Solar water heating system

SystemSystem Posts: 2,511 admin
Solar water heating system - not for water, but for heat! I am new here and do not want to cause a problem, but I am challenged to make a simple and very cheap heating system using solar hot water. If you are not mad at me for this question - then here goes:

My system is to use a solar collector on the roof and to store the hot water in a normal working hot water heater able to be fired up with propane when we have a lack of sun. It does not freeze here in San Diego.

The heated stored hot water will be circulated, pumped into auto heaters with fans from junked cars during the night, keeping the chill off us all.

Has this been done and any comments would be nice. Thank you very much.

Comments

  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Solar water heating system

    Actually, there has been a few detailed solar hot water / solar heating discussions held here over the last few months.

    With heating, you have several ways to go... Solar Hot Air--no freezing, simple fans and a glass/metal collector with some ducting. There are even places that sell the systems.

    And solar hot water, lower temperature for space heating, or higher temperatures for domestic hot water and space heating.

    These solar hot water systems even break down into further sub-catagories. Those for which there is no chance of freezing, light freezes, and places with hard freezes.

    Non-freezing can just use domestic water (fresh water) as the working fluid.

    Soft freezes, typically the can "drip" water when below 40F (new water from cold water supply is above freezing), circulate warm water back through the panel at night, or drain back, where the water drains out of the panels when freezing temperatures can occur.

    And for areas with hard freezes, typically a double loop system with non-toxic anti-freeze in the panel loop going to a heat exchanger in the hot water storage tank.

    Here are a couple of recent links:

    Link 1
    Link 2

    If you want to start with a kit system, look at www.solarroofs.com -- was recommended by Solar Guppy as an easy to install/maintain and relatively inexpensive system.

    In the above links there are several very good systems with pictures that have been home made--but made very well. Or others made with more comercial parts, and one where the guy wanted an off-gird system so he made (and now sells) his own DC/low power solar thermal controller.

    Lastly, but firstly, conservation is the key... Solar, whether thermal or PV electric is a relatively expensive way to gather and create power for our homes (and businesses). So--generally the best bang for your buck is to look at insulation, double pane windows, weather stripping, and Energy Star Furnace/Geothermal sourced Heat Pump/appliances...

    Solar Thermal systems with water/antifreeze as the working fluid are relatively inexpensive compared with Grid Tied Solar panels or Off-Grid power for a cabin... However, they do have a fair amount of maintenance. Plumbing leaks, pumps fail, air locks, corrosion, tank failures, etc. all add together to make keeping a solar thermal system a bit of work to keep running well.

    In the end, IMHO, much of the "cost savings" with going solar is really wrapped around the conservation and habit changes that also happen when people start looking at their lifestyles and invest/change accordingly.

    Look through the links and let us know what questions you have.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Solar water heating system

    In order to proceed with this project it is necessary to have all contributors on the same page, working together so to speak. Exactly what is it we are attempting to build and why?

    I am attempting to build DOG HOUSE heaters. They will be as big as we can make them, since they have housing for several hundred dogs and a hundred cats or so in this no-kill sanctuary. As you may imagine, there are essentially no funds for this project, but I was so disturbed to find the dogs in unheated houses, shivering from the cold, that I must find a fix for this problem. The cost to heat is simply out of the question.

    Not to cause an uproar, but keep this in mind, had these dogs and cats not been rescued, they would not have medical care, food, water, and lots of love, with at least a chance of being adopted into a loving home. About one a day is placed and unfortunately, one a day is rescued from the streets, cold, hungry, full of fleas, no shots, and in general, a mess that normally results in death at the hands of your local agencies. You would surly be in tears, if I told you stories about how badly we humans treat these loving animals.

    SO PLEASE, HELP ME MAKE THIS WORK!

    In general, about 10 large dog houses are all grouped in a row under semi open shelter and are shared with about 20 dogs in each pen. There are 30 pens and some new construction is being done due to a donation, and it is in these new housing units that I am attempting to provide minimal heat.

