Heating Systems
This building is located in Norther New Hampshire at about 1,600 feet elevation so winter is a major part of our year. After securing the building envelop, utilizing passive solar heat gain as much as possible and recycling existing heat within the building, we will then turn to other sources for heat.
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We are utilizing 6 different and complementary heating systems. We do have a built-in redundancy but not necessarily duplicity in costs. This is not as flaky as it sounds so follow me on this one.
System #1-Passive Solar
The passive solar rule of thumb says to face the building due south. Well, what if a view of a 160 acre pond is directly east? This was a tough one, but not an unusual dilemma for situation a building. We ended up facing the building 45 degrees off direct south, which will give us a view of the pond from all of the rooms. This trade-off will cost us passive and active solar gain but will give us an incredible view. We have also done computer modeling studies showing us shading effects for different times of year and times of the day. Combining our building orientation with window placement, window sizing and glazing, roofing overhang design, window shutters and space layout has aided in optimizing our passive solar gains in the winter and deflecting in the summer months.
System #2-Radiant Floor Hot Water
The main floor and second floor of the building have radiant tubing embedded in a thin layer of lightweight concrete combined with an insulation layer and then hardwood flooring. Hot water is pumped through the tubing which heats the cement like a heat sink storage system and then radiates through the building. With this type of heating system we eliminate most of the stratification differences and space fluctuation of heating a building. Bottom line is that your feet are exposed to the same temperature as your head. The air is not the only thing that is heated, the whole inside of the building is heated. This is especially helpful in the main floor with its barn type design that is open 30 feet up into the cupola.
The radiant floor system uses a 700 gallon super-insulated hot water storage tank as its heat source. There are a number of ways that we heat this hot water storage heat sink.
In the 17th century most buildings were heated with wood, but in Europe the wood shortage created such an energy crisis that the kings in Prussia, Sweden, Norway and Denmark ordered their craftsman and architects to produce better wood stove designs. This concerted effort produced radically new heat-storage masonry heater designs, which showed enormous improvements in efficiency and corresponding wood conservation. Many of these have survived hundreds of years and are still in use today in Sweden, Austria, Finland and Germany. Masonry heaters have been perfected so much that the Finnish government encourages the use of them today through tax incentives to reduce the use of natural gas, oil and electricity. The result is that 90% of the new homes built in Finland are heated with a masonry heater.
The masonry heater design we chose gives us the ambiance of a fireplace but the heating capacity and energy efficiency developed over hundreds of years in environments that demanded production or else they simply froze to death. Since we live in a working forest, the most prevalent and renewable natural resource other than sun is wood.
In a nutshell the concept of these heaters is that you light them twice a day, morning and night. The firebox design allows the short fire to reach temperatures of 1500 degrees, which in turn heats the massive masonry and rocks that make up the heater as well as burn the wood gasses so completely to give combustion efficiencies in the 90% range. The heated rock radiates heat throughout the day or night.
The Masonry heater does not need to use the radiant floor system to heat the building, it uses its heated masonry mass as a storage system. There is a water line running through the masonry heater that can be used to heat a hot water storage tank if we choose to.
System #4-Tarm Wood Fired Boiler
The Wood Boiler we use is manufactured in Denmark and distributed in the United States by a company called Tarm USA that is located right down the street from us in Lyme, New Hampshire and operated by the local Nichols family. This boiler can either use cord wood or another model can use corn or wood pellets. The concept is similar to the masonry heater. You light the stove once or twice a day in the winter and the 1800 degrees fire heats the 700 gallon super-insulated water storage tank. The hot water is used for the radiant floor heat and to heat domestic hot water for showers and washing. This high temperature, like the masonry heater, efficiently burns not only the wood but the wood gases as well.
Looking to burn wood efficiently and in an environmentally sound manner will allow us to use this resource that is literally all around us without a dependency on anyone. If we can utilize a renewable natural resource like wood from a sustainable forest and use it in a manner that will not add CO2 to our greenhouse issue or acid rain as well as stay away from burning fossil fuels then we do less harm to our environment and lessen our fossil fuel dependency.
System #5-Natural Geothermal Heat
The design of the Barn House uses the concept of a bank barn whereby the lower level backside is situated on a slope in the landscape. This was used so that tractors and livestock could enter the building on the backside of the barn and the other three sides of the lower level are below ground. The lower level of the barn house is 12 feet below ground level on three sides of the building. Ground frost in this part of New Hampshire usually goes about three feet in the ground, below that point the earth stays around 50 degrees. We will therefore be using the natural thermal insulation of the ground to keep this level of the building above freezing.
