Central Biomass Boiler Plant Heats Two Large County Jails

Two prisons that sit about 200 feet apart on land owned by Merrimack County in Boscowen, NH are now being heated by a new central biomass boiler plant that was built between them by Froling Energy in 2016. The new building contains a single Viessmann Vitoflex 300-UF Model KPT-1250 biomass boiler and an innovative “rake-type”, 50-ton wood chip storage system that feeds it.

Connecting walkways were also built to tie the two prisons together and these nicely enclose pipes that transport hot water from the 3,300-gallon buffer tank to the two prisons’ heat distribution systems.

It is expected that over 1100 tons of screened green wood chips will be consumed annually, offsetting the use of about 92,000 gallons of fuel oil. The project was contracted through Johnson Controls Inc.

A combination of the highly efficient Viessmann boiler and wood chips performs so well that the only emissions control mechanism required is a multi-cyclone on the output stack. This boiler system generates 3000 NH T-RECs per year.

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The Viessmann Vitoflex 300-UF Model KPT-1250 - 4.2 Million BTU
The largest Viessmann Vitoflex 300 boiler heats two prisons.
The built in touchscreen gives easy access to real time boiler status information, stored performance data and settings.
Two walkway connectors tie together two prisons.
Main Entrance to Merrimack County Jail
The new boiler house sits between two prisons--and heats both of them.
The Javo Toploader automatically draws all fuel towards the boiler augers.
After being dropped off, chips are pulled towards the boiler.
Large diameter heat pipes run above ceilings in the new walkway corridors.
Live floor semi-trucks back into the silo building to drop wood chips on the floor.
A 3,300 gallon buffer tank is kept hot for a quick heat response.

At 4.2 Million BTU output, the Viessmann Vitoflex 300-UF Model KPT-1250 is the largest of this line--over 4.2 million BTU/hour maximum output.

The boiler and buffer tank look small without any reference points, but the boiler is the biggest Viessmann Vitoflex 300 UF made.

The built in touchscreen on all Viessmann Vitoflex 300 boilers gives technicians easy access to real time boiler status information and stored performance data. These and dozens of settings adjustments can also be performed here or remotely via the internet.

Two walkway connectors coming out of the new boiler building not only allow people to pass between the two prisons but they contain large heat pipes in the ceiling.

The main entrance to the Merrimack County Jail in Boscawen, NH

The new biomass boiler house sits between two prisons and heats them both.

Using sonar sensors, the Javo Toploader automatically pulls newly delivered wood chips towards the boiler feed augers.

The Javo rake silo enables live floor semi-trucks to drop off chips the full length of the silo. Then it pulls them all towards the boiler augers.

Large diameter heat pipes from the boiler room feed heat to each of the two prisons, running above ceilings in the new walkway corridors.

Live floor semi-trucks back into the Javo Toploader in the silo building to drop PDCs on the floor. See connector to prison on right.

The big Viessmann boiler aims to keep the 3,300 gallon buffer tank hot so it can quickly respond to changes in heat demand.