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RMH design question  RSS feed

 
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I am brand new here and did look around at some of the posts about RMH's. I am also new to RMH's in general. I have one question about how they are designed and if I can incorporate one into my existing set up. Forgive me if this subject is covered somewhere else on this forum, I did not see it.

I bought my house a year ago. It has a brick chimney with what looks to me to be new stove pipe lining it. It comes into the house in the basement. There is no stove of any kind in the basement, just the pipe stubbed out. I already have a central air/forced hot air furnace(The heat is produced by propane) and a propane fireplace in the living room. Both of these are fed from the same propane tank in the back yard. I was looking at putting a wood stove in the basement for a back up heat source when I was re-introduced to RMH's.

I understand that a certain amount of horizontal distance is required for the exhaust on an RMH before it exits the house. All the designs I have seen show the exhaust leaving at ground level. My question is: Can I build an RMH in my basement to the correct specifications but have the exhaust pop up at the end and connect with the existing pipe coming through the wall at about 4 or 5 feet high and use the existing chimney for the RMH?

Any advice or info is greatly appreciated.
 
gardener
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Greg; RMH in the basement are frowned upon, but using your existing chimney should work . You need to know what size it is as well as its condition . Have a professional chimney sweep do an inspection. Make sure your insurance will let you use a wood stove. get a copy of ianto evans book rocket mass heaters and read up. Put the propane fireplace in the basement and replace your couch in the living room with the mass from your rmh , make it the heart of your home and you will love it.
 
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Technically... probably. And of course it depends. It is better to exhaust vertically out of the mass and to a point above your roof peak which this chimney probably satisfies. You will need to have a screened cap on it so animals and rain don't get in.

That being said, nothing is a slam dunk in exhaust or chimneys especially dealing with RMHs.

Do more research and see more systems. The fact that you weren't sure if you could go vertical after the horizontal run shows you still have a lot of easy helpful viewing and reading to enjoy.

Look at ernie and erica Wisner's work. Paul has a few good videos on his youtube channel. Also a few good podcasts with the three of them are very informative. The Wisner's sell plans and literature and the 4 dvd set "wood burning stoves 2.0". This is also available through Paul at "stoves2.0".

Every system is site specific to the install. Many factors can not be figured until an understanding of RMH design is coupled with the house, land, operators, etc, etc.

Hope this helps and happy investigating.
 
pollinator
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Greggery Kunkle : Welcome to Permies.com, our sister site Richsoil.com and a Big Welcome to the Rocket and Woods stoves Forum Threads!

Location, look at your name and L@@K at mine (and other long time posters ) While your fast answer is yes, kinda, we need more information from You!

At the Top of this page across from the Permies Spinning Sun is the Permies Toolbox. Find and click on the [MY PROFILE] space, at the next page you will be
directed to Add general information that will allow us to give you better reasoned answers appropriate for your location, and probably help you find a near
neighbor/fellow member with Rocket or Cob experience !

It would be nice to have the age, and style house with layout and minimum number of square feet you would like to heat say during a total power failure !

Basement RMH Location has some problems- amplified if there is a second story or just a cathedral ceiling ! Here we run into The fact that all houses
breath. If they are so tight they can not breath you are living within a plastic bag/ a sick house.

Houses breath out warm moist air at the ceiling and roof /sidewall sill plate ! The house breaths in Denser cold air at breaks, cracks, and penetrations
for utilities where the sill plate/ foundation meet!

Two terms you must understand well enough to explain them to your grandmother are Stack effect and Whole House Stack effect !
this can have a major affect on your ability to locate a RMH in a remote location in your basement!

Simply opening a 2nd floor window in a warm house can create a stronger 'Drawing' chimney than the one dedicated for Your RMH, causing it to draft
backwards into your basement! This problem can also occur when trying to simultaneously run a Clothes Drier vented to the Outdoors, or the exhaust
fan located in your Bathroom, or the range hood over your kitchen stove !