    Generally we have only a few upper 30's nights during the winter, but it is not uncommon to have many in the 40's, so what we need is to keep the temperature from falling below the 50 degree mark in the houses. I am having my complaints addressed by having the shelters insulated and adding plastic strip doors in an attempt to get the housing area warmer by keeping in all the animal heat we possibly can.

    In passing, I have 7 dogs and 5 cats and they all get under the covers on my bed and we all keep very comfortable. It is only necessary to use a solar powered small electric room heater for a very few weeks in the winter months to keep us all very warm and comfy. All my pets have all shots, endless love, and very good food.

    THE PROJECT SUMMARY
    This is a heat the water with the sun, store the water in a hot water heater that can be turned on during long cold, no sun periods, and circulate the hot water in junk auto heaters to extract the heat stored in the hot water to warm the room.

    PRIMARY SOLAR HEAT GATHERING AND HOT WATER STORAGE

    1. Sun heated unit:
    a. The commercially available units are too expensive
    b. Making a sun heat collector using copper or PVC
    c. Insulation and design
    d. Helpful tips from you

    2. Circulating the heated water:
    a. Storing the hot water in a hot water heater
    b. Circulating water pump and insulation
    c. Controls and solar power requirements

    SECONDARY HEAT DISTRIBUTION FROM STORED HOT WATER

    1. Circulating the heated water:
    a. Extracting the hot water from the hot water heater
    b. Circulating water pump and insulation
    c. Controls and solar power requirements

    2. Junk auto heaters as the warmed elements
    a. Truck heaters are good choice, get it all, and PVC pipe
    b. Using a thermostat to start the heat extraction
    c. End point alarm and starting the actual hot water heater using propane

    Boy I am exhausted already.

    Sincerely,

    SolarReady Bill.
  • mike95490mike95490 Posts: 7,874Solar Expert ✭✭✭✭
    Re: Solar water heating system

    Wow- that's an ambitious project. You want a simple thermosiphon storage system. For heating the kennels, I would not bother with salvaged radiators, I think a simple copper tube, run the length of the row of kennel houses, will dump a lot of heat into the huts. No fans, much less chance of a leak (likely with old cores), and your stored heat is more likely to last till sunrise. (slower dissipation) You just need to take the chill off, not needed to keep them toasty.

    You need metal pipe (copper !) to be in the collector end. You may get some commercial donations of "scratch & dent" units, if you send some photos of your compound, and a plan.

    PVC is not known for being good for hot water, long life with sun exposure, or good thermal conductivity. (I used PVC in the 70's as a thermal sleeve insulation for a underground copper hot water line)

    Also consider another heat source for the 3 cloudy, rainy days, when it's unlikely you will have enough sun to re-warm the tank.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • System2System2 Posts: 6,290 admin
    Re: Solar water heating system

    PRIMARY SOLAR HEAT GATHERING AND HOT WATER STORAGE

    1. Sun heated unit:
    a. The commercially available units are too expensive

    From what I have read and followed a few links on, it appears that the professional collectors are about $ 1,500.00 each. I do not have the experience to know the capacity of these units or the degree of heat collected.

    One of the questions that we seek is a comparison of the home made type and the professional type. Can we reach the low 90's with a home made unit and at what price? (this term "in the 90's" refers to a scale of from 00 to 99 it is not temperature, it is quality or success or goal achievement)

    b. Making a sun heat collector using copper or PVC

    Here again, I nearly fainted at the Home Depot when they said, this roll of copper tube is $275.00.

    About 10 years ago, I was living in Escondido California. It is very hot there, reaching in to the 90's and sometimes 105 or so. I decided to save on hot water use and so I built a solar heat collector. It was attached to the local water supply and several questions arise and are in need of discussion.

    First, the Dog House heater (this project) is not attached to local water - it is a closed system, used for heat collection and storage that is to later be extracted to heat the dog's rooms, we are NOT making hot water to wash with or use.

    I got 4, 10 foot, 1 1/2" white PVC (can not remember if it was thin or thick wall) and made a solar collector array. I just mounted this on the South side of the garage, no attempt to orient or tilt it, or any enclosing at all, but I did spray paint it black. I reduced to 1/2" and made connection to the local water and to the outside shower with a normal water valve. It looked like the letter M on the side, with connection on each upper and lower leg. I had so much hot water we even attached the hose to wash the car with hot water! It was very dangerously hot, HOT, HOT!

