Small Cabin

# Posted: 4 Sep 2015 09:48am
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Look for an automatic changeover RV propane regulator.

Here's a link to pipe sizing charts. Use the BTU INPUT ratings for all the appliances. Size the pipes appropriately. A guess will have to suffice on the unknown item. Size pipes to handle the volume needed

creeky
Member

# Posted: 4 Sep 2015 01:48pm
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might want to put your hot water heater on an outside wall just to make venting easier.

# Posted: 8 Sep 2015 08:38am
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So for the regulator, I don't need anything special? Just a regular RV one will work?

I have thought about putting the water heater on the direct opposite wall from where it is now which would put it on an outside wall. Probably what I will end of doing.

I struggle reading diagrams/charts but I will study the chart that was referenced above and see what I can come up with as far as pipe sizing.

# Posted: 8 Sep 2015 09:40am
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As long as the regulator capacity meets the needs of all the appliances. Check that. And as long as there is no inspection as most RV products are not approved for residential use. I should have pointed that out first.

MJW
Member

# Posted: 9 Sep 2015 05:04pm
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We have been using an RV auto changeover with our 2 100 lb tanks for over 2 years now. Works very well.

# Posted: 11 Sep 2015 08:02am
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So, I have bought the RV auto changeover regulator and the Bosch 330 hot water tank. The only thing left to buy is the direct vent wall heater which I haven't selected one yet. Home Depot has a 14,000 BTU unit for $469 which seems to be the best deal I can find.

I do have a question around the regulator to 100lb tank hook up. I ordered this regulator and two pig tails to go from the tanks to the regulator which you will see in the link below. My concern is that these pigtails are not large enough although in the description it states they are capable of handling 200,000 BTU's. I will be entering the cabin with 1/2 in. black iron pipe.

http://www.amazon.com/Camco-59005-Double-Stage-Auto-Changeover-Regulator/dp/B0024ECBC A

Also, my other question is around the tanks themselves. They did not come with the same fitting as you see on the 20lb tanks so I can screw on the pigtails. Here is a picture of what the tank connections look like. I ordered something that looks like this which I assume will work.

http://www.amazon.com/GrillPro-11051-Universal-Propane-Adaptor/dp/B0029T5U0A

Propane_Tank.jpg

# Posted: 21 Sep 2015 08:43am
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Has anyone installed a Bosch 330 Propane hot water heater? Would like to see some pictures of your installation.

I am struggling with a few things in regards to this unit. When reading the manual it appears that cold air can be pulled down the flu and potentially freeze some components of the heater. I am planning on installing a wood burner stove as well but when it is in use it could pull the cold air down into the flu down into the water heater. I also was planning on installing a vented propane wall heater. I have already bought the Bosch 330 and was going to install it in a 5 x 2 utility closet which is on an exterior wall in the bathroom. I was planning on venting it out the back wall and then straight up the side of the wall to above the roof using Type B Vent. The manual is confusing to me whether I can actually do this. I was going to go out of the unit with a 12" straight pipe and then a 90 out the back wall and then another 90 once outside so that it could then go straight up. I know that it would be better to just go straight up and out the roof but that would mean the B vent would go up through my loft area and be visible and also I assume the vent pipe gets hot to the touch when the heater is running. This room will be heated when we are using it in the winter but when not my plan is to drain it and blow it out with compressed air.

The other issue is in regards to combustion and whether I would have enough combustion air to run this unit safely. The cabin is 432 sq ft with a vaulted ceiling. I could be sure that the wall heater/furnace is not running when someone is taking a hot shower but what I couldn't control so much is the wood stove. The wood stove I was planning on using does not have the option to use a cold air intake to the outside. So now I am reconsidering swapping it out for one that does or not using one at all but I am concerned about just having the one heat source (propane vented wall heater). It could get expensive to run it all the time. We will only be using this cabin a few weekends during the winter.

Any help would be greatly appreciated.