RMHs should be a well crafted piece of built-in furniture, a multi-generational visual treasure given Ppride-of-Place in the heart of your home where the
tending of the RMHs needs is a rewarding and pleasant task. much like having a well endowed bank account into which you add regular deposits in the
form of small dry, fine split wood and make regular withdrawals of Heat, Warmth that literally warms your bones! It also can help cool your house
during the hot summers !

Why do you want the RMH in your basement, is it a finished basement with a rec-room, or do you have an office workshop area where you spend hours
everyday. Tending a Rocket when located there, can be a simple function done as you perform other duties in your Home, with no more thought than you
take adjusting your glasses while reading !

An RMH located in a remote area anywhere in the home will be an interruption of the pleasant household duties requiring you to put everything on hold
while you go check up on the fire in distant part of your house, often arriving late or too early, a drudges task, unwanted and often ignored! Your RMH
can only serve you as well as you serve it !

Your RMH must have a dedicated chimney of its own with NO other appliances trying to share that chimney. This means there must be a separate
chimney for your Fossil fuel fired Forced air (propane) Furnace, and likely one for your propane fireplace in your living room, it may have a horizontally
discharging exhaust exit mounted on an exterior wall of your home. Use a white handkerchief to wipe the area around its discharge to look for evidence
of carbon, soot deposits from a poorly breathing appliance that probably can not be run at the same time as your RMH !

Come back here often, If there is a rocket in your future we will help you find it ! For the Good of the Craft! Big AL
 
Posts: 19
Location: East coast USA
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Go with the basement, its only a backup?

Pros of a basement,
Dumping wood down outside entrance. try making a mess in your kitchen
Stacking 2 cords early in a basement, try this in your living room.
Heat will rise, heating floor boards, or old school, cut a large register right into floor.


Skip the mass rocket, and go downdraft, or cat wood stove.

I love making a mess in the basement, and sweeping it up without the other half blowing a cork about the dirt in the house.
 
Greggery Kunkle
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Thank you all for your advice. I am so sorry it has taken me so long to respond.

While I would like to put an RMH in my living room and move the gas fireplace to the basement, it's not going to happen anytime soon. Far too much work and expense involved then I can handle at the moment. I do understand the stack effect. I am assuming that the reason that RMH's are not a good idea in a basement is because of the stack effect. It competes with the air flow for the RMH.

My initial thought on the stack effect problem with putting the RMH in the basement would be to run an intake pipe from the outside connected to the input of the stove and have a door to feed the wood. This way the stoves air input would be separate from the house stack effect drawing from the basement. Just a thought. I know this would change the dynamic of the stove and would need to be researched.

I of course have looked at wood stoves and pellet stoves. I am researching RMHs to see if they could be a third possibility.

I very much appreciate all the info and suggestions on where to look for further reading. Thank you very much gentleman.
 
allen lumley
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Greggery Kunkle : I'm glad that you took the time to investigate the whole house stack effect,their were a couple of simple questions we need answers to -

Location size number of floors Minimum space you wanted to heat, how you expect to get the heat from the basement up stairs, do you have an office or
Rec-room to give you a reason to be down there !

You mentioned using an outside air supply,let me try again, on the upper right side of this page Below the Permies Banner and above the Permies video of
the week is the Permies Toolbox, look for find and click on the [Search] space, this will take you to anew page where you can enter the term outside air supply
for a rocket mass heater, At forums search scroll to the top and click on all forums then at the bottom of the page select a google search within
Permies this should deliver a few of the top articles on the subject .Ernie and Erica Wisner are the Forum moderators for Rocket and wood stoves, their
opinions are based on solid research. Good luck, happy hunting, For the good of the Craft ! Big AL
 
gardener
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Greggery Kunkle
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Thank you gentleman. I will check those out.

Quick answers to some of your questions. I have three floors total counting the basement. Square footage is approximately 1600 minus the basement. Roughly 800 more for the basement.

At present there is no real way for heat to get up except through the stairway with the door open. I am working on what will work best that I can do myself. I have a few ideas that I am researching.

The basement is mostly storage space with about a quarter of it being my work shop. One quarter of the basement where the steps come down is partially finished with two pocket doors leading into the rest of the basement. Those doors stay open. The previous owners attempted to finish the room off to be used as a living space but that is not what I use it for. Matter of fact I may have to tear out the finished walls to get to the basement walls to fix a minor water leak if I can't get to or fix it from the outside. The only part of the basement that is finished and that is where the water is entering, go figure. I plan on using this room for food storage mostly.

