Supplemental winter heat from sun brought in house?

I currently heat water for dishes, laundry, and showers from the sun, even in the winter. I live halfway between Williams, AZ and the Grand Canyon. We live off grid, only using solar power and inverter/batteries for electric. Using electric for heat at night would deplete our batteries. We have been using a small woodstove to heat our 352 sq ft home, mostly from 9pm through 8am, because of passive solar during our mostly sunny days and 6" insulated ceiling, walls, and floors keep house around 70. We are at 6000 ft and coldest nights in single digits December and January.

We are in severe drought and do not want to use our woodstove next winter (even though we have wood for at least 3 more winters. My husband wants to install a vented propane heater and utllize existing chimney and have large propane tank set. I do not want to use woodstove nor propane.

Here is my thought and would love feedback from you on the forum:
I want to put many 1 ltr and 2 ltr bottles of water enveloped in black socks/cut off tights that I recycle, clear plastic bags over those, let warm up behind glass during the sunny day, bring in before sundown and keep in insulated bags, then bring out hot bottles as needed at bedtime to radiate heat into room. I know that the water reaches 140-150 degrees in 1 ltr bottles in just 3 hrs in sun like above scenario, which I would leave in sun all day if using for heat. I am not sure if radiation from hot water can warm up or keep warm large area space that is already about 70 degrees.

Thanks in advance for your feedback.

M. A. Carey

That is an interesting concept.  What about putting them in the bed under the covers before bedtime to heat the bed then use them to warm the room when you go to bed.

Maybe someone else can offer some suggestions.

Actually, we don't need heat in the bed since our body heat keeps us warm under the blankets.

I am not sure how long the bottles of hot water will give off heat. I have a lot of left over foiled bubble wrap and my thoughts are to line an old cooler chest  or maybe two, with that and keep the bottles warm until we need them and bring out as needed. My husband doesn't think this will work.

I have also considered using rock painted black and bring those inside before sundown, in addition to my black sock covered bottles of water.

I personally think it is a lot of work and time to get you the heat that you are looking for. In my life anyway, if something takes a lot of time and effort, soon I find myself stopping the method and reverting to the old way.

I think there is a better way, and found this video that I think would work for you. Better yet, it is completely Do It Yourself. This video on Youtube explains the theory, but if you need help on how to build it, dig around and there are videos on how to build them. Again, only you can decide if this would work, but even off-grid, I think the blower unit would be manageable for you and give you the heat you would need.

Thank you, Travis, for the posted reply and video. I watched the video and had thought about doing this with pop cans or black screen, and had almost decided to do the black screen.  However, this only works while the sun is out, if I am correct. We have sun shining in our south windows that warm our home during the day, but I need to store heat to use from 8 or 9pm until about 8 or 9am.

I do not know how to store heat energy other than soak up sun through the day in rocks and water. Even at that, I doubt enough energy heat can be stored to keep warm all the way through the night.

So, in a nutshell, very seldom do we need heat during the day and even up until almost bedtime, but at single digit lows in the coldest part of the winter, we need heat at night until the sun shines again.

Even if we do not watch tv at night we would deplete our battery bank if we used electric heaters over night.

I will keep searching the Internet but may have to resign myself to burning wood or using propane vented catalytic heater.

Sounds like you need a solar water heater.
Plenty of simple designs out there.
Unlike most people,you want the water for its heat retaining abilities, but it should still work.
Some use solar heated water for floorslab heating,but it seems like a simple steel tank would serve you better.
You could even wrap it a  in a removable insulative cloak, like giant tea cozy.

Thank you, William. I will do some research on that. I have read a lot about radiant water heat in floor, but I'm thinking that is what needs to be done during floor construction. I have also read where some have a large water tank below floor or below house, but again, too late for that, and very limited funds.

I appreciate everone's feedback.

Would it be possible to quantify how much wood and of what species you burn over the winter, and in what kind of stove. Next would be you listed square footage and insulation but the missing variable would be square footage of windows and what quality. I believe you will find that a combination of active solar and good thermal drapes could get you most of the way there other then the worst night. A fun exercise on a rainy night.
Cheers,  David

I.ve had good success with this free heat loss calculator.  https://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm

David Baillie wrote:Would it be possible to quantify how much wood and of what species you burn over the winter, and in what kind of stove. Next would be you listed square footage and insulation but the missing variable would be square footage of windows and what quality. I believe you will find that a combination of active solar and good thermal drapes could get you most of the way there other then the worst night. A fun exercise on a rainy night.
Cheers,  David

Hi David. We burn very well seasoned ponderosa pine, juniper, and aspen. The woodstove is US Stove, cast iron, and is small, holds 19" logs. We cut 3 truckloads of wood 2 years ago (6-1/2 foot truck bed) and we have used about 1 truckload in 2 winters and expect we have enough for 4 more winters if we do burn wood. (each year we take stove pipe off, clean it and chimney, and move the woodstove to a wall to give us more room)

We have about 26 SF of windows and we use heavy fleece doubled for curtains. The largest windows are in the south side and are double pane Tapco windows amounting to 18 SF.

We have 6" insulated ceiling, floor, and walls.

Other than monsoon season June through September, we have probably 95% sunny days and even if high temps are in teens or 20s during the day and it is sunny we use no heat at all until close to bedtime.

I will check out the link for heat loss.

Thanks for the info.

Pelmets over the windows to stop cold air circulation
Can you add some thermal mass inside the building that can capture heat during the day and discharge it at night?
Have you thought of a rocket heater lounge as discussed elsewhere on this site?

