Wednesday, May 16, 2018

A Conservation and Comfort Conversion in St. Johnsbury, VT

The house is a two story 4,800 (total) square foot log structure built by its owners several decades ago. The roof is supported by scissor trusses, which creates vaulted ceilings and a small attic space above the ceilings. Originally, there were two boilers providing the heat, a Frank's Wood Boiler and separate oil boiler, both tied into baseboard hot water heat. Both boilers were replaced and substantial building envelope improvements were made.  The owners chose to dramatically reduce fossil fuel heat while at the same time improving their comfort and saftey as much as possible. This post describes the process and results.

The project started with a call to Ed Whitaker at Green Thermal Systems  Ed smartly advised an energy audit before any heating upgrades began.  An energy audit that was coordinated through Efficiency Vermont After the energy audit was performed by Adam Barrett, New England Foam and Coating was hired to insulate the attic and box sills. 

Box sills were spray foamed. Removing fiberglass insulation from the attic was the next step. Thinking about air quality, the owners were keen to remove fiberglass batting that was compromised and soiled from 25 years of mouse intrusion.  After removing the fiberglass, truss bays were vacuumed and foam was then sprayed to a depth of 2-3" on top of the ceiling, along the bottom chord of the scissor trusses. Using spray foam in the roof served three purposes. The foam not only added insulation itself, but also provided a vapor barrier for the 13" insulation that was blown in on top of the foam. The foam also provided an air barrier, which dramatically reduced the chimney effect within the home. Chimney effect describes warm air escaping from the top of a home while at the same time pulling cold air in through cracks lower in the home. Just as a boiler sends hot exhaust up a chimney while cooler combustion air enters the boiler combustion chamber, a house can lose loads of heat due to chimney effect. Chimney effect also can pull gobs of unwanted cold air into a home, making rooms feel cold and drafty.

Foam Sill Insulation

New Spray Foam in box sill

Interestingly, there was another counterintuitive alteration of the building envelope. The home had an unheated, airlocked entry space inside the main door on the bottom level. Because this space was cold and located inside the rectangular footprint of the home, cold air was exposed to the home through two extra walls and a ceiling. Rather than trying to add more insulation and air sealing in the existing interior walls, the exterior door was replaced and the airlock was removed so that the entire heated space was exposed to a single, exterior wall. Doing so reduced leak points as well as the square area of exposed walls.

Along with improvements to the building envelope, the heating system received major modernization upgrades with expert advice and control strategy planned by Ed Whitaker.  Paul Cornell of East Burke, VT did the acutal piping.  Under-floor radiant tubing was installed throughout most of the home. A primary goal was to provide low temperature heat distribution. Low temperature distribution allows greater utilization of most heat sources, in this case, water to air heat pumps, a wood boiler, and a condensing propane boiler. Three out of four heating zones were converted to radiant floor heat. Radiant tubing was stapled under the subfloor. Aluminum heat transfer plates were attached to the tubing and the subfloor. Foil faced bubble wrap was placed 2" below the tubing, then a 3" layer of Rockwool, followed by a reflective plastic barrier.

Radiant floor cross section

Radiant tubing and installation (example)

Radiant Floor Heat Insulation InstalledView of Installed Radiant Floor Heat

Radiant tubing installed in joist bays

The home was already heated with a Solo Plus 60 wood boiler from Tarm Biomass

HS Tarm Solo Plus 60 

Solo Plus 60

To allow the wood boiler to operate more efficiently, three, 300 gallon, pressurized thermal storage tanks were added to the heating system. The three tanks were plumbed together, effectively creating a single 900 gallon thermal storage tank. By batch firing the Solo Plus, the boiler operates more efficiently and with lower emissions.

3X300 Thermal Storage

Three x 300 gallon heat storage tanks are located in the blue foam box.  The tanks are also wrapped in Rockwool.

The tanks also allowed the homeowners to produce heat with their new SpacePak water to air heat pumps during relatively warmer, off-peak hours.

Heat Pump Air to Water Compressors Rear View

Spacepak heatpump compressors

The heat pumps are only allowed to operate if the thermal storage drops below 130 degrees Fahrenheit (F). The radiant floor tubing provides adequate heat with 110 degree F water during the coldest periods.

