solution for pump house heater?

SystemSystem Posts: 2,511 admin
We have lived in the mountains for 20+ years and are getting close to retirement. We've always tried to conserve but more so now with all the studies on global warming. Anyway here's our problem since we're both new to solar:

We have well water with both upper and lower pump houses. The lower house is buried in 75'+ old growth trees so we can't do solar for it but the upper one has good solar exposure with a south facing sloped roof. The houses are insulated but the 500 watt heaters still take a lot of electricity to keep them warm in our cold winters. I used a solar calculator to figure out the Total average amp hours per day of 1250. This is based on if it ran non-stop 24 hrs per day year round, which of course it doesn't but I don't know how else I should calculate it since it pulls 500 watts when it does run. The solar maps show that our avg sun hours per day is 4.87 which seems to mean that we would need a total solar array of 308 amps to heat the pump house. As close as I can figure this would mean 106 40Wt panels?? (approx the size of all our flat ground). What am I doing wrong here?

Comments

  • BB.BB. Posts: 25,058Super Moderators admin
    Re: solution for pump house heater?

    The short answer is yes, you are doing it sort of right, and in fact, you probably need more solar panels than you first calculated because winter sun is typically less than year round average sun...

    The longer answer--you will need to head down several roads...

    One road is to measure how much power you do need... A simple Kill-A-Watt meter for $30 or so will tell you how many WattHours or kiloWattHours you need per day... Example... The 500 watt heater times 5 hours per day would be 2,500 watt hours or 2.5 kWhrs per day... That would be 2.5kWh*30days/month=75 kWhrs per month or in my area, about $10-$15 portion of my electric bill...

    You can then size your array/batteries/etc. for your needs. With solar electric, guessing your needs can lead to either too small of system, or horrible over payment for the installation...

    The other path is more complicated. Basically, solar electric panels for electric heat is very expensive and usually a last resort (like a mountain top research site).

    Conservation is the first step... Insulation, using natural sources of heat (recirculating well water through the tanks), using a thermostat in the water itself to only turn on heat when needed (rather than just keeping the whole room warm), etc., would be places to start.

    Also, looking into solar thermal system instead of solar electric. Solar PV panels are only about 12% efficient whereas a solar thermal system can be close to 80% efficient... Your solar thermal panels can be much smaller for the same amount of heat. Also, solar thermal collectors are about 1/5 to 1/10 the cost of a solar PV panel array...

    A solar thermal system with non-poisonous antifreeze, a small pump, a controller, and some good engineering may work OK for your in-the-sun house... Solar Thermal can also lend itself better to home made solutions (keep the costs down)... For example you could build a solar hot-air type collector on the south wall and circulate warm air into your building...

    For your place in the deep shade--heavy insulation may be your best bet to reduce electric heat...

    From my little experience, the order of events:

    1. insulation
    2. more insulation
    3. monitor water tank temperature and only add electric heat when tank is near freezing--perhaps with an immersion heater.
    4. Solar Thermal System
    5. Solar Grid Tied electric system (really to reduce your whole home bill)
    6. Solar off-grid electric system (last choice--batteries, solar PV panels, etc. just are not a good fit for electric heat).

    Does this give you some ideas?

    -Bill

    PS: OK--there are only 30 days in a month on this world...:cool:
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Posts: 5,070Super Moderators admin
    Re: solution for pump house heater?

    Once again I have to agree with Bill.

    I would suggest that you visit these sites for more info regarding keeping your water from freezing.

    http://www.morelectric.com/pipe.htm

    http://www.deanbennett.com/wintergard-heat-tape-prices.htm

    http://www.heatline.com/kompensator.htm

    All these products use a semi-conductor that uses only as much as electricity as needed. Some of them can also be installed INSIDE an existing water pipe. The thing that many people don't realize is that because of it's mass, is quite hard to freeze.

