Solar room heaters
- Thread starter okra
- Start date
patandchickens
Crazy Cat Lady
The thing I run on the front of my chicken building is powerful enough that I seriously wish the S side of my house was better-suited because I would *love* to put a version there, I think it'd be well worth it.
The simplest thing (and probably not too much worse than fancier designs in terms of efficiency) would be any sort of basically-popcan-style heater, "plumbed" so that it is recirculating house air. The ideal way to do this would be with two actual openings in your wall, one at floor level and one near ceiling level (e.g. the opened top of a doublehung window).
If you cannot have an opening near the top of the wall, you will have to go with a smaller/shorter thus less-powerful unit, whose top is at the level of whatever opening you DO have available (like a regular window opening). It would still be best to have a floor-level opening as well. If you absolutely cannot or will not make a hole in the wall down there (note that in the summer it could probably have a cat flap or doggie door installed if you want!) then in principle you can plumb the cold-room-air-intake through the same window opening as you have the warm air outflow going through, with a duct going downwards inside the house far enough that you are not sucking in warmed air... BUT because the air must go up that duct, bend over the window sill, then down a duct to the bottom of the popcan heater unit, it will substantially decrease airflow and I am not sure how worthwhile it'd be.
The better you can insulate the back of the popcan-heater (-style) unit, and the better you can have it facing true south and at the correct angle (perhaps adjustable during the season) and keep snow off it, the better the thing will run. It can be removed and stored elsewhere for the summer.
HOWEVER.
There is one big thing to remember about any setup like this that relies on a thermosiphon to circulate air (i.e. hot air rises) rather than fans and thermostats. If the vents are left open when the temperature in the popcan heater unit is *less than* your room temperature, the whole thing RUNS BACKWARDS AND ACTUALLY COOLS YOUR ROOM OFF. Automatically. Whether you like it or not. (Not in summertime of course -- it's not like it's an air conditioner lol -- this only happens when temperature in popcan heater is cooler than room temperature)
You will therefore have to be VERY DILIGENT about always being home to close off the vents AS SOON AS it stops heating, and never open the vents until it is warmed up enough to heat. You can add backflow "preventer" flaps made of thin plastic like from a ziploc plus a grid or grille.... but they are not *that* effective and also do not prevent radiant/conductive heat loss.
This makes it useful for someone who is home almost all the time and good at paying attention to things (or someone who wants to invest in installing thermostatically-controlled vents or fans... although they should usually still have solid insulated covers put on manually during nighttime). But not so good for a person who is often away during the day, when the weather may cloud up, or does not get home til the sun is setting.
(I just went out about 45 minutes ago to open the front-run heater for my chicken building; and will have to close it up again around 4:30, unless clouds come in and they *are* supposed to, in which case I'll need to shut it earlier. It is surprising how much coolth it can blow into the building when left open at the wrong times
)
I have no BTU estimate for my setup, and it is not really a very efficient setup anyway for a whole variety of reasons (for one thing it is not a proper heater chamber, it is a 7' wide 8' tall leanto run that I cover with plastic and vent thru the popdoor and a slider window so that the chickens can go in there too). But I can tell you that this time of year, this modest sized unit can give me a 5-7 C boost (that's, what, like 12 to 15 degrees F) to the 15x40' building it's on. Fairly small heater, fairly big room. I have a feeling it would be Real Worthwhile as supplementary household heating on sunny winter days, IF we had a good place to put it. This would be particularly true for a house that has relatively little window area on the south side.
JME, good luck, have fun,
Pat
The simplest thing (and probably not too much worse than fancier designs in terms of efficiency) would be any sort of basically-popcan-style heater, "plumbed" so that it is recirculating house air. The ideal way to do this would be with two actual openings in your wall, one at floor level and one near ceiling level (e.g. the opened top of a doublehung window).
If you cannot have an opening near the top of the wall, you will have to go with a smaller/shorter thus less-powerful unit, whose top is at the level of whatever opening you DO have available (like a regular window opening). It would still be best to have a floor-level opening as well. If you absolutely cannot or will not make a hole in the wall down there (note that in the summer it could probably have a cat flap or doggie door installed if you want!) then in principle you can plumb the cold-room-air-intake through the same window opening as you have the warm air outflow going through, with a duct going downwards inside the house far enough that you are not sucking in warmed air... BUT because the air must go up that duct, bend over the window sill, then down a duct to the bottom of the popcan heater unit, it will substantially decrease airflow and I am not sure how worthwhile it'd be.
The better you can insulate the back of the popcan-heater (-style) unit, and the better you can have it facing true south and at the correct angle (perhaps adjustable during the season) and keep snow off it, the better the thing will run. It can be removed and stored elsewhere for the summer.
HOWEVER.
