Solar Water Heater Set Up

[WStayton]

Hi Guys!

  I'm thinking to build my own solar water heater, a la Solar Gary's descriptions on his exhaustive website.  Looks like a way to get 85% to 90% of the performance of a state of the art unit for about 25% to 35% of the cost, depending on how clever you are at sourcing materials.

  I have recently acquired some large sheets of 1/4 inch thick plate glass, so I think I have the material to cover them and Solar Gary covered making the fins and imbedding the tubing pretty well.

  On thing that I am uncertain about, though, is exactly what/how to build the circulation pump and electricity for it.  I am kind of leaning toward the "Laing Ecocirc D5 Solar Circulator Pumps 8-24 Volt DC" pump fed directly off of one of the 200 watt, 24 volt nominal panels that I will use for the solar installation.  The panel is serious overkill for this purpose, but I'm getting them cheap enough that I can't really go buy a "one-of" of a smaller panel and do a lot better.  The fact that the only produce electricity when the sun shines and hence when the solar panel is hot, and really need no control beyond a differential thermostat, is attractive to me - free standing and not tied to or bogged down by anything else.

  I am a little concerned, though, because I have read a couple of user reports that the performance of the Laing Ecocirc D5 Solar Circulator Pumps degraded after a few months in  use.  There is/was no real measure of performance in either of these comments, so I have no idea if the poster actually knew what he was talking about, or not, and there doesn't seem to have been any real attempt to measure the output, just the poster saying that the performance degraded over time.   I have emailed the manufacturer, but have received no response, so far.  Does anybody have any experience and/or opinions of these pumps, and, for that matter, of the way in which I am proposing to design the solution to the problem???

  All input is hereby solicited!

Regardz,

Wayne Stayton

[cujet]

Why not use a Grundfos 115V pump. There are versions with 3 speeds, the lowest of which pumps plenty of water at very low power draw. Maybe 25 watts.

[WStayton]

cujet:

  But if I use a 120 VAC pump, I have to run it off of my Xantrex Inverter/Charger and I only have 60 amps available, so I'm trying NOT to put anything on that which doesn't ABSOLUTELY have to be there.

  If I use a DC pump on a separate panel, it has no impact, at all, on the Inverter/Charger.  Also, I kinda like that you can just hook it direct with nothing except a differential thermostat in the loop and when the sun shines and the water gets hot, you also have juice to circulate the water!

  I already have a 120 v ac circulator pump that runs the heated water through the wood-fired boiler, a baseboard heat circulator pump and a 120 volt ac 1/2 horse power well pump to supply my domestic water and all three of these will be driven off of the Xantrex XW6048, so I am trying not to have anything else on the Inverter that I can get from somewhere else.

  Admittedly, the well pump shouldn't be a big load, but the other two, in periods of low sun and cold weather COULD be real hogs - hence I am putting a 120 VAC diesel generator in the mix also, with the heat from the cooling water going into the holding tanks, also, but the pump for that is engine driven and only runs when the generator runs.

  I am hoping that SOMEBODY will have some experience with the Laing Ecocirc pump and can comment on it!!!

  Thanx for your suggestion, though - I DID think about doing that, and I may yet it I can't find somebody who can comment intelligently about the DC pump in question!  I am reluctant to install something that has unresolved issues!  <grin>

Regardz,

Wayne Stayton

[rcavictim]

Wayne,

I think that is a damn fine idea and I cannot wait for you to stop talking about it and do it and then talk about it.     

I'd be game to try something similar if I could get my hands on a photovoltaic solar panel.  I've stashed away a bunch of double glazed aluminum framed patio doors in good shape for this possible re-use.  DIY hot water solar collectors.  My grundfos died when I was young and no way I can get my hands on their pump.  I'll have to use something else like you want to.  Maybe couple a DC motor onto a washing machine water pump, provided the nylon pump housing can handle the heat.  Maybe put it in the cold side?  OR... Run the pump off a tiny 12 VDC to 115 VAC power inverter like the cigarette lighter ones.  60-180 watts.  I got a little pump that might be for a washing machine that has what looks like a shaded pole syncronous AC record player motor on it.  That little inverter might power it.

[LowGear]

Math Quiz:  25 Watts is how many amps at 120 VAC?

