Solar radiant Heat

[philbuilt]

Has anyone installed one of these systems?
I pulled the trigger and will be posting the process if there is any interest.
I thought about the out door wood boilers But I don't have much wood on my land.

The tractor portion of this project was digging the 70' trench to the panel mounts.

Here is the thought process.
I already have a cold fire oil furnace. Fuel last year $3700.00 May07-08
cost have gone up.

Wood stove: I would have to buy wood and cut, spit,stack and store.
( I already don't have enough free time)

Geo thermal: Very cool plan but the heat pump will need more electricity again additional cost per month.

Pellet stove: very popular here in Maine but again, Purchase of consumables and storage needed and feeding the system.

So my first thought was to reduce the amount of energy required to heat the house. I currently have baseboard heat. this requires the furnace to heat the water to 195-215 degrees. So after some research Radiant floor heat only needs to be 75-90 degs. This would be a savings by lowering the water temps. (hopefully 20% savings) So I will retro the house to radiant floor heat.
This alone I hope to save on heating because of the lower water and room temps. (warm feet warm body)? so I have read.

OK now for the solar part. There is a company in Vermont that specializes in radiant heat for the DIYer. This is where I also would add the solar Panels. I called and worked with them and decided to do this. The panels will heat a 120 gal tank.

So there is the setup any interest?
Phil

 

[RichNJKubota]

I installed a solar hot water heater last fall. The collectors are evacuated glass tubes. Four collectors with a total of 110 tubes and they are made in China. They produce water at high temps. We have two 60 gallon solar hot water storage tanks. Last winter I turned off one of the tanks so the remaining tank would come up to temp (170F) faster and there would be excess hot water from the collectors to heat the house.
I installed a radiator (looks like a car radiator) in the air handler for the house heat. When the 60 gallon tank is up to temp the hot water gets diverted to the radiator and it heats the house. It works great.
But I wonder why you think you'll need less heat if you go radiant vs. hot water baseboard? If your house needs, let's say 100,000 BTU per hour at 0F outside temp, then does it matter whether it's radiant or baseboard? Or am I missing something?

 

[EddieWalker]

I'm very interested in any sort of energy savings. One thing that always concerns me is the amount of upfront cost, versus the actual savings and how long it takes to make up the difference.

JLC had an article last month with a list of things people do that they think will save energy, but cost so much to do that it's not a savings at all. Having new windows installed was one of those things that costs so much to have installed with only a limited amount of savings that it takes 20 to 30 years to break even. I have a client who had done that first, then they had a front door installed with hopes that it would cut down on their bill, it didn't make any difference.

I had remodeled their bathroom and when they asked me what to do, I told them to add allot of insulation to their attic. I brought it up to 12 inches, which gave them an instant 30% reduction in their electric usage.

Not living in a cold climate, I can't imagine what it takes to heat a house. We use two space heaters to heat our home. We cut our electric bill by $100 per month by just heating the living room with one or two of those space heaters.

I've been thinking of either replacing my water heater with propane, or adding a loop that will pre-heat the water going into my water heater. The pre-heating method would be the cheapest, but so far I'm still stalling on trying this.

Hopefully I'll see something in your setup that I can use in mine, or at least get some ideas for more energy savings.

Eddie

Oh yeah, the weather stick starts out every morning in the down position, then works it's way up during the day. It doesn this every day and has been great fun to see where it's at. It doesn't work here with our humidity, but jus the fact that it moves so much is amazing!!! Thanks

 

[Willl]

the weather stick

 

[therebarely]

Interesting post, because I spent almost $4,000.00 on propane last winter, and froze to death It's time to do something. I saw an article a few months ago in Mother Earth News about a home in Idaho. The owner built a shed/garage with a passive solar collector on the south side, and pumped the warmed water through his furnace in the house. I am going to try to duplicate it to some extent, probably next year. In the mean time, I am going to install an outdoor wood furnace this fall through the existing duct work in the house. I bought it as a closeout in April, so the expense was minimal (as compared to $4,000.00 for propane). Any ideas would be greatly appreciated.