We will admit that to us this concept sounds a tad sketchy and I sure hope it works because the water system for the whole house originates from that lower level. I guess we will find out this winter if our water pipes freeze or not.
System #6-Propane Furnace and Hot Water
Well, if the solar or hydro electric systems are not generating enough electricity to heat the hot water storage tank for our radiant floor system and we are too lazy or not at home to put wood into the Tarm Wood Boiler or the Masonry heater, then the high-efficiency propane furnace will kick in at a predetermined temperature.
We chose a Viessmann combination propane boiler and on-demand hot water system to not only act as our backup system but this will also be the control and monitoring system for our heating system. The Viessmann system has an efficiency of up to 98%.
Heat Recovery Ventilator
When Foam-Tech finished insulating the building they performed a number of tests to insure that the building envelop was sealed. After all of the testing the manager of Foam-Tech was kind of disappointed because he calculated that there was still 9 square inches of leaks in the building. He knew where most of them were and had a plan to plug them. I had to smile at this type of dedication; counting the lower barn level this is a three story building with 2800 square feet of livable space and this guy is upset about the 9 square inches of air leakage that are probably coming from the electrical conduit that is still open and the masonry heater that isn’t completed yet. He of course insisted on coming back when these things are completed so he could run a decompression and thermal imaging test again. I bet if I am in that building when he decompresses it I am going to need an oxygen tank to breath.
When a building is super-insulated as this building is you actually need to bring fresh air into the building during the winter because it is so tightly sealed. In bringing the fresh air in you also need to let some of the inside air out but you want to recover the heat that is in that inside air. That’s the job of the heat recovery ventilator. Each room is equipped with a fresh air vent and an overhead air mask that drops down in case of malfunction.
Water Drain Heat Recovery System
Recycle, Reuse and don’t waste. Now this one seems a bit of a stretch to me but the engineers tell me it works. When you take a shower, wash cloths or do dishes the hot water that goes down the drain is a waste of energy. Through a simple system of coils in the drain system, the energy embedded in the hot water that is going down the drain is recycled and returned to our hot water storage system. Now the water is not recycled at this point, the heat is. My first reaction was give me a break, how much heat could we recover and what does this heat recovery coil contraption cost. Well the contraption (technical term that means I don’t know) wasn’t that expensive so I said okay. This is a small one we are taking on faith but we will put this on our “to be verified list”. Remember, this building is a model where we are testing different conservation concepts and we need to have an open mind. I just want to make sure it is an open mind we have and not just an open wallet.
Hot Water Recirculation
Here's the deal, every time you turn your faucet on you usually run the water until it reaches a specific temperature therefore flushing perfectly good water down the drain as well as the embodied energy in the hot water that is not hot enough for you. With this devise you press a button and the water that is sitting in the water line is recirculated back to the tank so you have fresh hot or cold water instantly when you turn the tap on.
Masonry Stove Heater
Although this may look like a fireplace it is not. This is a Masonry Heater that was designed over 300 years ago yet is more efficient and less polluting than the vast majority of heating systems used in modern houses today.
In the 17th century the kings of Prussia, Sweden, Norway and Denmark commissioned their craftsman and architects to produce a better wood heating system to lessen the energy crisis that was upon them. This concerted effort and the added incentive of freezing to death produced radically new heat-storing masonry heater designs, which showed enormous improvement in efficiency and corresponding wood conservation. Many of these designs survived and are still in use today in countries such as Sweden, Austria, Finland and Germany.
Masonry stoves are still in widespread use throughout northern Europe and are highly regarded for their excellent heating abilities, safety features and environmentally positive aspects. Notably, the Finnish government encourages the use of masonry heaters through tax incentives, to reduce the use of natural gas, oil and electricity. The result is that 90% of the new homes built each year in Finland are heated with a masonry stove.
The Masonry Heater almost finished
Essentially the masonry heater is a large heat sink that radiates an even heat that warms the solid objects in the home, such as walls, floors and furniture versus heating the air. The concept is to burn a fast hot fire around 1500 degrees which will last about three hours and then be allowed to go out. The high temperature allows the stove to burn not only the wood but the gases as well.
The wood gases do not go directly up the chimney like most wood stoves and fireplaces but enter multiple channels and traverse up the stone mass then back down and in this design through a number of stone benches and then back up the stone mass again to exit the chimney. By the time the gases exit the chimney the temperature is nominal. The high temperature gases heat the stone mass and benches and radiates it back to the space slowly and evenly for many hours.
One can stand next to or sit against the heater when it is at its maximum surface temperature, a moderate 200 degrees. It will not cause burns if accidentally touched, making it safe for children. In the middle of a New Hampshire winter lighting the stove twice a day is all that is needed.