# Posted: 21 Sep 2015 10:05am
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Quoting: VC_YamahaRider

was going to install it in a 5 x 2 utility closet which is on an exterior wall in the bathroom.

I think that is a problem. That is what is called a confined space in heating lingo. Installing the heater in a confined space has special fresh air venting requirements. See section 4.5 of the installation manual. Reading that it would seem that even if the unit was installed in the main open space of the cabin you may not have a large enough interior volume to safely operate.

The manual mentions the potential problem of a wood stove drawing air down the water heater exhaust vent. It does not mention that there is also the potential problem of the water heater burner causing a down draft through the wood stove chimney.

If you look at the installation of a furnace and water heater in a typical new, built to code residence, you will see fresh air venting in place when the furnace or water heater is installed in an interior closet. That is to provide the needed combustion air.

Section 4.6.2 indicates that it is okay to run the B-vent horizontally as long as there is a minimum of 12"vertical directly above the unit. It also mentions the max ratio of horizontal to vertical pipe and to have a minimum upwards / outwards slope of the horizontal section. I don't see the B-vent as being a problem, however the combustion air needs proper addressing.

Can you return the water heater? Since this is a part time recreational property an old fashioned, well insulated, tank style electric water would not be horribly expensive to operate and it would not have combustion air or exhaust vent issues. That would also be much easier to drain safely for winter. Just my thoughts on it. Goes against the grain of water heater efficiency I know, but everything is relative.

# Posted: 21 Sep 2015 10:55am
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MtnDon - thanks for your reply.

Looks like the minimum cubic feet requirement for the Bosch 330 is 5850 cu ft. My total cabin is around 6500 cu ft. I assume that 5850 is the minimum if you have no air intake or other propane appliances running. Correct?

The only problem with an electric water heater is that I am off grid with a small solar/generator set up. I am only running a 300 watt inverter. I will use the generator for larger appliances. I know that there are smaller RV propane tank style water heaters but you have to provide an access to the outside.

# Posted: 21 Sep 2015 12:11pm
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I like the Bosch on demand heaters. Just thought there might be an easier installation, but I understand the electrical power issue. When you plumb that system try and include an easy method to drain and blow out the system. I have a friend who included a Schrader valve to permit easier air blow out. The plumbing inspector probably won't like it but that and some drains make it easier to winterize. That is critical.

Yes the cabin total volume is in the "okay" zone. But placing the heater in a closet obviates counting that larger space. If there was no door on the heater space that would likely change that. I believe there is danger of the burner flaming out and definitely a danger of CO production when there is insufficient interior air volume. When operating those consume a lot of air.

Off the topic at hand entirely, but your mention of being off grid and having only a small inverter raises the question of what kind of cookstove you will use. Propane range? With oven? If so are you aware that virtually all gas ranges with electronic burner ignition require 400 or so watts of AC in order to operate the gas oven?

# Posted: 21 Sep 2015 01:07pm
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I think now I am going to look into an RV style propane water heater. 10 gallon or so and cut a hole in the exterior of the cabin and access it just like I would my RV. Seems safer to me but I would like to find one that doesn't use any type of electronic ignition. I am okay with just manually lighting it.

I wonder if there is any pictures on this site where someone has used this style of water tank and cut an access to the outside?

Good question MtnDon on the propane range. I am going to use an older style propane range/oven that a friend gave to me. I think it might have an electronic ignition but was hoping I could just by pass it an light it with a match.

# Posted: 21 Sep 2015 01:46pm - Edited by: MtnDon
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Quoting: VC_YamahaRider

.... hoping I could just by pass it an light it with a match.

That works for the electronicstove top burners. But with those that almost always means the oven has a glow bar/plug and needs AC. AC could come from a generator of course.

We used an RV water heater; Suburban brand, 6 gallon size. Pilot light, no electronics.

I have photos of the installation here. and here more here You have to scroll through several days to see everything to do with the water heater.

