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Forum Index : Solar : adding solar hot water plate collectors
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| rgormley Senior Member  Joined: 22/02/2006 Location: AustraliaPosts: 245 |
ok got some photos... what pressure is the inlet gas line at? (Melbourne natural gas lines) what pressure is the pipe from the controller to the burner?? as i put my finger over the end of the burner feed and it was VERY easy to stop the flow of gas. like VERY easy SO i`m thinking a low voltage solenoid inline with the output of the controller and the burner. this will keep the pilot on but i can kill the gas feed to the main burner via a low voltage solenoid/valve plus timer. once again ideas please ** so mains gas supply pressure is only 2.75KPA ??) that really low, no wonder i could stop it with my finger. so the solenoid/valve looks viable yes? 
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
A solonide might not open under such a low pressure and flow rate. Also will the system leak if the burner is blocked off as the discharge side might not be ment to take pressure. You could fit a small stepper motor to the the dial and have it set to rotate the dial to the vacation position over night but i dont know what daily rotation of the dial will do for the life span of it. With the use of a stepper motor you could step it a count of so many steps one way at night and back the other way in the morning. A simple micro like a 08m picaxe could do the stepping count and control the driver chip and as for time it could be a timer or even a simple light sensor for night or day, as you would have enough stored hot water for after dark. By controlling the dial you could even use a temp sensor to increase or decrease the setting temp throughout the day so if by lunch time the solar had not raised the water to X temp then you increased the temp setting on the gas to a higher level to allow more gas heating. Or keep it simple and 2 micro switches as limit switches and a motor to rotate the dial between the 2 limit switches. Pete. Sometimes it just works |
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| rgormley Senior Member Joined: 22/02/2006 Location: AustraliaPosts: 245 |
hhmmm will investigate the discharge pipe blocking/leaak factor but the valve i was looking at is this one http://www.avfi.com.au/pdfsdec04/ZS%20NOR%20OPEN%20SOL%20VAL VE.pdf picaxe and such that`s adding a little to much electronics and points of failure also a little out of my experience) auto rotating the dial , yes agree the 730 turns per year may kill the dial thermostat. also mountings, limit switches, wire, heat, nahh not all that inside there, something will give over time... still going to look into a solenoid valve /12v /simple 240v gpo plug in timer but will do my home work on the discharge port blocking factor first would not want to have a internal leak inside the thermostat housing!! |
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| rgormley Senior Member Joined: 22/02/2006 Location: AustraliaPosts: 245 |
ok all finished!!! works a treat added this valve to the discharge pipe on the thermostat gas outlet [URL=http://www.appliancesupplies.com.au/shoponline/prod65.htm] bugger cant get the web link to work sorry.... It`s all controlled via the solar tube heat monitoring electronics via the direct "heating" relay contact in the main control box. have it set to turn on and off based on time and temperature (3 probe feed back) from midnight til 8am the valve is turned off (dont need shower hot water) any residual water is stil hot enough to wash hands etc. I can hit the "heat" boost button if required this will open the valve and bring the temp back up to 52-55 deg in the tank. from 8am till 11:59pm the valve will come on and off based on a turn on temp of 48deg and turn of at 52 deg if the solar tubes heat the water above this then the valve will be turned off and we have the sun heating the water. so all in all a good project. my total cost around $1400 for a 15 tube system feeding a 135 litre tank. Cheers! |
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AMUN-RA Senior Member Joined: 10/03/2007 Location: AustraliaPosts: 144 |
Don't see any mention of a check valve in the line above the pump to stop reverse thermo syphon at night, and armour flex needs to be either wrapped in foil or painted with an acrylic paint or after 12 months replace it as it degrades quickly if not protected. Pump set on one. Just some thoughts Mick Apricus Australia Evactuated Tube Solar Hot Water Systems Townsville Every day the sun shines & gravity sucks= free energy. |
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| rgormley Senior Member Joined: 22/02/2006 Location: AustraliaPosts: 245 |
Hi Mick Thanks for the comments. yep there is a one way check valve /cut off inline above the pump (see new photo of pump) Armour flex, now has a wrap of UV proof External duct tape, with a few large external UV proof cable ties..will see how it hold over time. the pump speed hhhhmm will have to look / experiment on that... As i have a long run of copper, 28 mtr`s in total. the other day when it was in full sun, i did not think to check **ALL** the settings in the control box , and the max tank temp was on 60Deg, anyway yep the max tank temp went to 60Deg and the circ pump pump was off. .... the manifold went to 137Deg!!! so hence i have set/ **ALL** the parameters in the electronic control box. now keeps circulating upto 75Deg, (yes we have a tempering 50Deg safety unit) 
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| rgormley Senior Member Joined: 22/02/2006 Location: AustraliaPosts: 245 |
looking for a answer to a question on my project on the pump circ speed my 1/2 inch copper runs up and back from the cir pump to the manifold are close to 14 mtr`s in total run length what would be a better speed to run the pump at... slow med or fast? the pump runs using around 23 watts on slow and around 60 watts on fast. i have it on fast (no idea why, to run slow or fast, just sounded better) any ideas?? Thanks |
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KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
OK here are my thoughts Agree, cheap flap type one way valve on the pump exit will stop thermosyphoning IF it becomes apparent that its an issue -which I doubt. 2 with 135L tank and that many tubes .....mate.... Problem! set the max temp for as high as it will go as you have already seen temp in the manifold goes ballistic =bad 3 may not be an issue -my farm set up very similar but pump mounted to tank not such a good idea as quite heavy -hope it will be OK. 4 all the effort on the gas boost -in my opinion wasted, you'll almost never need it, just set on vacation or slightly higher and you're apples. 5 -start looking for a bigger tank. mine at Highett was 225L and i'd easily boil it if I went away for the weekend, get a few hot days and all of a sudden you're forced to hook up a garden tap to the whole rig and wash the car in boiling water...... thats another thing I did, or turn on to the pool. In all top job, very pro looking and will perform exceptionally well. Oh and my opinion on the circulating pump.... winter set it on high so pipe losses arent as great, can circulate it faster, forget the power consumption on the pump, it is turned on/off by temp differential so running 3x faster it will run for 3x less the amount of time. summer same applies but in reverse, need to shift the heat away from the collectors as fast as possible so again run it on high. unless of course its noisy then run it on medium. I insulated half of the pump, ie just the impeller side, so still has motor cooling but doesnt waste as much heat... I use aluminium flashing tape to wrap the exposed lagging with, $25 for 10m sort of bitumen glue on it, sticks well to itself and sort of amalgimates. Karl  Luck favours the well prepared |
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| rgormley Senior Member Joined: 22/02/2006 Location: AustraliaPosts: 245 |
ok guys afer a few years running fine. I noted that my existing 135 ltr tank will get up to 70 plus degrees by lunch time, So i though it`s time to add a extra water 2012-02-09_092141_extra_tank1.pdf storage tank. I will be adding 135 ltr gas hot water storage tank and just using it as extra storage ony. can someone have a look at the diagram and let me know if i`m connecting it correctly the pics show as is and how i propose to add. 
Thanks |
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