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Glyn Tutt

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since Apr 18, 2013
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Recent posts by Glyn Tutt

I think Matt has included a refractory glass window do that he can see the flames - just like a traditional fireplace! WOW
4 years ago
I cannot wait for the findings! Best of luck with the fan-assist experiments.
4 years ago
Having thought about this thread over the weekend - I admire the laboratory approach that you guys are taking, if mechanically assisted flue systems are not explored, then a definitive conclusion based on experimentation will be lacking in the development of the RMH. However, I cannot help wondering why just designing a flue that is efficient in the first place is not a prerequisite for any heating system that burns 'stuff'. The principle objective of a flue is twofold; firstly to take away the poisonous fumes (CO, CO2 etc.) and secondly to provide a draw of fresh air containing that useful ingredient for combustion O2.

Is the problem that the RMH is too effective at drawing heat our of the exhaust gases that by the time the exhaust flue in the designed system starts the 'exit' path that they are too cold to create a thermal draw to the outside?

Clearly this state would exist upon start-up and if not designed into the system would mean that the RMH would never be easy to light. The traditional solution to this problem would be to have a bypass baffle in the flue circuit that would enable the initial flue gasses to bypass any heat sink route and exit directly to the 'chimney' part of the system. Once started the baffle would be set in the usual position (perhaps gradually) to enable the whole flue to be used. I have seen examples in country houses in England where in the 18th century, to maintain the architectural integrity, a house would be built without chimneys in the main building, but a separate chimney being built higher up on a nearby hill (Chatsworth House is one of these examples), of course, the initial draw of the cold system meant that no fires could be started in the house without pre-heating the flue, so the solution was to have miniature fires in 2 or 3 places in the flue connecting the house with the stack - once warm, the draw in the house was sufficient to maintain the overall system of fires.

So another solution could be a smaller 'fire hole' in the flue that enables the initial draw.....

I'm just offering these alternative ideas because any system that requires additional technology to keep it running relies on expensive and energy-intensive production processes, for me the simpler ideas would take preference over the more complicated ones due to their reliance on less resources. I love the idea that the RMH could produce electricity to charge batteries etc., but is the problem we are looking for here simply that we are designing RMH flue circuits for steady-state operation which has created a problem with the initial start-up do to the lack of draw in the flue? If it is a question of aiding flue efficiency the surely a passive improvement is more durable (and cheaper) than an active 'fan-assisted' type design?

By the way, I installed an Okofen wood pellet boiler last year and have just realised that the initial circuit within the burner/water boiler section is similar to the RMH. Initial burn with controlled air feed produces the primary combustion, with an additional air injection a little way above the base 'pyramid' for secondary combustion. the hot gasses then pass down the internal surface of the boiler and then up through holes within the water jacket, then out of the flue (see http://outilssolaires.com/pro/fabricants-distributeurs/okofen-france+e1051.html). The temperature of the outgoing gasses is rarely above 80°C and the ash I minimal - requiring a monthly check and dump. I know that this is far removed from the RMH design, but even with electronic controls and monitoring (and fan assisted air feeds and flue control) we still get ash and a warm chimney. If the problem is balancing steady-state energy extraction from the flue versus initial start-up effectiveness, then yes - I agree that some initial burn design feature should be used, just as the Okofen boiler has controls in the initial ignition cycle.

... gosh, that was a long post! I hope it provides some food for thought!
4 years ago
The Canadian fans are from a company called Caframo. I have two of these too - they work great.... as long as all you wish to do is move air around. The trade name for the product is Ecofan. I have had one for over 10 years now and just replaced the motor (was a bit warn and made a ticking noise at certain speeds. So all in all a repairable, eco-friendly device that does just what it is intended to do - move air around your stove without creating a massive draught.

But is Paul trying to generate electricity to charge batteries and things?
4 years ago
I think the information posted regarding the German manufacturer 'ThermalForce' is really good. the Unit that sits on top of a burner called '40 watts generator for fireplace heater' looks like the most promising. As an Engineer, I do not like the solutions which sit within the flue - however clean the burn is for the RMH, the last thing you want is a solution that is heavy on maintenance time. The surface mounting ones may be 'ugly' compared to an in-flue design, but practicality of something that sits on top of, or is attached against a surface would be my choice.
4 years ago
Dear Wytze,

The general impression regarding responses to your post have not been in favour to install an external air inlet directly into your woodstove. Personally, I would not install a woodstove without one. Not for building code or regulations purposes, but simply due to trying to increase convection within the space you are trying to heat. Any 'suction' of air form the space you are heating (and you have already stated that there is very little mass in your building - the air making up a significant proportion of it) will remove heat. Yes, your building may be leaky, but I too live in very old properties and want my draughts to go around the house, taking warm air with them - I don't want them to go up the chimney!

