Damp, Cold Off Grid Cabin - Heating

TenMile
TenMile Solar Expert Posts: 62 ✭✭
Hey all,

So this past weekend, I successfully installed a small off-grid solar system in the family cabin on Vancouver Island. Sufficiently sized to run some lights, a small TV/Satellite and the vacuum once in a while. It's got me thinking about the next solar project...

The cabin itself is used about half the year from April/May through to about October with the summer months seeing the majority of the use. The place is a 30 y/o log cabin, without a great deal of insulation. It's heated today with wood -- we have a Cast Iron Woodstove in the kitchen, an ancient (but effective) airtight stove in the basement, and an extremely non-efficient fireplace in the livingroom (we are considering converting this to a wood insert). No air movement or air handling systems.

The basement of the cabin is a walk-out, concrete slab on grade. The basement is very cold and damp feeling given the amount of rain we get out this way. The cabin is about 1000 sqft per level and that includes the basement, main floor, and loft.

We are trying to figure out the best way to get some heat into the basement so that the cabin is a little warmer -- this past weekend the external air temperature was in the mid to high 50's but in the basement you could still see your breath. We find that after the cabin has been sitting empty, it can take a day or more to take the interior chill off the place. Would love to have a system that can keep the chill off permanently so we arrive to a warmer place (not 70 degrees, just not freezing).

I was thinking a relatively efficient (however, costly) method for taking the chill off the basement year round would be to install radiant in-floor heating (powered by solar collectors) in a section of the basement floor over the existing slab using a product like this one (http://www.thermalboard.info/). I could do half to 3/4 of the basement floor with relative ease as it's unfinished today. Might also be able to take advantage of the hot water to supplement our propane hot-water tank. Also provides an option for heating the main floor as the joists are exposed to access to the underside of the main floor is simple.

Another cheaper alternative would be to replace some of the basement windows with solar window heaters. The basement is south facing, however, windows are under a deck and there is quite a bit of shading to the south. Adding solar windows to the upper area is a no-go because of the logs. Not sure if it would be effective.

Anyhow, is there a better method? We're not looking to use a method here as a permanent full time heating solution -- simply to take the chill off and augment the wood heat sources we have...

Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Damp, Cold Off Grid Cabin - Heating

    First task is to properly insulate and vapor barrier the basement. The concrete floor and walls are huge heat sinks, even though the earthq temp is fairly warm, it is cold relative to comfort. Adding foam on top of th e concrete would go a long way to solving your problem.

    I would suspect that you have hi humidity issues in the basement as well, possibly contributing to mold issues. Thermal breaking the slab and the walls from the cooler earth will help with this issue as well.

    T
  • TenMile
    TenMile Solar Expert Posts: 62 ✭✭
    Re: Damp, Cold Off Grid Cabin - Heating

    Yep -- agreed. That big concrete slab is great for keeping beer cold without a fridge, but sure keeps the place cold!!!

    Adding insulation to the floor likely means adding a sub-floor over the grade. If we are going to do all that work and add a sub floor, rather than foam insulation, we could do pex-tubing and sand over reflective aluminum for a hydronic heating system. Or, use that ThermalBoard product.

    That would provide both the thermal break, plus warm the air and should help warming the entire cabin...
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Damp, Cold Off Grid Cabin - Heating

    So... you are on the WET coast and have a 30 +- yr old cabin on a basement... I'll bet that the term foundation drains never entered the minds of the builder...

    If you can possibly check it out if all that rain you get is heading down to your basement floor to provide all that ice cold Kokanee or VIB ale ...
    Next as Icarus said you want to get some vapour barrier up and then add some moisture resistant (styro type) insulation. that will probably make a huge difference, then you can size your radiant heating system ... Use a hammer drill and use 2 x 2 's or 2 x 4 's if you want to go whole hog... there is a product called Iko board ( like the asphalt shingle co.) that is R 7 per inch , comes in 1 to 3 inch thick 4 x 8 sheets.

    you also might want to look into an inverter type gen set ( Honda E----i series comes to mind) to run you power tools while reno-ing , there are lots of threads here on the need for backup to recharge and save you batteries from sulphation.

    your inverter is pretty large for a 12 v system...

    How are your shade patterns?

    BTW we are in the process of a new build for a 9 - 12 month residence and I want to use solar heat to keep the chill ff while we are not there. Biggest problem I have had is getting someone to understand 'just to keep the whole place from freezing, not to "heat" the place' when h want you to buy a big install...

    HTH
    Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
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    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • TenMile
    TenMile Solar Expert Posts: 62 ✭✭
    Re: Damp, Cold Off Grid Cabin - Heating

    The basement of the place is extremely well built -- they had a commercial guy pour the foundation and he did it like an office building. It does have perimeter drains. The basement itself has never been wet or leaked. It's not a true basement as it's a walkout, so over half of it is at ground level.

    Yes, our inverter is a little on the large side, however to run the vacuum a few times a week and the odd power tool it comes in pretty handy. Checked out the vacuum on the weekend -- it's a commercial model that draws 9A at 120V. On the Trimetric monitor it was drawing almost 70A at 12V while cleaning the carpet and was using just over 40% of the inverter power.