Evacuated tubes - 1.5 MW

[Dave B.]

  I've waited a few months to report on my Solar evacuated tube DHW / Heating system. Since figuring out how to set up the controller to log kwh based on flow rate and temp diff. etc. I have just passed the 1500 KWH mark for 110 days. 1,500,000 watts of power here is equivelant to approx. $300.00 worth of electricity from the grid to produce that much heat.

  I am heating my domestic hot water and storing hot water for supplimental heat through water to air heat exchangers. Certainly oversized in the warmer months just for my DHW but the main intent is for supplimental home heating as much as possible. So far the performance is amazing no matter the ambient temperature with the evacuated tubes. 

  I'll plan another posting with more detail of the system and the custom controls I have set up. I just wanted to post an update and wondered also if anyone else is heating with evacuated tubes ? Nice to hear of your experiences as well.

Dave B.

[rossw]

wondered also if anyone else is heating with evacuated tubes ? Nice to hear of your experiences as well.

I am, but I'm not sure how my unit compares to yours in size.

I have a 60-tube (wet-tube) setup that was intended to provide DHW during summer (so I didn't need to run the genset or light a fire), and help with DHW and heating in winter.

I have a link to mine in my journals... (will come back and edit in the link)

[rossw]

I have a link to mine in my journals... (will come back and edit in the link)

Hmmm... seems I do not! Perhaps I need to do one?

Here's my array almost assembled:


The journal entry I was thinking of was on the low-pressure valve I made for it, http://www.anotherpower.com/board/index.php/topic,33.0.html#.T8LSmr8Uocp

[Dave B.]

I have 70 tubes of the heat pipe version, vertical tubes. This is much different than your set up but yes, they will boil water in a big hurry also. I was dumping heat today when my tank hit my set high of 160 deg F. about 2:00 pm. I'm running the pumps and controller off batteries being charged by my voltaic panels and wind besides, that is the icing on the cake. Thanks for your information and photos.   Dave B.

[rossw]

I have 70 tubes of the heat pipe version, vertical tubes. This is much different than your set up

Yes, the heat-pipes have some advantages, but the wet-tubes like I have also have some!
The wet tubes don't have the heat-pipe, the water flows directly into the tubes and is heated... wet tubes can be mounted vertically or (almost) horizontally as I have. With my 60 tubes, it was just easier to have a vertical manifold up the centre.

[Dave B.]

I have 70 tubes of the heat pipe version, vertical tubes. This is much different than your set up

Yes, the heat-pipes have some advantages, but the wet-tubes like I have also have some!
The wet tubes don't have the heat-pipe, the water flows directly into the tubes and is heated... wet tubes can be mounted vertically or (almost) horizontally as I have. With my 60 tubes, it was just easier to have a vertical manifold up the centre.

Is your system a closed or open loop ? Mine is closed loop with Glycol, I had thought about a drain back system but with my layout it would have looked crooked to get the drop needed and with the glycol closed loop there won't be any worries about freezing from poor draining like the drain back. Advantages to both but the main thing is that it sure does work.   Dave B.

[rossw]

Is your system a closed or open loop ? Mine is closed loop with Glycol, I had thought about a drain back system but with my layout it would have looked crooked to get the drop needed and with the glycol closed loop there won't be any worries about freezing from poor draining like the drain back. Advantages to both but the main thing is that it sure does work.   Dave B.

Mine is unusual. (As with most of the stuff I seem to do).
It's a semi-open system. The tubes directly heat water from my 2 large (2000 litres each) tanks, by a small pump that pushes water out the tank and up onto the "roof" only when the manifold reaches a set temperature. Then the water "spills" out the top of the manifold and flows back down into the tank. So only the "return" water is drainback but it's not a pressurised system. We don't get the cold some of you guys do, so in the (rare) event the array gets cold enough to be at risk of freezing, a short burst of warm water from below should keep it safe.