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Normatherm KKH20 / Passivhaus Boiler Stove

I just stumbled across some information about the Normatherm KKH20 Passivhaus Boiler Stove and am curious if anyone in here is personally familiar with them.

"The Normatherm KKH 20 stove which has a large square window in front of the fire, gives very little heat to the room at 1.9kW (6,483 Btu/h) and most of the heat to water at 17.3kW (59,030 Btu/h.) This means that you can run a Normatherm KKH 20 boiler stove in a low energy or Passvihaus and not totally overheat the room that the stove is in. Some small part of the heat may be needed for space heating for a few weeks of the year but most will be used for domestic hot water during the cooler months when the solar thermal input is that much lower. The Normatherm KKH 20 can be totally room sealed by connection to an external air duct and this air is thermostatically controlled to automatically regulate the output of the stove."

Any idea whether or not they're available anywhere in North America or have any intentions of being? It's intriguing technology for a Passivhaus and completely Green.


KKH20.jpg21.58 KB
Asked by Litawyn Eco-House
Posted Mar 8, 2012 9:34 AM ET
Edited Mar 10, 2012 10:15 PM ET

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9 Answers

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Answered by Litawyn Eco-House
Posted Mar 17, 2012 1:29 AM ET


Three comments:

1. The price is $5,844 plus the cost of shipping to North America.

2. Rachel Wagner, an architect in Minnesota, has had good success installing ordinary small wood stoves in homes built to Passivhaus levels of air tightness. More information here: A Superinsulated House in Rural Minnesota.

3. It's possible to put a stainless-steel coil in the firebox of a wood stove if you want hot water.

Answered by Martin Holladay
Posted Mar 17, 2012 5:35 AM ET
Edited Mar 17, 2012 6:15 AM ET.


I knew you'd know something about this thing, Martin. Thanks for the info.

Does a stove like this have to have gone through some kind of certification process to be able to be used in the States and to pass code? I've considered other European stoves in the past, only to be told they're not approved for sale or use in the US. Here is one such stove. It would be the perfect solution for me, but I was told by a US distributor of other models of their stoves (the only US distributor, it appears) that this particular model is only approved to be sold in 3 European countries, with no intentions of ever making it available in the US.



Answered by Litawyn Eco-House
Posted Mar 17, 2012 11:27 AM ET
Edited Mar 17, 2012 12:09 PM ET.


There are indeed a variety of regulations that apply to wood stoves sold in the U.S. These include EPA regulations (concerning air pollution) and, if the stove includes electrical components like a circulator, there's probably a need for U.L. listing.

I'm not quite sure why you're frustrated, though. There are many wood stoves available in the U.S.

In general, if you build a tight, well insulated house with excellent windows, you don't have to worry too much about how you heat it or how your heat is distributed. All these concerns become secondary with a good thermal envelope.

Choose a good wood stove that you like, sized for your design heating load, and you'll be fine.

Answered by Martin Holladay
Posted Mar 18, 2012 4:27 AM ET



I'm not frustrated about the lack of stoves that I could use. There's a plethora of them. I'm frustrated when I find that some really awesome Passivhaus technology that should be available in the US is still limited to just a few European countries. That Rika stove I mentioned is unlike any I've seen available here in the states, in that it uses actual logs, draws its air from the outdoors, and is able to maintain an output of just 2kW depending how you load it up. You simply don't find 2K wood stoves (not pellet!) like this available in the US. That's just 6,825 Btus! I think it would be awesome to be able to have what appears to be a classic wood burning stove with a roaring fire you can enjoy that only produces 2kW! Are YOU aware of any other wood stoves that meet these criteria and are available here in the US aside from the Normatherm and the Rika models I've mentioned? Tell me about 'em. I'm all ears! Even the awesome little Morsø Squirrel 1410 wood stove, which produces between 9,500 and 22,000 btu/h, doesn't have the ability to draw its air from outside. I could make a stove like this work, but it's far from optimal. There are probably ten more models that would be ideal, but they're only available in Europe. And that's what I find frustrating.

My hunch Martin is that aesthetics simply aren't high on your list of priorities, if on your list at all. You're practical, pragmatic and would likely be happy as a clam with something as long as it simply works, even though it may be a freakin' eyesore to look at. For me, aesthetics ARE a factor I take into account.

Take a look at the top two stoves below. They both could probably DO the job, but I sure as heck wouldn't want to have to stare at the one on the right in my home. For you however, they're both just stoves: You'd likely be happy with a rusty little box as long as 1) it worked, 2) it was safe, 3) it was inexpensive, and 4) it was efficient. We just differ on how we value aesthetics.

If I had to make a decision today, I'd still go with the MCZ Toba pellet stove (bottom photo), but if it were possible to get that little Rika Vitra Passive House stove (upper left photo) to be able to burn actual logs, I'd grab it in a heartbeat.


stoves.jpg MCZ_Toba_Black.jpg
Answered by Litawyn Eco-House
Posted Mar 18, 2012 11:35 AM ET
Edited Mar 19, 2012 12:56 AM ET.


The link I provided (A Superinsulated House in Rural Minnesota) does not show "a rusty little box"; it shows a house with a brand new Hearthstone Tribute wood stove.

I provided the link because the stove is being used successfully by a satisfied homeowner is a house with Passivhaus levels of airtightness and a design heating load of 15,100 Btu/h.

Answered by Martin Holladay
Posted Mar 19, 2012 6:05 AM ET
Edited Mar 19, 2012 6:13 AM ET.



I'm in need of a stove in the 2 - 4kW range, and I'd most likely be running it on low most of the time. If a wood stove can't efficiently maintain an output of 2.5kW or less, it's not going to be of interest to me. The home in Minnesota, as nice as it is, had a MUCH broader range of options to choose from. Their estimated heat load requirement is 15,100 Btu/h; mine is 9,100 Btu/h. A stove like the Rika Vitra Passive House could be run at around 2.5 kW and would be ideal. The challenge is maintaining a constant temp with a wood stove. If I were to go with a pellet stove, it would adjust to a thermostat automatically making things very easy.. I just like the idea though of burning real logs instead of pellets, which I feel would work best if the mid-range of the stove's output would be right around 2.5 kW. Options for such wood stoves available in US is quite small, to say the least.


Answered by Litawyn Eco-House
Posted Mar 19, 2012 7:22 AM ET



Did you find a small modern wood stove? I am facing the same issues as your self. I am designing a near passivhaus on a rural lot with lots of wood. Although a realize I don't need one with the mini-split I'm using it would be nice to have a fire. I came across the Rika Vitra online but it doesn't seem to be available. My house is of modern design and I find most American designs butt-ugly and simply would not place one in my home.

Answered by Stephen Carlton
Posted Dec 29, 2012 3:33 PM ET


Make sure you understand the term Passivhaus. That is vital when installing combustion devices in such a structure.

The Normatherm KKH 20 would be a certain killer if installed in a PH if it has no independant air supply.
Secured via pressure differential.

The PHI has a list of certified heating equipment and boilers.

Make sure as well that you understand the difference between a boiler and a stove. Which is another vital issue.

There are heating engineers out there who are able to advise on boiler installations and the safety issues to be looked at.
Get professionals in, pressurised boilers like the Normatherm KKH20 are no child play.

Answered by Hein Bloed
Posted Dec 29, 2012 9:20 PM ET
Edited Dec 29, 2012 9:27 PM ET.

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