct temp is used large air volumes will be necessary to carry enough heat. If high duct temps are used, the furnace will have to operate with a higher (Stack) temp.

Engineers recommend that a grille Temp be at least 125 degrees and that duct temps be near 140 degrees. The lowest temp needed to obtain these result depend on the duct lengths. Knowing that the specific heat of air is .24 BTU/LB the weight of air needed is found by the specific heat equation

Room heat load = .24 X wt, of air X the temp difference.


To obtain the volume you must first find the volume of one pound of air at the duct temp. This value is obtained from a psychrometric chart.

One pound of air = 17.1 Cu.Ft.



David I have a book with all of these formulas but I think I have made my point don't go there, not a good Idea for the HI, I do not use a meter to check air volume and do not state so in my reports. My statement is generally System appears to be performing or system appears not to be performing. Let the Hvac's make the determination.

Charley,

When I seen your numbers, it changed my mind.

Thanks.

[Robert J. OConnor]

Originally Posted by dvalley

Charley,When I seen your numbers, it changed my mind.

Good call ... it gets sticky ...