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JohnGuest

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Posts: 27
Reply with quote  #21 
Not sure how to respond to that one Greg [smile]
Consider a panel that alters its cross sectional shape as a result of an increase or decrease in flowrate.

Archdemon

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Posts: 25
Reply with quote  #22 
Read Everything and taken some stuff into consideration, what ive tested is to run a total of 5 fans of solarpower and powerbanks which work quite well since the fans run of the thermostat they aint Always running.

But to my question, how would i measure and put it into numbers how much a air heater generates in Kwh?

Need something for my wife so i can justify a 6m long heater on the front of the house.

6m Long. (might split it into 2 separate collectors)
1m High.
200 Deep.

5 90mm Fans on the far left side of the collector (bottom if it would be standing), rated at 50 m3 each individually controlled to vent the collector if it gets hot or i need to move more air, they run of solar Power and Power banks. Same with the fans below.

200mm Fan blowing in at 250 m3 at the floor in the basement.
200mm fan blowing out from the collector in the top.
3layers mosqito net mesh or something similar,it was black atleast, 3,5cm between each layer.
75mm insulation in the back.
10mm Twin "glas" glazing polycarbonate somthing?!
4 Wireless Zigbee temp sensors

Reason for 200mm Deep is that no one seems to have tried, wanna see what happens if its more like quantity over quality thing.

stmbtwle

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Posts: 2,474
Reply with quote  #23 
You can go to: http://pvwatts.nrel.gov to get an idea of your production. Enter the nearest city in the location box.
The site is intended for PV, so in "system info" enter only the tilt and azimuth of your collector. In the "results" page use the "solar radiation" column, multiply by the size of your collector (6 sq m) and a reasonable efficiency.

Other folks can tell you what a "reasonable efficiency" is.

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Willie, Tampa Bay
gbwillson

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Posts: 2,065
Reply with quote  #24 

Archdemon-

 

Below is an excel spreadsheet that can be used to calculate the BTU’s and Watts being produced. You only need to fill in the 4 orange fields. The numbers you are looking or will be in the yellow fields on rows 8 and 9.

So in the example file, 400CFM moving is moving through the collector. The temperature at the collector input is 60˚F, and the exhaust is 100˚F. The test is being run at 1000’ above sea level. This means at that moment, the collector is producing roughly 17,000BTU’s per hour, equivalent to just under 5,000Watts or 5kW per HOUR. Not too shabby for a DIY unit.

In case you are wondering, these numbers are NOT exaggerated. They are from my 4’x16’ ZP collector last winter. I only rounded the numbers slightly to simplify the example. And if you were wondering just how much heat we are talking about in the above example, a small portable electric heater like you probably have in your home uses about 1,400 Watts per hour, giving you roughly 5,000BTU’s of heat per hour. Soon the example file, my ZP collector was producing the equivalent of over 3 electric space heaters per HOUR!

A single, larger heater will give you more heat than 2 smaller heaters, assuming the square footage is the same. This is because the air is inside the large heater longer, thereby absorbing more heat. The trick is to move enough air to capture the heat so it doesn’t get lost through the back, sides, and especially the glazing.

While the 200mm collector depth is deep, I do think the extra space is somewhat wasted. But perhaps the materials being used make that depth practical. My tests have shown that with a ZP collector, very little air moves outside the screen gap. And a deeper collector contains more mass that needs to warm a bit before the collector activates in the morning. On the plus side, the extra depth gives you more room to work, and keeps the screen gap farther from the cool glazing.

Having a collector that looks like a quality build is important, especially on the front of the house. So be mindful of the materials used and if that means spending a little bit extra for some nicer trim, so be it. And once your wife feels the warm air spewing from the exhaust, I’m guessing she’ll be hooked. And if not, you can always use your new heater as you spend your time in the doghouse. Every time I walk past the warm output air I stick my hand in front of the output and smile…

Greg in MN 

 
Attached Files
xls Easy SAH Output Calculator (version 1).xls (16.50 KB, 7 views)

Archdemon

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Posts: 25
Reply with quote  #25 

Well i was thinking of using a glasfiberarmed polymercomposite for the  trim since thats most likely what we will be using for the house as well.
http://www.steni.se/produkter/fasadskivor/steni-colour/

But the trim is something ill fiddle with when im satisfied [smile]


Weather resistant and insulation is good.

Guess i could draw it up and drop it here for suggestions, was thinking of breaking out the tools tomorrow [tongue]

Archdemon

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Posts: 25
Reply with quote  #26 
By looking at that sheet i should increase the CFM? or does it just inflate it?
gbwillson

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Posts: 2,065
Reply with quote  #27 
Increasing the CFM will reduce the output temp, but will almost always be more efficient in the long run. So capturing lots of heat, having plenty of available CFM, and the ability to adjust the airflow, will allow you to optimize your system for maximum efficiency. Feel free to experiment with the air flow. 

Once you have your system up and running you will have a better idea as to the output. From there you can experiment with flow rates until you find the one that best matches your preferred comfort/efficiency level. A lot of lukewarm air will give you far more BTU's than a small amount of hot air. 

Greg in MN
Archdemon

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Posts: 25
Reply with quote  #28 
How do i account for actual hours the sun is out? 2000 per year but maybe 800 during the oct-march period
Rick H Parker

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Posts: 651
Reply with quote  #29 
How do i account for actual hours the sun is out? 2000 per year but maybe 800 during the oct-march period


The best way is historical data. Post your longitude, latitude and time zone. I'll get the solar resource data for your location on a monthly basis and post it.

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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
gbwillson

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Posts: 2,065
Reply with quote  #30 
Archdemon-

I'm not sure what you are asking.

Solar tables will give you an idea as to the potential solar output for a given location. But they can't accurately calculate the amount of BTU's, or watts collected in a given year from a DIY heater. There are far too many variables such as the size, type of collector, and the quality of the build for an estimate. 

The coldest winter days are usually the sunniest. Even with the brutal winters where I live, the collector saves me more than 2/3's of my heating bill. Most of the fall and spring my home is almost exclusively heated by DIY solar heat. During the deepest, darkest parts of winter, it nicely supplements the forced air natural gas furnace, producing great heat as long as the sun is shining, regardless of how bitterly cold it is outside. The furnace only runs in the early morning on a cold, sunny day.

Greg in MN
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