.208

Installation Quiz:  How much does it cost to install a PV panel, wiring and pump VS plugging a 120 volt pump into the wall?

Do people ever use those remote bathroom hot water circulation pumps?  Is it as irritating waiting for cold water as it is for hot?

Casey

[Carlb]

I agree with Casey on this one  I wouldn't worry to much about a circulator  pump that only draws 25 watts @ 120vac. I would not dedicate a 200 watt panel to run a small circulator pump.

Carl

[WStayton]

Hi All!

  You guys, at least MOST of you guys (<grin>) are sort of missing the point here . . .

  The 120V AC plug on the wall is going to be fed by a solar set-up.  As I have already detailed, I have concerns about the loads on this set up.

   As to the .2 amps - let's just look a little deeper . . .

  With the losses from wiring and controllers and inverters, this would be equivalent to at LEAST .25 amps.  .25 amps X 120 volts =  30 watts. 30 watts x 12 hrs a day = 360 watt hours. One of my solar panels is 200 watts and produces for (?), maybe, six hours a day in the winter, so I get 1200 watt-hrs / day.  The solar circulating panel is going to eat about a third of a solar panel from the solar 120V set-up.  There ain't no such thing as a free lunch!!! <grin>  everything has to come from somewhere!!!  That is why I am reluctant to "just plug it in" as most everybody suggests!  If I just "plug it in" with everything that comes along, I will soon have a demand for 50 panels and the ability to deploy (due to roof size limitations) a maximum of 18 panels and the abilty to AFFORD maybe the 18 I can deploy.

  "Just plug it in" is one of the reasons that the average on-line household uses about three to four times the electricity as the average solar houshold.  I am trying NOT to be an energy spend-thrift and most everybody keeps saying just use it!!!  Sorry, NO!

  That's my story and I'm sticking to it!

Regardz,

Wayne Stayton

[Carlb]

While we are grid connected we do have a substantial solar array on our property.  Not all of our panels are roof mounted we have about 1/2 of our panels on a ground mount.  We power all of our loads via ac power and don't utilize any of the dc produced with out it being inverted to A/C, but we don not have a battery backup.  We have two solar hot air heaters and both of the blowers are fed directly from standard household current. 

I just find it a waste of a 200 watt panel to run a small circular pump.  If I had a hot water system I surly would run it on A/C

Just my 2 cents.

[LowGear]

Good Money VS. Bad Money?

I'm sorry but money is not a cosmic force regardless of where it comes from.  It's money.

Nice electrical assessment Wayne - Just not valid.  The pump doesn't run 12 hours on a good day.  Off and On and Off and On and while its Off that excess panel capacity is just setting there staring at the Sun.  Waste, Waste, Waste I tell you.  Remember a solar panel is a terrible thing to waste.  One of the reasons that we invert the DC to Ac is the convenience of the household wiring.  Small, efficient (after its made) and PAID FOR!

Even if you had a simple thermostat in the out line of the water panel and directly wired the pump so it ran all the time you're still be using hand grenades to hunt cat fish.  Perhaps if you had a PV that was appropriately sized this discussion would be mute.  You should utilize what you already have installed, or planned installation, put to its best use.

Here's what we're trying to do at Project Central - Hawaiian Division.  Stop thinking up new projects and finish just one stinking project this friggen year!  I know you don't come to this website for this kind of screw ball radical thinking but I just had to put it out there for your consideration.  Hey, how about hooking up an attic vent fan to the panel as well - Oops.  Or running a DC line down to that laptop you picked up at Goodwill last month - damn!  No my brother in unbridled imagination and enthusiasm we want to finish just one major project before Christmas.

And when Carlb agrees with me you should know something is afoot.

Casey

[bschwartz]

Although I agree with not using the solar panel directly, I will respect your request for solutions based on your criteria.
An automotive coolant circulating pump like this

http://cgi.ebay.com/ebaymotors/MERCEDES-AUXILLARY-COOLANT-PUMP-124-E-CLASS-1990-1995-_W0QQcmdZViewItemQQhashZitem19c31c9a7bQQitemZ110647614075QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_662wt_734

They are rated for high temperatures, low draw, and 12v.

Hope this helps.

