Hydronic retrofit in Beaver, Alaska
In Alaska, a plumbing and heating service call might take a number of days, a long drive, a trip on a ferry boat with a loaded service truck, or an arduous journey in a small airplane. It only makes sense that whenever possible, service calls be avoided because of the time and expense involved. This is why internet-enabled control systems have been gaining acceptance lately in Alaska. If a service call can be avoided using remote monitoring and remote control adjustments, the savings can be substantial.
Just such a system was recently installed and started-up over this past winter in the remote Village of Beaver, Alaska. It is an interesting combination of self-reliant technologies including Micro-grid diesel electric generation, waste heat recovery and Micro-district heating using hydronic heat tubing to connect several buildings together. The potential for solar heat is designed into this system, and of course, the New Standard hydronic heating configuration with internet enabled monitoring and remote control capabilities. The system is designed to be installed in several phases, and so the entire installation is not yet complete. But, because of the modular nature of our Standard piping and controls, the part that is installed has been enabled and with some remarkable results.
The Village of Beaver
Beaver is a small First Nations village with approximately 80 residents. It is located in a remote area north of Fairbanks, on the north bank of the Yukon River in a very cold winter climate. Electricity is provided by a diesel generator that runs 24/7. Potable water is stored and distributed to the village from large central tanks, and of course the water storage and distribution system must be freeze-protected.
There are three public buildings that contain services used by the entire village:
- Water Plant/Washiteria building
- Generator/Workshop building
- Clinic/Tribal Office building
About two years ago, the village leaders decided that some of the amenities were in dire need of repair and upgrade. The hydronic boilers that heated these buildings were old and inefficient. A repair and retrofit project was undertaken to improve the energy efficiency and to improve the reliability and effectiveness of the heating system. The result might be called a Hybrid Combi-system, or a Combined Heat and Power (CHP) system since it combines higher electrical efficiency with higher thermal efficiency for a significant reduction in overall fuel combustion.
This hydronic heating retrofit project was largely defined by the equipment in the existing buildings, some of which could not be modified or relocated easily. Early in the design process we were presented with the following lists.
- Water Plant/Washiteria Building
- Oil Fired Hydronic Boiler #1
- Future Connection for Wood Fired Hydronic Boiler
- Future Connection for Solar Heat Collectors
- Domestic Hot Water tank for Laundry Machines and Showers (boiler indirect)
- Clothes Dryers that use hydronic coils for heat
- Water Holding Tank – large raw cold water storage
- Water Treatment Tank - cold water storage
- Hydronic space heating zones
- Freeze protection zone for Utilidor (utility tunnel)
- Generator/Workshop Building
- Hydronic heat is piped from the boilers above between buildings
- Diesel Generator with Hydronic Heat Exchanger exists here
- A Large Insulated Heat Storage Water Tank exists here
- Hydronic Space Heating Zones
- Future Connection to send heat to the Clinic/Office
- Future Connection to send space heat to a school building
- Clinic/ Office Building
- Oil Fired Hydronic Boiler #2
- Domestic Hot Water tank for Clinic (boiler indirect)
- Hydronic Space Heating Zones
- Standard primary loop takes shape
Anyone who reads this column regularly might recognize the list of equipment above as simply a number of heat sources and a number of heat loads. Some of the sources are intermittent and some are “on demand.” Some have temperatures that are well regulated, and some have temperatures that can fluctuate. The heat loads have various temperature requirements that are not all the same.
This situation is exactly what our New Standard primary loop plumbing configuration is intended to manage. By arranging the heat sources and heat loads around a primary loop in the correct temperature order, this collection of equipment becomes an integrated standard heating system that can be centrally controlled using our standard control strategies without writing any custom software and with minimal design work. Figure 86-1 shows a block diagram based on the original concept that we gave to the installer. A detailed piping diagram based on this concept was provided as the final plan to retrofit the heat piping that began to take shape last winter.
Micro District Heat
Notice that there is a rectangular outline drawn around the equipment on the Left of Figure 86-1, indicating that all this equipment is located in the Generator/Workshop Building. The equipment outlined in the center of the diagram is located in the Washiteria/Water Plant Building. The equipment on the right is to be located in two other buildings as labeled. When hydronic fluid is circulated from one building to another like this for shared heating, it is known as District Heating. It is a Micro-grid for hydronic heating (if you will).
In this case, the District is rather small, including (at the most) only four buildings, and they are not very far apart. The buildings are connected together by well-insulated underground heat tubing that is part of the primary loop on the left, and consisting of secondary loops on the right. Because we have not deviated from our typical Standard Primary/Secondary Loop Configuration, the whole system can be controlled centrally with our usual internet-enabled control system without any custom modifications.
The parts of the system that will be installed in the future (seen in green) do not exist yet, and so closely spaced tees are stubbed out and capped where these connections will be made. Also, the connection to the Clinic/Office building and some of the space heating zones are yet to be completed. Despite these missing pieces, the components that do exist have been activated, and the control system has been sending data to us over the internet since February.
The most striking results so far, is that the constantly running diesel generator provides an amazing amount of heat. In fact, the residents report an 80 percent drop in the use of the hydronic boiler (fuel oil) since the generator was connected through the primary loop, allowing it to provide heat to anything that needs it. Even today, as I look at the remote display from my office in Santa Fe, the generator in Beaver is providing 157°F to the primary loop. The 2,200 gallon heat storage tank is holding steady at 150°F, the DHW tank is at its set-point of 122°F. This combination of direct heat (from the primary loop) and stored heat (from the heat storage water tank) recovered from the generator takes care of most of the heating needs for laundry, showers, clothes dryers, freeze protection and space heat so far. And, this is before the wood boiler or solar collectors have even been installed.
These articles are targeted toward residential and small commercial buildings smaller than ten thousand square feet. The focus is on pressurized glycol/hydronic systems since these systems can be applied in a wide variety of building geometries and orientations with few limitations. Brand names, organizations, suppliers and manufacturers are mentioned in these articles only to provide examples for illustration and discussion and do not constitute any recommendation or endorsement.
Bristol Stickney has been designing, manufacturing, repairing and installing solar hydronic heating systems for more than 30 years. He holds a Bachelor of Science in Mechanical Engineering and is a licensed Mechanical Contractor in New Mexico. He is the Chief Technical Officer for SolarLogic LLC in Santa Fe, N.M., where he is involved in development of solar heating control systems and design tools for solar heating professionals. Visit www.solarlogicllc.com for more information.