    As Bill suggests, insulation is the key. If properly insulated very little heat is required to keep pipes from freezing. Remember, you are drawing water from the well (I assume) that is probably~ 50f year round. All you have to do is keep it (the water in the pipe(s)) from going below 32f. No reason to keep the air in the pump house warm.

    Any money saved here will allow any solar PV system to be that much smaller and therefore less expensive.

    Icarus
  • mike95490mike95490 Posts: 6,417Solar Expert ✭✭✭✭
    Re: solution for pump house heater?

    If you have a pump house, you likely have 120V power there already, for the pumps.
    I'd suggest a ordinary pipe heater tape, and set it's thermostat to 34F, most of them are set to 40F, which is pointless.
    A propane heater is also less expensive than a solar heater.
    If you have water to waste, you can leave distant tap open a tad, to keep the water circulating. This will make the pump run more too. (but don't flood your septic system)


    If you really want to spend $ for solar, get a solar hot water collector for your house, and/or you could also install a Solar PV Grid-Tie system, which will cut your electric bill, and uses the grid for your nighttime battery (electric needs) Over the course of a year, you can end up with a nearly zero electric bill, which you have traded for payments on your $30,000 PV system.
    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 ,

  • Solar GuppySolar Guppy Posts: 1,959Solar Expert
    Re: solution for pump house heater?

    Solar thermal is 1/10th the cost of solar PV.

    A thermal collector could be used to keep a hotwater tank warm ( typical thermal ) and then a simple H20 baseboard that uses the tanks water ... a do it yourself deal could be done for under 1K easiler. Since one doesn't need high pressures, a 200 dollar pool type collector could be used and low cost controller/pumps
  • System2System2 Posts: 6,290 admin
    Re: solution for pump house heater?

    The Kill-a-watt shows that we are using about 2.05 kw per day which is a lot better than I thought we were using. I'm sure that's due to all the insulation that we have in the pump house already. I'm confused by the 50 days/month that BB used in the calculation.

    It sounds like using solar heated water or solar thermal is a much better way to go anyway. One of the links that Icarus provided has a temperature activated outlet which we can hopefully use for the heater to come on when the solar heating isn't enough.

    This upper pump house has the cistern for the house which is filled with the water pumped up from the lower pump house. There isn't much of a problem with the water itself freezing since the cistern tank is below the pump house but there is a pump, lots of pipe, and a pressure tank. We only leave a tap running when it's REALLY cold (sub-zero) since each of the pumps draw 1500w.

    If we can reduce the electricity we use to heat the pump houses that will definitely help. Down the road we would still like to incorporate some alternative energy to help power the rest of the property but based on the number of panels we would have needed for just the 500w pump (based on my original erroneous estimate of consumption), I don't see how it would be possible. We had thought about ways to use wind to help generate power but from what we have been able to find out it doesn't look like our county will allow it. We are in Boulder County, Colorado which if you have ever heard of Boulder you would think that alternative energy is their middle name. I understand the noise issues of wind but PV just doesn't appear to be affordable.
  • BB.BB. Posts: 25,058Super Moderators admin
    Re: solution for pump house heater?
    julieo00 wrote: »
    I'm confused by the 50 days/month that BB used in the calculation.

    It's been a long December... :roll:

    Fixed...

    Sounds like you might have Grid Power... If so, Grid Tied solar is not the worst way to go to save on your overall electric bills (maybe in the ~$0.25 range per kWhr without any rebates--lots depends on how much sun you get in your area)... But, in any case, that is a big up front chunk of change.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: solution for pump house heater?

    Thanks for the correction. I thought it might be some sort of "loss of efficiency" multiplier I needed to take into account when doing calculations.

    Yes we are on the grid but don't want to use more than necessary, both from conservation and budget considerations. We're trying to get our consumption down as low as possible and get used to living that way before we start sizing power systems. Plus, our local rural electric company is just starting to consider grid tie-in's so payback isn't an option yet.

