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jeffgreef
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# Posted: 30 Jan 2012 08:57am
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If you mount a small 'camper' type on demand water heater on the outside of your cabin, the pipes will freeze in winter when it's not in use. Mounting inside will prevent this, but the camper types are not designed for an inside flu. An inside type water heater will work, but most of those are designed to plug into house current. The camper types use batteries.
Anyone seen a low capacity, battery operated, propane, indoor mount, on demand water heater?
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jeffgreef
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# Posted: 31 Jan 2012 03:16pm
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Answered my own question. Bosch makes several models of propane on demand water heaters which are made to install indoors with standard B type vents, and which use a Piezo type ignition which does not require any electrical hookup. This is what I need for my off grid location, where I want the heater mounted indoors so that in winter the pipes will be protected. If you do this kind of installation, be sure to do the following:
1-Install the gas piping to the heater carefully and do a pressure test on the system to ensure that you won't be leaking gas into your cabin. Put a shutoff valve on the end of the hard pipe so you can disconnect it.
2-Provide adequate combustion air for the heater to use while burning gas. Instructions should tell you minimum requirements.
3-Install the B vent through the roof with a jack that will cover it but freely allow the gasses to escape. Maintain 1" clearance to combustibles around the vent itself.
Your local building department wants you to get a permit for installation of any gas burning appliance so they can inspect to avoid the potential dangers. If you don't get a permit, research the entire installation to be confident that you're doing it right. It's not worth burning your cabin down or killing yourself and others in it with carbon monoxide.
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wakeslayer
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# Posted: 31 Jan 2012 03:32pm
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I am curious as to why your pipes would freeze on the outside installation, but not the inside. Where are you? Do you always heat the inside?
Also, you can just blow them out to prevent freezing. The Takagi I have has a drain built into it, as well.
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MtnDon
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# Posted: 31 Jan 2012 04:10pm
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Not all on demand heaters are provided with drains. Also, not all drain dependably unless carefully blown out with air. I know someone who thought they had drained it properly, but they found otherwise and had to replace the unit. Sorry, but I have no recollection on the brand or what brands will drain completely enough to avoid the freeze problem.
Outside mount on demand heaters used in an environment where there is a grid power connection will sometimes have an electric heat element to prevent freezing. Not good off grid.
When using an on demand indoor model be careful about the combustion air requirements. IIRC, there is usually a minimum number of sq ft floor space recommended. As well they are not permitted under codes, to be installed in a sleeping area unless it has an outside source of combustion air.
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jeffgreef
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# Posted: 31 Jan 2012 06:14pm
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Thanks Wakeslayer and MtnDon-
Wakeslayer- As Don says it can be drained, but when I am there I don't want to drain it every night when I go to sleep, if it is outside. I'm in the California Sierras at 4,000 feet where it gets in the 20s at night. When I am not there I plan to drain the system, but MtnDon's point that it might not drain completely is relevant, because as soon as I leave and the woodstove is not lit, the whole cabin freezes at night, whereas when I'm there an interior installation will be inside the heated space.
MtnDon- Good points all. I will need to check about drainability of any unit I get. I will arrange all the copper piping to drain from valve outside, but if water remains in the heater element and can't escape during a drain, it will freeze and screw up the unit, probably what happened to your friend.
You are right that the codes prohibit installation of a water heater in a bedroom. So, is installation of a water heater in a dedicated closet in a one room cabin therefore in the bedroom? The local building official will have to decide. At worst I'd have to make an exterior mechanical closet, but then I'm back to the freezing pipes issue.
Combustion air is critical in any interior gas burning appliance situation. In a small cabin, it's not wise to rely on the volume of air in the cabin, even if it is large enough to meet the code requirements. I was going to route air to the water heater closet up from the under floor space. When you do this, check the codes to see what dimensions such ducts or in-wall air spaces must be to supply enough air.
Thanks
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MtnDon
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# Posted: 31 Jan 2012 08:23pm
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Quoting: jeffgreef So, is installation of a water heater in a dedicated closet in a one room cabin therefore in the bedroom?
The IRC permits a fuel burning water heater in a sealed closet in a bedroom. That means there must be an adequately sized source of combustion air. The water heater closet must not be used for any storage.
A direct vent heater does not need to be in a sealed closet as it draws combustion air from outside.
Our home draws the combustion air for both the furnace and water heater from a duct that extends from the unconditioned attic space down to the floor of the heating utilities closet. The doors are "sealed" with tight fitting weather stripping. The closet walls and ceiling are also sheetrocked with 5/8 type and the door has a metal skin on the inside.
As a side note, we used type X in our cabin wherever drywall was used; better fire resistance, just in case...
A further side note re on-demand water heaters... Some manufacturers limit or void the warranty when used in areas with water above a certain hardness level. Best to check on that before purchasing. The heater coild get scaled easily with hard water and the high temperatures on deman heaters produce.
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jeffgreef
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# Posted: 31 Jan 2012 08:50pm
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I wasn't aware of that in the IRC, Don. Thanks
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DirtBikeMomRN
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# Posted: 1 Mar 2012 08:04pm
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Jeff thank you for all of your posts about water supply. Hubby and I have owned a cabin in PA for 10+ years and are finally getting around to installing an rainwater catchment system for an indoor toilet/shower/sink use. I am grateful that you have shared your experiences, questions, and answers.
Best wishes!