As I said I am just trying to see if an RMH could work and I appreciate all the tips and info you guys are sending my way. Please keep them coming. I am at work right now so I will check out the info you guys suggested this weekend. Thank you all again.
 
allen lumley
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Greggery Kunkle :In no particular order, With all of us jumping to welcome you to Permies and offer advice, none of us asked the most important question,
have you been to Rocketstoves.com to Download a PDF file of the brand new 3rd edition of Rocket Mass Heaters This was missed be cause it
falls under the category of ''but every one Knows how important that is !

It may be mistaken faith, but we all rely on a central belief that "The Book'' is always there as a back up to our answers. It allows you to further check our
advice and ask specific questions- like, in the book it says- Please get, read, and understand 'The Book'.

With over 100,000 rocket mass heaters Built word wide, Most of them were made following The Book, (look at the list of the languages this book has been-
translated into !) and 95% of all the new, 1st time builds ( that worked ) were made following the book.

Again your Key to a successful build is reading and understanding the book, it increases your pleasure in the build, as it reduces frustrations and saves time
and money, it also gives you a common language to use when you come here with questions and observations of your rocket mass heaters RMH Size(s) ,
Shape(s), and the orientation of its parts and to the whole

Your description of the chimneys location 4-5 feet up the wall, and the mention of your leak and down cellar work shop make me think you probably have a
basement about 2/3rds in the ground, and 1/3-ish above ground with a external door, to help move things into and out of your basement! So level ground
or built into a slope, or Am I All wet ?

You will need to check out the exterior chimney that stubs out of your basement wall, Size, like the ladies say is important, as is condition, see if you can get
your hand in there holding a mirror on a brite but cloudy day, a simple hand mirror will let you observe much of the chimneys condition. Later, if we go
forward with this basement project you will want a pros opinion of its condition, right now we need to know that no other heater is using the same chimney,
the interior of the chimney appears smooth, and the size pipe the chimneys builder thought to be appropriate for his build

You shared your houses size, and that it has 3 floors- counting the basement where you want to site your RMH. As installing an RMH any where in your house
is a retro-fit, some trade offs and less than ideal results must be allowed for, in this case without major surgery, it is unlikely that you will get much heat up
to your 3rd floor during a power outage and your plan for dealing with that event must include draining/protecting the plumbing in those locations !

There is a very interesting article on 'Heat Pipes' at Wikipedia as a way of transferring heat, and there is work being done now on using this principle to trans-
fer heat from Your RMH to another location, but it is very early days to walkabout this technology and its costs now !

I do want to make sure that while you are looking for ideas for your build, you use extreme caution, and skepticism when viewing anything on U-Tube.

There is a huge boat load of Steaming Crap out there in U-tube land! Plan on using nothing you see there until it has been vetted by one of your fellow
members here at Permies !

If I have come across as bossy or authoritarian, that was not my intent, I/we are just trying to show you a lived path as otters have done for us! We are just
paying it forward! For the Good of the Craft! Big AL




stove pipe size, 1/2 basement,leak the book location u-t wiki heat pipes
 
Greggery Kunkle
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Thank you Allen. I have not yet read "The book" I will do that. It makes sense to get myself on the same page and use the same language as everyone else.

I will use the mirror trick and get back to you.

Yes the house is built on a sloped property. The basement wall facing the front of the house (North) is completely underground. The two side walls are about half and half as the basement comes out of the ground as it slopes down. The back wall is completely above ground with about a third of it being covered by a foundation room for the sun room that was added in the mid 2000's. The walk out door is in the right rear side wall.

I just had a thought. I assume I can attach photos here? I see the different tools on this post. If so, I can take some photos of everything in question and post here to help you all see what I am dealing with.
 
allen lumley
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Greggery Kunkle : Yes you can! My Mac does not play well with others! don't ask me how ! Big AL
 
allen lumley
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Greggery K. : This will help your problem, not mine, But - at the bottom of this page where it says permies >> forums >> energy >> rocket stoves click on forums

This will take you to the forums listings page, scroll down to permies.com and find and click on tinkering with this site this should help you! !!! Good Luck !