-Brett

[sailawayrb]

If you can make 115 VAC work, why not just use a standard hydronic floor heating circulating pump?  They are rated for 230 deg F water and there is a wide selection of options (i.e., various head/pressure performance curves and 1/40 to 1/8 HP).  I doubt you would exceed 1.5 amps with even a 1/8 HP pump and the actual duty cycle will be low so amp-hours will be small.

http://www.pexuniverse.com/

Bob B.

[Carlb]

If you can make 115 VAC work, why not just use a standard hydronic floor heating circulating pump?  They are rated for 230 deg F water and there is a wide selection of options (i.e., various head/pressure performance curves and 1/40 to 1/8 HP).  I doubt you would exceed 1.5 amps with even a 1/8 HP pump and the actual duty cycle will be low so amp-hours will be small.

http://www.pexuniverse.com/

Bob B.

And you can buy them all day on ebay dirt cheap.  Even buy an extra as a backup. 

Carl

[WStayton]

LowGear:

  About the panels "cycling" their pump:

  I was under the impression that as long as you had sunlight impinging directly on the panel, the circulator pump neede to run, otherwise you got an overheat condiotion that boiled the woring fluid and caused the relief valve to releve!

  I have not, noe, actual experience with these units, so I am foced to take your word for it - so, in your considered opinion, waht percentage of the time that the sun is shining on the panel, will the circulating pump need to run???

  I am envision a differential thermosat that will run the panels pump anytime they are hotter than the coolest of three sequential tanks of about 450 gallons, 2700 lbs each.  There will be a heat exchanger in each tank, so that I can have antifreeze in the panel loop and not worry about freeze-ups.

  There will also be an "override" thermostat that will turn the pump on  when the panel temperature get to 205F (?) to make sure that there are no blow-offs/loss-of-coolant.  I am not sure if 205F is low enough, but that is what I will try and see how it works, with the other control circuit disabled.

About me not doing anything:

  As you will recall, I was restricted by a medical professional to not do ANYTHING until released which was six days ago.  Perhaps you DO NOT follow medical advice, but it has been my exerience that I should listen to somebody who hase ten or twelve years of medical training when they tell mo to do, or not to do, something.  YMMV.

  I have another problem that i really haven't mentioned much, because there really isn't much that can be done - I had a completely worn out knee (bone-on-bone/no-cartilage left) replaced that made a whole new problem in that the replaceing of the knee, casued the leg which, over time had "settled" in to being about 3/4" shorter than the other leg, due to much earlier surgery, to now, after surgery, be 1/2" LONGER than the other leg.  My spine had settled into a gentle curve over forty years and with stenosis of the spine over years, it is unable to UN-cuve, so it causes the vertabrae to impinge on the nerves.  I'm sure rcavictim can identify that when you are gritting your teeth to keep from screming, while standing in my case, its hard to get much done!  There is a short term cure, which I am having again, day  after tomorrow, where they inject a long acting local anesthetic and cortisone directly into the interstitial spaces of the spine - three on each side in my case.  The results are immediate and spectacular - pain completely goes away and I am free to do whatever I want for about six wekks at which time the pain returns.  The Dr. will only inject every eight weeks, so I am stuck with a couple of weeks of semi-invalid-ness at the end of each six week period.  Sitting/reclining makes the pain go awy, standing/walking is excruciating.  The procedure is not a bundle of joy, by the way - since they are poking hole in you spinal column, they want the procedure done in a sterile envisonment - aka operating room and it is sufficiently painful, I am told, that they want you out to do it.  Sorta ties up a whole day, what with getting in, getting it done and then recovering from the anesthetic.

   So, when you criticize SOMEONE ELSE's performance, just be advised that there may be factors that you aren't aware of! <grin>

sailawayrb:

  About using a 120 volt pump:

  I have SIX of them sitting for use, its is just that I don't want another 120 volt load if there is a way around it.

  I was chagrined to discover, after I did lots of research, that the Xantrex solar controller would not control the six set of panels to NYSEG's satisfaction - I have, finally, with mike90045's guidance, settled upon a MidNite Solar Classic that WILL let me use the full set of six panels that I can deploy, and make NYSE happy.  Another reason not to jump off of the high board until your sure how deep the water is LowGear!!!  I was a day or two from having the Xantrex irretreivable on order and shipped before I solved the most recent problem.

