Here’s some of what we’ve bin up to

Yesterday was a big day at the MWS installation.  A crane was on hand to lift the custom pellet storage bin into place and to lift the insulated flue liners up to the top of the chimney for a top-down installation.  Lots of pictures!

Resting on a trailer before its long life of service…  The bin was painted to blend in with the brick of the school.

Here’s Mark putting a good seal on the sight glasses.  These allow you to glance at the bin quickly to get a sense of how much stored wood-pellet fuel remains.

Up it goes!  You can see the fill hatch on top (to the left).  It opens via a cable and is designed so that it won’t open more than 90° (and flip over backwards).  The pellet delivery man will pull on the cable to open the hatch, then run an auger up to the hatch.  That’s one way to fill this bin.  You’ll have to stop by to see the slick way pellets can also be pumped in from the bottom.

5000 lbs of welded steel getting up on its feet.

There it is (minus a few inches)!

Airborne, and on its way to the concrete pad next to the building.

While it was hanging there, the crew attached load cells under the four feet.  These will allow us to monitor the fuel levels remotely.  Load cells are heavy-duty scales that measure the weight on top of them and then send the information on to the data monitoring equipment.

Here’s the crane operator from O’Brien Tree Service.  He made himself useful when not operating the crane. (That was useful, too!)

Sometimes, it’s hard to see the wood-pellet bin for the trees!

All done.

Good Control = Long Life

Here’s a photo of the variable-speed circulator that moves water through any or all of the three boilers.

Upstream of it (on the left) is a mixing valve that allows us to carefully regulate the temperature of the water returning to the boilers.  This is important for two reasons.

  1. A sudden delivery of cold water to a hot boiler can cause what’s called “thermal shock”, which has the potential of damaging (cracking) the boiler.
  2. Sustained delivery of cold water to a boiler can lead to flue gas condensation within the boiler.  Basically, the returning water cools off the hot combustion gases (mostly steam) until they condense.  The condensate can corrode the boiler.  This situation is most likely to occur when an aggressive outdoor reset is used.

Huh?!  What’s outdoor reset?

Outdoor reset is a technique used to conserve energy by lowering the temperature of the water supplied to the building according to the outdoor temperature.  For example, it’s possible for a room’s radiators to keep the room warm on a mild Fall day using relatively cool water temperatures.  In other words, if the radiator needs 180°F water on the coldest day to keep the room warm, then maybe it requires only 140°F on a cool day.  Using lower temperature supply water has two benefits:

  1. The lower the temperatures used, the lower the system heat losses to places where heat is not wanted (up the chimney, in the boiler room, etc.)  A hot pipe loses much more heat than a warm pipe.
  2. The lower temperatures allow for a more even delivery of heat to the room.  Rather than repeatedly hitting the room with a big pulse of heat from the radiator and then turning the heat off, it’s possible to steadily heat the room with a more appropriate temperature.  This cuts down on drafts and temperature oscillations.

Actually, a new standard just went into effect for new residential boilers requiring that boilers provide this type of control.

The downside of using outdoor reset is that it takes more pumping (= electricity) to deliver a given amount of heat at a lower temperature.  This isn’t a huge deal for us given the high-efficiency circulators we’re using.

Back to the idea of protecting the boilers…

When 140°F water is circulated to the building to keep it warm on a mild day, it returns to the boiler room cooler (since it has lost heat to the rooms).  Maybe the return temperature is 120°F.  This is easily cool enough to condense the combustion gases in the boiler.  Since we want these boilers to last a good long time, we’ll adjust the mixing valve to ensure that the water going into our boilers is safe and warm.

One final note:

The pellet boiler—the Fröling P4—does have a built-in mechanism for handling cool return water temperatures.  However, a new line of these pellet boilers will not have the same protection.  The oil boilers do not have this protection.  So, we’re protecting the oil boilers and standardizing the procedure for new projects so that all boilers will be safe.

Progress Report

The existing boiler began to leak heavily in March and April and the school limped along with little to no heat at the tail end of the heating season.  The failed boiler gave Mark and Henry the incentive to pull together a business model they had been discussing for some time.  Surely, they could help out the school in such a way that would be financially sustainable for their new business.  They promptly drew up a draft of a collaborative arrangement with the school whereby both parties would benefit from the savings achievable from installing advanced biomass systems.  Negotiations and refinements took us through late summer, when we came together with an agreement to move forward.

When work began Monday, August 27, the first order of business was to remove the failed boiler from the school.  Froling Energy set right to work.

One of Froling Energy’s trucks on the job.

Here are some shots of the dead behemoth:
Dismantling the old boiler.

Scrap metal.

Interior view of the boiler sections–pretty! Check out the corrosion at the bottom.

The sections were so heavy, they had to be removed with a Bobcat.

The old floor was very uneven. A new one was poured…

A clean surface to work on.

Rebar and forms were prepared for the concrete pad supporting the 13+ ton pellet storage bin.

That was the end of day 1!

Progress continued all week:

Pouring the pad.

All done! The custom bin to go atop this pad will be filled with wood-pellet delivery trucks that can drop off up to 20 tons at a time. No hazmat team is required for fuel spills!

New peaking oil boilers were brought into the boiler room…

…followed by the Fröling P4. Like the color coordination?! The black bin on the right will hold a small amount of pellets before they are automatically fed into the boiler.

The buffer tank was brought in and piping work began over the Labor Day weekend.

The welder at work.

This shows the valve (top left) that adjusts the temperature of the water circulating through the building. The meter tracking how much energy is delivered is at the bottom.