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Radiant heat is distributed more evenly than convection heat. It does not dry the air or circulate dust particles. Since heating continues after the fire is out, one can leave the home without concern for an untended fire. Since the main room of the Barn House is over 30 feet high the radiant heat eliminates the heat stratification that a conventional forced hot air system would produce.
EPA monitored tests show that the high burn temperature results in very clean combustion with significant reductions in particulate emissions compared to EPA certified Phase II catalytic and non-catalytic woodstoves. Certified woodstoves must meet a 7 gram per hour particulate emission rate. Masonry stoves emit 1-2 grams per hour. This minimum hourly emission and the fire only burns for a few hours per day versus burning most of the day with other heating systems.
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Because of the weight of the stove it must be adequately supported by a proper base if the stove is built above a basement. The base is built with concrete block and has an ash storage compartment and combustion air channel incorporated in it. The base is built roughly the same size as the stove above. Support for hearth extensions can be cantilevered beyond the edge of the block when the capping slab on top of the base block is poured.
Initial drawing rendition of Masonry Stove
8/17/2006
All the rocks for the stove came from the property, they are stored in the middle of the floor
Backside of heater on second floor bedroom showing heater channel
Internal Masonry Structure with Heater Channel
All the rocks for the stove came from the property, they are stored in the middle of the floor
Wood Waiter to transport wood to the second floor
Wood for the masonry heater will be brought in by tractor into the lower level of the Barn House. The wood will then be loaded into a Wood Waiter to be lifted into the main floor. The company we used for the wood elevator is woodwaiter.com.
Radiant Floor Heat and Domestic Hot Water
The design of the radiant floors had many challenges to solve.
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First, we wanted natural wood flooring that was milled on the property and because we have a 200 year goal for the building, we wanted the wood boards thick enough to be able to sand them down and refinish them in the future.
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Second, we did not want a pre-manufactured flooring material that contained glues or petrochemical products.
Third, we wanted to keep the temperature in the radiant floor tubing as low as possible, therefore we needed products that would enhance and hold the radiant heat as much as possible.
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The file below includes the architectural details of the floor plans.
First Floor Radiant Plans
Second Floor Radiant Plans
Radiant Floor Architectural Plans
The above drawings for the radiant floor for the first and second floor are well done except one critical component was not accounted for. Which direction will the flooring be placed? This is important because the light weight concrete flooring system requires sleepers which need to be run in the opposite direction of the flooring so the flooring can be nailed to the sleepers. The wood ceiling in the buildings 2nd floor under the roof and the 1st floor bedroom really dictated that the flooring be run in the same direction which is length wide with the building. This was one of those O'$%#@ that was realized onsite a few days before the radiant floor tubing and sleepers were going to be installed.
Now granted we could have called the Engineers and had it redesigned but schedules were already committed to and our HVAC contractor had a comfort level that he could use the concepts above just kind of reverse it. Hopefully we will be able to produce an "As Built" plan so what is in cement is similar to what is in our drawings.
Tarm Wood Fired Boiler
The Wood Boiler we use is manufactured in Denmark and distributed in the United States by a company called Tarm USA that is located right down the street from us in Lyme, New Hampshire and operated by the local Nichols family. This boiler can either use cord wood or another model can use corn or wood pellets. The concept is similar to the masonry heater. You light the stove once or twice a week in the winter and the 1800 degrees fire heats the 700 gallon super insulated water storage tank. The hot water is used for the radiant floor heat and to heat the domestic hot water for showering and washing. This high temperature, like the masonry heater, efficiently burns not only the wood but the wood gases as well.
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Looking to burn wood efficiently and in an environmentally sound manner will allow us to use this resource that is literally all around us without dependency on anyone. If we can utilize a renewable natural resource like wood from a sustainable forest and use it in a manner that will not add CO2 to our greenhouse issue or acid rain as well as stay away from burning fossil fuels, then we do less harm to our environment and lessen our fossil fuel dependency.
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If we are too lazy to either feed the masonry heater or the Tarm boiler with wood or we happen to be away, the Viessmann on demand propane boiler will automatically start if the temperature of the building drops below a preset temperature.
Viessmann On Demand Propane Boiler
The Viessmann On Demand Boiler operates as a backup to the Tarm wood fired boiler for our radiant floor heating system and as an on demand hot water heater for domestic hot water. The Viessmann is used as the control system and will turn on if the heat in the Barn House drops below a preset temperature.
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For hot water for showers and sinks it has a separate temperature gauge and if the domestic hot water drops below a specifc temperature it will operate as an on demand heater and bring the water up to the desired temperature.