Tue, 19 Dec 2023 06:25:46 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17669&Focus=299273#Comment_299273 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17669&Focus=299273#Comment_299273 Sat, 17 Dec 2022 12:38:12 +0000 freemp31 I have opted to mount them at ground level because my roof is E/W aligned, and the S end is shaded by trees, plus the fact that I have 3 hectares of land which is just grass.
However, to get sun for the maximum day length, the panels will need to be some 40M from the tank, which sounds like a hell of a lot of cold water needing to be circulated from the manifold before any heat gets to the coil.
A Laddomat (which I have on the accu's primary circuit from the gasification boiler) feels a bit like overkill - especially at their current price - anyone found a reliable solution to this problem?]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17669&Focus=299274#Comment_299274 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17669&Focus=299274#Comment_299274 Sat, 17 Dec 2022 16:22:44 +0000 Peter_in_Hungary How do you intend to control the flow from panels to tank? Short cycling could cost more in losses than the gain. What is the volume of the water in the panels?

Perhaps a small very well insulated accumulator tank (small is a relative term !!) at the panels which is switched on (by thermostats) when there is enough hot water at the panels to be worth a pumping cycle, that way you reduce the number of cycles and so reduce the losses.

Health warning I have not had this problem before so the above is just a thought.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17669&Focus=299325#Comment_299325 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17669&Focus=299325#Comment_299325 Wed, 21 Dec 2022 09:06:14 +0000 GreenPaddy
Logic would be to have the circ pump outlet linked directly to the return to the solar, with a 3port valve (or 2 2ports), which only opens, to let water go to the cyl when the temp at the pump outlet is close to the temp at the solar tubes (say delta 5oc ON, delta 3oC OFF).

It's a double logic system, with temp diff (cyl to tubes) to bring on the pump (existing I guess), and then temp diff (circ pump outlet to tubes) to let the water go to the cyl.

You might even find your existing solar controller (assuming that's what you're using) has the option for two relay outputs, for two arrays, and so use one relay to start the pump, and the second to move from bypass to cyl feed. Need to think carefully about where the comparative temps were taken, so might not work.

Maybe simpler is just set a timer for the 3port (or 2ports), which you would determine by testing, to ensure the cold slug was circ'd back to the tubes, until warm was avail. Might be say 1 minute, erring on the safe side of excess water recycled to the tubes.

Hope that sparks some ideas for you?]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17669&Focus=299375#Comment_299375 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17669&Focus=299375#Comment_299375 Fri, 23 Dec 2022 22:34:38 +0000 freemp31 However it might well be that the manifold recovery rate (in full sunshine) is sufficient to deliver enough heat that it doesn't cycle.
To start with I think I'll just plumb in the controller and the collectors direct to the coil - but with lots of isolator valves to allow mods without a complete drain-down.]]>