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Renewable Energy: DIY Solar project connection help

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  1.  
    • CommentAuthorbudbecks
    • CommentTimeApr 12th 2012
     
    Hi all,

    Ok i have a old rad and can make a box similar to the one described here

    http://www.diydata.com/projects/solarpanel/solar_collector.php

    All i want to be able to do is heat 1 rad from the "solar collector". Both rads are about the same size, if anything the rad indoors is slightly larger.

    The "solar collector" is outside about 7 meters away from the internal rad. All the pipes will be super insulated using 32mm wall 15mm armaflex. It can be pumped using a heat stat and pump or failing that just gravity.

    Could anybody show me the simplist way to plumb this in ?

    Could i literally connect each rad up, the solar being lower to allow to rise ? possibly adding a vent to the rad ?

    Any help would be great
    •  
      CommentAuthorSteamyTea
    • CommentTimeApr 12th 2012
     
    The 'collector' needs to be lower that the 'emitter'

    So the hottest point needs to be the lowest.
    You can vent at the highest point to allow for expansion or vapour release.

    If it is pumped then just make sure that water is always pumped uphill, so pump at lowest point, then from the bottom of a radiator to the top, up the insulated pipe to the bottom of the next radiator, out the top and back to the pump. Vents at the top again and make sure that the vent pipe has liquid in it to stop air being drawn in.

    I would think
  3.  
    I agree with ST
    but would add that I would not pump it - gravity is simpler and is self regulating. If you put in a pump then controls are needed to stop cooling the inside when there is no heat outside. Gravity will stop as soon as the lower rad is cooler than the upper rad and the hotter the lower rad is, relative to the upper rad, the faster the circulation will go. I would also put antifreeze in the system.
    • CommentAuthortony
    • CommentTimeApr 13th 2012
     
    what is the your intended project?
    • CommentAuthorbudbecks
    • CommentTimeApr 13th 2012
     
    My intended project is to simply see if i can get it to work. We are south facing and get sun most of the day so would like to see if i can heat the rad in my bathroom.

    I cannot install an F+E tank very easily, although it is possible, would prefer to try and do without it.

    Yes the rad outside lower, about 1.5 - 2 metres lower.

    If i was to use a towel rad as the "emitter", could i just take 1 or 2 of the plugs out of the top to act as the so called "vent". fill it with slightly less water to allow for a little exspansion ? or use a auto-vent rad plug ?

    Thanks again
    •  
      CommentAuthorSteamyTea
    • CommentTimeApr 13th 2012
     
    If a thermosyphon system then any vent to atmosphere at the top will work.
    To transfer more heat (the word heat is just energy) you need large bore pipes as it it is the mass moved by the temperature difference.
    • CommentAuthortony
    • CommentTimeApr 13th 2012
     
    it will work well in summer but in winter only a bit.

    have a go and try it, use as few elbows as possible in the pipes, ideally none and I would use plastic pipe.
    • CommentAuthorEd Davies
    • CommentTimeApr 13th 2012
     
    Given that you can get evacuated tube panels for £200 (incl VAT) on special offer:

    https://www.navitron.org.uk/forum/index.php?topic=16798.msg191877

    or for about £360 or £375 (incl) at normal prices:

    http://www.solarproject.co.uk/
    http://www.eco-nomical.co.uk/

    I wonder whether making a significantly less efficient DIY panel is worthwhile. The efficiency of the panels is not so important from the point of view of the amount of energy harvested (you can always add more panels to compensate) but from the point of view of the length of the effective heating season. A DIY panel will likely give you good heating in summer which is completely useless for space heating applications whereas an evacuated tube panel is likely to extend that use well into the autumn and spring when it is useful.

    PS, I have eight of the special-offer Navitron panels stashed away.

    http://edavies.me.uk/2012/03/et/
    •  
      CommentAuthordjh
    • CommentTimeApr 13th 2012
     
    Posted By: SteamyTeaIf it is pumped then just make sure that water is always pumped uphill, so pump at lowest point

    On a solar thermal circuit the pump is always on the cold side. i.e. in this case it would be pumping downhill. :devil:

    Posted By: Peter_in_HungaryI would not pump it - gravity is simpler and is self regulating.

    But gravity also requires larger diameter piping and the pipe is a major source of heat loss, even if well insulated. :devil:

    Posted By: tonyit will work well in summer but in winter only a bit.

    Yup.

    Posted By: Ed DaviesI wonder whether making a significantly less efficient DIY panel is worthwhile.

    Yup.

    But if it's just an experiment, have fun!

