help Multi building heating.

[dfergx]

I have come across your site a bit ago. I have already been saved from buying an OWB. The gasification sounds very good. My situation is a bit unusually though. I have 2 existing building one is about 515 sf the other is about 150sf (see Photo buildings 1 & 2) these are heated by baseboard and space heaters, not so great. I would like to heat these to buildings plus a new 515 sf building, and hopefully 2 others (bottom of photo in green) each about 250 sf. That is the situation. now what do I do?
First, I know very little about heating choices but I am researching. I am building another 3300 sf house that will be geothermal. My first thought is to build a small outbuilding to house a gasifier and fuel and then run lines underground to the 3 buildings. the 2 existing (1 & 2) with water baseboards, and the new one radiant floors. also the new building has hot water heaters, hopefully those could be tied in.
Kinda complex situation
here is the building run down:
1.) existing, heated with baseboard, no water
2.) existing log cabin, heated with electric oil radiator space heater, no water
3.) Proposed building, radiant floors and, hot water heater for 2 showers and 3 sinks
I apologize for my ignorance and beg you to forgive any gross mistakes on my part. Any info is helpful.
Also. I cannot figure out what the fuel consumption is on gasifiers and what different fuels they can use.

 

[dfergx]

Oh we have lots of wood for burning, but fuel oil is pretty expensive.

 

[wdc1160]

I think you will be guessing at a best solutions if you don't do attempt a heat load calc www.heatinghelp.com has one available for free.

 

[Bob Rohr]

Gosh buildings that small shouldn't require much heat if well insulated. A couple light bulbs should heat 150 square feet How far apart are the buildings? You would want a well insulated and water proofed piping between them. Seems like a lot of expense for small loads? Why not pipe the geo-thermal to all the buildings if you have commit-ed to that expensive?

hr

 

[dfergx]

It is 95 feet from building 1 to building 2. I guess I should call them huts though.
The building that is Geothermal is too far away to link into
I am trying to get the heat loss calc to work I will post when I get it

I am thinking I will put an outbuilding halfway between one and two, but I don't know what the heck I am doings so that is not set in stone. Anyone have any thoughts on geothermal?

 

[smangold]

Hi, geo thermal is very nice but expensive. wood gasifiers are very nice and expensive. So your going to be buying caddilac sytems for both . It seems to me that hooking up the wood system to the home and the huts would be ideal, How far away is the home from the huts . I've seen info from wood boilers( outdoor) that said you could heat buildings as far apart as 500 or 600 ft. as I recall.

 

[smangold]

Also little one room cabins might benifit from solar air heaters (solarsheat), assuming good solar exposure.

 

[Nofossil]

This is an interesting application. The (probably) small heat loads might change the typical system configuration as well as allowing smaller buried lines. Line loss will be higher on a percentage basis than in most systems.

Seems like a bit of heat storage in each building would be good if it's possible - you have to push a lot of cold water through every time you initiate a heating cycle, and the amount of heat you'd need each time would be small unless you're in Antarctica, or those buildings are uninsulated sheet metal. Perhaps something like an indirect DHW tank with a little bitty circulator, where the DHW tank is recharged from the boiler to 180 degrees when it gets cold.

 

[dfergx]

I should explain my situation a little bit. I live in a community. We are expanding quickly at this point. We live totally off the donations of others and this influences the way we make decisions in a big way. first we are environmentaly consciences, as are most of our donors. Second we are much more willing to pay a large initial cost to get a better product (it is easier to get donations for a project then for maintaining existing). Third and most important is we have limited juice. We will be expanding our current service to around 2000 amps on single phase. so power is a big concern.
Ok now to reply.
smangold, are you talking about tying the geothermal and the gasifier together? what would be the benefit? The 3300sf building is 400feet away. I will look up solar air heaters, but we get great solar for 8 months and the other 4 are not so good.
nofossil, I think I could get tanks in the one room buildings, the new one (#3) was already planned to have a HW tank, I don't know if I could in the 2 existing structures not much room. If I would be pushing cold water through the radiators then wouldn't I just be pushing cold water into the HW tank?
Why isnt there a fricken glossery on this page I dont know if I will every figure out all these abbreviations. Thanks, I am going to do the heat loss calc right now.

 

[Nofossil]

My concern was the slug of cold water in the lines between buildings - those lines are harder to insulate well. If you cycle circulation on and off frequently as you would have to do to maintain constant temperature in a small building. you're pushing a lot of cold water through the lines every time you need to move a little bit of heat.

With a small onsite storage tank, you wouldn't have to move water between buildings as often. Sorry I wasn't more clear on my explanation.

 

[dfergx]

Ok I did the calc sorta. I got 41,000 btu/hr for the 2 existing that the proposed
the other 2 small buildings will not be here for another year or so but I think they shouldn't be over 10,000 btu/hr each
I have no idea how to factor in heat loss for pipeing also there will be a lot of dhw use that I don't know how to factor.
P.S. nofossil, you website is awesome I will be reading from end to end in the next few days.

 

[canyon]

For multiple buildings/ community heating needs check out the Garn.