 

[thunderworks]

But I wonder why you think you'll need less heat if you go radiant vs. hot water baseboard? If your house needs, let's say 100,000 BTU per hour at 0F outside temp, then does it matter whether it's radiant or baseboard? Or am I missing something?

I have no technical expertise, only anecdotal experience. I built a new home 3 years ago and used radiant floor heat (geothermal heat source in my case). I am a very cold blooded person, normally hunkered down by a wood stove all winter. My wife convinced me to eliminate the wood stove, and heat the floors instead. Her argument, which I now believe, is that by heating the floor mass, which retains heat, you need to input fewer btu's, simply because the floor is essentially acting as a heat sink, retaining the warmth. The longer it's retained, the less frequently you input new btu's to maintain a comfort zone. I also believe that when floors are warm, your respond differently physiologically to the sensation of warmth, and really need less to be comfortable. I can't document squat about my opinion. . . . simply my opinion after 3 winters in thenew home.

 

[philbuilt]

RichNJKubota,
I looked at the tube as well. When I compared the overall performance the tubes only use 60 % of the space for producing heat. The panel that I ordered are 96% usage.

Eddie,
I was thinking that this would be a great setup for the showers at your camp ground. You guys heat in the winter?
I,m glad the weather stick is still working. I thought that perhaps the termites would eat it like it was imported candy.

Will,
Do a search for Maine weather stick.

therebarely,
I had come across the same article I believe. The guy built a shed with a homemade water tank. Is that the one? That was what got me going one this quest.

thunderworks,
Thank you that is just what I want to hear. My basement maintains a temp of 55 deg and ground water is the same. What temp is the water that is circulating in your floor?


So here is the big plan.
Solar panel loop closed ! circulater pump with antifreeze.
It heats the water in the large 120 gal tank. Domestic cold into large tank out to my current 50 gal superstore. What was cold in will now be preheated by solar. This will provide hot domestic and feed the heat exchanger for the radiant floor loops. When the sun is not shinning my furnace will continue to heat the superstore.

I will get into more detail as I do the install. Now to start posting some of the progress.
Phil

 

[js5020]

My house has radiant floor heat, heat source is an oil fired 50 gal Bock water heater, and I also pull domestic hot water from the system, the house is around 2500 sq ft with 6 people living in it. The house is 5 yrs old and fuel comsumption is around 650 gals per year. I thought about adding solar as a supplement last season,,,, so I did some data collecting ( very unscientific ) but none the less,, I found that most days in Dec thru Feb ( when the heat is really needed ) in my area are very cloudy with little if any sun,, I know they tell you that you just add collectors to compensate but pretty soon you get into the situation Eddie is talking about,, it takes so long to pay back is it worth it? At this point I haven't concluded whether or not it would be cost effective.

Using a water heater, be it the Bock (oil) or the Polaris (gas) I my mind is the way to go,, I have my aquastat set at 100 degrees, I do not need a tempering valve,,, never could figure out why you would heat up water only to dump cold on it ? I could run it lower than 100, but I start to hear it when people are in the showers. The heat is constant and steady,, I have wood floors and you can walk on them in your bare feet on the coldest days,,, it doesn't feel cold while waiting for the next heat cycle and when the cycle occurs your not looking to shed the sweater. I like the floor heat and would not even consider anything else.

 

[philbuilt]

Here is the study that I did to find the optimal direction for the panels.
I painted lines in the lawn by the clothes line pole. 6:30am though 6:30 pm. Them I measured out 10' feet each way and put a pin. This allowed me to pull a string and have the proper long day orientation.


The trench starting at the house.


My wife first time operating the BH


The completed trench 70' Long 4.5' deep.


Phil

 

[glmf]

Phil, thanks for the post. Please keep us posted as I live in Maine and am throwing some ideas around. I don 't mind spending money on the things I like, but spending huge money to heat my house drives me crazy. I have been getting free firewood for years but that is going to run out, and looking for alternatives,,, thanks again

 

[RichNJKubota]

I chose the glass tubes because, after talking to several installers and homeowners, they worked better than the flat panel collectors.
I found many people who disliked the glass tubes also. It seemed like it was allot like the regular oil vs. synthetic "debate".
In the end I chose the glass tubes but my neighbor has a flat panel system that's still working from the 70's.
The thing that amazes me is the glass tube collectors will even make hot water on a cloudy day.

