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Forum Index : Solar : Deciding if I should build this solar heater
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| Warpspeed Guru  Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
That sounds about right for a nominal 100K at 25C thermistor. The resistance goes down as temperature rises. I could not find any of the really tiny ones, but at least these are in Oz and should arrive in about a week. https://www.ebay.com.au/itm/274030259235?hash=item3fcd79ec23:g:ryQAAOSwZpVdkEP8 Cheers, Tony. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852 |
Mmmm ... those look exactly like the ones in the logger now. I may need to persevere with what I've got I suppose. Cetainly this one responds more quickly than it did before. One thing that is disconcerting with the chart is that it looks like the fan is pumping air in, right down to about 16 degrees (during the early cycles for the day) ... ... but the temp dropping down to 16 is simply the sensor floating back down to the room temp and not the system pumping in cold aitr. I need an indicator that shows when the fan turns on and off.  Cheers, Roger |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
That is significant. Takes reasonable power to get a temp rise like that in a decent size room. Does you house hold the temperature well when the sun goes down or do you start up the fire? Temp in my place drops like a rock when there is no active heating, thermally soaked or not. Wasn't bad last night, had a Veritable heatwave of a Minimum of 12oC!! That's a whopping 15o warmer than we had the other morning with a -3. Cars had frost so thick it looked like they had been snowed on Had to get water out the Kitchen to defrost them because the hose was frozen solid too. Was down to 9o at 7 pm tonight and forecast to only get down to 8 which is good! Surprising as last night and tonight are perfectly clear skies.... and a full moon. My long lost Brother Roger!! That is hilarious. With the cold windy weather of late I cleaned up the cave a bit this week and went through all my electronic boards and bits and Pieces to have a sort out and put them in some organisers I bought a while back. I have a shoe box sized container just for my relays. Bunch of those SSR's, DPDT rail mounts, little DC solid state types on boards, 4 and 5 pin types, ones I salvaged from dead Inverters. Got a few of the Voltage controlled relays and there is a Box of at least 100 Relays of various types I have pulled out of cars in the yard up the shed. They come in some weird and wonderful flavours now. I was looking at the ones down here after pulling them out from everywhere and putting them in the one box thinking What da fluck was I thinking I was going to do with all these? I do remember ordering one lot which never showed and ordering another lot and the second ones showed up and then the first lot arrived a couple of days later so I'm pretty flush with those. Also got a bunch of contactors and some 3 phase relays I pulled out of Air cons my friend was scrapping. There are some nice relays and contactors in that industrial stuff. Don't think I'm going to need any more for a while. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
O/k, I looked through e-bay but could not find any that are really small like these that I have here, which are only just over a 1mm blob.  Just breathing on these and they respond pretty much instantly. If you PM me your address I will get a few off in the mail to you today. Cheers, Tony. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Just found these on e-bay, I think they are the right ones ?? This is selection, ten types, ten of each type, only the 100K versions will work for you, but they are cheap enough. https://www.ebay.com.au/itm/284185659346?hash=item422ac907d2:g:zq0AAOSwuQpgKsvR Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Are the small ones so reactive because they are tiny they have so little thermal mass? |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852 |
Yes agreed, and I haven't seen that for a while. And it's hard for the lounge to get warm because it is wide open to the rest of the house and the wood fire wasn't contributing. Ours is the same and that's why I hate running the aircon for heat because as soon as you turn it off, it's immediately cold. Haha and it's not just me. As you know I fix boards for a living and early on I used to get these output boards .. and some were full of triacs and some were full of relays. Thinking that triacs were later technology than relays, I assumed the triac boards were a newer version ... but it took me a while to find out that the relay boards were the newer. If a major manufacturer decided that relays are a better option than triacs ... then we are in good company. I don't know if it was the reliability or the cost ... but it's definitely easier to replace a dud relay or two than to clean up the mess from exploded and smouldering triacs, especially being surface mount ... and still make it look presentable afterwards. I've certainly collected plenty of old relays from scrapped equipment over the years too ... but I have several hundred new ones in stock for the various boards I do. In fact for one type of board, I buy a hundred at a time. If the relay has never been replaced, it definitely gets changed ... but the same boards also have mosfets for switching external solenoids ... and they often fail too ... so considering what they go through, the relays are still very impressive. Cheers, Roger |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yes, they are absolutely tiny and there is almost nothing there to heat up or cool down. Heating just the air in a room is not a big deal, provided there is sufficient airflow from the heater (whatever it is) to circulate the heat. What takes a lot longer, is heating up the walls, the floor, the hard objects in the room. Until EVERYTHING heats up. Remove the heat source, and all the cold surrounding objects will suck the heat right out of the air in an instant. Cheers, Tony. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852 |