The document sited below about scientific evidence states that increased system energy is unfounded, but then did not go into any detail. Yes pressure differentials and fluid dynamics are very important in reducing airflow and in modern housing that creates a problem for humans as air gets stale and humid - not good for people, or indeed the fabric of the building. Clearly in such an airtight building, to combust wood would then require additional air, so that is why your installer mentioned the need for such air supply in modern builds.

However, you, like me, live in older houses (mine is over 400 years old) - and I still value the idea that heat dissipated from my stove is heating air that will remain in my house. I always draw air from an unheated part of the house (i.e. an outbuilding) or directly from outside. It certainly reduces that 'rush' of air that does indeed appear to hug the floor as it travels to end of the room where the fire/woodburner is, I also think that it helps ventilate the outbuilding/cellar that it draws air from.

I am not sure that your suggestion to draw the air from the 'worst' bit of your cellar - but providing more airflow generally will help with your damp problem and then using that air in your wood burner won't affect the burn quality as the air as it is heated within the burner (you mentioned that your model does this, Jotul or Clearview I presume), it's ability to absorb water increases and it is the wood and how you burn it (good secondary burn) that has the most effect on performance.

If you do wish to passively ventilate the air from the bottom of your cellar, why not add a secondary flue that enters your chimney flue near about 1 metre above your woodburner so that it draws a small amount of air as the expended gasses pass through from the woodburner?

At the end of the day, your little woodland cabin will never be as efficient as your main place of residence, but at least you should have a stove that quickly heats up the internal air without all of it going out of your chimney every 5-6 hours.

4 years ago
Hi Everyone!

Sorry for being 'European' in this matter, but generally we (Europeans) make coffee in a stronger (uses less water) manner... and then add milk to taste (if at all!). So in order to make really nice, strong coffee, we tend to use the good old fashioned percolator type method, but with a higher pressure.

Europe has changed its attitude to coffee in recent years, with quality being more sought after than quantity (and therefore price is less important) - Yep Starbucks has helped, but people now understand what real coffee can taste like, so I'd like to add to this thread and enquire whether an Italian Style coffee 'Stovetop Coffee Percolators' are acceptable to the ideals of a less plastic, durable and therefore eco-friendly coffee addict community?

Here is what I mean.... (photo attached)

It can be easily used on top of a RMH or wood stove, as easily used on a conventional cooker and, although I have never tried, could be made to work on an open fire. The seal between the 2 halves is a rubber gasket that is again, not a polymer but a natural product and these things last for years.

And make GREAT coffee

So why try to re-invent the wheel when there is an old-fashioned, does-not-need-electricity way already out there?


5 years ago
Great videos, but some of teh 'challenge' of living and surviving a year on a 17th century farm were lost on me within the first 5 minutes when teh narrator explained that "due to 20th Century Health and Safety Laws they could not stay overnight on the farm".

So the challenge of actually living on the farm is removed - the need for water to clean clothes, cook and wash is not an issue, the need to repair and maintain the farmhouse as a habitable space is not required - surely the 17th Century farm is not just a place to produce food? In a time before the Enclosure Acts that allowed Lords of the Manor to sell off land rather than collect tithes from his peasant farmers the peasants did not only grow food, but they maintained and lived in the same building over many generations.......

In reality, I know of no 'Health and Safety' Law that would not permit a group of volunteers to really try and do this properly. The reason for this probably originated from the BBC or it's supplier creating a commercial product that in turn required people to be employed - the Law only applies to employees, not volunteers who accept certain conditions that an employee, by law, cannot have in a place of 'work'.

So remember all of those longs days 'at work' followed by a hot bath and a modern bedroom and possibly a good dinner of pie and chips down the local pub....... Removing the need to actually survive makes this more of an academic study than a real one. (I'm English by the way!)
Keep going - great start and best wishes. The photos are a must for those of us looking in with intrigue!
Hello Chris,

I accept your points entirely, my offering is just consistent with my personal experience of shitters (I prefer that name!) I just have never seen a mobile one - except for the type I have in my garden which is a simple bench and hole...... left in a secluded place that has lots of leaves around!

I also understand fully the unpleasant nature of the stuff that is deposited during the process, but again, a well ventilated and managed arrangement is not at all smelly - the main issue is flies and such. Surely that is the point of permaculture? We live in a wonderfully smelly and messy world, getting back to basics is what it is all about and if our solutions constantly need oil based polmer products (i.e. plastic containers) when there are solutions that do without, then how perma is the culture?

I know Paul wants a mobile 'pooper' - so he will have one. I'm only questioning the basis of that need - I run a lot of projects and always approach a new project with the following questions of guidance....

Why are you doing it?
What else could be done instead?
What are the consequences of not doing it?
How have your timescale/resource constraints been determined?
How does it contribute to your strategy/goals?
What is its priority/importance?
Who is the user and how will it be maintained?

Thnaks for the feedback!

GT
5 years ago