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swattley
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# Posted: 3 Mar 2012 11:13am
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dirtbikemom i would like to hear your plans, i have my cabin in ny state and thinking about rainwater for showere and sink. for toilet i have a sunmar compost toilet so no need for septic, and i plan on a eccotem L10 water heater with a dc pump for head pressure that the heater needs
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rayyy
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# Posted: 3 Mar 2012 02:42pm
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I must admit,I have an Eccotemp L-5 mounted to the wall next to my bath tub/shower stall.The way I see it,the propane gas burner in this heater is no different than the propane gas burner on my kitchen stove.I take a nice hot 2 minute shower every morning.(With the heater)than I heat a nice hot cup of 2 minute water for my coffee.(On the stove).either sorce,the amount of fumes is neglegable.The cabin is not that air tight to pose a risk.I do have a C.O.detector monitering the air in the cabin just to be safe.If the tempiture falls below freezing whether your heater is inside or outside,your heaters gonna freeze.Best to drain it all down completely if your gonna leave your cabin unattended and unheated.
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jeffgreef
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# Posted: 3 Mar 2012 06:06pm
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Rayyy- I'd say there is a big difference between your water heater and heating a cup of coffee. In a two minute shower you use several gallons of water, and use probably 10-20 times as much propane as it takes to heat a cup of coffee. Granted- all indoor stoves put off products of combustion that you breathe, but an on-demand water heater burns a lot of gas in a short period of time.
Could be that with just one or two quick showers a day it's no problem, but that one time someone takes a long shower... I hope the CO detector saves you then. Please be careful. Don't mess with gas, or it'll mess with you.
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jeffgreef
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# Posted: 3 Mar 2012 06:08pm
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Thanks for your appreciation DirtBikeMom
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beachman
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# Posted: 5 Mar 2012 08:38pm
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Great thread here. I am installing a Bosch 1600 LH (piezo ignition) this year at our place for a shower along with a low-water Sunmar toilet and a small DC pump with 35 gal water tank above to complete the whole works. I have the Type B venting installed already and have the shut off valves so I can remove the unit in the fall as I do not want it to freeze and not sure if I can drain it properly. It will be in use during the Spring, Summer and Fall but I do not think I can use it in the Winter as the camp will be unattended for long cold sessions and will be in sub-zero temps for long periods. I'll let you know how things work out later this summer. I have no outside venting to provide air for the unit so I will have to watch it - there is a window that I can open temporarily to provide air if needed. MtnDon makes good points. I may have to provide some sort of venting from under the floor with a screen for critters - we'll see.
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jeffgreef
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# Posted: 7 Mar 2012 07:41am
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Beachman-
I hadn't thought of removing the water heater for the winter, that certainly works, but I will visit my cabin in the winter and don't want to have to hook it up every time.
To clear it, I thought of this- on both the water inlet pipe and water outlet pipe place two valves, total four valves. At each pipe one valve shuts off the pipe to the house system, the other valve opens a drain. Then, I planned to blow compressed air into one of the drains so the water flows out of the other. I don't want to bother with an actual compressor for the air, though small cheap ones exist that are electric powered and can be charged with a small generator. Rather, I thought I would keep one of those hand pumps at the water heater which is made for filling air mattresses. I hope, but don't know for sure, that this would provide enough pressure and flow of air to clear the water heater passages.
Then I'll drain the whole water system, which means it must be designed and built to facilitate this.
Post with how your Bosch installation works out.
Does it require a certain amount of water pressure to operate correctly?
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wakeslayer
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# Posted: 7 Mar 2012 10:09am - Edited by: wakeslayer
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Jeffgreef,
I think this is a perfect fit. I used one to blow my water heater and water system out. Portable, and doesn't take much juice to fill. I think an actual air compressor will ensure you get more water out than a hand pump. It also runs small airtools nicely. Lastly, it is very inexpensive.
Senco
Just sayin'
Mike
kick ass little air compressor
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beachman
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# Posted: 7 Mar 2012 07:35pm
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The Bosch system works best (so they say) at around 3-4 gal pm. I got a Whale pump and accumulator tank from a marine supply shop that will run on a 12 v system to drive the shower. I think you need at least 3 gpm to run the piezo igniter. Blowing out the system is a good idea. That compressor looks good and would do nicely I suspect. Make sure stuff is open or you'll blast a hole in something.
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jeffgreef
Member
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# Posted: 9 Mar 2012 08:37am
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Wakeslayer- I probably will benefit from having the compressor a lot more than I think during construction- finish nailer, stapler, etc. I'll put it on the long list....
Beachman- I thought that the Piezo is just a push button that ignites a pilot- you seem to imply that the Bosch piezo is operated by water flow. Is that so?
In my case I have a large water tank up the hill so water flow is not an issue. But it definitely is an issue for those with rain barrels on the cabin itself. If you collect water off the roof, the barrel it's in is too low to provide any water flow to the cabin. So you'll have to pump the water up on the roof to a barrel there or up a water tower. In this case you still may not get the water flow required to operate the unit. Larger supply pipe size will increase the flow rate, even if the last 6 inches of pipe to the water heater is only 1/2" pipe.
Anyway readers should be aware of the flow requirements of any water heater they consider.
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foxdud
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# Posted: 20 Oct 2013 10:32am
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I use the EZ Tankless propane on demand water heater. I do have it mounted indoors beside the shower and above the toilet vented out through the wall. I have a main water line coming from my 12v sureflow pump It works just like your water would in your house, flawless! I can not say enough about the EZ Tankless they work well!
As far as fumes, there arent any and for as much as you use it fumes should never be a issue.
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