John C Daley wrote:Pelmets over the windows to stop cold air circulation
Can you add some thermal mass inside the building that can capture heat during the day and discharge it at night?
Have you thought of a rocket heater lounge as discussed elsewhere on this site?

I just read up on pelmets because I didn't know what that was. We have a storage shelf already above one south window that I will talk to my husband about making a pelmet from that as the top is already there, and then make one for the other south window.  He can also make pelmets for east windows that are medium sized. We have no windows on the north except a small porthole window with screen for summer air flow, west only small porthole windows with no screens and heavily shaded right now. They are for natural light only.

As far as adding thermal mass, we have wood floors now but we are going to install ceramic tile next month. My husband does not want a rocket mass heater and bench because of the amount of space it takes up and the weight. He will allow me to bring in some lighter weight mass such as pavers though.

Thank you, John, for these suggestions

M. A. Carey wrote: My husband does not want a rocket mass heater and bench because of the amount of space it takes up and the weight.s

Show him this one for example.

http://batchrocket.eu/en/applications#redbell

When you do the ceramics add a cement board layer under them or if you have the space a layer of thin pvc tubing for radiant. The extra mass takes up no space and could make a difference and you will have your solar hot water radiator. from the wood burn number you gave that is not much heat loss. The traditional solution is plate collectors or vacuum tubes and water storage to be circulated to a heat exchanger  at night maybe your beautiful new radiant ceramic floor... 13 years and counting. I've never regretted going radiant. No solar element to it though.

M. A. Carey wrote:Thank you, William. I will do some research on that. I have read a lot about radiant water heat in floor, but I'm thinking that is what needs to be done during floor construction. I have also read where some have a large water tank below floor or below house, but again, too late for that, and very limited funds.

I appreciate everone's feedback.

Yeah,putting anything under the floor wouldn't make much sense at this point, but a 55 gallon steel drum or a derelict water heater, stripped of insulation, would take up about the same floor space as a wood stove.

I imagine it would work like this:
An elevated,insulated box,with a steel tank (painted black) inside and some glass over top, could sit in the sun all day.
At dusk the user opens a valve and the heated water flows inside the dwelling,into an uninsulated steel tank, which radiates heat into the living space for the rest of the night.
In the morning, a pump slowly pumps the water back up and outside  into the collector.

As a bonus, if you have any excess generating capacity during the day, you could divert it to a coil in the  collector tank.

Satamax Antone wrote:

M. A. Carey wrote: My husband does not want a rocket mass heater and bench because of the amount of space it takes up and the weight.s

Show him this one for example.

http://batchrocket.eu/en/applications#redbell

He isn't  interested mainly because of the weight of 2 tons. Also we have an existing wood stove. I have always wondered if we could make a smallish RMH from the wood stove, like substitute the cast iron firebox for the steel drum and build a small mass bench around it. My only concern about continuing to use our wood stove is that it is so dry here (6% humidity) and continued drought conditions forecasted. I do not trust that the spark arrester at chimney top will prevent a spark from releasing and start a prairie fire. We have plenty of wood and we do not burn a lot of it. A RMH, I think, would not have sparks coming out of the chimney and therefore safer, plus not much wood to burn VS wood stove.

M A Carey

Just cobble a garden J tube, with a cast iron plate on top, to use as a plancha in the garden. Cook meat on it, when you will have raised his interest, it might be easier to convince him about the RMH!

Thank you to everyone for all your ideas, suggestions, and feedback. After careful thought and discussion with my husband, we have decided to continue using our wood stove since it is already paid for and we still have several years worth of seasoned wood already cut and stacked. However, my concern over flying embers starting an unintentional wildfire, even though we have a spark arrester atop chimney under the cap, which is 5/8" mesh, my husband is going to add 1/4" steel mesh to the outside of existing spark arrester, lind of like a basket surrounding it.  We have researched online and spoken to our go-to guy at our local True Value store, and have been assured that the 5/8" mesh spark arrester is code in our area, but to give in to my safety concerns, he has stated not to replace code mesh, but to attach no less than 1/4" steel nesh fashioned to attach to existing spark arrester but with a couple inch spacing so as not to clog mesh with soot.

My husband takes apart the chimney flue and removes upper portion so as to clean thoroughly each spring and we move the wood stove to one side (it is in middle of house during heating season). He tells me there is hardly any soot built up for a couple feet below roof.  

Anyway, to make a long story shorter, we are still going to install cement board onto our existing floors and install the ceramic tile atop of that so we will have some thermal mass. I am still going to experiment with black rock and my black-sock covered water bottles encased in clear plastic to bring in at night in a large cooler insulated with foiled bubble wrap and pull out just before bedtime and/or in the middle of the night to see if that can keep the house warm enough until early a.m.

He is also going to build pelmet boxes above windows and I am going to double up my thick fleece curtains so we are thinking this will help also.

I so appreciate everyone's input and we are doing some of the suggestions. I think with the extra thermal mass in the floor, the pelmet boxes with even thicker curtains, and maybe, just maybe, my water bottles heated during the sunny days to radiate heat at night, we may not have to have but one fire before bed and one very early morning, and stay warm enough all winter.

Here is a picture of 2 of my quart bottles of water heating for my dishes.

M.A. Carey

What you have created there to heat your jars is a method known as Jar in Jar solar cooking.     If you wanted an even higher temp you could add a mylar car shade to the jars this would give even higher heat than you have now,   I pick up mylar car shades at garage sales.

I saw a trick on youtube:
That bubble wrap with big bubbles sticks to windows if you dampen the flat side.   Serves to insulate the windows and looks like art glass.   You can remove them during the day if you want.