    PS Steamy, Peter, just trying to start a fight :tongue:
  10.  
    Ed , cheers for the link to the Nav. specials , just ordered up a couple.
    • CommentAuthortony
    • CommentTimeApr 13th 2012
     
    efficiency is almost irrelevant when the heat is coming for free.

    would take several lifetimes to pay for ET to heat a towel rad.
    • CommentAuthorEd Davies
    • CommentTimeApr 13th 2012
     
    Posted By: tonyefficiency is almost irrelevant when the heat is coming for free.


    Indeed. But if the panel is so inefficient that it loses almost all the heat it receives during the times of year when it would be useful...

    And even a DIY panel isn't quite free - even if it's totally made from available scrap materials there might be other uses for them.

    This is written by somebody who has made a small DIY solar warm-air panel which did produce a little bit of useful heat this morning. However, it's only in the last few weeks that it's begun to do so this year and only on a few bright days. It's not ideally sited (east facing and shaded by a hill when the sun's low) so it's not an entirely fair comparison but it was producing nothing on a day when an ET tube outside was heating water at a rate equivalent to about 100 W/m².
    • CommentAuthorbudbecks
    • CommentTimeApr 13th 2012
     
    Hey !

    Thanks for all your comments and advice.

    This is just an experiment and wether or not it will work for me who knows ! But 99% of the materials are free and i can do all the work myself. Even if i had to pay for a few things i wouldn't mind. If i get any heat at all i would be made up !

    Only time will tell, I will however let you know whether or not any part of it works. Interesting little project i think.

    Cheers all.
    •  
      CommentAuthorjoe90
    • CommentTimeApr 13th 2012
     
    This is a very good site for DIY bods like myself, may give you some more idea's.

    http://www.builditsolar.com/index.htm
    •  
      CommentAuthorSteamyTea
    • CommentTimeApr 13th 2012
     
    Posted By: djhOn a solar thermal circuit the pump is always on the cold side. i.e. in this case it would be pumping downhill.

    I will bow to superior knowledge on this, but would need to know why.
    I really cant think why it would matter where the pump is as long as no air gets drawn into it.
    • CommentAuthorEd Davies
    • CommentTimeApr 13th 2012
     
    I think it's just a matter of extending the life of the pump by running it cooler.
    •  
      CommentAuthorSteamyTea
    • CommentTimeApr 14th 2012
     
    Posted By: Ed DaviesI think it's just a matter of extending the life of the pump by running it cooler.

    That would make sense, so on a pumped system with the collector and vent higher than the radiator (or on the roof), the pump would usually be at the lowest point (and the coldest) then.
    •  
      CommentAuthordjh
    • CommentTimeApr 14th 2012 edited
     
    Posted By: Ed DaviesI think it's just a matter of extending the life of the pump by running it cooler.

    Indeed so, and especially if the collector stagnates and steam comes along the hot side!
    • CommentAuthorwookey
    • CommentTimeApr 17th 2012 edited
     
    I really can't see much point in making a system that will heat your bathroom radiator only on hot summer days. Is that really useful? Those DIY collectors really do only work on hot summer days. I guess if it's just a science experiment then fair enough. But it won't be free - you need to spend money on copper pipe, high-temp insulation, maybe a pump, one way valve, various plumbing bits. You also need an expansion vessel, pressure release valve and antifreeze.

    I'm with Ed - get a decent panel. And it makes sense to connect it to your hot water cylinder rather than one radiator.
    Solar hot water is really good, but it'll work a whole heap better if you do it properly.
    • CommentAuthorbudbecks
    • CommentTimeApr 21st 2012
     
    Wow,

    ITS AN EXPERIMENT !!!!!

    If i spend money, then i spend money, no big deal. Worse things have happened at sea !!

    i dont have room or anywhere to put any evac panels (well not without a lot of work) and then thats where you DO start spending money. If you read, 99% of the materials i already have or can get hold of completly free of charge. I may spend a little but thats fine by me.

    Im on the way to having a new combi fitted so instead of connecting this to 1 towel rad i am going to connect it to the existing hot water cylinder and then to a rad to see what happens.

    Its an interesting project for me and if it doesn't work then i have lost no money from my wallet :)

    Thanks for the advice
    • CommentAuthorEd Davies
    • CommentTimeApr 22nd 2012
     
    Please bear in mind that comments made in response to your posting may not be only addressed to you but also to other forum members and passers by who might be interested in a wider context.
    • CommentAuthorGaryB
    • CommentTimeApr 22nd 2012
     
    Budbecks

    Experiments are welcome and are of interest to both members and guests - please let us know the outcome, whether positive or negative.
    • CommentAuthorbudbecks
    • CommentTimeApr 22nd 2012
     
    Hey,

    Of course, not a problem. wont be for a while but i will let you know the outcome.

    Cheers all.

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