Whoops, I replied earlier without refreshing the page to see the extra replies. It's a ripper day down here today ... the system only fired up around 9 ... but it is nice and sunny ... so expecting to cook the house if conditions don't change. Thanks very much for your kind offer Tony but now that you've found those others I'll grab some of them instead of depleting your supplies. I'm looking forward to fitting one to the outside logger too. The photo shows a comparison between the original logger one and the sensor from the Owon multimeter.  Cheers, Roger |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
This is the same as my place. I have the Diesel in the kitchen which is 72M2. The Media room is attached and open and that's about another 19 sqm. The hall way is also attached which I can't close off and the laundry is always open because that's where the cat box and the dogs food and water are. The diesel can run at 3 Kw all day and I very rarely see the temp get to 20. 19 Seems it's happy place and that's fine. Interesting. Not just my pathetic glass house then. Must be great to live in a truly well insulated home. I am Triac Ignorant. I only just discovered the miracle of Mosfets last year from the interest Tony created and things I wanted to do. I made a touch switch for my father for something using a mosfet and he's fascinated by it, especially that I made it! The only thing with relays is I have wanted to do High speed, long term switching which is obviously going to take a big toll on anything mechanical. Most of the timers I have are Relay driven but I did find some with small Mosfets which are suitable for what I want and can also be driven to tenths of a second. One of these applications was driving the fuel pump for the diesel heater. it requires only about a 10/th on time where all the relay units I found had a min of 1 second which was too long to keep the solenoid engaged. The other thing is the Solar panel Driver which I also wanted to operate in milliseconds so was out of the realm for relays. I did make up a spark generator for an ignition coil from some relays But I think the runtime on that would be limited, not that I wanted to run it for hours on end. :0) |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
If you need some high voltage sparks to light stuff, the best thing for that is one of the igniters for a gas stove cook top. Connect one of those up to 240v and they spark about once per second. Very simple and low cost. Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Yep, that was exactly my idea with trying to keep the place heat soaked at the beginning of winter. I am convinced it is the way to go. My father has had this Philosophy with his wood heater for years. Better to keep it going with a few bits of wood through the day than let the ( older) house cool off... which then takes as much timber or more to get it back up to speed and then by the time it is comfortable, time for bed. When I think about it, it's exactly the way I have run my wood fire Pizza oven for nearly 20 years. Thing weighed about 1 Ton and had to be heat soaked to work. I'd light it 2-4 Hours before I wanted to cook, get the thing hot ( as in glowing bricks sometimes) and then let the fire go down and use the radiated heat. Even with that and surrounded by hebel for insulation, the temp would fall right off in 60-90 min. By then Cooking is done so it would be stoked up again for sitting around. I built my neighbour a similar oven and she would have a small fire in it all day but never really got the thing hot and it was useless to cook in. I'd have to run it flat out for as long as I could to heat soak it otherwise you just could not get the Pies right. Clearly the same principal works in the house although as one wants the place permanently warm, ongoing input is essential..... Except for places well insulated like yours! :0) I'm not sure it's more economical for me to maintain temps with the diesel heater or using electric with the AC or fan heaters but it sure as ship makes the place a LOT more comfortable than cycling it and I am more than willing to pay the premium for that. My friend said to me the other day how freezing the winter has been. We have thought of it as quite good. Our temps here are Minimum 5 below where my friend is and usually lower and normally he is the one saying it hasn't been that cold so I took this as an indication that keeping the place warm has been working. I have been keeping a fan heater running through the day even when the kitchen is warm enough. It's output is pretty pathetic really but it seems having something just to offset the losses is worthwhile as well. Once it gets to 4-5 PM, more to the latter atm, I crank it up or the diesel and hit the AC as well to help level the place out and before the ambient temps outside fall to double Digits. Easier for the AC to extract the heat and put it inside. I am a bit surprised how well the heat travels. My mate in AC told me it wouldn't work well but although obviously the main heated room is the warmest, the other rooms haven't had that icy Chill. I think when I can double or triple the heat input, I can run the AC on fan mode and circulate it round even better. I am Building the Veg heater to go DOWN to 10 Kw but will have plenty of capacity to go higher. I think running the house temps up through the day and letting the furniture, walls and floors radiate heat OUT at night will be the bees Knees. 