There is one big thing to remember about any setup like this that relies on a thermosiphon to circulate air (i.e. hot air rises) rather than fans and thermostats. If the vents are left open when the temperature in the popcan heater unit is *less than* your room temperature, the whole thing RUNS BACKWARDS AND ACTUALLY COOLS YOUR ROOM OFF. Automatically. Whether you like it or not. (Not in summertime of course -- it's not like it's an air conditioner lol -- this only happens when temperature in popcan heater is cooler than room temperature)
You will therefore have to be VERY DILIGENT about always being home to close off the vents AS SOON AS it stops heating, and never open the vents until it is warmed up enough to heat. You can add backflow "preventer" flaps made of thin plastic like from a ziploc plus a grid or grille.... but they are not *that* effective and also do not prevent radiant/conductive heat loss.
This makes it useful for someone who is home almost all the time and good at paying attention to things (or someone who wants to invest in installing thermostatically-controlled vents or fans... although they should usually still have solid insulated covers put on manually during nighttime). But not so good for a person who is often away during the day, when the weather may cloud up, or does not get home til the sun is setting.
(I just went out about 45 minutes ago to open the front-run heater for my chicken building; and will have to close it up again around 4:30, unless clouds come in and they *are* supposed to, in which case I'll need to shut it earlier. It is surprising how much coolth it can blow into the building when left open at the wrong times
)I have no BTU estimate for my setup, and it is not really a very efficient setup anyway for a whole variety of reasons (for one thing it is not a proper heater chamber, it is a 7' wide 8' tall leanto run that I cover with plastic and vent thru the popdoor and a slider window so that the chickens can go in there too
). But I can tell you that this time of year, this modest sized unit can give me a 5-7 C boost (that's, what, like 12 to 15 degrees F) to the 15x40' building it's on. Fairly small heater, fairly big room. I have a feeling it would be Real Worthwhile as supplementary household heating on sunny winter days, IF we had a good place to put it. This would be particularly true for a house that has relatively little window area on the south side.JME, good luck, have fun,
Pat
patandchickens
Crazy Cat Lady
Afterthought --okra said:
you don't mean the unit is on the INSIDE of the window, do you? That would be pointless. Whatever heat has come thru the window is already in your house by then. The point is to be able to have additional collector area *above and beyond* your existing window area)
Pat
- Thread starter
- #4
Excellent point but I am certain I saw one somewhere but I cannot find it again. It probably will not be as efficient as an outdoor collector but I see to remember that it still raised the temperature by a few degreespatandchickens said:
patandchickens
Crazy Cat Lady
No it won't, not beyond what the window is already doing *anyhow*. I mean, X amount of solar radiation falls on the window, and it is ALREADY entering your house and the extreme majority of it transformed to heat (unless you have a totally white or mirrored room LOL)
Seriously.
I am sure someone out there has designed a thingie for a window but it is basically pointless.
Pat
Seriously.
I am sure someone out there has designed a thingie for a window but it is basically pointless.
Pat
k0xxx
Mr. Sunshine
We made a test model that we placed in the kitchen, which has a large south facing window. The heat at the outlet was measured at 130 degrees. It did not have a fan, and the temp would have probably been lower if it had, as the air would have spent less time inside of the heater.
That was a couple of years ago, and although I wanted to build an outside unit for the kitchen, I never did get around to doing so. Maybe this is the year that I finally do... :/
That was a couple of years ago, and although I wanted to build an outside unit for the kitchen, I never did get around to doing so. Maybe this is the year that I finally do... :/
patandchickens
Crazy Cat Lady
Yeah but the heat that is blowing out of the unit is heat that was already in the house. It is concentrated all in one place instead of dispersed throughout the room, but it is not any *more* heat total.
Pat
Pat
- Thread starter
- #8
Thanks for all the input. I think I will have to look at external units from which the heat is transfered into the house. Looks like the most popular design is the aluminium soda can type. Anybody got one attached to their home? All thoughts and ideas are appreciated
Marianne
Super Self-Sufficient
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http://www.builditsolar.com has tons of DIY passive solar heaters and information.
Pat, you brought up an excellent point. We had made a simple hang inside the house unit back when we were building and had no heat. And here we thought we were generating 'new' heat!
Pat, you brought up an excellent point. We had made a simple hang inside the house unit back when we were building and had no heat. And here we thought we were generating 'new' heat!
k0xxx
Mr. Sunshine
Not so, my friend. It certainly is more heat. If it weren't, where did the 130 degree air come from?patandchickens said:
While there was no fan to disperse the heat more efficiently, there was air flow through the unit. The ambient air in the kitchen was about 65 degrees going into the unit, and double that coming out of the unit. It wasn't much, but it definitely added heat to the room that wasn't there before.
If this had been a heater using electricity to heat the air, how would it have been any different?
