Need opinions on heating, etc. for 14x20 cabin.

[mboehler]

Hey everyone,

I've been lurking for a few weeks now.  Gleaning lots of great information from all the posts in here.  Since you all seem to have experience with such things, I thought I'd ask opinions on a few options I have been considering.

We are planning to build a small cabin, like the one from the recent Mother Earth News article.  It will be 14x20 including the 4' porch (14x16 inside).  We own 10 acres in south central Kentucky, and will be building this as a temporary dwelling before we build our larger permanent house.  When that happens, the small cabin will become a mother-in-law suite, or workshop, or something along those lines.

The site has running water and electricity, but not gas.  We planning to use an LP direct-vent heater and an on-demand LP water heater.  We'll use a window air-conditioner in the summer.

I have been checking sites for LP direct-vent heaters, and am leaning towards the Empire MV-130.  It seems to be reasonably priced and seems to be around the right size for the space.  Does anyone have any experience with this type, or other similar heaters?

Our hot water demands are a shower, kitchen sink, and washing machine.  Only one of these would be used at one time.  My friend, who owns property nearby, has a Coleman hot water on-demand camping unit that uses a propane cylinder.  He said he'll sell it to me at half what he paid (since it's used).  I've heard that they have been used in cabins before with success.  What concerns me is that it says "For outdoor use only" on it.  Also, would this be able to be connected to each of the 3 devices conveniently?

If not, what are some good choices for "real" on-demand water heaters?

Thanks for all the great info!  
Mark

[glenn kangiser]

Bosch Aquastar 125 HX LP (NG is Natural Gas)  pilotless water heater supplies one large - one small fixture - no standing pilot to waste propane - saves about $100 per year at current rates.  It contains a small dynamo to generate a spark for ignition so requires no electrical hookup.  Min about 20 psi water pressure I think.  It will taper flow and heat slightly or you can turn it down.  Not turning it overly high prevents mineral buildup.  We like ours.  About $600 online

[Billy Bob]

I looked at the Coleman unit and while it is a neat idea, I think something like Glenn's suggestion would give more satisfactory results.  You would need an adaptor to run the Coleman from a tank, or else buy and change out lots of little cylinders.  It didn't look like it would conveniently tie into a plumbing system, though I didn't spend much time, having already decided against it.  The caution about it being for outdoors use only is largely a venting issue, I think.  It is a combustion source, and can deplete the oxygen in a closed space.

I spent one winter in a 14'x20' cabin heated by a gravity flow, direct vent LP heater.  It worked fine, though I could not now tell you the make.  One aspect I enjoyed was how quiet it was; just a little muffled "whump" when the gas ignited, then a soft hiss, maybe a couple of metallic pings as it warmed up.

[Daddymem]

We are going with Rinnai for our FirstDay Cottage after researching the direct vent heaters; they seem to be a better product after seeing both the Empire and Rinnai units in person.  I'm sure you have run into Al on the internet, but just in case:  http://www.alsheating.com/RinnaiLPGasHeaters.htm  He comes off like a kook at first, but it appears his knowledge is good.

Another FirstDay builder near us is using a tankless water heater to provide both hot water and radiant heat, you could look into that as an option.

[Kevin]

Here is a one that is vent free. saw it on ebay. Anyone have any ideas on it?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=6038546150&ssPageName=MERC_VIC_RSCC_Pr4_PcY_BIN_Stores_IT
They also make one for propane.
Kevin

[PEG688]

  I'm sure you have run into Al on the internet, but just in case:  http://www.alsheating.com/RinnaiLPGasHeaters.htm  He comes off like a kook at first, but it appears his knowledge is good.

Al is quite funny , seems honest as well. [highlight]I would not  use ANY vent-less gas appliance in my house either  [/highlight]

We have used Rinnai's on demand water heaters , no one has complained yet. Except the heating guys , there is a learning curve on getting all the required valves into the metal box.  I don't do the installs but I've heard the stories . Also the metal box is a FAT 14 1/2 " so space that stud bay accordly or bring the BFH to get the box into the hole.

