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manwithtool
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« on: April 19, 2007, 11:38:37 PM » |
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Thought I'd add a few bits of info on my install.
As stated its 2 lots of 10 70mm tubes feeding a 140 litres Hot water cyclinder. The panels are either side of a Velux window facing SW, so I miss a few hours of early morning sun !
Over the last 3 sunny days I have heated the tank from around 15 deg to 50-55 deg Watr use during the day is minimal. However most of the water is used up at night when the whole family washes.
I have rigged up a Heat dump using the second relay on the Resol BS 4 controller. This is programmed to open when the top of the solar tank reaches 65 deg (I might increase this temp later) The heat dump simply draws water from the bolier heated tank into a water butt outside. So far this has not kicked in.
The system all works very well, although I did hope for higher temps given the sunny days and the high efficiency tubes...although I guess facing SW is not ideal....and I always start with no heat in the tank at all.
Over the last 3 days I have just fired the boiler up for 1 hour each evening to warm the water in the bolier heated tank and to get some heat into the bathroom radiators. I hpe that as temps increase I won't have to do this...But I suspect that one of the failings of a "2 tank system" is that the tank you draw water from is not going to be hot enough....We'll have to wait and see !
Any comments welcome ! And yes I hate to waste water...so if the system does start to dump lots of water it will be easy for me to lean out of the window and cover up part of the collector....Bit of a crude but effective fix ?
Cheers
Martin
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Antman
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« Reply #1 on: April 21, 2007, 09:54:18 AM » |
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Martin
Forgive me if my memory is getting this wrong, but if I remember correctly you have the solar cylinder feeding the boiler heated cylinder, yes?
If so, why dump water from the boiler heated cylinder? Why not dump it direct from the solar heated one? The reason is that the solar tank will be the one to overheat but there is no way the boiler heated tank (drawing the solar water into it) will overheat, as the boiler cylinder will always be at a lower temperature when the dump activates.
Therefore you run the risk of dumping (paid-for) boiler-heated hot water in order to satisfy the overheat on the (free) solar cylinder.
If I have your system config wrong, please correct me and appologies for the incorrect assumption.
Regards
Antman
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20 x 47mm, 172 litre cylinder, Heat Dump, 15 x Sanyo HIT-H250E, SB4000TL DIY Solar System Support at: http://homepage.ntlworld.com/anthony.cooper267/index.htmlAll support is wholly voluntary and free of charge. I'm not employed by Navitron and have a full-time job so responses may not be same-day |
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manwithtool
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« Reply #2 on: April 21, 2007, 07:26:41 PM » |
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Hi Antman,
You have remembered well....From the last few days of nice weather I'm finding that the water in the bolier tank is cooler than the water in the solar tank...therefore I am having to stick the bolier on for an hour or so (gravity fed !!) to warm the tank up before we draw water from it....But the hour is always in the evening so handy for the radiator in the bathroom anyway.
My theory is that when the dump kicks in I will be dumping the cooler water from the boiler tank....replacing it with nice hot solar heated water...removing the need to stick the boiler on for an hour in the evening....Make sense ?
My only problem is how quickly or slowly the warm water in the bolier tank mixes with the solar heated water coming into it...
I'm hoping it mixes rather than sits at different levels (stratification ?? ) but I think I might be wrong there....Even so if the Hot water doesn't mix with the cooler water then I assume it will find it's way to the top of the tank ready to be used.
Hopefully in warmer months I hope that the water in the boiler tank will in fact be the previous days solar heated water...so if it does get dumped it will not have been heated by the boiler anyway.
Hope that makes sense...I've dribbled on for a while there...
Just for the record today was quite hot...although a little high cloud stopped some direct sun.....I have the solar heated tank upto 47 deg.....so I guess the boiler will go on for an hour tonight, but that will give me a fairly hot 160 litre bolier heated tank and a 47 deg 140 litre tank....quite alot of hot water for 1 hour's worth of boiler. And the boiler being a gravity fed system for hot wter will be stopping and starting during that hour. Also the water in the boiler tank will be mainly yesterdays solar heated water. This reminds me I must get some sensors ont he boiler tank so that I can be a bit more accurate with the amount of time I stick the boiler on for.
Cheers
Martin
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Antman
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« Reply #3 on: April 29, 2007, 09:17:06 AM » |
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With side-by-side cylinders(?) a gravity inter-cylinder circulation (from solar cyl to boiler cyl) is not possible but I suppose another option would be to install a 'bronze' pump so as to circulate water from the solar cylinder to the boiler cyl on heat dump. That will exchange the boiler heated water with solar cylinder contents and tend to equalise the temps before any dumping  takes place. Antman
Edit after re-read - added 'heated' as in boiler heated above - to avoid any confusion in case anyone thinks I may have been suggested mixiing yucky boiler water with potable cylinder water  |
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« Last Edit: April 30, 2007, 02:55:13 PM by Antman »
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20 x 47mm, 172 litre cylinder, Heat Dump, 15 x Sanyo HIT-H250E, SB4000TL DIY Solar System Support at: http://homepage.ntlworld.com/anthony.cooper267/index.htmlAll support is wholly voluntary and free of charge. I'm not employed by Navitron and have a full-time job so responses may not be same-day |
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manwithtool
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« Reply #4 on: April 30, 2007, 01:04:07 PM » |
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Hi Antman,
I like the sound of your idea ! it would avoid wasting water...and should give me hotter water...That might well illiminate some of the disadvantages of my twin tank set up !..I will leave it a while to see what does happen....it seems I'm still a way of reaching the "dump" temps. I think one of the advantages of my system is that because the water is cold to start each day I am getting the most out of any sun...ie with a dual coil setup I assume it will already have some hot water in it ?
