Sunlight instruction presentation and information

Note that the vactubes are lined up north south to catch all of the east west sun from dawn to dusk. Because they are round they receive light from 360 degrees. Keep shading from the frame to a minimum.

6000 watt vactube heater design.

Build a 6000 watt solar evacuated tube space heater that heats a 2500 sq. ft. room by circulating air in the room through 25 evacuated tubes on the roof using one 65 watt fan even on a cloudy day.

Evacuated tubes are like long thermos bottles with a clear outside glass and coated inside glass that changes light to heat. The vacuum between the two locks the heat in.

This one generates 250 watts

We should manufacture them here in the USA.

Always wear gloves when working with sheetmetal and glass.

Cut a 3 inch hole in each end of the outside manifold for the inside manifold to slide in to. Cut a notch for the tabs that will stick up once you are finished building the inside makifold. Refer to the pictures below.

Building the inside duct

To make the inside duct slide the 3" x 8' galvanized duct into the outside manifold and mark it for drilling. Use a jig to center the marks. Drill 5/16 holes in a perfectly straight line for start holes and cut an 8 slice pie our from each hole for shoulders and tabs that hold the copper air riser tubes in place. Straighten the seam, align the holes perfectly straight again and then solder the seam so the hole manifold can't twist or come apart.

The fan forces filtered air from the room into this end and the only way the air can get out is through the holes and up the riser tubes. Then it blows the heat down out of the evacuated tubes into the ourside manifold and back into the room.

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Seal off inside

Seal off the end opposite the input with an oval of sheetmetal installed with screws and silicone diagonally from just past the last riser hole angleing in so the air is angled up into the holes.

Cut the pie slices on the sides and ends into shoulders for the riser tubes to sit on. Use a small piece of tubing to form the fit around and make sure the sheetmetal is formed so the seal will be good between the copper tube and the inside manifold.

Cut the slices on the diagonal into tabs that stick up to hold the risers in place

The copper riser tubes fit on top of the 3 inch input manifold. Make sure nothing protrudes down inside the manifold or the air turbulance from it will reduce performance.

The vactubes sit on the rubber shoulders at the base of these holes.

Install the inside manifold and cut the input end flush and the other end inside a couple of inches so it can be insulated with foam and covered with sheetmetal.

Cut a 4" hole in the outside manifold for the output duct before you mount the inside duct.

Mount the outside manifold pointing north south where it receives the most sun and where you can easily run the ducts into the attic and to the ceiling vents.

Always wear gloves when handeling the glass tubes.

The risers are made from 60 inches of thinwall copper tubing from Home Depot. Cut 10 foot pieces in half and be sure to remove all burs and clean off all stickers or they will burn and stink.

Keep the inside of the manifold smooth. Anything inside will create turbulence and reduce performance.

Seal the inside and outside ducts air tight with high temp silicone and install with 1/2 inch sheetmetal screws.

Make the input and output ducts out of 8 inch and 4 inch galvanized duct with foam in between. Seal them and paint with galvanized metal primer. Install them with silicone and 1/2 " sheetmetal screws.

8 inch centrifugal fan Grainger # 4YM45

Use a yard light photocell to switch a 120 volt single pole double throw relay to turn the fan on at dawn and off at dusk. Note that everything plugs in to a standard outlet to avoid an electrical permit.

8 inch flexible duct from Home Depot.

Seal all the joints with silicone.

Run a section of flexible duct to the input vent. Use 25 feet to deaden the fan noise. Use 14 x 21 vent cabinets with filter in the input vent and 8 inch reducers for the flex duct. Insulate the fan, intake and output vent cabinets.

25 tubes heats a 2500 square foot room even on cloudy days here in the Northwest.

The output vent has a remote temprature sensor so I can monitor the temprature rise

The input duct is 14 x 21 inches with drop down door and filter.

The thermostat is below on the wall and a thermometer with a remote sensor so I can monitor input and temperature rise.

Cut a 4" hole in the outside manifold for the output duct before you install the inside duct.

Make your frame on the ground first from the supplied stainless. Make sure the plastic holders fit and the top does not touch the tips of the vactubes. I installed the feet on the back legs with bolts through the roof and used washers and nuts.