G/L PEG  

[Amanda_931]

I have the Coleman hot water heater.  Use it for laundry down at the barn.  It works just fine, pulling water out of a bucket sending to the washing machine as long as I remember to keep the "this side up" on the pump up.  

But if you are going to use it for a shower you will be happier if the machine is at least four feet off the ground, the water supply not much below that.  It starts reliably enough that you can just turn it off to shampoo your wet hair, then turn it on again to rinse. It doesn't make for a generous shower, though.

You do need access to either 12v or 120 to recharge the battery, which it looks like you are going to have.

I can't remember if you need a regulator to hook it to a grill gas bottle.  Those hoses run a fair amount.  Less, but still not cheap if you just need a plain hose.

I was thinking about pumping hot water up to an insulated water tank for the day.  I may still do that.

You do need standard running water (minimum 20 psi--city water may be double that) for the demand water heaters to work.  Looks like you are going to have it.

[Amanda_931]

Excel units propaganda says that 10 psi is all the pressure you need.  (some of the others don't work well on the minimum pressure, I understand)

Propane unit is a bit less expensive than the natural gas.


http://cgi.ebay.com/EXCEL-VENT-FREE-TANKLESS-GAS-WATER-HEATER-LPG-Gas_W0QQitemZ290010592113QQihZ019QQcategoryZ42234QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[mboehler]

Does anyone know if there are "direct-vent" tankless water heaters?  I was reading about the Bosch Aquastar, and while it has an exhaust vent, it gets its intake air from the room.  If the room is not big enough, holes must be cut in the wall above and below the device to supply it with enough air.  My  14x16 cabin will not be big enough to supply the air, and I don't like the thought of opening holes in the walls for heat to escape.  I also don't want to install it outside because of the freezing danger in the winter.

Thanks!

[glenn kangiser]

I had a little foreign one from an RV that direct vented but performance was very poor.  

Note that I am direct venting my Bosch -- no vent stack -- but it is in my uphill patio greenhouse area.  My neighbor put his in his attic with no vent except attic ventilation - not a recommended install but he did it and he's a fireman.

[desdawg]

I have a tankless water heater mounted on the outside of the building and the vent running up the outside wall. I live in AZ where freezing isn't an issue. It doesn't have to be mounted indoors. An enclosure could be provided if need be.  

[Amanda_931]

That Mexican 4-plex that was linked to yesterday had little utility rooms whose door was to the outside, they had gas tank type water heaters that apparently needed to be turned off and on all the time because of a not altogether reliable water system.  

But the idea would work perfectly well for a tankless water heater, assuming you had enough outside wall to mount it on.  And the little room stole enough heat from the main part of the house to keep it from freezing.

[mboehler]

Now that is a good idea.  We were planning to build a storage shed on the outside of the building anyway.  Installing the heater in there sounds like a great way to do it.

If one were to do this, would you recommend decreasing the amount of insulation in the wall between the main cabin and the shed?  Or perhaps putting in a small vent or window that could be opened or closed to help keep the shed warm in the winter?

Also, what size LP tank would you recommend?  I'm thinking of a 100 gallon tank with perhaps a 20 gallon backup, in case the main tank ran out.  It seems like 20 gallon tanks would have to be switched out fairly often.  I don't know if a 250 or larger tank would be worth installing, as we are only planning to live in the cabin for a year or two before the larger house it built.  I guess the tank could always be upgraded to a larger one in the future if needed.

Thanks for all the great advice!
Mark

[peg_688]

The Rinnai heater I'm talking about is for domestic hot water , the metal box fits in a stud bay. it direst vents right out the front which is removable for servicing the unit.  No vent pipe goes up , a "blow off" over temp , emerg. line is run out of the unit , generally not visible , except it must be 18" , no more can be less, turned down , think 90° so IF the unit over pressurizes it can blow off hot water , think steam , so the unit does not explode , just like every standard hot water tank .

I can't find a photo of the one we have been using , I can take a picture next time I'm on a job with one, which will be later next week. If you'd like to see it.

G/L PEG    

[Amanda_931]

Since the only thing I am running on the grill gas bottle is the stove--and basically I heat water for coffee, maybe cook something more exotic than ramen once a week, a pair of grill gas (20#) bottles last me a bit over a year.

