Can i have an rmh too?

I live in eastern Ontario. Last winter we had 45 days in a row of nighttime temps of -25C or colder. My house is new and well insulated (R30 ceilings and R40 roof) total sqf of 1500. My chimney flue is 7inches.

What has given me pause is this quote from Ianto's book.

"In very cold areas or house over 1200 square feet you may need a bigger system altoger including a bigger barrel"

Since i am stuck with a smaller system (7") live in a pretty cold climate and my house is larger thati have 3 strikes against me.

What are peoples thoughts?

7 incher batch rocket with plenty of mass should do the job, as long as you leave all inside doors open.

Jeff M : Ianto Evans built his houses around his Rocket Mass Heaters, rather than adapting a Rocket Mass Heater into an exiting house as you are considering.

Also like most other wood stoves a RMH works as a Space heater keeping the core area of your home toasty warm. Attempting to use an RMH to heat the whole
of your house in frigid conditions will almost certainly result in overheating the core of your home while still leaving the far corners chilled.

So- starting from there- As a minimum your existing ( Fossil-fuel Fired Furnace/ heating plant? ) should never share a chimney with another appliance like a
water heater, wood stove or a Rocket Mass Heater RMH, However leaving your existing system intact while adding an RMH allows you to do two things that you
will see as very important in a minute - - - -

1) Allow you to be away from your home over a long weekend say, or a short stay in the hospital, or extended visits with relatives - weddings and funerals

2) Turn down your Thermostat, to provide supplemental heat at the far corners of your home occasionally as needed !

Consider how much of your house that you will actually need to heat, certainly you should be able to shut off parts of your house or at least turn down
thermostats,close off heat runs or zone valves !

I am sending you a link to a Sister Site of Permies.com to look at a way that major heat energy savings was made to an existing home -simply to review what
is possible. Your level of comfort, and Your Families level of comfort will be different than mine, this is mostly a thought exercise -

http://www.richsoil.com/electric-heat.jsp

Considering this option will allow you to more realistically consider exactly what an RMH heating the core of your home represents !

A final thought, This all assumes that you are willing to HAVE your RMH located within the true core of your home where it will be near your elbow easy to tend
to without any more thought than you would give to adjusting a pair of reading classes. Any attempt to place the RMH in an out of sight, out of mind, location
will result in finding that tending to the RMH Is a too frequent interruption of your home life, quickly becoming a Drudges task, unwanted and often ignored, the
results being that your RMH can no better serve you than you have served it !

If you want to carry this search farther we will need to have a sketch of the layout of rooms and number of floors to have a clue to help you find if a RMH is in
your Future

Think like Fire! Flow like a Gas ! Don't be the Marshmallow ! For the Good of the Craft! Big Al

(I had problem submitting a single long reply so i will try a few shorter ones)

RMH will be basement on concrete floor. In the middle of the room. Not on a wall.Once complete basement will become family room. during dark winter months I would be lying on the heated bench from 7 to 11 so stoking the heater regularly wont be a problem

I only heat with wood, with a Pacific Energy Vista unit. Too small. I have No furnace. No fossil fuels. Last winter house was in low 40s when I got home, low 50s when i left for work. So lowering the thermostat is not an option.

House is passive solar design, with an active solar space heater.

House is open concept, 22x24. walkout basement. Kitchen and dinning room on main floor. Two bedrooms and bathroom on 2nd floor

There is only one chimney so the rmh will replace the woodstove.

Have i missed anything?

7 incher batch rocket with plenty of mass should do the job

Jeff M. : While it is possible to have a remote radiator -generally called a 'Bell' here- after the Rocket Mass Heaters RMH's Bench/thermal mass. This is
well outside of my comfort area to begin offering advice on. It would seem to require an inside chimney.

So you want to heat three floors with Your RMH in the Basement, there are a few potential problems. You will have to Google 'Stack Effect' and 'Whole
House Stack Effect', this is not a intellectual exercise or 'Who-da thunk it' quick read- but a concept that you need to take in and understand in its entirety.

While having a new house mitigates Some of the problems, a really tight house creates its own problems providing proper draft for a RMH, such household
appliances as A Clothes drier, The Range hood, over your stove or a simple bathroom fan started while the RMH is running will often cause ''smoke back ''
into the home !

You say open layout, Probably a floor plan would help here if all the heat could just float up an open staircase most of the year you would end up with your
hottest air stratified at ceiling level Even w/out a ceiling fans this does not seem like a working mix with passive solar. Perhaps there is some existing
thermal mass that can be tied into

Inside chimneys have much to offer in squeezing out all the available BTUs, also the RMH has been proven to give the best results when the Final vertical
chimney is purpose built to exit on the lee side of the house about 5' above the Roofs peak ! Hopefully this is very close to what you have now .

Again, Retro-fitting anRMH into an existing home will Always create problems, but it does seem that you have not set the bar very high if all you want is to
better what you already have and save on Fuel ! For the good of the craft Big AL

My chimney is internal. It goes up through the house and comes out a few feet on the windward side of the peak and extends above the peak. Not sure if its 5 feet above. Probably more like 3.

The house stack effect is something I think I have already been living with, with any woodstove. I dont own most of the things that would cause smoke back. Just a range hood.
Looks like the consensus is that I can build an RMH that would keep my house in the 50-60 degree range on the coldest days.

If I put enough mass into thermal battery, is there any reason why I cant burn it for 5 hours each night in the coldest weather if I ever had to? I wont burn out my barrel or anything?

Many thanks for all the great input.