    I also had leaks and had to fix it several times. Since I had it connected to the main water supply, it was pressured to 120 psi, 60 is the regulated pressure in a home. Since it was a closed system, no pressure release valve was included and on one occasion, it popped - exploded under pressure - than God we were not near it, as we could have been dangerously scalded with the hot water. So several issues are learned here.

    PVC worked just fine, but has a few problems. As I understand it, there is a schedule 40 and 80 and a new type called CPVC.

    PVC piping:
    schedule 40 is WHITE and PSI 198 @ 73 D 140 MAX
    schedule 80 is GREY and PSI 282 @ 73 D 140 MAX
    ABS piping:
    schedule is BLACK
    CPVC piping:
    schedule ?? is and PSI 200 AND 210 degrees
    PRIMER/CEMENT IS Different for CPVC / 200 MAX
    VOLUME OF WATER IN PIPE 100' 15 GAL 2"
    100' 60 GAL 4"
    As a guess, then about 80' 10 GAL 1.5"

    Can any of you help fill in this table?
    ===============
    Below is for later, after your comments on the above.
    c. Insulation and design
    d. Helpful tips from you

    SolarReady Bill.
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Solar water heating system

    If you will be doing concrete work for the bottoms of the pens, you might just include radiant floor heating tubes (typically orange plastic piping). You can also use the same tubing by bending up some sheet aluminum panels and place it under wood sub floors too (in one of the links I provided, there was a guy forming his own metal sub floor radiators).

    The Solar Roof panels cost (PDF file) around $300 for 10sqft or $560 or 20sqft...

    Solar Guppy has used these before and found them to be well built--although you may have to replace the clear plastic cover once every 10 years or so.

    Regarding using White PVC piping--it does not take hot water well at all. I think you had it rated at 140F--But solar collectors can get over 212F very easily in full sun and with no circulation.

    I used to form PVC by running steam through it (212F) and it would turn into a limp noodle.

    If you are using concrete floors with radiant heating--you might be able to get away with no storage tanks... Just use the thermal mass of the concrete itself... We had radiant heat in one of my schools growing up and once there was a valve failure and it overheated the room (all the floor tiles came loose)--took at least a day for the room to cool down to a reasonable level.

    The other method would be to collect hot air from the attic space (or an actual solar thermal air based collector) and keep thermal mass (concrete blocks, drums of water, gravel pile, etc.) around to keep the heat levels more or less constant.

    Designing the system is always an issue to make it safe a reliable. Too hot of water will cause its own issues (safety, cracking concrete, etc.).

    And, you might look at generating domestic hot water too... What ever you do to reduce energy costs will save money (whether saving hot water costs or kennel heating costs).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Solar GuppySolar Guppy Posts: 1,959Solar Expert ✭✭✭
    Re: Solar water heating system

    I beleive one would find that the animals BTU output would be many times the amounted needed to maintain a comfortable tempature if the "house" was well insulated.

    Some rough google numbers puts a person at 350 BTU/hr, scale for the pets weight and quanity per house and you see thats a signifigant heat source.

    Just make the homes have good insulation, a flapper door and bedding and your done. Doing a thermal system would cook the animals unless regulated.

    Cost wise, insulating will be many times cheaper than any solar heating system you could build.
  • Ralph DayRalph Day Posts: 873Solar Expert ✭✭✭
    Re: Solar water heating system

    The Guppy hits it on the head, again. Insulation will provide all the heat you need, from the animals themselves. Shivering is natures way of warming an organism up...the involuntary muscle movement and twitching produces heat and that keeps you warm (or at least warm enough to survive). When temperatures go down, feed more. Animals kept outdoors will adapt to temperature conditions, just make sure they have enough calories to keep warm.

    Dogs will shiver when distressed, perhaps that was what you observed earlier. My dog will shiver whenever he's taken on a road trip, he's nervous about travel. I've never seen him shiver in the cold.