Heat exchangers air to water heat pumps 

Heat exchangers from exterior heat pumps.  These are connected to the thermal storage, which then feeds the heating supply maniford.

Currently, the radiant floor zones are manually temperature controlled.

Heating Manifold

Heat distribution manifold with manual tempering valves

We encourage the owners to replace their manual tempering valves with active mixing valves, such as the Smart Comfort by LK Armatur These mixing valves and controls will set radiant floor temperature according to outdoor and room temperature.

110,120,130 SmartComfort

LK Smart Comfort mixing valve control

Excess heat made by the heat pumps is stored in the 900 gallons of water for use in the radiant floors after the sun sets and temperatures drop. Using their heat pumps in off peak hours makes it more likely that power being produced by the on-site 13.5 kW Solaflect photovoltaic arrays will be used directly on site, saves the homeowners money by not using power during high demand periods, and reduces pressure on the power grid when the grid is receiving its highest demand. From the standpoint of incentivizing heat pump use, using air to water heat pumps and thermal storage makes a lot of sense.

Solaflect PV Panels

Solaflect tracking photovoltaic panels

A backup condensing boiler was installed as well. The owner confided that at his age, he wanted to make sure that should he be stricken with illness or injury, he would have a conventional means for heating his home regardless of outdoor temperature. Maybe he'll be willing to consider a new Fröling pellet boiler to replace his wood boiler if that day comes.

Manifold and IBC LP Boiler

IBC Condensing propane boiler

Heating vital statistics:

10 Cords = Amount of wood burned per year with Solo Plus 60 before envelope upgrades

4.5 Cords = Amount of wood burned after envelope upgrades

2.5 Cords = Amount of wood burned after thermal storage and heat pumps are added in December 2017.

? = power production and consumption has not yet been tallied.

Stay tuned for more details about system performance.

Tuesday, May 8, 2018

Brian Millette, Steadfast for 29 1/2 Years, Retires from Tarm Biomass

Brian Millette is retiring!  Tomorrow, Wednesday May 9th, will be Brian’s last day at Tarm Biomass. 

Brian started working for Nichols Hardware in September of 1988.  I was still in high school at the time.  Brian was originally a floor clerk in the hardware store, which was owned by my Father Jim Nichols and Uncle Lloyd Nichols.  Possessing numerous talents learned from working on his own home, vehicles, and a wood working hobby, Brian was a perfect fit in a hardware store.  The store had a small engine shop and Brian even filled in making repairs to Husqvarna chainsaws.  By the time we closed the store in 2005, Brian played about every role, from checking in new stock to selling stoves and even helping install stoves and chimneys.  At that time Brian had little role at Tarm Biomass, which we picked up in 1994.  However, when the store closed and we focused only on boilers, there was no question to us that Brian would stay on our staff.  With his quick wit, affability, humble nature, and pride in a job well done, Brian has always made friends with customers and colleagues. 

Brian has suffered through the deaths of Jim and Lloyd Nichols.  He’s tolerated ownership transitions.  He’s worked through business transitions.  He’s taken hold of product line transitions.  He’s handled it all with aplomb.  His quiet assumption of the next duty has seemed as natural as taking a breath. 

For the past 13 years Brian has been the parts man for Tarm Biomass.  Many will know him for his soft, low voice and Northern New Hampshire accent.  What most will recall is Brian’s expert knowledge about spare parts and ability to get parts out the door ASAP.  One of Brian’s unsung traits is making sure that our customers get the parts they have paid for in perfect working order.  Our rate of parcels damaged in transit is almost zero.  There’s an authentic talent there rooted in taking pride in a job well done.

It is hard to know where to find guys like Brian, who show up on time regardless of the weather, regardless of how he feels, or for any other cause.  Heck, even his boss, yours truly, can’t match his on-time record.  When Brian’s been here to work, he works; that’s it. 

If you’ve done business with Brian over the last 29 1/2 years, please drop him a note and wish him well in retirement if the spirit moves you.  We’ll be in communication with Brian from time to time and will pass everything along. Don’t forget to wish us luck.  Brian is a hard act to follow.  

We count ourselves lucky to have been able to know and work with Brian for so long.

Which would you choose?