As you can see I added insulation around the heater tank. One reason was to keep the cabin interior cooler in summer. A side benefit of that has been that for most of the time the pilot gives enough heat to keep the water hot enough for regular use. Regular use meaning for anything except shower use. Even then if there is only one 'navy style' shower there is enough hot water. The water actually reaches a temperature that would be called unsafe in a normal residence. When we arrive to a cold tank I light and start the burner. When the burner shuts off then I usually turn the control to pilot.

Last time I looked there were still water heaters by Suburban that were pilot light models.

Of course with one side open to the exterior the tank will freeze if left full and the burner off.

The Suburban should fit through the wall with studs 16" OC. Atwood, the other RV water heater brand requires larger spacing or cutting studs.

# Posted: 21 Sep 2015 02:57pm
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More to think about.... Is your propane in small or large cylinders? 20# being small, 100# being large. Small cylinders can run into problems in cold weather. The cold makes propane slower to turn from liquid to gaseous state with small cylinders. I ran into that over the first winter.

Some info regarding winter weather and propane in small cylinders.... I thought I had posted that here but could not find it.

# Posted: 21 Sep 2015 04:34pm
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Wow MtnDon, I haven't seen your cabin set up yet until today. It is amazing! Thanks for sharing.

I think the Suburban tank is the way to go. I think I seen a 10 gal option available. Are you still using the RV water heater currently? If so, you happy with it's performance?

I am using 2 100# propane tanks.

# Posted: 21 Sep 2015 06:01pm
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Quoting: VC_YamahaRider

If so, you happy with it's performance?

Yes it still does the job for us. There is a 10 gallon version as well.

There are 4 different combinations.
The basic pilot light version (mine)
Pilot light plus a pilot light version with an included 120 volt electric heater element.

Direct spark ignition, no pilot
Direct spark plus the electric element.

In hindsight I wish I had gone the extra for the pilot plus electric element model. Reason? Then I would use excess solar power to heat water. Not a big deal but it would have been cool.

# Posted: 21 Sep 2015 09:44pm
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I think I am going to go with the basic pilot light version in 10 gallon. I would like to go with the pilot plus electric element model but it is $100 more. Need to watch the budget. Does these RV propane models require combustion air from the inside of the cabin? I know I need to get a door for this but what else do you recommend me getting to get this tank installed? What size propane line does it require? It will only be about 10 feet from the propane tanks.

I need to check my oven/range now to see if it has a electronic burner ignition. It is probably at least 20 years old.

# Posted: 21 Sep 2015 09:56pm
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Hi Yamaha- just a couple things to add to MtDon's good advice.

Your total BTUs, if you use the Bosch and a 30k stovetop, would be about 180k. Looking at the chart for 11 in. WC, on the 30 foot column, this puts you just over the capacity of a 1/2" pipe. So any trunk line you run that is supplying all appliances should be 3/4", but as soon as you branch off a major appliance the trunk can go to 1/2".

I suggest you reconsider using the Bosch, and install it indoors in its own sealed cabinet. This is what I am going to do. Any water heater you put outside the heat envelope of the building will be subject to freeze problems. Having the Bosch indoors will keep it warm.

You are wise to be careful with combustion air. To avoid problems, install a combustion air duct under your woodstove so it can suck air from outside while in use. What I plan to do is place a Bosch 330 in a sealed closet and provide outside combustion air to the unit via 6" ducts that run from the closet to the outside. You need to supply outside air to the bottom and to the top of the closet, then weatherstrip the door to the closet to separate it from the cabin air. I'm not going to insulate around my closet so cabin heat will contact the water heater. The 330 has explicit instructions on combustion air, read them carefully.

B vent flus should never be run less than 45 degrees for proper venting, and the total horizontal distance covered should never be more than 75% of the total vertical distance run. You can run a vent connector horizontally, or minimum 1/4" per foot. A vent connector is in the same room as the appliance, does not pass through any wall or divider, and connects to a flu that does. The 75% rule still applies.

