Hello I am new to this board. I installed my solar system around 25 years ago. It is a Thermomax system. I have recently discovered that the tubes are somewhat tired now. They are still working but do not get anywhere near the temperature they used to. My question is has anyone tried to repair or alter these type of tubes before, as I believe they are no longer in production. the tubes are of the type that has a screwed nut to attach them to the tank which sits above them. I have seen the u tube video of a man making his own evacuated heat pipes, and am thinking along similar lines. I made one a little longer than his, and although I am not getting the temperature high enough yet, I am impressed enough to carry on "tinkering". Has anyone else tried this?.
Hello Charlie, Welcome to the forum. It sounds from your post that the insulating glass tube is not doing its job anymore. The heat pipe 'insert' could well be fine but with the vacuum lost, it will not get up to the sort of temp that it used to. There are a few tricks to get twin wall evac. tubes going again when they lose the vacuum but I am not sure about the single wall designs. Some of those older designs of single wall tube leak between the insert and the glass. I suppose it is because the seal between the two breaks down. The different expansion coefficients of the insert and the glass won't help. I wonder would it be possible to rehouse the heatpipes in new twin wall glass? The spare glass tubes are not expensive. I am sure that Cye will be on later, he is well read on this subject and may be of help. Would you be able to post a few pics? conor
Caveman, Thanks for your reply, Cye very kindly helped me with the solar loop calculations and sorted me out with a pump a little while ago. I cut down one of my tubes, a used one as I managed to find 5 "newer ones" only around 12 years old that would fit my system. The one I cut down I was surprised to find the heat pipe was made of steel. it was rusted pretty well and I suspect it had "grown" a little inside the seal and thus lost the vacuum. so I think what you say is spot on. What I had in mind was to cut off the end of the existing glass tube, remove the existing heat pipe and replace it with a copper one, and make a manifold to clamp to the top of the heat pipe, so as the heat pipe will not touch the water, gycol mix in the solar loop. the problem is to be able to seal it inside the glass tube and pump out the vacuum. Plus till I try I dont know how easy it would be to cut the glass tube, any thoughts tricks or tips would be most welcome...
Hello Cye, There is no metal cap but it has a metal tube on the end of the heat pipe, but also attched inside the glass tube is the copper sheeting/fin which is bigger than the hole in the end of the glass. the end tapers in to at a guess is a one inch hole, while the heat pipe and fin is around two and three quarters wide. If you can picture a ship in a bottle.... I have tried to post a picture of the tubes on my shed roof with the tank, but I dont realy know how, The DIY heat pipe is the acetone thing, but the pipe is 10mm Not 5mm.
Hello Cye, they do not look like the one in your picture, but I was thinking along the lines to make them look very similar to the ones in the picture if I can increase the temperature in the heat pipe I am tinkering with. Mine are single skin, the difference being the glass tapers at the end.