For the Good of the Crafts ! Big AL

 
Richard Wood
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My basement, is similar, 3 foot exposed most of way around, with the garage doors at ground level. easy to get wood in.

How mine heats, is downdraft stove, No insulation in the ceiling of basement,garage the exhaust rises up through chimney, and new pipe cuts right through were fireplace used to be. Hole is opened up to let some draft action.

Floors will radiant heat , they get nice and toasty, to walk with bare feet.
1st floor, house (not base ment) will get 68 degrees. we like it there.

2cd floor, chilly. we just use elect space heaters if we need to go up there.

One day i'll get ichy and water tank next to my heater, and pipe a tank were the fireplace was, to transfer heat to water and let it rise.

hopefully you follow my jibberish.
 
allen lumley
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Richard Wood : I think you too will learn something good from the wikipedia article 'Heat Pipes', this was discussed at the innovators gather at wheaton labs.

It is certainly early days to plan on prompt heat bering delivered to remote regions of your home, bout the potential, AND the potential for transporting Coolth is
likely there !

For the Good of the Craft ! BIG AL
 
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Greggery Kunkle wrote:I am brand new here and did look around at some of the posts about RMH's. I am also new to RMH's in general. I have one question about how they are designed and if I can incorporate one into my existing set up. Forgive me if this subject is covered somewhere else on this forum, I did not see it.

I bought my house a year ago. It has a brick chimney with what looks to me to be new stove pipe lining it. It comes into the house in the basement. There is no stove of any kind in the basement, just the pipe stubbed out. I already have a central air/forced hot air furnace(The heat is produced by propane) and a propane fireplace in the living room. Both of these are fed from the same propane tank in the back yard. I was looking at putting a wood stove in the basement for a back up heat source when I was re-introduced to RMH's.

I understand that a certain amount of horizontal distance is required for the exhaust on an RMH before it exits the house. All the designs I have seen show the exhaust leaving at ground level. My question is: Can I build an RMH in my basement to the correct specifications but have the exhaust pop up at the end and connect with the existing pipe coming through the wall at about 4 or 5 feet high and use the existing chimney for the RMH?

Any advice or info is greatly appreciated.



Using an existing, tall chimney is usually preferable to building in the basement with a lower type exhaust.

There is no minimum requirement for a horizontal run on a rocket mass heater (you can hook one directly up to a chimney right at the manifold/barrel outlet, it just draws ridiculously hard and you'd have to crank down the air controls at the feed throughout most of the burn). The horizontal run is where you get your most useful comfort heat for a seating bench/bed, and allows a large storage mass with its load spread out over minimal foundations and its heat output low in the room to mitigate warm-air stratification. If a heated bench doesn't fit the space or intended use, a tower-like bell or a wall-shaped series of horizontal channels stacked on top of each other will also work.

A 2- to 3-story house will definitely have some of the stack effect that Allen so enthusiastically warned you about. You may need make-up air, or intelligent control of the natural draft up the stairwell while running the heater.

I favor make-up air (to the room) over outside air because it's easier to install safely, and easier to adjust as conditions change (you could put a vent on each side of the house, and just open the one on the currently-upwind side, for example). Bringing in outside air directly to the firebox in a basement is non-trivial - the outside air would need to come from that daylight side, not as a possibly-competing chimney trying to snake discreetly down the wall.

Intelligent operation:
If you did end up with negative-pressure problems not amenable to simple fixes, you might shut the stairwell door during sub-optimal draft conditions (while starting the heater / if anyone is running kitchen or bathroom vent fans / if the outdoor weather was creating a disadvantage for your chimney such as gusty or misdirected winds).
This should reduce the "suction" effect on your basement fire room.
You could probably open it again once the draft was working well (once the fire is going strong / mass and chimney are warm and drawing well / outdoor temperature and wind conditions give advantage to the stove).
Because of the mass storage, you would still be able to heat the upper parts of the house using stairwell convection by building heat-exchange channels into the mass, and using the mass as your heat source at most times.