    I am already semi-retired due to an auto-accident and my husband is heading that way in the next year or two, so cost is definitely an issue too. Thanks for the Kill-a-watt suggestion, it's already paying for itself in 2 days. After looking at some of the DIY plans we think we might be able to build one for the pump-house but still have at least one question, if not several more as I think of them. (Are we nuts to try this with such little experience?)

    Our house has baseboard hot water heat and uses fins over copper pipe to provide radiant heat. Would that be a practical approach for the pump house to provide heat during the solar portion of the day?

    The reason I ask is that the pump house is only about 4x6'. By the time you add the depth of insulation already on the walls and ceiling, and the floor space needed for access to the cistern and pump, pipes, and pressure tank there isn't a lot of room left for a holding tank to hold the solar heated water and whatever mechanism we need to emit it into the room. There has to be room left for my husband to be down on the floor working on the pump, etc when there are problems.
  • westbranchwestbranch Posts: 4,184Solar Expert ✭✭✭✭
    Re: solution for pump house heater?

    Now that you have a K-A-Watt, another useful tool is an indoor/outdoor max/min thermometer . Placed at the top of the pump house room with the outdoor sensor at the floor you can see just how warm or cold it gets inside and adjust the heater accordingly. The better ones also record hi and lows , probably run about $15... or less. If you want to keep the door shut, use 2 mounted outside with the probes top and bottom, so you can monitor easily...

    ps are the heaters plug-in or hard wired, ie can you use the K-A-W on them for consumption?

    Cheers
    Eric
     
    CL 647 asleep  24V 900Ah C&D AGM
    CL29032 FW 2079/ 2073/ 2054 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,Omnicharge 3024,
    Linksys Wet54g WiFi Bridge, ASUS RTN10 router, Hughes1100 Sat Modem
     Eu3000i & 1000i Gens, 1680W & E-Panel/WBjr to come,
    West Chilcotin, BC, Canada



  • System2System2 Posts: 6,290 admin
    Re: solution for pump house heater?

    The heaters are plug-in. That's why the Kill-a-watt was able to show us that we were using 2.05w instead of the 500w I originally based my calculations on.

    The indoor-outdoor thermometers are a good idea. It may be that we have the heaters set to a higher temperature than necessary to avoid freezing the pipes, but would that make a difference once the higher temperature was reached? Wouldn't it just use more electricity to reach that higher temperature the first time and not take much more to keep it there than a lower temperature setting since it would still be coming on just as often as the temperature drops whether at a higher temperature setting or a lower one?

    I'm researching the thermal collector Bill suggested as a heating source. We have a lot of high winds and I am concerned about the effect of the wind on the working of the thermal collector. Since it would be on the south facing wall or roof would high winds "back-siphon" the heated air instead of allowing it to vent into the pump house and thereby prevent it from working?

    Our windy-season is from October thru late April/early May. Gusts of 70-100 mph are not uncommon. The pump house gets some shelter from the house because of it's placement but the south facing roof still gets some impressive wind exposure. (ex. My clothes lines are in front of the pump house roof and also face south. The wind blows from the west pretty much non-stop during those months. When I hang out my clothes I use 4 clothes pins on each piece and everything is pushed down the entire length of the lines to the east end when I go out to take them off after drying. It also tends to blow our metal lawn furniture around the deck.)
  • westbranchwestbranch Posts: 4,184Solar Expert ✭✭✭✭
    Re: solution for pump house heater?

    Just like a house, the higher the temp setting of the thermostat the more energy you will use... so having the heaters set higher than needed is costing you kWh.

    Monitoring your useage over a week or more will show what happens under various temp conditions.

    based on your wind comments, I guess you have the pump houses air tight (sealed) as well as insulated.

