SOLAR HOT WATER HEATERS

[JAYCEE]

I think that the price of energy--including electricity--will only increase from here. Apparently, electric hot water heaters are the biggest power users in the average home. So I started looking into sloar hot water heaters. The system I have decided on is an open loop direct roof-mounted system with 1 40 sq ft collector. I plan to install it myself. The cost is about $2000 and it qualifies for 30% tax refund. It is the same as 2kW of electricity on a sunny day.

How hard are these to install? Are they reliable? Are they worth the effort? What are your experiences with these systems?

 

[Schmoe]

My former in-laws owned and operated the Solarhart division in Guam. The local governement had a similar tax deduction plan and they did quite well. Some of the problems they had with customers was explaining how it doesn't work all that well when it's an overcast day. Sometimes the customers plumbing systems were screwed up and they ended up having to modify the whole house. There were also some issues with the lack of water pressure, as those units are mounted on the roof. In Guam, all houses are built out of concrete and can withstand the weight, but overhere with typical wood frame construction, I'd make sure the roof could support the weight. I'd also check your insurance policy. There were some issues with the tanks leaking and flooding the downstairs part, might want to see if your covered for that scenario should it happen.

 

[kanling]

We used to have a system when I was a kid. It worked really well. It used an extra tank ahead of the regular hot water tank. Basically a solar pre-heat. But, in the summer, the pre heat would be hotter than the set point for the regular tank, so no electricity was needed to post-heat. The system ran antifreeze to the collector and had a heat exchanger module. Other types of systems run water to the collectors, but have to have an automatic drain out for below-freezing temps.

You have to give some more information on the system itself for me to comment.

 

[Al]

Every hot water system I have seen installed ultimately fails to come up to expectations. Maybe in Texas it makes sense. Do a cost analysis. I think you will find that the payout for solar comes up short.

 

[drm7]

I'm with Al on this. I'm building a new home as we speak and I've tried researching low-energy heating, water, insulation, you name it. From what I can tell VA doesn't give any incentives and with the costs of most alternatives so high in comparison to "standard" practice I just can't justify spending the money.

Right now I've settled on a SEER 15 dual HVAC Trane system for my two-story house. This is way better than the SEER 10 unit in my old place. I've looked into demand hot water systems and from what I can tell they are realistically estimated to save $20-40 per year. Hardly worth paying $800 for when the new water heaters rated 0.90+ efficiency ratings are half that. I think the one thing I am going to pop for is the spray foam insulation. With the upgraded HVAC and sealed house I'm hoping to significantly reduce my electric bill.

 

[Schmoe]

drm7, those are new tax incentives that came out this year. They are for your federal return, not your state.

 

[Al]

"Right now I've settled on a SEER 15 dual HVAC Trane system for my two-story house. This is way better than the SEER 10 unit in my old place

My information is 5 years old. But I had a good friend who installed HV&C units big time. He said to stay away from the ultra high efficiency units bc of the electronics. Circuit boards would go out and you had a $500 bill minimum.

 

[Master ACiD]

i have installed a few solar hot water heaters before. i am not expert on this however i can give my perspective. i found out that most people install them wrong or skimp on the parts trying to save a few bucks. its these same people who are not happy later on.

when you have a solar hot water heater set up properly, the electric hot water heater should almost never come on. it is transformed into a standby part of the water heating system, which only plays a supplemental role incase you have some temporary large hot water demand, such as the inlaws comming to visit for the weekend. and infact the entire system should require zero grid power under normal use, even at night. the little circulation pump that circulated water between the storage tank and the solar panels is normally run off a 12v electric solar panel, which is ideal because you do not want the water solar panels flowing water during the night time, because this turns the whole setup into a solar water cooler instead of a heater. the sunrise and the circulation pump starts working. when the sun sets the pump quits. perfectly timed, no matter 2what time of the year it is. no timers or fancy whizbang bells and wistles needed.

most people dont buy enough solar heat exchangers. you can never have too many heat exchangers really. my dads friend has a solar hot water heater and a backup electric heater on her house. she keeps the circut breaker to the backup heater flipped off because its never used. the solar hot water works good enough for a household of 4. the water is awalys scalding hot, which is hotter than it really needs to be really. but then again she didnt skimp on the installtaion.

heres another thing most people dont realise. you can buy the solar hot water heater parts fairly cheap used. i actually have about 20 used panels right now.

the bottom line is that if you set up a solar hot water heating system properly, you save just about 100% of youre hot water heating bill each month. how much does the average hot water bill cost?

i also dont know how solar hot water heaters work in northern climates, espically when there is snow on the roof. all of my expierence is based in south florida.

however, if you need hot water in the winter up north, why not make a heat exchanger that works off the wasted furnace or fireplace heat?

 

[kanling]

The system we had ran off electricity (to run the cotroller and circulation pumps), there was no photovoltaic electric generating component.

A thermostat at the solar panels on the roof would turn the system on and off. If the temp at the panels was higher than the temp of the water in the pre-heat tank, the system would turn on. When the sun began to get low in the sky and the tank water was hotter than the panel, it would shut off.

