What is the safest office building heating for a redneck HVAC engineer?

cowdog

Large commercial building manager looking for supplemental heating to reduce natural gas and electricity cost. It is currently heated by natural gas furnace for common areas and PTAC units electroresistive for individual offices.

He is a "redneck engineer" that knows how to build things, but not formally educated on HVAC.

Available cheap fuels are marginal wood(from furniture factory), coal, waste motor oil, waste motor oil filters, and pizza restaurant & bakery trash.

What is the safest equipment for a redneck engineer to heat a building? Don't have to be very reliable, because it's supplemental heating anyway.

Jamie Hall

Unless the redneck engineer or someone she hires is going to be there 24/7 monitoring the equipment, none of those would be, in my opinion, safe.

Ironman

An approved outdoor wood boiler would be the only safe option, but that requires proper design and installation. It’s not something that a redneck can simply throw together.

I’m a redneck, or so I’ve been told.😂

JUGHNE

If the PTAC are not already heat pumps, that would be an upgrade for savings.
Heat pump use in moderate weather and then electric resistance when colder.

Simple slide in exchange using existing wall sleeves.

vtfarmer

There's a flooring warehouse/storefont near where I used to live in Vermont that was heated with three large outdoor wood boilers. The building was probably 30-50k sq ft and you would always see staff out back with a tractor, splitter, and piles of cordwood. If the wood is free and the labor to process the wood is free then this is probably your best bet. I wouldn't be surprised if they burned 50+ cords a year.

One of the local sawmills up there heated their wood drying kiln with a huge wood boiler that they fed with wood scraps and sawdust (note that firing sawdust can lead to unintended explosions, so proceed down that path with care). That seemed to work well for them, but it was part of the infrastructure of a working saw.

I personally heated my house, a rental, and a greenhouse with a single large outdoor wood boiler when I lived up there and while it was great to thumb my nose at fluctuating oil and LP prices, I still had to cut, skid, buck, split, stack (seasoning is very important) the wood then feed it 2-3X a day from October-April (and shovel out the ash, clean the flue passages every week or so). Not that much fun.

If you have waste oil available and don't want to put labor into firewood then that's probably your best option. There are companies that make low maintenance, fully automated, UL listed waste oil fired boilers and hot air furnaces. I have encountered a number of them in my travels and they seem to work well as long as you don't get water or other contaminants into them.

cowdog

vtfarmer said:

There's a flooring warehouse/storefont near where I used to live in Vermont that was heated with three large outdoor wood boilers. The building was probably 30-50k sq ft and you would always see staff out back with a tractor, splitter, and piles of cordwood. If the wood is free and the labor to process the wood is free then this is probably your best bet. I wouldn't be surprised if they burned 50+ cords a year.

One of the local sawmills up there heated their wood drying kiln with a huge wood boiler that they fed with wood scraps and sawdust (note that firing sawdust can lead to unintended explosions, so proceed down that path with care). That seemed to work well for them, but it was part of the infrastructure of a working saw.

I personally heated my house, a rental, and a greenhouse with a single large outdoor wood boiler when I lived up there and while it was great to thumb my nose at fluctuating oil and LP prices, I still had to cut, skid, buck, split, stack (seasoning is very important) the wood then feed it 2-3X a day from October-April (and shovel out the ash, clean the flue passages every week or so). Not that much fun.

If you have waste oil available and don't want to put labor into firewood then that's probably your best option. There are companies that make low maintenance, fully automated, UL listed waste oil fired boilers and hot air furnaces. I have encountered a number of them in my travels and they seem to work well as long as you don't get water or other contaminants into them.

Wood scraps from furniture factory is already dry and small size. As a "half solid fuel", can waste motor oil filters be fired cleanly in outdoor wood boilers? Aluminum recyclers want the oil burnt, because they can then immediately melt the casing to ingots for cross country transportation. What about pizza restaurant and bakery trash?

