Ammo said:
I just purchased a 40 tube Apricus system with 315 ss tank. I am in Melb.
The tubes are mounted at 52 degress on stands to minimize summer generation and venting.Have you thought about removing the internal working parts from say 5 tubes and putting the glass back on the manifold and see how you then go. If you were keen you could then put the guts back in the 5 tubes soon as the summer heat is over for autumn and winter?
A bit of mucking about but I would be happy with that and getting significant hot water in winter as well.
overheating (venting) of evacuated tube system
(40 posts) (18 voices)-
peter69_56
MemberPosted Sunday 13 Nov 2011 @ 12:59:25 am from IP # -
peter69_56
MemberWell I now have 24 evacuated tubes with partabolic mirror into a 315 litre tank. Only had one day to day where it stagnated for a short period. I think its the equivelent of 30 Apricus tubes. I have made up 2 covers for when we go away in Feb for 2 weeks. Will leave 2 six tube panels exposed and have it on holiday mode and I am hoping all will be well.
I believe the system is now slightly oversized but with the covers I can manage. Was going to tilt to 50 degrees to assist all this but I can see the issue will be wind damage. With the mirror back it now has an area of 1.5m x 3 m to act as a sail. A lot of force on the roof and frame if a strong wind. I can also see that it could blow the mirror back off its aluminium frame and so damage it. So while they are great as a collector they do have their issues as well.
I am considering my options.
The Stratco installation kit says;
Tilt Mount:
• Region A – N1, N2, N3 – Maximum tilt angle 38°
• Region B – N1, N2, N3, N4 – Maximum tilt angle 30°
(Checked to AS/NZS 1170.2:2002)Posted Saturday 24 Dec 2011 @ 2:32:50 am from IP # -
Bullwitter
MemberLance wrote: "Just be aware that with evac tube systems, if you use the solar blind you should make sure that the blind completely covers each tube, not just halfway down or whatever, as uneven heating of the tubes may cause failures..."
There are situations when tubes are in partial sun (without using solar blinds). How serious a problem is this? Has anyone had tube failure due to partial shading? I am about to install vertical ET solar-boosted-solar where there will definately be partial shading of ETs.
Posted Sunday 1 Jan 2012 @ 6:59:56 am from IP # -
Ben1
MemberToday (a very sunny hot day), I noticed steam escaping from the fitting between the tank and the return line of my evacuated tube system. Concerned, I checked that the pressure/temperature relief valve was working (and it was), so I assume there is no serious risk. However, I have two questions: (1) is it possibly just a leaking fitting? and (2) when some hot water was eventually drawn off, I could hear "glug, glug" noises coming from the tank. Will these be steam bubbles at the top of the tank? It sounded just like the sound you hear when purging air bubbles from a newly filled tank.
A bit concerned! Thanks.
Posted Sunday 1 Jan 2012 @ 9:41:22 am from IP # -
peter69_56
MemberWhen I added the extra panel I obviously had a fitting between the banks of tubes not quite tight. When it began to all heat up I saw some steam coming from the fitting. A bit of adjustment and all was well. If your tank is around 80C the panel maybe in stagnation (no flow) so can heat up above 100C thus any water leaking from any fittings will turn to steam immediately.
Cant comment on partial shading as I have non other than a TV aerial that might cast a tiny shadow. Have heard that partial covering can cause damage, but the question is how much is bad. I would expect that it would have to be significant shading, say 1/4 tube or so?
Ben is your system a direct heating system (tank on the roof or a split system, tank on the ground?
Posted Sunday 1 Jan 2012 @ 10:19:22 am from IP # -
Ben1
MemberPeter, it's a split system. The fitting involved is at the tank (on the return line), about 30cm from ground level. Closer investigation suggests that this fitting leaks slowly all year round. There is a think track of moss growing down the side of the tank.
Posted Sunday 1 Jan 2012 @ 10:48:02 pm from IP # -
peter69_56
MemberBen1 said:
Closer investigation suggests that this fitting leaks slowly all year round. There is a think track of moss growing down the side of the tank.You must have used the same plumber as me. The pathetic way they didm all the copper joints meant they all weeped. I had to remove them all and redo each one by cleaning up all the mess they put on the threads, 13 wraps of teflon and magic, now no leaks anywhere. I have an isolator to the panels so I can shut off the pump, shut the isolator and remove either pipe from the panel and work on it with no loss of water from the panels or tank (tank to be depressurised first before opening fittings). If you do that then you should be able to fix the issue. I really hate poor workmanship, and the trades in the main do not do their work proffessionally. I think the apprentices are not shown how do do good work, but fast work to make a buck.
Bullwitter, This is my personal opinion only and based on what I think. I suspect the U tube are more at risk, as if you break a tube then the system will lose heat and not work well at all given the water runs down the tube. If you break the Apricus type tubes, you will still lose some heat but not as much. If you have Apricus style, and have say 2 tubes in shading, then you could always remove them, remove the heating element and replace just the glass tube. This way the integrity remains and the tubes wont fail. You do lose the heat output from the now empty tubes though.
If I was having a system installed commercially then I would talk to the installer about the shading issue and ask in writing warrenty to say the shading is ok and not an issue for the integrity of the system.
Posted Sunday 1 Jan 2012 @ 11:46:33 pm from IP #
Reply
You must log in to post.