    Check out SPCA requirements for housing dogs outside (in a colder climate than yours) and you won't see furnaces listed.

    Hit the local building suppliers for donations/price breaks. They may want the publicity of helping out a local shelter.

    Ralph
  • System2System2 Posts: 6,290 admin
    Re: Solar water heating system

    Here is the solar collector I have in mind:
    sc.jpg 22.6K
  • Solar GuppySolar Guppy Posts: 1,959Solar Expert ✭✭✭
    Re: Solar water heating system

    read our replys, you don't need solar for this application

    If you still decided to move forward with solar you will absoultely need to have tempature regulation for each pet house or you could kill the pets with too much heat!.

    Solar Thermal can easily make water boil and cause burns if not addressed in the design, this is not to be ignored or taken lightly!
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: Solar water heating system

    try passive solar and paint the doghouse or whatever black.
  • mike95490mike95490 Posts: 7,874Solar Expert ✭✭✭✭
    Re: Solar water heating system

    Look into the IGLOO style of doghouses, they are insulated, plastic, and easy to clean. Small entry tunnel keeps heat in.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • System2System2 Posts: 6,290 admin
    Re: Solar water heating system

    I recognize the wisdom of others on this list, but as I attempt to convince myself as to the real way to go with this, I would still like to ask and get good answers to several item questions. I sure do not want to build it if it is truly not needed as has been suggested.

    This should NOT be construed for anything more than exactly what it is - a question in need of an answer.

    1. You will notice that in the solar collector design for a home made system, I included the use of reflecting insulation to be stapled or glued on the back board forming a surface to hold as much of the collected heat in for as long as possible. Upon return from Home Depot, I find several kinds of insulation. Some is just fiberglass and some is with backing and some is with reflective (foil) backing. What are the uses of such insulation type and why?

    Making a hot water heater blanket and a solar array and insulating the walls of the dog kennels, for example.

    Thanks.
  • xiphiasxiphias Posts: 52Solar Expert ✭✭✭✭
    Re: Solar water heating system

    Try http://www.homepower.com/home/ for design/build for just about anything under the sun (pun intended).
  • mike95490mike95490 Posts: 7,874Solar Expert ✭✭✭✭
    Re: Solar water heating system
    solarready wrote: »
    1. You will notice that in the solar collector design for a home made system, I included the use of reflecting insulation to be stapled or glued on the back board forming a surface to hold as much of the collected heat in for as long as possible. Upon return from Home Depot, I find several kinds of insulation. Some is just fiberglass and some is with backing and some is with reflective (foil) backing. What are the uses of such insulation type and why?

    Fiberglass is highly heat resistant, and very irritating. In outside solar collectors, it should work well, as shipped, fluffy. Don't pack it in, you loose the insulative air pockets.
    For around the dogs, some of the denser foil backed foam boards could work
    here: http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/collectors.htm
    they talk about the different grades/types of sheet foam board.
    polyisocyanurate insulation - light brown color, will handle up to boiling water.
    polystyrene foam sheets - pink , blue, white, only up to about 160F
    some other solar hot water stuff here http://www.arttec.net/Solar/10-6/Oct6.html

    The foil is used to as both a vapor barrier, and radiant heat reflector
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • System2System2 Posts: 6,290 admin
    Re: Solar water heating system

    Thank you all for that very good link - he sure did a great job - it also answered the question of glass or plastic ( ha ha ha ). Now in passing, the store clerks have no idea what CPVC is or that it requires different cement and so on.

    Now, I would expect to use specially treated wood for long lasting use.

    I am now in need of instrumentation, good quality, fair price.

    Checking the usual sites, WOW they are high as a cat's back!

    Typical items: temperature, pressure, pressure relief valve, valves, circulating pump, flow meter, control switches, small solar panel.

    FOUND pressure for $ 7.95 each

    In some cases the old brass meters are preferred, but now in some cases we have digital that allow you to remotely measure and even record. Any things I missed, be sure to mention, and again, should you choose to accept this challenge, the tape will vanish.

    Thanks in advance,

    Solar Ready Bill.
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