50+ cord = 100 tons of wood, the pizza+bakery restaurant yields around 100 tons of combustibles every year, but it's hard to store this fuel during non heating season. is there any solution of shredding, compacting and storing cardboard-ish fuel for half a year?

vtfarmer

cowdog said:

Wood scraps from furniture factory is already dry and small size. As a "half solid fuel", can waste motor oil filters be fired cleanly in outdoor wood boilers? Aluminum recyclers want the oil burnt, because they can then immediately melt the casing to ingots for cross country transportation. What about pizza restaurant and bakery trash?

50+ cord = 100 tons of wood, the pizza+bakery restaurant yields around 100 tons of combustibles every year, but it's hard to store this fuel during non heating season. is there any solution of shredding, compacting and storing cardboard-ish fuel for half a year?

Oil filter housings and heads are steel, not aluminum. They get recycled in an electric arc furnace where the fuel value of anything attached to the scrap is negligible compared to the electrical input (70+ MW, or a quarter billion-plus BTU/hr). You can crush used oil filters to extract the oil but its minimal and only done to reduce their size. The oil that comes out is pretty dirty and needs lots of screening before going in your waste oil furnace.

You have reasonably viable commercial options for cordwood, clean wood scraps (get one of these https://www.renewenergies.com/outdoor-wood-furnaces/central-boiler-classic/central-boiler-pallet-burner/ ), or waste oil ( https://www.cleanburn.com/clean-burn-products/ ). Combusting anything other than that will require costly and complex controls and environmental monitoring to be legal and practical. This only makes sense at large scale, but once you get the scale it makes a LOT of sense.

I did some work at this plant a while ago:

https://www.energieag.at/Konzern/Ueber-Uns/Gesellschaften/Energie-AG-Oberoesterreich-Umwelt-Service-GmbH/WAV-Informationen

It does basically what you want: burns virtually anything, heats buildings (the whole city of Wels plus a wood pellet factory), and it makes "free" electricity to boot. You just need about a billion dollars to set it and the infrastructure around it up and you'll be golden. With all of this talk of district heating I thought I would add this link to this thread.

Larry Weingarten

Hi, Is there anything that can be done to make the building more efficient? If so, I’d “race” efficiency and whatever other fuel, cost and lobor wise to see which approach wins.

Yours, Larry

psb75

https://www.energieag.at/Konzern/Ueber-Uns/Gesellschaften/Energie-AG-Oberoesterreich-Umwelt-Service-GmbH/WAV-Informationen

The Austrian government factors LARGELY in subsidizing the entire biomass heating industry--right down to re-planting the forests. They'd really like to avoid using Russian gas. Hence, Austrian pellet burning equipment is the best in the world. See: Windhäger, Fröling, Hargassner, Ökofen.

cowdog

JUGHNE said:

If the PTAC are not already heat pumps, that would be an upgrade for savings.
Heat pump use in moderate weather and then electric resistance when colder.

Simple slide in exchange using existing wall sleeves.

Very good idea, but replacing all these PTAC units in offices are expensive, costs more than $1000 each, and there is a shortage of PTAC units, it will be a $100K project, while there is only $10K budget.

cowdog

psb75 said:

https://www.energieag.at/Konzern/Ueber-Uns/Gesellschaften/Energie-AG-Oberoesterreich-Umwelt-Service-GmbH/WAV-Informationen

The Austrian government factors LARGELY in subsidizing the entire biomass heating industry--right down to re-planting the forests. They'd really like to avoid using Russian gas. Hence, Austrian pellet burning equipment is the best in the world. See: Windhäger, Fröling, Hargassner, Ökofen.

The bottleneck of pellet heating is not burning equipment, but in-situ small scale production. Pellet stoves are already more efficient than wood stoves.

Pellets cannot compete with natural gas in cities. Pellets compete with coal, propane and oil for rural/far suburb market that has no natural gas. Pellets have no cost advantage if it's milled in a central location and shipped everywhere -- in order to reduce pellet cost we have to efficiently mill it in small scale.

EdTheHeaterMan

Has Jeff Foxworthy been doing heatin' systems stuff as a side job since the the Blue Collar Comedy Tour stopped performin'?

Jamie Hall

The big McNeil generating station in Burlington, VT, burns mostly wood, although natural gas is used as a backup fuel source.