Any way....yesterday was quite sunny....most of the day and my tank reached 53 deg. still 12 deg off the dump temp of 65 deg. I might increase this temp to 70 deg later, but I'd like to see the dump valve working first before I rely on it too much !
Thanks for the comments....It's a nice idea
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manwithtool
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« Reply #5 on: May 01, 2007, 08:46:52 AM » |
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Well yesterday 30 Apr my system came up to 59.9 deg ......my highest temp yet ! that's a whole tank of free hot water,,from an initial temp of about 17 deg. Fingers crossed for today.
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O MidKnight
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« Reply #6 on: May 01, 2007, 12:57:01 PM » |
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25 years ago some systems were fitted by raising the domestic hot tank. A dumpy solar cylinder was fitted on the floor and with the aid of 28mm copper pipework, the dumpy used to thermosyphon it`s heat up to the normal hot cylinder.
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Solar heating - makes you feel good when you open the hot tap and when you look at your heating bill
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manwithtool
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« Reply #7 on: May 01, 2007, 01:14:03 PM » |
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Even better....Where were you when I was desiging this system !...Bit late to move the existing cylinder up now....maybe in 5 years when it's all firred up again !!
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Antman
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« Reply #8 on: May 01, 2007, 01:55:40 PM » |
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25 years ago some systems were fitted by raising the domestic hot tank. A dumpy solar cylinder was fitted on the floor and with the aid of 28mm copper pipework, the dumpy used to thermosyphon it`s heat up to the normal hot cylinder.
This brings back memories of last summer and Dazzmoss bombarding us with posts aka http://www.apexfuelsaver.com/  |
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20 x 47mm, 172 litre cylinder, Heat Dump, 15 x Sanyo HIT-H250E, SB4000TL DIY Solar System Support at: http://homepage.ntlworld.com/anthony.cooper267/index.htmlAll support is wholly voluntary and free of charge. I'm not employed by Navitron and have a full-time job so responses may not be same-day |
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O MidKnight
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« Reply #9 on: May 01, 2007, 02:26:51 PM » |
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but but my dear Manwithtool - I was around and I did mention it although in not enough detail Always used killaspray pump up bottles to fill systems even if there was a filling loop with double check valve somewhere on the installation. Been to a system where a plumber topped up the system with a filling loop. This burst three panels in the winter so very expensive. Caution when fitting a seperate solar cylinder much higher than the normal domestic hot water cylinder. If the solar cylinder is fitted in the loft and the normal domestic cylinder is a floor lower all will be fine when the solar water is cold and the domestic cylinder water is hot. If the other way around though with the solar hot and domestic cold the flow will be reduced even with a diverter valve fitted to allow solar water direct to the taps. Over the years I have been to systems where the cylinder of hot water in the loft has prevented water coming from the hot taps. Why? Lack of cold water storage tank height above the solar tank and also because the hot water being lighter than cold water the solar hot water did not like to push the cold water in the pipes down hill. Heat rises. In the late seventies a solar firm used to fit a small dumpy tank under the existing hot water cylinder and encourage the dumpy solar to thermosyphon. Of course the best solar tank is a twin or triple coil.
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Solar heating - makes you feel good when you open the hot tap and when you look at your heating bill
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manwithtool
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« Reply #10 on: May 01, 2007, 09:50:29 PM » |
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DOH !
Should have read it more carefully !!
1 May and my tank got upto 61 deg....pretty happy with that. I had the gravity fed boiler on for 40 minutes, and have now had one shower and one bath (large bath) and still seem to have a fair bit of hot water left...at least enough for another power shower.
I will have to get my finger out and get some sensors on the boiler tank to see exactly how much hot water is left, and see if I can get away with no boiler at all.....Just can't face an angry wife coming out of a cold shower !
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O MidKnight
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« Reply #11 on: May 02, 2007, 04:53:00 PM » |
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Sorry to hijack your thread. Picture 2 cylinders side by side as your installation Manwithtool. Fit a one inch essex flange near the bottom of each cylinder. Fit another essex flange near the top before the dome. Connect them up in 28mm pipe with a cytrol or similiar thermostatic automatic valve in between the two flanges. I presume that valves are available that will open on temperature rise? Failing that a zone valve could be used with 230voltage. Result could be some thermosyphon from the solar tank when it reaches the predetermined level.
Some drawbacks.
Space could be a bit tight.
Cost.
Cylinder warranty invalid. But from new the cylinder could have the 1inch tappings fitted at the factory
Any more Antman?
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« Last Edit: May 02, 2007, 08:29:13 PM by O MidKnight »
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Solar heating - makes you feel good when you open the hot tap and when you look at your heating bill
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O MidKnight
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« Reply #12 on: May 02, 2007, 08:28:25 PM » |
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Why use essex flanges. Could the inlets to both cylinders be connected together in 28mm pipe - plus the same for the outlets? There has to be a zone valve in between both still.
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Solar heating - makes you feel good when you open the hot tap and when you look at your heating bill
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manwithtool
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« Reply #14 on: July 03, 2007, 01:19:41 PM » |
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Getting back on the Temperature thread.....I'm not getting much benefit lately.....stoopid weather really seems to be stopping my system doing a great deal. Just lately it seems to be getting upto 30-45 deg depending on amount of sun (not alot !)
Still I am manually operating the boiler activation to minimise the amount of time it's in action.
Still....anything the systme does is less the boiler has to do....but I was hoping to turn teh boiler off completely....not looking promisiing just yet :-(
Just to be clear, I'm not questioning the equipment !!!! It's the waether, and the fact my panles face SW...so miss some of the morning sun.
Fingers crossed for July and Aug.
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