    Not versed on thermal heating so will leave that to BB


    Eric
     
    CL 647 asleep  24V 900Ah C&D AGM
    CL29032 FW 2079/ 2073/ 2054 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,Omnicharge 3024,
    Linksys Wet54g WiFi Bridge, ASUS RTN10 router, Hughes1100 Sat Modem
     Eu3000i & 1000i Gens, 1680W & E-Panel/WBjr to come,
    West Chilcotin, BC, Canada



  • BB.BB. Posts: 25,058Super Moderators admin
    Re: solution for pump house heater?

    One thing you need to understand is that 500 watts is the equivalent to 50 miles per hour... 2.05 kW is actually 2,050 watts for 1 hour--equivalent to 50 MPH for 1 hour takes you 50 miles... The first is how fast you are using energy, the 2nd (with hours) is how much energy you have used...

    Or, for your case:

    2,050 watt*hours / 500 watts = 4.1 hours your heater was on (for the measuring period)...

    To be honest, as a "young guy" who played around with anything electrical/mechanical as a kid--the Watt vs Watt*Hours confused the heck out of me. And I really did not pay attention until I went to get my engineering degree... Also, it did not really matter to me since my parents were paying the utility bills. :roll:

    Regarding insulation--you may have two other types to consider... High prevailing winds may indicate that weather stripping may help a lot--Since you don't "live in the pump house", it is possible that you are not aware of how much heat is getting sucked out by small cracks and seams.

    The other thing to look into is radiative type insulation. Here is one company that sells foil backed bubble wrap (I don't know anything about the company or the product other than what I have read). I have seen others post that foil based radiant shielding can really be helpful--supposedly, fiberglass and other types are not very good at radiant shielding (cold/clear nights). Since it does not take up much room (thin)--it might be worth experimenting with (and let us know if it helped or not).

    Lastly, spot insulation and heat tape will probably be much cheaper in the long run than trying to keep the "room" itself warm.

    Building a thermal system--probably your best bet is to look around on the web--I have not needed to build one for myself yet.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: solution for pump house heater?

    Guess I'll spend some time sitting in the pump house to see how windy it really is in there. I'm also checking out the site for the foil insulation and the indoor/outdoor thermometers.

    Bill, when you suggested thermal heating did you mean the kind that take in cold air and then warm it on the way through the panel and then vent the warm air into the building (which is the kind I thought we might be able to build), or did you mean the kind that heat a non-lethal liquid of some sort and then run it into a tank and somehow transfer the heat to the room?
  • icarusicarus Posts: 5,070Super Moderators admin
    Re: solution for pump house heater?

    I keep going back to the basic premise,,,you don't care about the air temp, just the water temp. Because water has much more thermal mass, keeping it above freezing is much easier than keep air warm. If you super insulate your pipes, and your tanks, then keeping them just above freezing with low wattage heat tape is a breeze, instead of heating the air with a space heater, and trying to get that heat through to the pipes and then to the water. The heat loss from the pump house is significant, and therefore makes it tough (expensive kw wise) to keep the water warm. In most locales, well water comes out of the ground ~50f. It already has considerable heat in it. The trick is too keep it in.

    A wrap of semi-conductor heat tape around a pressure tank every 6" should be enough to keep it from freezing. If the water comes it at 50f the tape won't even turn on until it has dropped below. With good insulation, and daily use, it wouldn't drop low enough to draw many watts most of the day. Overnight the tape would keep it from freezing. Ditto the piping. A pressure tank holds (depending on size of course) 10-50 gal of water. Thats a lot of mass to cool enough to freeze.

    Icarus
  • BB.BB. Posts: 25,058Super Moderators admin
    Re: solution for pump house heater?

    From what I have seen, thermal heating runs along several lines. The "cheap" and easy to home build are types of heater that will not produce heat very much above ambient temperatures. Those simple pool heaters on roofs are a good example. They are very cheap and efficient--but the water temperature is only about 80 degrees F.

