Masonry Heater/Finnish Furnace Questions

fin29 · #1 01/03/07, 07:47 AM

For those of you who have or have operated one of these things before, I have a few questions. For those of you wondering what the heck I'm talking about, see here for an example: http://www.mainewoodheat.com/rothschild1.html

1)How do you control the heat it radiates? If you build a fire in one for 3 hours to radiate heat for 24, how do you ensure it's not going to sweat you out of the place? Are there damper systems to control that?
2)What is the best backup heat source for someone in a cold climate who is concerned about leaving the home for a week or two and needs to prevent frozen pipes, etc.
3)Would it be advisable to have an additional "quick" heat source like another smaller woodstove or monitor heater for those days that you're particularly chilled, sick, etc.? In other words, how much flexibility do you have with a furnace like this?
4)How well would/does a water boiler work? Could a person rig a radiant floor system into the heater (with a propane backup, perhaps)?

Thanks in advance.

beorning · #2 01/03/07, 08:43 AM

I had something similar to this in my apartment when I lived in Germany. The fire box and door seemed a bit smaller than what is pictured, and what I've seen advertised in the U.S. The firebox was about 1 foot square with an 8" door. I'd fire it once, it would burn for about 30 minutes, not counting smoldering coals and would put out heat for a couple of days. The whole unit was five feet tall, about three feet wide and five feet deep, built into a corner. The fire burned hot and fast.There was a damper, but again, too much heat was not an issue. The masonry absorbs most of the direct heat.

The heat from the unit was very slowly released. It was installed as a supplemental system to radiator heat. It was definitely not a device that I used as a primary heater. I never had any problems with it putting out too much heat. It did help with the heating bill significantly. It seemed to be a fairly passive system. Not something to warm a place up quickly at all.

We are going to be building a place in a few years and I plan to have one of these installed.I'm going to install a gas furnace with a side by side woodburner in addition to the masonry unit. We're planning on radiant floor heat which won't be hooked up to the masonry unit. We're building in a lot of passive solar features and I'm planning on utilizing the masonry unit as a heat sink for that in addition to it's own heat production. The plan is to use the gas furnace for maintaining temperature when we are away, and burn wood for everything else.

I haven't had any experience with using masonry units for water heating. It seems like it might be fairly inconsistant, given the way they operate.

kabri · #3 01/03/07, 07:44 PM

We also plan to have one of these built. Our heat will all be radiant floor, and we'll use an on-demand propane water heater for back-up. We hope to be able to have coils in the masonry heater too, to help warm up the water for the floors!

Chas in Me · #4 01/03/07, 07:54 PM

Fin,
Dr. Richard Hill, who used to teach at the University of Maine, invented a heating system that is called the Hill furnace, if memory serves me right. The furnace used a forced draft firebox and heated water which was stored and fed through the heating system.
He still writes for the Bangor Daily News and has a radio program on WERU out of Blue Hill.
The U of M bookstore may have some books on the system.
Chas

mpillow · #5 01/04/07, 06:46 AM

also known as Russian fireplace....my SIL had one in a house she rented in Augusta and loved it...

http://www.gobrick.com/BIA/technotes/t19d.htm

As far as backup heat alot of factors to consider....expense, DIYor not, inside or outside fuel storage....unsightly baseboard or hidden radiant flooring...some like old radiators...I despise forced air because of the whole dust issue....

If you want to PM more info. I can ask Gary what he would do and get back to you---he designs the heating systems at Winslow Supply

Dubai Vol · #6 01/04/07, 06:56 AM

Masory Heater Association:

http://mha-net.org/index.htm

They are selling a book with several tested plans for $75. I'll be buying a copy, cheap at twice the price!

fin29 · #7 01/04/07, 07:40 AM

Quote:

Originally Posted by mpillow

also known as Russian fireplace....my SIL had one in a house she rented in Augusta and loved it...

http://www.gobrick.com/BIA/technotes/t19d.htm

As far as backup heat alot of factors to consider....expense, DIYor not, inside or outside fuel storage....unsightly baseboard or hidden radiant flooring...some like old radiators...I despise forced air because of the whole dust issue....

If you want to PM more info. I can ask Gary what he would do and get back to you---he designs the heating systems at Winslow Supply

For backup heat, expense is definitely something to think about, but moreso, I want flexibility--it might be 10 times a year that I want to jack up the heat or keep the place from freezing when I'm away and can't fire the heater, but those 10 times would be a royal PITA if I don't plan it right.

We're planning a home that's basically an open cape with all the family living area and a wing off the back that would house the sleeping quarters. So the masonry heater would do the heat for the main house and then we would have radiant for the bedrooms, since we want a separate zone to keep that area cool but comfortable. So I'm wondering if radiant put throughout the house with a shut-off for the main house would be the way to go, so that when we can't fire the furnace, the radiant could get switched on for the whole house as backup.

mpillow · #8 01/04/07, 07:46 AM

Just use different zones---thermostats and use environmentally friendly anti freeze in the radiant loops...

We have HWBB with 5 zones (one is domestic hot water boiler mate) in just 1500 ft living space but heat primarily with woodstove.

I think we have whats called a low mass cold start furnace...meaning there is no coil and it heats only the hot water on said zone.

mpillow · #9 01/04/07, 08:05 AM

anti freeze is called "no-burst"

here's some info

http://209.85.165.104/search?q=cache...ient=firefox-a

Ed0517 · #10 01/04/07, 04:56 PM

You really control them by the size of the load of wood. You burn hot and fast, and then you have a ton or more (I think the usual definition is 800+ kg) of warm (not very hot) rock in your house. Almost no creosote, and a gentle heat - lean on it, some have built-in heated benches - you can't do that with a stove. Of course, you can just open a window - they are slow to get a room hot, but also slow to overheat one. Oh, and they are area heaters - best heat where you can see the heater, so open floor plans are advisable. If you may be away a few days, DO have alternate heating, bith for when you are away, and when you return - once that rock gets cold, a lot of your first charge will be heating up the rock again.

Major disadvantages - cost and the weight restricts placing.