These are evacuated glass tube solar collectors. Basically like a thermos bottle.
Open on one end, closed on the opposite end. 60 tubes make up one unit.
30 tubes per side. Open ends terminate through a silicone ring into the common center manifold.
These units are intended for use with an open system outdoor wood burning unit (owb). Units are normally mounted on the ground, near the owb.
Plumbing consists of two lines. One from the bottom of the owb connected to the inlet (lower) of the solar unit. And one from the solar unit outlet (upper), to the upper inlet on the owb.
They rely on “thermal siphoning” to transfer the solar heated water to the burner unit.
My installation is a challenge due to the fact that I want my solar units on the roof of the barn.
Because the owb is open system (no pressure), I had to use a 50 plate heat exchanger to isolate the two systems. I also used a 3 speed circulating pump to get the water up to the roof and back.
I’m using a 10′ piece of 4″ Schedule 40 PVC pipe as an expansion tank. So far it’s working well.
I started out with three units plumbed in parallel. I found that I could not shed the generated heat fast enough to keep the unit from making steam, and ruining my temporary plumbing hook ups.
I am now plumbed to just one unit with 1″ copper tubing. One unit seems to be doing the job so far.
On a sunny day, without firing the owb, the water in the system (325 gal+) maintains ~ 165F. Dropping to ~ 130F overnight.
It’s a work in progress.
Comments welcome 🙂