Friends who do rather a lot of cooking, but that's their only use for gas fill up their 100# tank once a year.  

Both of us take the tank to somebody to refill.  But that hundred pound job is probably as big as you'd want to fight with.  Although you can legally get at least one size bigger.

Have to get a bit bigger for them to come to us.

(but the coffee is moderately exotic French Press!)

Friends with (no water pressure, and off-grid), a gas stove--which they use all the time, a gas combination generator/water heater (I think, know they were talking about something like that--but I can't find it with a search) and one or two (unvented) gas infrared or "plaque" heaters to supplement their wood stove find that the smallest rentable/they come to you tank is more than enough for them.

[hunter63]

We used a 2-1/2 gal elect water heater, water from a 55 gal drum, filled by a gutter system, thru a "on demand sprayer pump" 12 v w/ adapter. ( Take as long of a shower as you want, but you only have 2-1/2 gal of hot water.)
Set the t- stat on low as it goes, worked fine. Plug in only as needed. took only 15 min to heat.
Could have used a 6 gal as well.
Now the cabin has 30 gal electric. Same deal, turn on 15 min before use, but now has a standard pump, shower w/ mixing valve.

[desdawg]

You can install two exchange type cylinders 20# or 100# with an automatic change over regulator. The regulator will use the fuel from one tank and when empty automatically swiches to the second tank. The regulator has an indicator that turns red when the first tank is empty. This is all accomplished with gas pressure and no electricity is required. When the first cylinder is empty you can refuel it while still using gas from the other and not interupt your usage. Most RV's have this system installed on them.

[jraabe]

Did you see the photo in the 1000 sf house thread?



Don't know which brand that is (there are several Japanese Mfgrs) but it is a propane fired tankless water heater that mounts on the outside of the wall, takes no interior space and provides all the hot water for a small house. You can also use these as radiant floor heaters for smaller places that are energy efficient.

Do a site search on Tankless water heaters as there have been several discussions.

[highlight]This is not the same thing as a ventless heater[/highlight]. And I agree with PEG - don't use any combustion appliance that vents its exhaust gases to the interior of the building. Good way to make yourself sick or dead.  

[Amanda_931]

I really do love a gas cook-top, though.  You can and should run an exhaust hood (for any stove) but AFAIK there is no supply air intake system for a gas stove.

[mboehler]

Hmm.. with what I've been reading in another thread, maybe we should just go all electric.  Electric heater, electric water heater, or perhaps electric water heater w/ radiant system.  I wouldn't imagine it would cost too much to do a radiant system for a 224 fsq ft cabin.  

Electric seems like it would be easier to install and less dangerous.  Of course if the power goes out, everything goes out.. lol

[glenn-k]

Many demand electric water heaters require more power than your whole house - possibly have to double your service size for the larger ones.

[bartholomew]

If you want electric and radiant, you could also look at some of the wall or ceiling mounted radiant panels by Calorique, Enerjoy, etc. I think they'd be quite a bit cheaper than a pumped water system and might be more appropriate for what might become a workshop... quicker to heat, no concerns about freezing.

[mboehler]

I did a Google search on those electric cove heaters.  They look pretty interesting.  You are supposed to mount them about 4 inches from the ceiling.  I wonder if they work with cathedral ceilings as well.  

If we do go with an electric water heater, it would be a tank type, something small, like a 15 gallon probably.

[Amanda_931]

I used to be on a list with a woman who just loved her electric demand heater, thought it really did save her 20 bucks or so a month.

And it took up so little room, she had room for more of her art supplies.

No way I would have a one-heat house.  Been without electricity for days on end, and that was in the city, gas can get scarce, wood takes quite a bit of fussing, etc.   Kerosine may be considered more dangerous than it is (you "clean" one of those portable heaters by letting it run out of fuel), but it still doesn't seem like something you should leave on when you are asleep or gone. etc. Those fuel oil systems like Glenn has may be just fine, but see Ranting Al on that subject.

[peg_688]

Here's the Rinnai we use:

 

 



It vents out the slot in the access door , the gas is not yet hooked up on this unit .