Here’s the new Grundfos 40-120 circulator. Variable speed, very efficient. Lots of electricity savings to come! (By the way, the school keeps all of those!)

Monadnock Waldorf School: Great Room for Improvement in the Heating System

There were several very common attributes of the heating system at MWS that made it a great candidate for replacement.

  1. A single, oversized boiler kept hot 24×7 throughout the heating months.
  2. A large distribution circulator running 24×7 throughout the heating months.
  3. A control system that allowed setbacks to be accidentally overridden indefinitely.

The Oversized Boiler

If you put a Mack truck’s engine in your VW Jetta and drove by alternately flooring the accelerator and slamming on the brakes, do you think you’d get good mileage?  Would the car last very long?  Of course not.  However, this is a direct analog to the heating system present in many, many facilities.

First of all, you can improve matters by putting the right engine into the car, as it were.  Actually, it’s much easier to right-size a boiler plant by breaking it into multiple boilers, each capable of providing a portion of the heat needed.  Think of it as the hybrid car with two motors: the electric motor and the supplemental gasoline engine.  Two engines, one car.

In this case, we’re installing multiple lower-capacity staged boilers.  This means that at low-load situations (cool Fall weather, for example), a single, variable-output pellet boiler can handle the base-load heating requirements.  This constitutes the first stage.  In fact, this variable-output boiler–the Fröling P4–can provide more than 90% of the heat needed by the school throughout the course of a heating season.  In the very coldest weather, a “peaking” (i.e., satisfying the peak heating load) oil boiler kicks in and supplements the heating delivered by the base-load boiler.  This constitutes the second stage.  As a safety precaution, we are installing two identical peaking oil boilers so that if there are any issues with one boiler (oil or pellet), the other two can handle the heating while adjustments or repairs are made.

By installing several smaller boilers (including one that has variable output), we are able to avoid overpowering the system with too much heat.  This arrangement minimizes wasteful on/off cycling of the equipment and allows each appliance to run at high efficiency.

By controlling the boilers more effectively, we’re able to avoid keeping them hot (= heat lost up the chimney) when heat is not needed by the building.

The Oversized Circulator

A single, 1-hp circulator ran 24×7 throughout the heating season.  What would you expect happened when just a single zone valve opened?  The water screamed through the pipes, creating noise and possible erosion.  Never mind the wasted electricity…

We decided to install a variable-speed, ECM circulator (Grundfos Magna) to handle the distribution of heat throughout this zone-valved system.  Even if it had to run at 100% output to duplicate the old circulator’s flow, it would use only 1/2 of the electricity.  However, it meters its output to provide just enough flow to satisfy the current needs of the building, whether there are 20 or 2 zone valves open.  Of course, it will be off when no heat is needed.

Wasteful Controls

Heat on each floor of the building was governed by a timer that enabled that floor’s thermostats.  If the timer was in an off cycle (such as at night, or on the weekend), people using the building could toggle an override switch that kept the thermostats active until the switch was turned off.  Unfortunately, it was very common for this switch to be forgotten and left in the override position for days on end, needlessly wasting energy.  In addition, the timers would need periodic resetting due to Daylight Saving Time/Standard Time and power outages.  These corrections were not always performed in a timely (haha!) manner.

As part of our new control system, we will be incorporating a single timer that needs no adjustments.  In addition, the override switches will be replaced with mechanical crank timers, so that accidental indefinite overrides are no longer possible.


These simple, yet powerful, design and control modifications will help the new heating plant use less fuel, less electricity and will require fewer repairs.  As part of the Xylogen Thermal Service Agreement, both the school and we will benefit from these improvements.  Stay posted to see how much we can save together!

Xylogen’s First Project: Monadnock Waldorf School

Groundbreaking work began in more ways than one last week at Monadnock Waldorf School in Keene, NH.  MWS has formed a long-term collaborative agreement with Xylogen LLC, which will provide the school with a heating service fueled primarily by locally sourced wood-pellet fuel.

Xylogen LLC has crafted a novel business model whereby we install, maintain, operate and fuel new biomass (wood pellets or wood chips) heating plants on our customers’ property in exchange for annual service payments.  Our unique program allows customers to enjoy many of the financial and environmental benefits of using local renewable fuel sources without needing to worry about how our advanced technology works or how to pay for it.  As Amory Lovins from the Rocky Mountain Institute might say, “People don’t want boilers, they just want to be warm!”  (They also don’t want to pay an arm and a leg…)

In the case of MWS, where the existing boiler failed, we’re able to provide a brand new system to the school for zero capital cost and with lower annual operating costs over the contract term.  In doing so, we’re able to eliminate the school’s consumption of well over 4000 gallons of oil each year.

Other than saving thousands of gallons of oil and saving the school money, what’s the big deal?  We have figured out a way of structuring the agreement so that when Xylogen LLC or MWS takes any action that reduces fuel consumption (e.g., keeping windows shut or operating the boiler at top efficiency), we both benefit financially.  The school receives a rebate each year the annual fuel consumption drops below historical levels. We benefit, too, since we don’t need to purchase as much fuel.  We’re not familiar with any such mutually beneficial arrangement.

We will be posting pictures and updates on this site to keep you up to date with Xylogen’s installation at MWS and to help explain how our unique arrangement works.  We’re thrilled to be working with MWS!  Feel free to follow progress here or via Twitter @Xylogen_LLC.  You may find additional information posted on the school’s Facebook page.

Please join us as we document the journey!