Good luck.

# Posted: 21 Sep 2015 10:29pm
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MtnDon - I was looking at your pictures and posts from the links you provided above. What model direct vent wall heater are you using?

bldginsp - my plans were to install the 330 inside. I can build a cabinet and do what you are saying with the 6" ducts that run from the bottom and top of the cabinet to the outside but what do you do with the B vent? The B vent will have to come up through the top of the cabinet as well, right? I can meet the minimum 12" of vertical pipe directly out of the water heater but I have to do a 90 degree elbow right after that to then terminate through an exterior wall. Once outside, I then would do another 90 degree elbow so that I could go about 20 feet up the side of the exterior wall to reach above the roof line.

The wood burner that I was planning to use is one of the vogelzang boxwood stoves and it doesn't have the option to vent to the outside. I am now reconsidering selling it and purchasing a stove that I can vent to the outside.

The vented propane wall heater does vent to the outside so I am assuming it doesn't pull air from the inside of the cabin, right or am I wrong on that?

# Posted: 21 Sep 2015 10:42pm - Edited by: bldginsp
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Correct about the direct vent wall heater, it gets its air from outside. It has a double flu. Good design.

You don't need to connect a woodstove directly to a duct to get air from outside. Just install a 3" duct under or behind the woodstove, that goes to under the cabin or out the wall and just lets air into the room. It lets cold air into the building but it doesn't matter if it's next to the stove. Put a screen on it to keep out the leprechauns.

B vents don't like 90 degree turns. I suggest you go straight up through the roof, whatever it takes. It might work with the 90s, it might not. Definitely not code compliant, but that doesn't mean there is not a chance that it will work. If it doesn't work the water heater closet/cabinet will fill with gasses and you don't want that. B vents need mostly vertical orientation so the hot gasses can flu upward and outward. This is called drafting and it is not automatic, the design has to allow it to work.

I plan to extend my water heater closet all the way to the roof and run the B vent inside of it. There is a code provision that says if a water heater is installed in any sleeping room it needs to be in a sealed closet like this. All small cabins are sleeping rooms of course. The idea is that if it screws up the combustion gasses are kept out of the sleeping area. A pretty good idea since every year a certain number of people die in their sleep from carbon monoxide poisoning from screwed up gas appliances. Yuck.

# Posted: 22 Sep 2015 08:08am
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Unfortunately I don't have the option to go straight through the roof because of my design.

Looks like will have to go with the RV water heater. I just seems to be safer and easier to winterize. I hate that I have to cut a big hole in the exterior wall but I just feel this is my best option.

For the wood burner, a 3" duct seems to make sense and easy to do. What type of material do you use? Just 3" PVC?

# Posted: 22 Sep 2015 08:15am
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Yes anything. You are just letting air in from the outside so the woodstove doesn't create a vacuum in the cabin. But you need to screen it for critters and maybe install a shutoff door for when the stove is not in use. Most woodstove manuals will tell you the area that is required. 3" is probably way over that. For my little Morso it says I think 2 sq inches. You don't need much. All it does is equalize any pressure difference between inside and out.

# Posted: 22 Sep 2015 10:33am - Edited by: MtnDon
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Quoting: VC_YamahaRider

The vented propane wall heater does vent to the outside so I am assuming it doesn't pull air from the inside of the cabin, right or am I wron

Correct. Ours is a Housewarmer, bought from Northern Tool. The larger model, new version has some changes. Made by Empire.g on that?

# Posted: 22 Sep 2015 10:48am
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Quoting: bldginsp

B vents don't like 90 degree turns. I suggest you go straight up through the roof, whatever it takes. It might work with the 90s, it might not. Definitely not code compliant, but that doesn't mean there is not a chance that it will work.

Are you certain on that?? Found this CA Residential code document online. It appears to have no problems with 90's at least they illustrate many. Isn't it just that a horizontal run reduces the BTU rating / capacity of the fkue size? And there is supposed to be something like 75% vertical to a maximum of 25% horizontal?