    The intermediate types include those with an internal copper (or other material and water, oil, or antifreeze) heat exchanger and a cover glass/insulated box. These work better in colder weather and at providing hot water for domestic hot water use (~120-180F).

    Lastly, there are high-tech vacuum tube types (with antifreeze or water) which work well in very cold climates at producing at domestic water (because they lose very little heat to cold ambient air/wind).

    The simple type (corrugated fiberglass and/or false south facing walls) are something that can be home built and as long as you are not too interested in raising the temperatures above 40-50F--they are probably cheap and easy enough to build and see how they would work for you...

    However, the problem (that I see) with "hot air" type exchangers, is how you get heat transfer to the water (what you really want to keep warm), and not lose a bunch of heat at night.

    I would be tending towards building/buying/EBaying a liquid type heat exchanger that can transfer heat directly to your tanks (say plastic or copper coils wrapped around or dunked in the tanks, under the insulation)...

    But this is not an easy solution... From what I have read, you will have to worry about possible corrosion from antifreeze and problems with collectors overheating in the summer (boiling/cooking the fluids).

    Again, I would just start googling around (and maybe some people here have good links/experience)--especially for use around farms (some state agriculture agencies also have solar help websites for farmers).

    But getting "heat tape" and pipe/tank insulation will probably be much cheaper in the short term--and possibly long term--then trying to get a too high-tech solar solution.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: solution for pump house heater?

    Thanks everyone for the great information. We are going to try a combination of better weatherstripping, heat tape and additional insulation. We're going to get a couple of the min/max thermometers to see what temperatures we are actually running in the pump house so we can get to optimal temperatures for efficiency. The solar sounded like a "best solution" at first but after reading all the responses I think this is a better way to go. We'll have to monitor it pretty carefully until we know it's a working solution since frozen pumps and pipes become pretty expensive as we learned years ago when we first moved to the mountains.

    If we wind up trying the bubble/foil insulation I'll let you know how it works.
  • BB.BB. Posts: 25,058Super Moderators admin
    Re: solution for pump house heater?

    There is some interesting self regulating heat tape that has no fixed length resistance requirement (heating element is between to "parallel bus bars")... Don't know anything about the company, but I had a friend who worked on the Alaska Pipe Line many decades ago and he swore by the parallel self regulating stuff (don't know if this is the same company or not).

    Your mileage may vary.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: solution for pump house heater?

    julio00,
    you may find the slow responce and difficulty of using some thermometers to be frustrating. you may benefit by the more instant responce of an infrared thermometer. they cost around $50-$100. they do have their limitations, but i have found it nice to see temperature variations at an instant along say my walls. i even saw the temperature of a lit cigarette show well over 600 degrees f and blinking indicating it has exceded the maximum temperature reading capability of the thermometer. the dips indicated cold air infiltration. the greater the distance to the object the lesser the accuracy and know that highly reflective surfaces could throw off an accurate measure especially when the infrared is reflected back into the thermometer. in general it beats the numerous thermometers otherwise needed to see trends without some of the wait time needed for the thermometers to catch up to the temperature of the object.
  • icarusicarus Posts: 5,070Super Moderators admin
    Re: solution for pump house heater?
    BB. wrote: »
    There is some interesting self regulating heat tape that has no fixed length resistance requirement (heating element is between to "parallel bus bars")... Don't know anything about the company, but I had a friend who worked on the Alaska Pipe Line many decades ago and he swore by the parallel self regulating stuff (don't know if this is the same company or not).

    Your mileage may vary.

    -Bill

    The above link to HeatLine, as well as several others is linked in a post earlier in this thread. These products have been around for a long time, and have had a good service record. The way they work, is that as the temp drops, the semi conductor between the busses changes it's resistance and generates more or less heat as the temp changes. (And draws more or less wattage per foot as well).

    They are available in 12vdc, as well as 120ac, 240ac. Many of them can be installed INSIDE a water pipe, which is the IDEAL way of doing it.

    Icarus
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