 

[RonMar]

I chose the glass tubes because, after talking to several installers and homeowners, they worked better than the flat panel collectors.
I found many people who disliked the glass tubes also. It seemed like it was allot like the regular oil vs. synthetic "debate".
In the end I chose the glass tubes but my neighbor has a flat panel system that's still working from the 70's.
The thing that amazes me is the glass tube collectors will even make hot water on a cloudy day.

That is the beauty of the evacuated glass tubes, they will heat water, only slower, on a cloudy day. Because of the convection and conduction thermal losses with an air filled panel, it produces very little heat on a cloudy day. The collector in a vacume has none of these losses, only radiation losses, and if you are continually pulling heat out of the inner conductor into the water system, the radiation losses will are minimal.

The biggest advantage of radiant heat is that it slows the vertical heat transfer. radiant heat does not heat as much air. Baseboard and central air heating heat air and try and fill the room with this warm air for comfort. Because of the small surface area of the radiator surface around the tube, they need that higher boiler temp to heat air at a reasonable rate. They have all those fins to help enhance that process but they have to move a lot of air thru the fins to be effective. Because of density, that heated air from this or central air furnaces rises and transfers it's heat to the walls and ceiling, which conduct it away to the outside. That is why the attic insulation makes such a big difference.

Radiant heating is like walking past a brick wall that has been in the afternoon sun, just after the sun goes down. You can feel the heat against your skin. How is the heat getting to you? Thru direct radiation... It is heating air also, which is immediatly rising, but because of laminar flow, it is not heating very much air, just a thin layer along the surface. The air closest to the wall absorbs heat, but it then acts like water in a wetsuit as it travels up the wall and provides insulation.

This is a problem in heat exchangers and air heating elements that engineers work hard to overcome by designing in turbulators to mix up the fluid and break up laminar flow. With turbulence, more fluid is exposed to the hot surface and more heat is transfered faster at lower temp differences. A warm floor will warm the air in contact with it, but this is a far slower process than a baseboard heater as the flooring or carpet is not a good heat transfer medium. It is also heating the coldest air in the room. If the floor is warm it will radiate heat like the brick wall, and objects or people in the room will absorb this radiation and be warmed. That sun warmed wall I described earlier is probably only around 100F-105F, but your exposed skin can sense the heat for several feet. If it is a cool calm evening without a breeze to chill your skin, you can feel the heat for quite a distance.

 

[Luremaker]

I don't want to steer away from the op's solar project which I think is great project. I tend to agree with Edie and think store bought solar panels are very expensive and the payback is much too long to make it a feasible investment. Adding more insulation where possible should be the first step to saving energy. Building your own panels is the only way to make a solar project financially feasible for most of us.

Having said that, I too am also thinking of building a few solar hot air collectors this year. I want to build collectors similar to the one in the picture below. Aluminum pop cans painted black is the heat collector in this design which I got from the following link. the Otherpower.com Discussion Board || Solar Air Heater - Pop can heater there are a number of other similar designs on-line. This design is suppose to generate up to 200 btus per sq foot per hour in full sun. Less in partial sun. Should come very close to a one year payback. Biggest problem with this type of solar collector is you can not store the heat for night use.

Now if you can read Hungarian and like this design you should take a look at the detailed design steps in this guys site: sörösló by sztgyi

 

[therebarely]

Phil, that is the one. I am really wanting a passive system for heat, but that will have to be a long term goal. Did a total gut on my 102 year old farm house 4 years ago, and didn't even consider using radiant floor heat at the time. Costly mistake, and I should have put low voltage wiring in for lighting, and used solar panels, batteries, and a wind mill for lighting. Electric from the Rural Electric Coop went up 25% April 1st. Next big project will be rain water collection for watering the cattle. Hope to have it done by late fall.