In the summer, I clearly recall that the temp of the water would get to 160 degrees in the pre-heat tank on a sunny day. In the winter, it peaked out about 120 degrees. So basically it was free hot water in the summer and probably a little bit of electric warm up required on winter mornings. Of course, always some warm up required when it was cloudy. This was in Maryland. Pre heat tank was 80 gallons and the regular hot water heater was 50 gallons. There were two solar panels, run in series I think. Each, I guess, was about 4x8 feet.

 

[Razl]

I've done some reading on solar water heaters too. Because I'm in the NorthEast, I would need a freeze-proof (closed-loop) system, and with a tank will be around $2,500-3,500. I haven't calculated payback, but I think it will be 7+ years. That's a little longer than I would like. My other hesitation is figuring out how to run a chase from the roof to my basement.

As another option, I am considering a drain water heat recovery system. Apparently 80%-90% of the heat energy you produce to make hot water goes down the drain...pun intended. Basically you replace a section of your drain water pipe (usually 3-4 feet) with a copper heat exchanger unit that is plumbed into your cold and hot water.

It is supposed to be able to recover about half of the hot water energy that you normally loose in the drain pipe. The only company I found that sells this device is GFX. They have different unit sizes to fit different setups. A typical 5ft whole house unit will cost around $500.

Does anyone have any experience with these units?

 

[simple_gifts]

We had the same set up as kanling with THREE 4 x 8 collection panels. My father had 3 times the required panels installed so that in the future it could be used to heat the house (forced hot air) Our preheat tank was 150 gallon @ 190F summer 170F winter. Our house had direct sun and was 3 degrees off south. This was in Connecticut

Closed loop system with antifreeze. Worked really well.

 

[tom slick]

OT (sorta)
funny observation;
why do we call it a "hot water heater"? Do we "heat" hot water? it's common language to call it a "hot water heater" but it is really just a "water heater"

 

[sprintman]

We have Edwards. From WA exported all over the world U.S included. Saving us a heap and multiple govt rebates dropped the price a heap!

http://www.edwards.com.au/default.asp.

 

[kanling]

The system we used to have was a "Grumman Sunstream". I think it was installed around say about 1982 when there were big gov't tax credits for such things.

I know that it did pay for itself in savings, but it took a few years to do so. Installation costs were a lot smaller back then and I think the tax credits were comparatively bigger.

I remember that there was a pump failure that we fixed on it. Sometime in the early 90s, the preheat tank started leaking (just like any water heater.) It could have been replaced, but it was a special tank with two inlets and two outlets, so it would have been costly. By then, the kids were out of the house and the hot water demand wasn't worth it. Then the heavy-**s solar panels came down to re-roof... they never were re-installed. We sold all the components for $150 to a guy who was going to use it to warm his pool.

The extra inlet and outlet in the tank were for water to be pumped in to the heat exchanger module.

If you have a place where the temp never goes below freezing, a solar hot water system can be a lot less complicated and you could easily design and istall by yourself.

I agree and it is sad that usually the savings on any "energy saving" product is small in comparison to the higher initial cost. I recently had our central AC replaced and decided to go for a 12 SEER unit because a higher SEER would have taken over 10 years to pay for itself. In fact, a 12 SEER didn't even economically make sense over a 10 SEER, but 10 SEER units were all bare bones on quality and features.

 

[drm7]

Al: The govt minimum now is SEER 13 (if I remember correctly) and I've been told that it's hard to get anything under that now. They've been horded by the big builders because they are cheaper to put in spec homes. The Trane offers 10 year warranty and I "think" it is bumper-to-bumper. I'll have to check that out. Anyway, SEER 13 to SEER 15 wasn't to big a price jump if I remember correctly. I haven't purchased the system yet so I still have some time for research.

Schmoe: correct. But some states offer incentives too (I believe). VA doesn't.

Basically, if it's going to take 7 years for payback I feel that is too long. If I were to move then I would be out the additional cost. I actually hope to be in the place 20 years but....you never know.

 

[Gary Allan]

quote:

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nd with a tank will be around $2,500-3,500.

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Those fancy tanks with ss coils and whatnot are nice and all ..but $100 worth of coiled flex copper in any medium that will hold the heat will work ..and then have another $100 of coiled flex copper running to your demand water heater. Anything that won't decay ..parafin was a material of choice at one time. I guess you could fill both the sump (a 55 gal drum works fine) and the recirculating loop with PG mix. That would make it non-tox if any cross contamination occured.

There are even small (I can't find a link) heat exchanger demand tanks. They have one flanged access port on the bottom with two coils. They were about $600 about 12 years ago. They were a little bit bigger, IIRC, then a common demand tank for well service. You needed a recirculating pump. They were designed for furnace/boiler coils to exchange into ..to extend the gpm surge capacity of the in furnace units. It allowed the 5 gpm coil to handle 10 gpm demand for a limited time. Basically a cyling buffer (peak shaver

).