 

[dfergx]

nofossil,
It was not your explanation that is the problem, it is my lack of knowledge. I was thinking you meant an electric hw tank that was supplemented by the gasifier. I realize now that you already said it would be recharged by the gasifier, I am supposing now that this means it is just a holding tank with no heating capability. so I guess the gasifier would run to the DHW tank, that would run to the radiators, and those would run back to the gasifier? so the advantage is that the gasifier would only run water to the building when there is a large need (the tank gets too cool) and not for the many small needs of the radiators.

 

[Nofossil]

nofossil,
It was not your explanation that is the problem, it is my lack of knowledge. I was thinking you meant an electric hw tank that was supplemented by the gasifier. I realize now that you already said it would be recharged by the gasifier, I am supposing now that this means it is just a holding tank with no heating capability. so I guess the gasifier would run to the DHW tank, that would run to the radiators, and those would run back to the gasifier? so the advantage is that the gasifier would only run water to the building when there is a large need (the tank gets too cool) and not for the many small needs of the radiators.

Almost exactly. Indirect DHW tanks (sorry about the acronym - Domestic Hot Water) have a very effective finned heat exchanger coil inside. My thought was that you would have a small circulator that would circulate water from the DHW tank through the radiators, controlled by a thermostat. When the aquastat on the DHW tank called for heat, the gasifier would supply it. You'd want to run the DHW tank up to a pretty high temp - 160 at least, and you'd want to run it down to 120 or so, lower if you have extra baseboard or radiant. A 40 gallon tank cycling between 120 and 170 would give you about 40,000 BTU of storage - 4 hours by your worst case guess, but probably more like 8 or 10 hours in any but the most extreme weather. That would help keep the building comfortable while reducing the number of demand cycles on the gasifier.

You would likely also want storage at the boiler building.

Garn boilers are a good choice for community heating - there is a project here in Vermont that's doing that, I think. My only hesitation is that your heat load is small compared to the output of a Garn. It would spend almost all it's life idling. My image is a Mack truck towing a little red kid's wagon......

 

[dfergx]

So there would be 2 circuits, one indoor closed circuit between dhw tank and radiators. and the other between the boiler tank and the indirect dhw tank.I have goto ask how much your extensive setup cost, I really dig it, I am wondering if I need to go radiant in the 3300 building, the plan right now is geothermal with forced air.

 

[Nofossil]

So there would be 2 circuits, one indoor closed circuit between dhw tank and radiators. and the other between the boiler tank and the indirect dhw tank.

Yes. The boiler needs a higher flow rate, and you could use glycol in that loop if you needed to.

I have goto ask how much your extensive setup cost.

I scrounge a lot, and I didn't keep detailed records. I think I have between $6K and $7K in my system, not including the oil boiler and baseboards.

I am wondering if I need to go radiant in the 3300 building, the plan right now is geothermal with forced air.

Radiant is nice for wood heat applications. It can use stored water at much lower temperatures than radiators, which has the effect of allowing you to store more usable heat in the same sized storage tank.

I hve no experience with geothermal - others will have to chime in with pros and cons there. You can use a water-to-air HX (think automotive radiator) in the ductwork to use a boiler with a hot air system. I just prefer hydronic, and especially radiant.

 

[smangold]

the Garn info I got from a dealer shows a multi-unit and multi building set-up with 5000 ft. of piping.If you got the small unit you would probably need a fire every other day for the whole project and could skip the big bucks on the geo thermal setup .My understanding, although limited, is that Garns don't idle, you burn the full load and heat the water than draw heat of that. The btu draw will determine length of time between firing. In a community there are many people around to fire the unit if someone is sick or something. Always keeping the temp up.And in a rural area the size of the monster shouldn't be a problem. That being said I don't own one so maybe I'm just guessing.
.

 

[dfergx]

I haven't been able to find the info on how there this generate the super heated flame to combust the wood gases. Do they use electric resistant heating, or a fuel oil? What is the consumption on this secondary fuel on say a 100,00 btu/hr system.

 

[dfergx]

what is the bt output on the garn? there website kinda sux

 

[Gooserider]

I haven't been able to find the info on how there this generate the super heated flame to combust the wood gases. Do they use electric resistant heating, or a fuel oil? What is the consumption on this secondary fuel on say a 100,00 btu/hr system.

There isn't a secondary fuel, or rather the secondary fuel is the wood itself... The way these units work is that you build a standard fire like you would in a fireplace or any other sort of stove (some details about how you arrange the wood, kindling etc. vary, but the idea's the same) This heats up the firebox and the wood until the wood is putting out more gasses than the fire can consume, at which point the gasses go into the gasification combustion chamber and are ignited. Part of the heat from the gas burning goes into keeping the firebox hot enough that the wood keeps cooking out more gas in a self perpetuating reaction.

In some units there are "bypass dampers" that connect the firebox directly to the chimney to make it easier to get the fire going, and reduce the likelyhood of smoke coming out the loading door when adding wood, but these generally get closed as soon as the fire is going well.

The fine details will vary a bit from unit to unit, but the basic idea is the same in all of them.

Gooserider

 

[dfergx]

Thanks Gooserider.