 

[charlz]

I've been thinking of either replacing my water heater with propane, or adding a loop that will pre-heat the water going into my water heater. The pre-heating method would be the cheapest, but so far I'm still stalling on trying this.

I would look real hard at the seasonal price of propane in your area. Last November we were hitting $2.62/gallon and I am thinking prices will be more like $3/gallon here this winter if not higher. I switched from propane to wood pellets for heat as they are about 45% the cost of propane on a btu to btu basis.

I would love to put in solar water heating for hot water or at least pre-heat in the winter. "Idaho lets you take a personal tax deduction of 40% of the cost of a solar system on your residence in the first year that the system is installed and an additional 20% a year for three years thereafter. The maximum deduction in any one year is $5,000. Total maximum deduction is $20,000." I _believe_ that includes solar thermal as well as solar electric. That would go a long way to recouping costs from the system. Unfortunately due to a couple of issues I am not likely to move ahead any time soon.

 

[Roger2561]

My problem I have is money, or shall I say the lack thereof. I own my own house (my dad left me the house and property when he past away - built in 1845) and with the high cost of home heating oil (2 weeks ago Irving Oil was asking $4.899/gal) and I use 810 gallans per year...coupled the high taxes here in NH, I have nothing left to attempt an alternative heating system. I have no choice but dole out nearly $4,000.00 in heating oil this year. I have heard through the grapevine that the "experts" believe the price of heating oil will be at or near $7.00/gal next year. If it does, I don't know what I'll do. And, I hear absolutely no solutions coming from our "leaders" in Washington, DC, whether they be Democrat, Republican, Independant...everyone is quiet on this issue. I don't understand. I'm off my bandwagon now. Roger

 

[philbuilt]

Wow! allot of great input here.
Here is the link to the solar shed. SolarShed

It a good read on what you can do yourself.
On the same site there is a project where the guy ran a pipe from the attic space. I believe a 4" PVC pipe with a small thermostatic fan would blow the heat from that space to the basement. I plan on trying this as well. I do know that my attic power vent does run on some days in the winter.

Phil

 

[philbuilt]

Back to more pictures.
The trench had about 60' of gravel and 10' of clay.


I used wood boiler pipe.
The first plan was to cut 2' thick foam and dado to lay in 2 1" type m copper pipes and then cap with 2' pink foam and back fill. I had a concern if ever a leak that I would have to dig it up.
The boiler pipe is 2 1" pex triple foil wrapped and in the corrugated non perfed pipe.

18" above that I put a 1/2" pvc pipe for the panel thermostat wire.
The last pic is the auger that I use to put the sonotube in for the panel structure. the holes are placed 12' on center using the orientation from the study.


I did originally plan on putting the panels on the roof but the angle was not optimal.
Phil

 

[RichNJKubota]

My pipe run is about 70 feet also. Most of it being in the house and then a short 25' trench outside. The best thing about the solar hot water is that it just works. Nothing to maintain so far and it's so simple it will probably last many many years.
How big is the collector? How many footings?
Will you be using a glycol solution for the loop out to the collectors or a drain back system where the water in the collectors drains back into the house when the pump turns off?

 

[philbuilt]

RichNJKubota,
How big is the collector? How many footings?
Will you be using a glycol solution for the loop out to the collectors or a drain back system where the water in the collectors drains back into the house when the pump turns off?07-14-2008 05:23 PM
I will be using 3 panels 47-1/4" x 95-1/4"
2 footings 1 frame details to follow. The plan is a closed loop with glycol.

Here are some pictures of last weekends work.


The steel prep, I know everyone likes to see welds this was done with a Lincoln 125 .023 wire and stargon gas.
the assembly and paint crew.
Last but not least the frame cemented into the sonotubes.
The steel verticals are 4x4"x3/16" and the angle is 60deg.
the horizontals are 3x3"x3/16" sq tube.
Height to the bottom of the frame is 5' and we set this inplace
with the fel on the 1260
Bonus was the 1260 has reached 400hrs.