RMH for outdoor horse arena seating?

Hi.  
What might be the cleverest way to provide heat to the most people who are spectators to outside horse events?  I'd like to incorporate a RMH into outdoor horse arena seating in middle TN, so it needs to be warmish late fall and then very warm Dec-Feb, back to warmish in Mar-Apr.   Would have to be covered; no Uncle Mud-style barrel only heater.   Stoking the heater in advance = no problem.

-arena is 180 feet long, adjacent spectator area is flat
-possibly a pebble style to start so I can move it around/manipulate it
-raised seating for spectators when it's not being heated
-I'll enclose the barrel so it's not accessible by spectators
-possible multi-tier?
-max practical length?

I haven't yet built an RMH but am looking forward to experimenting this winter.

Thanks in advance for your ideas!

Hi Cindi;
Well depending on the number of people, that's a tall order!
You certainly will want it to be an 8" J tube and being outdoors, you will defiantly need to start  burning it early to get the heat built up in the mass.

How many spectators are you thinking of seating?
Any chance you could make it a permanent "grandstand?"

With a permanent grandstand, a brick bell could be built  inside the insulated grandstand box.
Radiating heat into all the seats   (higher would be warmer.)

Or a 20-40' long  brick bench.  

Several 8" J tubes   with brick benches?

Using a bell design bench rather than a piped mass would radiate heat sooner.

The core area would benefit from a cover (roof) but a sheet of plywood would keep rain out of the core.

Hi Thomas.  

Yes we certainly could do a grandstand-type, multi row approach.     After I posted I looked more at the J tube construction inside some of the greenhouses.  

Attached is photo of area.

I am a fan of RMH without having anything more than youtube experience with them, so take this thought with a grain of salt.

I think some of this will depend on how many people you want to seat. Even the biggest rocket mass heaters I have seen are not for more than half a dozen people sitting. More of course if you are around it. This feels a bit like you are a fan of RMH, and you need to keep people warm while they watch, and you are trying to put them together without really seeing if they match. Maybe they do, as I said, I am not an expert, but I think maybe a hot water solution would be more easily regulated and expanded as needed.

Why not use a rocket stove of some sort to heat water, then use a solar water pump to pump it through some pex embedded in the seats. This would make it much easier to control the temperature and even allow for other sources of heat like a solar hot water heater. If you are thinking of a dozen people, I'd say yeah, go ahead and build a big RMH. If its lots of people, then perhaps something that makes it easier to expand and build in modules.

Hi, Matt.
I'll certainly think about it...First I need to get one under my belt, then I should be able to better suss out difficulty.   I suspect that water-circulated heating will be more complex and might not be the first iteration.   I like the idea of being able to warm up ~40' of bottoms using an 8" RMH.

-C

Hi CindiD,
It would certainly add some complexity as you say. Also, I imagine even in middle TN, you may need to worry about freezing temps sometimes... which means either a more complicated system or using some anti-freeze of some sort... so yeah, my idea may not be practical.

Keep us updated on your progress, I'd love to see how it turns out. I imagine having a really long horizontal run may complicate starting the fire initially. I think I have heard that people using fans or heating elements to start the flow of smoke/air through the horizontal runs. Then after it gets going, there is no need.