110% convinced keeping the temps constant rather than Cycling is the way to go. I think if Roger can pump good heat into his house though the day and regularly, it will work well for him too. If he can get the place to say 25 During the day and let it drop at night, the heat will be radiating not the cold. Also want to look at that window Film again but what a Nightmare job that's going to be on this place. I reckon I could buy 100 sqm of the stuff and not have much if any left over. All the windows have these stick on Dividers to make them look like small panes of glass when they are one. I don't know how easy that will be to get off then I'd have to put them back on again over the film. Bad enough cleaning the windows, I's pitch them to buggery but Mrs loves them so if they disappear, so will I. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yes, I agree, and even if it needs some help right in the middle of winter, it will probably be sufficient in the months leading into winter, and coming out of winter. It does not need to supply all of the heat all of the time to significantly cut down on fuel costs. Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
That one escaped me. At the time I was facinated driving an ignition coil with relays so that was as much the " Miracle" of making that work as the application I was going to put it to. I have bought some of those 10/ 20? 5 Million ( add your own Chinese inflated number here) KV stun gun coils which seem to work pretty good. Connected one of them up to a spark plug and seems to work. I also just the other day came across the pinout for some electronic car ignition coils I have which are the coil on Plug type. I think I could drive them with a Timer board or an arduino on a mosfet and get a good arc out of those. I'm thinking to have press Button Ignition for a burner. Start the thing on gas for pre heat and then switch to oil. Ultimately I'd like to have this automatic off an arduino or the like where it controls solenoids for the gas and oil and maybe even runs the blower speed as well. That will be well down the track and require much more learn'in however. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Yep, that was exactly my idea with trying to keep the place heat soaked at the beginning of winter. I am convinced it is the way to go. My father has had this Philosophy with his wood heater for years. Better to keep it going with a few bits of wood through the day than let the ( older) house cool off... which then takes as much timber or more to get it back up to speed and then by the time it is comfortable, time for bed. When I think about it, it's exactly the way I have run my wood fire Pizza oven for nearly 20 years. Thing weighed about 1 Ton and had to be heat soaked to work. I'd light it 2-4 Hours before I wanted to cook, get the thing hot ( as in glowing bricks sometimes) and then let the fire go down and use the radiated heat. Even with that and surrounded by hebel for insulation, the temp would fall right off in 60-90 min. By then Cooking is done so it would be stoked up again for sitting around. I built my neighbour a similar oven and she would have a small fire in it all day but never really got the thing hot and it was useless to cook in. I'd have to run it flat out for as long as I could to heat soak it otherwise you just could not get the Pies right. Clearly the same principal works in the house although as one wants the place permanently warm, ongoing input is essential..... Except for places well insulated like yours! :0) I'm not sure it's more economical for me to maintain temps with the diesel heater or using electric with the AC or fan heaters but it sure as ship makes the place a LOT more comfortable than cycling it and I am more than willing to pay the premium for that. My friend said to me the other day how freezing the winter has been. We have thought of it as quite good. Our temps here are Minimum 5 below where my friend is and usually lower and normally he is the one saying it hasn't been that cold so I took this as an indication that keeping the place warm has been working. I have been keeping a fan heater running through the day even when the kitchen is warm enough. It's output is pretty pathetic really but it seems having something just to offset the losses is worthwhile as well. Once it gets to 4-5 PM, more to the latter atm, I crank it up or the diesel and hit the AC as well to help level the place out and before the ambient temps outside fall to double Digits. Easier for the AC to extract the heat and put it inside. I am a bit surprised how well the heat travels. My mate in AC told me it wouldn't work well but although obviously the main heated room is the warmest, the other rooms haven't had that icy Chill. I think when I can double or triple the heat input, I can run the AC on fan mode and circulate it round even better. I am Building the Veg heater to go DOWN to 10 Kw but will have plenty of capacity to go higher. I think running the house temps up through the day and letting the furniture, walls and floors radiate heat OUT at night will be the bees Knees. 