To reduce the hassles of this kind of gamesmanship with your stove, you can configure it to put a bit more heat out the chimney. Less efficient, but also less of a hassle. Build it with a bell with slightly less internal surface area than Peter's recommendations for a given batch box, or a shorter set of pipes (2/3 or less) than the maximum length guideline for that J-style. The more heat you put up that chimney (200 or 300 F is common for masonry heaters), the more it will work for you as a positive, draft-ensuring feature of your rocket heater. The less heat you put out the chimney, the more of the intended fruit of all this effort remains in your house. It's a straight tradeoff, with about 500 years of development behind the current industry practices for all chimney-equipped indoor wood-burners.

Given the basement situation, and that you really do want some heat to those upper floors...
I'd be tempted to suggest a batch box with a bell (if you can get the skill to do a reliably-sealed capping slab or dome of some kind). The bell will not necessarily be lower-mass than the bench, depending how you make either of them, but it can be taller with less floor footprint.
I'd consider locating the heater where I can cut a hole in the floor, and let the suitably-insulated top of that bell poke up into the living area of the home as a heated floor, bench, or bed.
I suggest this because it sort of combines the functions of building a foundation to put the heater up in the living space, with your original idea of having the heater in the basement. It is more trouble than several other options, but might also give you more tangible rewards.
(While we're at it, the other problem with basements is tending the fire. You could do a periscope or fiber-optic board to let you see how the fire is doing. I'm envisioning one periscope to see the fire itself, and maybe another one that is oriented so it will only flicker if the flames are misbehaving (e.g. coming out the air intake or something).
Though a batch-box does operate on a more predictable schedule the way Peter tells it, so maybe a timer would be fine, along with a stove-operation log that lets you notice what conditions (weather, end of season, etc) affect that timing in the case of your particular stove. Ideally of course, the stove does not operate unattended; you're down there puttering in the workshop most evenings, and the upstairs signalling-board is just for convenience the odd night or two a week.

To pass the heater through a combustible floor, you'd make the cutout bigger than the heater, and re-frame the cutout with double or triple headers. Depending how the floor is laid out, you may need post-and-pier supports for the resulting spans. The heater should not be load-bearing, in case it (or the house) need future work.
The area between the heater and floor would either need a 2" air gap with non-combustible insulation to protect the floor, or a masonry wing-wall to connect the combustible floor and heater masonry. I would definitely consult a heater mason with more experience than me about the technical details, since the above two suggestions are from different parts of the masonry heater documentation (ASTM E-1602), and I'm not sure which would apply.

This is kind of a 'dream solution' that would address some of your goals, but probably cost more in time and expertise than a more standard solution.
A batch box / bell system without the hole in the floor would be simpler to install, and might do just fine (it might even turn the basement into a prime hang-out space, kind of the winter rec-room). A J-type heater with reclaimed materials could be much cheaper to install, and could also work just fine.

The beauty, and the cost, of site-built heaters is enhanced when they fit your situation like a glove. It sometimes takes an experienced expert to make all those tailored changes sing together safely.

Another thought from the cost perspective: If you think of this heater as supplementing your household heat budget, not as the primary heater, you might want to just use it when you're down there and not worry about storing heat in masonry mass. The basement walls are usually massive, and in direct contact with damp or even frozen ground outside. If there is insulation outside your concrete basement walls, hurrah! You have an ideal heat-storage battery, and even a plain low-mass radiant heater down there will effectively bank mass-storage heat in those walls for you.
Heating up the whole basement to the point where it's a net heat source for the building may not happen without insulation. So you might think in terms of a smaller-mass, clean-burning, wood-fired heater that lets you warm up yourself and your shop by direct radiant heat when you're down there puttering, adds a little bit of benefit upstairs as a token for the missus, and doesn't involve the complexity or expense of the higher-end masonry heating options just discussed. Something like a metal radiant bell on a 6" batch box, or a small barrel on an 8" J-type heater, whatever is closer to the current size of your existing chimney flue.

yours,
Erica W
 
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