Regards

Jeff Marchand : If a picture is worth a thousand words then the video in the link below should speak volumes !

https://permies.com/t/25435/rocket-stoves/video-great-rocket-mass-heaters

This has 4 winters after being constructed at a Ernie and Erica Wisner http://www.ernieanderica.info Workshop and has been trouble free.
The RMH is the main source of heat- with the original heating unit a wood cook stove from the late 1800s as extreme cold weather back up !*

The heated area is two floors as the basement is used as a root cellar/storage only !

Again Bon Chance ! For the good of the Craft _ Big AL

*Location of the Quebec 'earthship" is unknown to me, a tour of the house located close to Canton N Y Is possible ! A . L .

Jeff, read all of this one!

http://donkey32.proboards.com/post/15600/thread

I too encourage you to continue reading and studying other successful designs, with more weight given to those running for two or more heating seasons. If I properly understand what you describe, I think you'll be able to add a significant amount of comfort to your living conditions. By the way, I also suggest you read up on masonry heaters, there's a lot you can pick up in that field as well. And really, despite some differences in vocabulary / terms, a well designed RMH strikes me as a variation of masonry heater ( especially the batch-style systems )

So study up this summer, and take your time to lay out your plans. Kick around ideas. Find out what resources you have near you and start working out pricing options.

I built a prototype last winter, without any thermal mass, just to test the j-style operationally. For myself, I am better suited to a batch style. I'd much rather read a book than tend a fire every few minutes. Thus, I learned that the basic system works well in my location, although a side vented chimney does NOT, and I now know I prefer the batch style ( more similar to a traditional masonry heater design ) and also that I can build a safe j-style ( I very closely monitored temperatures at a number of points in the system, so I have a good overall idea of the temperatures I generated for the weight of wood burned, and I was able to see how the materials I used help up, etc) even on top of a carpeted wood floor ( although I would never build a thermal mass on top of my floor without a great deal of bracing in the basement - the temporary prototype I built ( j-style with 55-gallon barrel ) I calculated to weigh in at under 40-pounds per square foot; and I would exercise extreme caution if doing something like I chose to do, researching methods of keeping the heat from the floor ( which mine controlled extremely well ), and very, very closely monitoring the actual temperatures generated throughout your system )

I am of the opinion that a well-research, well-built, well-tested RMH may be of great value; and I am of the opinion that cutting corners may result in building a death trap. Caveat emptor.

Erik Weaver wrote: I'd much rather read a book than tend a fire every few minutes.

the amount of info here (and elsewhere) is overwhelming to me, and I'm far from the point I'd be able to consider one of these. BUT in my outside world job, I asked one of my "energy committee" members to take a look at RMH as an alternative. (We're trying to help folks find affordable 'biomass' alternatives.) He was equally overwhelmed when I sent him to permies to reseach - and his one quick hesitation was "but how often would you need to feed this?" (He's leaning to pellet stoves.)

Now that it's part of my work assignment, I can take the time to echo that question:

How often does a RMH need to be tended? How does this work for the working guy who needs to leave the homefires 10 hours a day? Is this only 'supplemental' in that case?

thanks in advance!
~laura

rmh need to be operate only 1-4 hours a day.
at this time you need to feed it every 30-60 min
so you need 1-8 feeds in 24h

With a house that is suited to a central radiant heat source, and an RMH sized to the load, the owner would probably fire it in cold weather once in the morning for an hour or so, and again in the evening for one to four hours depending on conditions.

Any house that is currently satisfactorily heated with a woodstove can be heated much more economically and probably more comfortably with an RMH.

Laura Emil wrote:

Erik Weaver wrote: I'd much rather read a book than tend a fire every few minutes.

the amount of info here (and elsewhere) is overwhelming to me, and I'm far from the point I'd be able to consider one of these. BUT in my outside world job, I asked one of my "energy committee" members to take a look at RMH as an alternative. (We're trying to help folks find affordable 'biomass' alternatives.) He was equally overwhelmed when I sent him to permies to reseach - and his one quick hesitation was "but how often would you need to feed this?" (He's leaning to pellet stoves.)

Now that it's part of my work assignment, I can take the time to echo that question:

How often does a RMH need to be tended? How does this work for the working guy who needs to leave the homefires 10 hours a day? Is this only 'supplemental' in that case?

thanks in advance!
~laura

Research the batch style. It is more like a traditional masonry heater, in terms of firing. Get it going and it should burn itself out in 45-60 minutes. Do that one in the morning, and then again in the evening (once or more, depending upon the weather). Seems weird if you're used to "wood heat" from wood burning stoves (which are very INefficient), but pretty normal mode of operation for a well designed masonry heater. So not all that bad in terms of managing them.

The J-style is a different kind of critter. Maybe I don't know what I'm doing, but I had to keep fiddling with it every few minutes. Not major efforts mind you, moving the bricks to keep them reasonably snugged up to the quickly burning (and therefore reducing and disappearing) wood mostly. But that still means I have to get up and walk over there every 5 or 10 minutes. Maybe I'd get away with 15 or 20 minutes sometimes. Like I said, I'd rather be reading.

The counter argument might go something like this.... read by the J-style RMH, sitting right on the bench beside the fire feed point, so all you have to do is reach over and snug up the brick

I get that. I do. But I'm still building the batch style for next winter.

Live in michigan did the rocket mass heater 2 years last year 300 $ to heat my 2100 sq foot ranch buying wood. Im switching gears this year doing PV solar and heat pump. 4 months ago my elec bill 125 $ on budget plan and I owed them 400 $. Paid the 125 today they owe me 56 $. Solar is amazing now cheaper and more efficient than ever my panels are putting out a little even at night. Have 920 watts of panels + a harbor freight set 45 watts. The HF kit just charges batteries that I switch to my grid tie inverter after dark. They do not come any badder. And Im not playin games.