110% convinced keeping the temps constant rather than Cycling is the way to go. I think if Roger can pump good heat into his house though the day and regularly, it will work well for him too. If he can get the place to say 25 During the day and let it drop at night, the heat will be radiating not the cold. Also want to look at that window Film again but what a Nightmare job that's going to be on this place. I reckon I could buy 100 sqm of the stuff and not have much if any left over. All the windows have these stick on Dividers to make them look like small panes of glass when they are one. I don't know how easy that will be to get off then I'd have to put them back on again over the film. Bad enough cleaning the windows, I's pitch them to buggery but Mrs loves them so if they disappear, so will I. Edit: I did a quick measurement of the windows in the place. The main ones worked out to 70M2. That wasn't including the glass doors or the little windows in the bathrooms and laundry. My guess of 100M2 was pretty close to the money and that's assuming no wastage. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Roger, I was just digging through the cave Cupboard again and I came across some more relays I bought recently. Feast your eyes on these babys! :0) 900V, 500A DC relay Forgot the best ones I have! Typical. Still in their own neat little foam padded box. Might put them in the glass display cabinet in the lounge room till I need them.... with a small spotlight trained on them so their full glory can be appreciated!!  Bought them for Controlling Solar DC output. I can use the inbuilt thermostat in a water heater to drive these as the coil current is bugger all and they have an optimiser once they are engaged. I can use one of those little power supply's Tony put me onto off the DC input to drive them. Those boards are extremely handy little things! Also be good for a Solar Welding/ Carbon arc Vid I was thinking of doing so If I am running from an existing array of 360V or so, I can turn the power on and off instead of having constantly live leads. They weren't cheap but from all reports, they are good! |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852 |
Just thought I'd throw up todays results and come back later to answer some of the above comments. Gotta go out and practise my ally welding otherwise this new one will never get finished. We started at about 17 degrees in the lounge this morning and got up over 22 in the arvo. When I came in at 7pm, the house was still nice and warm and I was almost tempted not to light the wood fire ... but that would be a mistake because it would freezing by morning. I edited the image to show when the fan was running.  Edited 2021-07-27 02:03 by rogerdw Cheers, Roger |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Its interesting how the tube temperature was slow to climb initially, but then suddenly took off just before 9am. I think you mentioned earlier about shading from a fence. Once its up on the roof it should get going much sooner. Imagine how this will go on a good day with three times as many tubes and no shading ! It will heat up much faster in the early morning, then the whole house can absorb the heat which should then stay warm for longer in the evening. Edited 2021-07-27 05:49 by Warpspeed Cheers, Tony. |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 852 |
That's a big kitchen ... you could hire it out as a ballroom. I don't think I'll get away with just 19 here ... my wife hates the cold and always wants it warmer ... though she has commented a few times that she can feel the warmth as she walks down the passage past the lounge room openings. 21 or 22 would be nice. Yeah, I don't even know if we have insulation in the walls here, though we have it in the ceiling. My electronics workshop is in the other end of the shed I showed a while ago and it has a ceiling and is lined ... and also lots of insulation. It is very noticeable because it stays cool in summer and remarkably warm in winter. People often ask where my air conditioner is when they walk in in summer, but there isn't one. It does get warm after a few days of constant heat ... but the insulation has me sold. Yes, me too. Yesterday with the warmth being pumped into the lounge ... it was still noticeable at 7pm when I walked into the house. The lounge is at the front of the house and we rarely use the room ... but being so open it spreads around quite well. Yeah, I can see the possibility of having that as our main warmth ... and just turning on a gas heater for a couple of hours at night to see us through to bedtime. And also really cold mornings. Haha, very nice. I see something like that in my future too. Exactly ... we'll definitely need extra heat in evenings and early mornings, but this should supply the majority. If we only use gas for a few hours here and there is a lot better than all day. I think yesterdays was also because of cloud on the horizon ... it looked quite sunny outside but it took a while for the sun to get up over the cloud. For early mornings I keep thinking of a reflector curled up on the far side reflecting back across the array. Of course it has to fold back down for the afternoon so it doesn't shade it. And then, the same on the other side to catch more of the setting sun. I know, dreaming! I was up till all hours welding pipes. I've gone back to using the oxy and normal aluminium filler rod. I wouldn't say I'm good at it yet, but definitely getting better ... but so many more to do ... and then I have to weld them all into the angle at the top. Starting to think that an extra $500 for some new tubing might be a good idea. Will save me a lot of time apart from a trip to the city to pick it up ... and 20 x 6.5 metres lengths too ... I'll have to take my hacksaw!!! The irony is that then I'll end up with 20 x 1.2 metre offcuts ... which is exactly what I'm welding together at the moment! Cheers, Roger |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
A much simpler thing to try first might be placing a shiny reflector behind the tubes. Something like plywood or cardboard covered in aluminium cooking foil just to try. Edited 2021-07-27 11:55 by Warpspeed Cheers, Tony. |
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