  About the 120Volt panels: Lets suppose that the duty cycle is 50% (though I can't see how the panel will not overheat if it isn't given continuous flow of coolant in the sun - but that's another argument!  <grin>).  And, lets suppose eight hours of sunshine in the winter. So that will be four hours of 1/12 HP (what my pumps are) or 746+losses=900 watts(?)* 1/12 = 75 watts.  75 watts x 4 hour = 300 watt hrs/day.  The DC pump that I sited would use about 1/3 of that electricity and would do it without tying up ANY of the available 7200 watts of inverter power available from the XW6048.  I have this nagging feeling that if i just keep adding things on to the inverter, electric pancil sharpener's, electric floor buffers, electric toothbrushes, electric knife sharpener, etc., etc. without giving any concern to whether or not I have the power available for it, I will soon have 15,000 watts of load trying to drive off of a 7200 watt inverter.  Direct DC driving of the circulator pump is one small way of keeping one small load out of the inverter system.

  If there is no other way to do it, of course I will use the inverted 120 V AC, I MUST have some sort of circulator pump and if I can't do it via a reasonable DC load, it will have to be AC, even if it's three times what the DC load would be.  Since I have the 1/12 HP circulator pumps sitting there, it is an easy, if inelegant,  "fix".

bschwartz:

  About the Mercedes electric coolant pump:

  I have tried to look up the current draw of the pump which you pointed out, but, absent the Mercedes part number for the pump, I can't find jack squat!!!  <grin>

  The approach looks attractive, especially for the standpoint of first cost, but without knowing how much "juice" it is going to eat I very leery of investing - my experience with automotive stuff is that current draw was pretty low on their list of considerations, so to replace a 75 watt ac pump with a, maybe,  250 watt Mercedes pump would be a giant step backword . . . though the panel does have 200 watts of output . . . hmmm. . .

  Thanx for the input guys - as always!

Regardz,

Wayne Stayton

[LowGear]

Wow!  Wayne is back and with a full chapter.  

After I rereading my cajoling message I realized that it could be taken more than one way.  When I enjoy someone I'm often too familiar with them.  This may be the case with you and your wonderful projects.  I believe I speak for most everyone when I write - "Please Don't Stop Anything Because Some Smart Ass Gives You Some Crap On The Internet."  Alternative approaches are the spice of life.  Your unbridled enthusiasm is a wonder.  Thank you for your contributions.

One of the things I like about this thread is that I'm going to price aluminum rails and stainless hardware Friday when I get into the big city so I can move my not being used water solar collector over to a much smarter location on the roof and directly above the existing water tank.  I'll hook it into the bottom drain hole and bottom heater element.  You are a motivating force for thought and action.

The differential thermostatic control is the hint that the pump doesn't run all the time.  Over here the thermosiphon systems with tank on the top of the collector are very popular.  It's been down to 63 degrees here once a couple of Januaries ago.  Any expansion will just be pushed down the cold water pipe but an air gap / bleeder is required.  My neighbor has a 12 Volt DC hot water pump I'll have to trade him out of and my other neighbor has a 45 watt panel that really should be doing something rather than hanging around waiting to be broken.  If I had a 200 watt panel that wasn't doing much I'd pick up an Enphase inverter and let it help the rest of the system besides running my AC hot water pump.  I don't know if it'll tie into a Xantrex grid.

I assume your use of antifreeze means you'll have an expansion tank something like an automobile.  

Run times.  With half of Lake Michigan to heat it'll run all the time it's over 120 degrees.  I set my hot water to that number so folks won't get cooked.  The water needs some rest in the collector to more efficiently pick up the heat.  And I'm already over my head.  I'm thinking 205 degrees is cutting pretty close to the bone.  I don't know what mixture of antifreeze your going to use but once it's above 160 why wouldn't you want to be dumping all that heat into your tanks?

My little gray cells are exhausted and lunch is up.  Keep up the great work and wonderful ideas.  While I have met a couple of jerks on the Internet and have, with some success, been one myself - I have never seen you in that light for even a moment.  Have fun; I'm off to work on the electrified Polaris after lunch.

Casey

[sailawayrb]

And you can buy them all day on ebay dirt cheap.  Even buy an extra as a backup.  

Carl

Agreed, they have been become quite affordable in recent years and they are extremely robust.  I recently put a Taco 009 1/8 HP pump into service for drip irrigation.  Works great for this application and avoids having to use a pressure bladder tank.

Bob B.