Input needed from folks who have large spaces

[talltuk]

Hi all.

So, I have a massive opputunity to build a rocket heater, or two, in a scheduled monument, a 16th century brewery and bakehouse. Essentially its a barn, 8m wide by 22m long, 5.5 m to the eaves and 9m to the ridge. Its got a mezzanine floor at 3.3m off the ground with a central space looking down to the ground floor, and the back half of the ground floor is walled off, going to be a kitchen. The owner is going to hire it out for events and workshops etc, the upper floor will be an art gallery and event spaces while downstairs will be a stage. I will upload a sketchup tomorrow when I have it drawn up. This is going to be occasional use and they want the different areas heated seperatley so they dont have to heat the entire building when using one part, say one end of the mezzanine. So not only do we need flexible heat storage, its got to warm the place quickly so that the heat is usable. They have considered just a standard box burner and backboiler with rads, but are interested in doing somthing different and forward thinking.

My thoughts, along with a new contact I made who builds masonry heaters, were that a heating wall based around a masonry heater (lots of channels) downsatairs and a metal bell upstairs, each controlled by a damper so each could be heated indivudually, would give a good balance. My mate thinks a slim enough wall could be brought to temperature quite quickly, while I believe the metal bell upstairs would be lighter and provide quicker heat. This would then be copied at the other end of the buliding

First question - Am I mad for even considering trying to heat a space like this, with this level of flexibilty, with thermal mass and radiant heat, rather than convection

Second question - If not, does this sound like a workable plan? I can picture it in my head but the technical details are a bit beyond me right now

Third Question - Most importantly, does anyone have any experience heating this sort of sized space?

I have done heatloss calcs and it needs 24kw to keep 18oC in side whith -5oC outside. Apparently in masonry heater circles that is unheard of. I think my calculations need looking at in that area.

I am determined to get this to work if it is even slightly possible as it would be a major win for rocket heaters in the uk. Just need to find me a copy of BS EN 15250:2007 Slow heat release appliances fired by solid fuel. Requirements and test methods. They charge £200 for the pdf!! And its law! I see what was niggling Aaron Schwartz now.

[morticcio]

Found this description of BS EN 15250-2007:

This European Standard specifies requirements relating to the design, manufacture, construction, safety and performance (efficiency and emission) instructions and marking together with associated test methods and test fuels for type testing residential slow heat release appliances fired by solid fuel. This European Standard is applicable to hand fuelled intermittent burning slow heat release appliances having thermal storage capacity such that they can provide heat for a declared period of time after the fire has gone out. This European Standard also specifies a minimum time period from the appliance achieving the maximum differential surface temperature and falling to 50% of that maximum value. These appliances provide heat into the space where they are installed. These slow heat release appliances may be supplied either as an assembled appliance or as a manufacturer’s pre-designed unit consisting of pre-fabricated components designed to be built on site in accordance with the manufacturer’s specified assembly instructions. One off installations are not included. These appliances may burn either solid mineral fuels, peat briquettes, natural or manufactured wood logs or be multi-fuel in accordance with the appliance manufacturer’s instructions. Wood pellets which are hand fuelled may also be burned either on the existing appliance bottom grate or in a special basket arrangement which is placed by the user into the existing firebox. This European Standard is not applicable to mechanically fed appliances, appliances having fan assisted combustion air or appliances with boiler.

Does the one-off installation bit mean it would be exempt?

[morticcio]

That's a big space to heat! How about a large batch box/bell near the centre to provide the main heating and then one or two of Peter's steel drum type heaters to give the rapid heat capability plus another one upstairs to heat that area? Okay it means more flues (and expense) but it provides flexibility heat wise. Add a few benches for butt warming and they become a focal point.

[talltuk]

That is the current plan but having a batch box at each end with a masonry heater style heating walls downstairs(labarynth through wall rather than open bell) and stainless steel bells upstairs. Cant go in the middle as a stage is going there. The second stove will be in a walled off area to be used as a kitchen. Still debating what size to make the batch, thinking 250mm. Not sure if we can fit a second metal bell downstairs but iy would be nice to.

anyone know how long a metal bell stays hot for after fire dies?

[Robert]

HMMMMM. i would try to think also about the air heating system. just pick the hot air from above the barrel and send it with insulated pipes to the four corners of the room... that could be a nice trick i think.

[DCish]

What would happen if the heated walls were not a labyrinth, but just a long, narrow bell? Also, if some of the wall (maybe at a middle or lower level, less hot portion of the wall) incorporated metal panels, would that give you some nice immediate heat such as a barrel ordinarily might in a more typical system, just interspersed with the mass?

[talltuk]

Possibly. I like the idea of the metal panels, though my mate might frown on it. It's our first project together so I want him to play to his strengths. He can calculate exact heating dynamics of a wall like this.

as for piping hot air, we have considered optikns like that but they all use fans, whuch adds lots of complications and that our customer wanted to avoid.

I have considered a metal bell on top of the wall, like a hat, with its own damper controlled input. Also thinking no barrel, just piping straight off the top of the riser to keep hot burning areas to a minimum

[talltuk]

After further consideration this might be to large a space. Quick heat means convection which means heat flying straight up to the ridge