Thread: solution for pump house heater?

1. julieo00 Guest

solution for pump house heater?

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?

2. BB.
Just some guy
Join Date
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SF Bay Area (California)
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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...

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...
Last edited by BB.; January 1st, 2008 at 11:17 PST. Reason: Fixed: 2.5kWh*30days/month=75 kWhrs per month or in my area, about \$10-\$15 portion of my electric bill

3. 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/wintergar...ape-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

4. 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.
Last edited by mike95490; December 30th, 2007 at 19:23 PST.

5. 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

6. julieo00 Guest

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.
Last edited by julieo00; January 1st, 2008 at 11:13 PST.

7. BB.
Just some guy
Join Date
Mar 2006
Location
SF Bay Area (California)
Posts
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Re: solution for pump house heater?

Originally Posted by julieo00
I'm confused by the 50 days/month that BB used in the calculation.
It's been a long December...

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

8. julieo00 Guest

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.
Last edited by julieo00; January 1st, 2008 at 13:01 PST.

9. 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

10. julieo00 Guest

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.)
Last edited by julieo00; January 1st, 2008 at 14:41 PST.

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