Initial Discussions on Co-op Energy Supply (water & heat)
The co-op is far from carbon neutral this year. In fact we used well over a $1000 in natural gas this winter to heat our home. Our Natural Gas water heater, on it’s 13th year, is about to RIP and we desperately need a new electrical service. The current 100amp service is illegally double tapped to the max. How can we combine all of these needs and jump in the direction of energy sustainability & carbon neutrality? This discussion looks at the supply & sources of heat needed. Follow up posts will analyze reducing energy consumption.
The core of our energy supply problem is our reliance on a inefficient natural gas furnace and water heater. Their heat is inefficiently distributed throughout the house by forced air venting. Our 1911 bungalow as been added on on and re-framed with apparent disregard for heating vents — one rooms is hot, another is cold.
To remedy the heat distribution problem we have installed radiant tubing between the basement sub floor and the bamboo flooring. We plan to run radiant tubing between the floor joists to evenly heat the upstairs. — More details on our radiant heat adventures to follow.
Initial look at Heat Supply Options:
Efficent Hot Water Heating (showers, landry, sink..):
Natural Gas Tankless water heating:
Typically Natural Gas Tankless hot water heaters are installed because they can provide endless hot water for an entire house in northern climates. The colder the water enters the house, the more energy must be used to heat up the water.
Unfortunately, the Natural Gas demands are substantial for an on demand heater - when it kicks on it uses a lot of gas. When no water is flowing, the burner shuts off and it uses no gas, this makes tankless (or “on-demand”) systems much more efficient then a typical tank system which uses a bit of gas most of the time.The downsides to Natural Gas systems are:
- Installation costs, we would certainly need to retrofit a new stainless steel exhaust piping either through the roof or out the side of the house, this installation alone is likely to cost a least $1,000.
- Natural Gas burns cleanly but releases substantial amounts of carbon dioxide and contributes to global warming.
An initial Natural Gas search brings up a coupe of options:
Takagi(These seem to be the best reviewed systems)
Bosch 6.4GMP @45 F
Electric Tankless water heating:
The appeals of an electric tankless systems are:
- An electric heater does not require expensive stainless steel venting saving hundreds of dollars.
- With an upgraded electrical service, we can probably install them ourselves with plumber to connect the plumbing for $200 or so.
- Through a combination of garage solar panels and purchasing wind power from our local utility, