*sigh* Retreat version II.

Discussion in 'Designing, building, making and powering your life' started by dgriffith, Mar 12, 2008.

  1. dgriffith

    dgriffith Junior Member

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    Re: *sigh* Retreat version II.

    Very tempted by those evac tube systems..... $900 isn't too bad either. Got an address/phone no?

    Unfortunately I need mains (or close to mains) pressure for a low-flow shower as we have limited tank supply.
    First thought was just to pressurise the hot/cold mix just before the shower head.
    But the water pump can't handle more than 70 degrees C (being plastic bits) and on occasion the hot water surpasses this.
    So I need to pressurise the system on the cold side, before the hot water tank.
    Which means (sigh) I either need a mains pressure tank, or a heat exchanger in a vented tank. Besides that, it'd be good to pressurise the rest of the house water system as well.

    At least after all this finangling I'll be able to easily add an evac tube collector - have added a couple of spare connections on the tank for another thermosiphon loop as well as the stove set. One good thing about doing it yourself I guess.
     
  2. MonteGoulding

    MonteGoulding Junior Member

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  3. dgriffith

    dgriffith Junior Member

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    Re: *sigh* Retreat version II.

    Got one of those shower heads, it's quite alright, except it appears to have a US-style NPT pipe thread fitting instead of the BSP type that's common here. So it only screws in a few turns.....
    Running from the 12V pump, it flows at about 5 litres per minute or so which is pretty good. There's plenty of apparent volume from it - it draws a fair bit of air in like a tap aerator. If you put your hand over it to block air entry, it decreases in volume to a trickle like someone pouring out a cup of water.

    Pressure-wise, our full tank still doesn't have enough oomph to get a good flow from the shower head. If I put it at my feet in the tub, it's OK, any higher and it drops off quick. The bottom of the tank is about 3 feet above the bottom of the bathroom tub, so there's not a great deal of head pressure available. Still waiting for the new hot water tank, so I can plumb the pump, heat exchanger and gas booster in. Tank guy had some trouble sourcing double-ended fittings that will go through the tank wall for the heat exchanger coils, want it to be welded to be leak-proof (and without any o-rings,etc that could perish). Next week, he says.

    Getting another set of 5 x 20W panels, should be here next week - days are getting longer now, so haven't been running the genset too often at all, only for an hour or two in the evening on cloudy days. The new set of panels should help keep up with my laptop + sat modem, which has been running a fair bit lately. They'll also help charge things up quicker too.

    Building a carport (*cough* pergola if the council is looking) out the back, and also adding a small enclosed patio to the front of the house in a northeast-facing corner formed by the kitchen and laundry. Going to put a bit of laserlite on it to soak up the sun and block the wind. It's a bit of a long term project, need the carport first, been getting a little bit of small sleet/hail lately.
     
  4. dgriffith

    dgriffith Junior Member

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    Re: *sigh* Retreat version II.

    Seem to have been really busy this week.....
    • Built a 'pergola' to put the two cars under. Covered with a bit of shadecloth to keep the weather off - got a small bit of hail/frozen rain about 20 minutes after we parked the cars under it. On to the sun-room/lean-to out the front of the house.
      [/*:m:3vf57w16]
    • Got the new solar panels up. They're a smaller physical size than the other set, still nominally 20 watts per panel - the individual cell size is different, with a higher number of grid wires on the face of each cell. Today at lunchtime, the whole lot put out 16 amps at 13.8 volts - 220 watts. Cost so far for the 10 panels + aluminium framing has been just under $1500. Considering a hundred-watt "Name Brand" panel runs about $1000 or so, it's not too bad. Longevity is the question I guess - I did have to seal the junction box at the back of each panel, it was pretty open to the weather. I guess time will tell how they go. The extra output seems to be matching our current usage in moderately sunny weather, so hopefully the genset will be much less used now.
      [/*:m:3vf57w16]
    • Hot water tank finally done - for cash-in-hand at $600. Certainly looks the part. Fitted the heat exchanger coil,put the lid on... leaked around the lid. Tried again, using more sealant... leaked. Hmmm- the sealant wasn't curing on the flange and the water in the tank was forcing it out. Cleaned off all the goop, put two strips of self-adhesive 5mm draft-stopping foam around all sides of the lid... no leaks, except for one tiny weep around a single bolt-head, which I'll sort out tomorrow before insulating the tank with a few Pink Batts I've got spare. No, the water in the tank is static and isn't used for drinking.
      [/*:m:3vf57w16]
    • Once the tank was plumbed up to the stove and relatively leak-free, did some more plumbing. Put in a 50L pressure tank (from ebay - $90) that the pump pumps up - it gets pressurised by the 12V pump and feeds the cold water taps in the house and the gas booster via the heat exchanger coil in the tank. 50 litres is enormous. It's two (and more) full sinks of water before the pump even starts up. It really helps to stabilise the flow to the gas hot water system - I found with the low-flow shower head, the pump would cycle on and off, cutting the booster off... giving you cold showers. So pressure tank is good. Probably could have gotten away with a smaller one though - it literally is wedged in next to the hot water tank.
      [/*:m:3vf57w16]
    • Got the gas booster on the wall in the kitchen and plumbed up. Need to put the outside flue on before we wind up with CO poisoning though. At present,we open the window next to the booster - getting the flue on Monday. With the top half of the tank water warmed to 30 degrees C by the stove after a couple of hours of wood, the 4 degree water in the heat exchanger is heated up enough that the gas booster can do the rest and steaming hot showers ensue at about 5 litres/min. Success![/*:m:3vf57w16]

    So, after all that, I think I'll try and take it a bit easy for a little while now :D
     
  5. dgriffith

    dgriffith Junior Member

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    Re: *sigh* Retreat version II.

    Updates again:

    • Got the sunroom moderately finished out on the north-east corner of the house. 3m wide x 5m long x 2.5m high, clear laserlite on the sides, "bronze" laserlite on the roof. Enough room for a fair few potted things in there. Hopefully will help against some of the extremes we get here - went from lows of 4 or 5 for the last few weeks to -7 two days ago. Bit tough on the plants, but the broccoli has taken off in the little greenhouse though.[/*:m:kiwdiff0]
    • Popped one set of MOSFETS in my 1000W inverter, by inadvertently turning the toaster and the washing machine on at the same time. Now the inverter only puts out about 110V. Obviously not quite the overload protection that the little sticker on it so boldly claimed. I'll fix it one day when I've got the time..... In the meantime, bought a 1500W PowerTech one for $400 to replace it temporarily. Found a Latronic 12V 2KW sinewave inverter on eBay, got it for $1300. It's a recent model, new price was about $2700 or so. Weighs 22KG, so it's a bit of a slow trip from Darwin, but hopefully will turn up next week. Will keep the 1500W one as a spare, or maybe pass it on to some relatives.[/*:m:kiwdiff0]
    • Panels are good - in clear skies, can put out 19 amps at 13.5V = 250 watts. Regulator actually managed to get into it's auto-equalise mode and equalised the batteries yesterday. [/*:m:kiwdiff0]
    • Got a tempering valve for the hot water system to keep the hot water at a predicable level - $65 from ebay.[/*:m:kiwdiff0]

    Next major thing is water. Either need a bore put in, or a big tank. Total house tanks at present is about 10kL, which isn't enough for my liking, especially with dry summers.
     
  6. springtide

    springtide Junior Member

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    Re: *sigh* Retreat version II.

    Hiya,
    I was talking to someone the other day who was saying that the newer modified sine wave inverters are nearly as good as a pure sine - all the modified sine wave ones i have owned or seen make transformers buzz like crazy and dont react well with televisions and stuff- do you know if the new ones are any better? They also said that some of the cheaper pure sine inverters put out a dirty wave form - any ideas? I am looking to buy one and there are a lot of good deals on ebay but i dont know much about them.
    I am going to do a few more units next year to get BSCE accreditation but i think only trial and error will tell.

    Any suggestions?
    Cheers n keep up your posts they're inspiring stuff.
     
  7. dgriffith

    dgriffith Junior Member

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    Re: *sigh* Retreat version II.

    With the new 'improved' modified sinewave inverters, you're still talking about a very harsh square wave at approx +/- 170V each side. The edges (the rapid switch from off to on) of the square wave are the culprit for the buzz in transformers, and the cause of overloads when your inverter tries to charge a great big mains capacitor in the switchmode power supply to 170V instantaneously.

    Don't confuse the modified sinewave inverters with 'digital sinewave' ones. Digital sinewave ones pulse at a high frequency (40kHz or so) with varying pulse lengths and all the little 170VDC pulses are then smoothed and averaged and you get a quite reasonable sinewave approximation out of it. As for harmonic distortion (the 'dirty waveform') anything under 5% is fine - grid mains is can easily reach that figure with various reactive/inductive loads all plugged in. As an aside - the latest "ReNew" magazine has a good review/overview of all the sinewave inverters + inverter/chargers on the market at present.

    The new 1500W powertech one I just bought is fine for tools and lights and stuff (with minor buzzing from CFL's), it has a lot of issues with the switchmode power supply for the TV. Flicking on the TV at the wall will sometimes cause the inverter to trip on overload and then blink / 'soft-start' over the next few seconds. The TV also causes it's cooling fan to come on constantly - and this is just a power supply for a 70 watt LCD TV. Didn't have any real issues with the old Paco 1000W inverter, but then, it did blow up in the end...

    The old CRT TV - while nominally using more power at 80 watts or so, has a more traditional power supply in it which the inverter has no issue in powering.

    Hence my decision to bite the bullet and get the Latronics sinewave inverter at a very cheap price (compared to new). Having gone through winter here and survived :) , and with the subsequent increase in power from the new batch of panels,I might as well get it all sorted properly.
     
  8. springtide

    springtide Junior Member

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    Re: *sigh* Retreat version II.

    Thanks for the prompt post,
    i'm going to borrow a mod sine inverter for a bit to test some stuff, it has a 3500 watt surge rating so i am going to create some sizeable switch gear for it. I had a few industrial 100amp tripple throw MCBs that i've cut apart to make a 4 pole and bridged them in pairs to make it 200 amps, then i am hoping that the RMS values should take it to 280 amp. I am also going to use some 300mm2 bar to make a junction box (yes i like overkill :razz: ). I'm a bit scared to try it on our LCD tv though, might try it on the beer fridge and some other stuff first - my cheapo 500 watt pure sine (1kw max) trips out on the 180 watt fridge so dunno there.
    I want to get this all set to put in a house in a year or so (eventually 24v). I will have to wait and see - and tell the insurance company it was a lightning strike!

    Thanks again. :wink:
     
  9. dgriffith

    dgriffith Junior Member

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    Re: *sigh* Retreat version II.

    You can never have too much overkill :)

    Regarding the MCB's and the inverter's surge rating, it depends on their trip curve as to how sensitive they'll be to inverter surges. Seeing as the 3500W surge rating is usually specified for only a few cycles, it should be right.

    My 1500W inverter is wired via a 100A fuse (gold-plated, for extra bling) - with fuses, you normally have to be at least 20% overcurrent for an hour before you'll pop/melt it. So even though it's undersized (1500W / 12V = 125A minimum) it's really just there for catastrophic failures only.

    Fridges and their compressors are a real pain for inverters, they don't enjoy trying to start a stalled motor at all. When testing your fridge, make sure if you unplug it from the mains, you leave it for at least 20 minutes before trying the inverter on it - this gives it some time for the head pressure on the compressor to drop off and makes for easier starting. Most fridge thermostats do the same kind of thing - they don't flick on/off quickly, the lag in temperatures means the compressor usually is off for a fair length of time.

    Regarding the switchmode supplies, basically, what I do is:

    - Plug the power supply in by itself if possible (eg. with TV unplugged from the pack), observe inverter behaviour and battery load current. If it's the only thing plugged into the inverter and the inverter is drawing more than half of the power supplies rated supply wattage out of the batteries, that's not good. Unplug it.

    - Whilst plugged in listen for any loud buzzing. A bit of buzzing is OK on a mod. sine inverter - if you can feel it buzzing when you're holding it in your hand, it's probably not good.

    - If those tests seem ok, leave it plugged in for 10 minutes and check it's not getting hot. Anything more than "body heat warm" is suspect in my opinion, but the best bet is to compare it to when it's plugged into grid AC.

    - Then plug it into the TV and check that the TV functions normally, and that the power supply isn't getting hotter than usual (on grid AC) after 10 minutes of operation.

    Generally, if after all that it seems to be functioning normally, you should be right.
     
  10. dgriffith

    dgriffith Junior Member

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    Re: *sigh* Retreat version II.

    Got the inverter - had to trundle off to Hobart to get it from the freight company.

    Took it apart to check things out (it has a very heavy toroidal transformer in it and it's a lot of rattling from Darwin to get to here). Found a loose wire from a mod the previous owner made to turn the cooling fan on full time, resoldered that.

    The main leads had been cut reasonably short (about 10 inches from the back of the inverter) but that wasn't a hassle, fitted two lugs to them and bolted them to the leads I had for the other inverter.

    All works good, the auto-start can sense when a 5W compact fluoro is turned on in the house and fires the inverter up. No more buzz from lights/TV/Stereo etc, and the toaster does toast a bit better now :lol: Batteries also seem to be a bit higher in charge at the end of the evening compared to the mod-sine inverter, I suspect the switchmode supplies were a bit hard to run for it.

    Fitted the tempering valve to the hot water system, much more stable showers now. Can turn the shower right down now with the same output temps, until the hot water booster cuts out due to lack of flow. If the hot water gets too hot at low flows, the booster is cycled on and off every few seconds by the tempering valve keeping the hot water at 50-ish degrees - at that point, I usually turn the water flow up a bit to stop it cycling. I've a temperature gauge on the hot water pre-heater tank and I'm slowly figuring out what temperature is the point where I need to flick the booster from "summer" to "winter" to keep the water temp up without it cycling like that.

    Regarding water - counted all the water tanks again today, currently have 10,000 litres of storage all up. The two main tanks that the sink/shower are fed from are about 5900 litres in total, and one's 1/3rd full, while the other is still full. It's been about 7 weeks since the last decent rain that filled them (and when I installed the shower), so that works out to be about 50-60 litres/day from those tanks. Two smaller tanks of about 1500L each are joined to do the toilet exclusively, one's shut off and is full, the other is half-full, so that's OK at the moment.
    Hopefully a bit more rain will wander past before things get too serious.
     
  11. springtide

    springtide Junior Member

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    Re: *sigh* Retreat version II.

    box n breaker.jpg[/attachment:tr3gs1at]
    Hi all,
    i finally finished my junction box and main breaker. I know the bolts are a bit all over the place but the bars and most of the rest are all recycled stuff from various places i have worked at. We can't do much with our current house but we are slowly learning and getting ready for the big move.
    :) :) :)
     
  12. dgriffith

    dgriffith Junior Member

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    Re: *sigh* Retreat version II.

    Looks pretty good - got room for a shunt or two in there later on? A Xantrex Link-Lite or a Trimetric/Pentametric is a handy thing to help keep an eye on battery charge.

    Been eyeing them off, haven't gotten around to getting one yet.... one of these days.
    Got talking to a neighbour who visits his shack - he's got the 'bug' as well, going to go with a wind generator. I said to have a 50W panel or something as a standby, just in case. Says he's getting a bunch of Telstra 2V cells off a mate for $80 each - they weigh 45kg each , so they're reasonably large. Said to let his mate know that I'll take a few if he's got any spare.....
     

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