# DH's Passive Solar Water Heating Idea (?!)



## ChristieAcres (Apr 11, 2009)

What DH was proposing was to put black pipes on the roof of our house and run water through them in the Summer & warmer months only. This heated water would then be sent to our Water Heater to bring it up to the correct temp, thereby using far less propane. Now, I am wondering if this is a good idea or not, and why. If not, is there a better way? I know there are those of you who would know, so input please


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## J2E1 (Oct 15, 2009)

http://www.builditsolar.com Best place outt there, IMHO, for information on this and probably the best route to go for solar hot water heating.


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## wy_white_wolf (Oct 14, 2004)

It can work if done properly.

There is one at Gary's site set up like that for a summer shower.
http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm#Showers


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## rightathome (Feb 10, 2009)

My dad did something like that to heat our swimming pool back when I was a kid, it worked great!


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## ChristieAcres (Apr 11, 2009)

Thanks for the links & responses. We were just discussing how it would work and how DH would tie it in to our existing system using the same pump as the one being used for our wood stove water heating system. Since the wood stove heats the water during cool and cold weather, this is a good option! On the pool comment? DH wants to put a large water feature in and you just gave me an idea for it...he will be putting in three ponds, each larger than the one before it, and the last being the size of a pool. Heating that water would be a great idea!


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## byexample (Aug 28, 2009)

I've seen this work.

Only potential catch I see is that you'll have to have a way to turn it off on cloudy days or when the tank is full of hot water... or it will circulate your hot water up onto the roof... thereby wasting energy. You'll also want to make sure you are pulling water off the bottom of the tank... where the coldest water resides.

Please let us know how you make out and what, if any, challenges you run into.

Best of luck!


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## ChristieAcres (Apr 11, 2009)

> byexample- I've seen this work.
> 
> Only potential catch I see is that you'll have to have a way to turn it off on cloudy days or when the tank is full of hot water... or it will circulate your hot water up onto the roof... thereby wasting energy. You'll also want to make sure you are pulling water off the bottom of the tank... where the coldest water resides.
> 
> ...


byexample, DH currently has a system set up using our wood stove to heat our water. The cold water is drawn from the bottom of the water heater (that is off), and the hot water is returned to the top. This includes a pump that can be set to temp for auto shut off OR manual shut off. I posted a picture of that setup below. Haven't taken a better one during the day, but will sometime this week. DH will be tying in the roof passive solar system into the current one we have, using the same pump (so we can access it easily in our living room and it will be less work for him). I posted a thread about the wood stove set up that also included a radiator (in shop talk, "Custom woodstove soon to be modified...radiator...

Yes, I will take pictures and post a thread on this project, when DH tackles it  Thank you!


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## SolarGary (Sep 8, 2005)

lorichristie said:


> byexample, DH currently has a system set up using our wood stove to heat our water. The cold water is drawn from the bottom of the water heater (that is off), and the hot water is returned to the top. This includes a pump that can be set to temp for auto shut off OR manual shut off. I posted a picture of that setup below. Haven't taken a better one during the day, but will sometime this week. DH will be tying in the roof passive solar system into the current one we have, using the same pump (so we can access it easily in our living room and it will be less work for him). I posted a thread about the wood stove set up that also included a radiator (in shop talk, "Custom woodstove soon to be modified...radiator...
> 
> Yes, I will take pictures and post a thread on this project, when DH tackles it  Thank you!


Hi,
I'm sure you have already done this, but just to remind everyone that its really important to have a properly placed pressure/temperature relief valve in the systems that circulate water through a wood heater -- they can be like a bomb without one...
http://www.woodheat.org/dhw/dhw.htm



Gary


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## Ross (May 9, 2002)

Yes they do Gary there's quite a thorough write up of the wood stove water heater on Shop Talk. Never hurts to restate things like that though!


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## byexample (Aug 28, 2009)

Good reminder Gary. I try to remember to throw that warning in when discussing diy hot water projects... forgot to mention it this time though.

lorichristie, thanks for posting the pic. Sounds like you guys have things well in hand. The thermostat controlled pump should definitely help avoid the potential problems I mentioned. Pretty cool setup. I'm a big fan of multi-fuel & multi-power systems. I'm going to have a look at the other post you mentioned.


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## ChristieAcres (Apr 11, 2009)

There is a Pressure Relief Valve on both incoming/outgoing pipes to the wood stove, and one on the Hot Water Heater (total of 3). We have had zero problems as we are here when we burn fires, control it with built in valve for air inflow. There is a temp gauge on incoming water (the temp of the bottom of the hot water tank should be close to this) and the outgoing water (after it has gone through 2 heat exchange units, which are inside the firebox) for a total of 2 temp gauges. Of course, the Hot Water Heater has one, too. We also have a radiator in our bedroom hooked up to the Hot Water Heater. So, the wood stove also heats the water that is pumped to this, and heats our room at night. If any is thinking about converting a wood stove to heat their water? Here is a good book to read first:










It sells for $9.95 at Lehman's:

http://www.lehmans.com/store/catalog?Args=


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## ChristieAcres (Apr 11, 2009)

The update:

Len finished his project, just coiled the black pvc up on the roof, secured it, then tried it out. Since he wanted it to be more effective, he doubled it to 400 feet. That is set up as beforehand described- cool water off the bottom of the tank, then hot water back to the top. Now, our wood stove & this new passive solar setup are both hooked up to our hot water heater, which we keep off most of the time now. There are valves to shut off one system and open up the other. The circulating pump is located under our home and is used for both systems. Today, it was 88F and we have a full tank at 120F. The switch to stop the pump, thereby stops the circulation. That is shut off when the sun isn't shining on the roof. We had had some practice using one system and then the other lately. Until just a couple days ago, we were getting temps in the 50s & 60s...


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## woodsy (Oct 13, 2008)

Congrats and welcome to SHW club !
Sound like a good setup with one pump able to circulate 2 loops.
What do you have for a pump ?
We've been running on solar only quite a lot lately.


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## ChristieAcres (Apr 11, 2009)

Thanks Woodsy! I don't know what kind of pump it is, will ask later. Len told me the amps used equaled 1/2 a light bulb. Where we are, Passive Solar is only an option part of the year. To be effective, we'd need Solar Panels (not in the budget right now) and a wind generated device (we really get the winds here in the Winter). Last night, we were discussing building an exterior furnace to heat water. Although our wood stove & this setup work great, there will be those in between days, overcast...


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## ChristieAcres (Apr 11, 2009)

A few days ago, we were in the high 90s, this morning 55F?! Fired up the wood stove, but figured it would warm up in a few hours, maybe a few more, well, no warmer than 60F today (?!). We are back/forth between the passive solar setup and our wood stove... I had to take my clothes in off the line and hang them on our indoor drying rack!


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## Jim-mi (May 15, 2002)

Lori . . .curious to where your at north south wise..........

Up here in Mich. the pipe on the roof could work for some of the year, but oh boy it sure would need to be a drain back deal.......

Enjoy that solar heated water..............


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## ChristieAcres (Apr 11, 2009)

Jim-mi- We live on the Olympic Peninsula of WA State, close to the Hood Canal, SW of Seattle (Zone 8b). The passive setup is only for summer use. It will be drained completely before we get freezing weather (closed off by a valve). We use an efficient water pump for both our setups (we have a wood stove with an internal heat exchange). That is what heats our water in the Winter. It works very well, DH put 2 heat exchange units in it (a large wood stove). When funds allow, we will be adding Solar. We get a lot of wind here, certain times of the year, so are looking into utilizing that, too.


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