Not to mention the 90 degree on our water heater and that I see 90 degree bends listed in the Selkirk B-vent catalog. Confusing.

# Posted: 22 Sep 2015 10:55am - Edited by: VC_YamahaRider
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MtnDon - You mention that your water heater has a 90. Are you referring to your RV water heater?

Does these RV propane models require combustion air from the inside of the cabin? I know I need to get a door for this but what else do you recommend me getting to get this tank installed? What size propane line does it require? It will only be about 10 feet from the propane tanks.

# Posted: 22 Sep 2015 02:31pm - Edited by: MtnDon
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Quoting: VC_YamahaRider

a 90. Are you referring to your RV water heater?

No the one in the suburban house, built by a developer. I have no idea what code changes there might be between then and now. But the supply departments have loads of 90 degree B-vent elbows. ????

RV water heaters use no inside air. It is direct vent to the exterior. All you need is the water heater and the exterior door accessory. Note: they are not listed / approved for residential use. An inspector might fail one. But they do work. Also note they are not the most efficient heaters; lots of waste heat is vented. For limited use I have no issues though.

RV's use 3/8" copper tubing for the propane hookup. It is a flared fitting on the heater. I would install a gas shutoff someplace close to the unit. I do that for all gas fueled devices.

There are clearances that should be observed too. If you read the installation instructions for a direct vent space heater you will find a list of clearances from windows, doors, etc. Follow those to be safe... applying the same rules to the RV style water heater.

That section of the IRC does require some study to make sense of it, same as much of the code does.

# Posted: 22 Sep 2015 03:00pm - Edited by: MtnDon
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This page has a table for vertical and horizontal (lateral) runs and different size vent pipe as well as fan forced air vent and natural (no fan). You can see how the appliance rating in BTU/Hr gets reduced as the lateral component of the vent increases in length.

As with all codes, local governing bodies can make the requirements more stringent than that in the code adopted by the state.

The pertinent section of code also makes many references to follow the instructions of the appliance.

# Posted: 22 Sep 2015 03:29pm
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You're right Don, 90s in B vents are compliant, I was wrong that they are not, but I think still not desireable unless you follow the listing instructions for the vent pieces carefully. Note that 90s in the vent reduce the capacity of the vent to handle the BTUs of given appliances.

Here's the basic rule out of the Mechanical Code:

802.6.1.1 Type B or Type L vents shall extend in a generally vertical direction with offsets not exceeding 45 degrees, except that a vent system having not more than one 60 degree offset shall be permitted. Any angle greater than 45 degrees from the vertical is considered horizontal. The total horizontal distance of a vent plus the horizontal vent connector serving draft hood equipped appliances shall not be greater than 75 percent of the vertical height of the vent. [NFPA 54:12.7.3.2]

But this can be superceded by listed products, such as 90 bends, which are pretty common. But the manufacturer will have specific instructions on how they can be used and the limitations of the overall design of the vent system in which they are used.

The general idea in any venting system is- keep it going up. It can't draft horizontally unless there is enough vertical rise to literally suck it through the horizontal part. The vertical rise of hot gasses is what gives the drafting force that keeps the gasses moving. All the old mechanical contractors drilled that into my head early. Exceptions are for connectors and listed equipment. But just because it is listed doesn't mean it will necessarily do the job- too little hot flu gas in a cold flu may not rise and begin to draft. I'd be very cautious with any installation involving a length of horizontal flu, no matter how short.

# Posted: 22 Sep 2015 04:35pm
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As of right now, I think I am still leaning on towards returning the 330 and getting the 10 gallon suburban RV water heater.

I looked at the Housewarmer 15K BTU unit and it looks like a decent heater. This will be installed about 30 feet from the propane tanks. What size gas line does it require?

I am working on printing off both of the manuals for these appliances so I can read up on the clearances.

I really appreciate your help MtnDon and bldginsp on these topics.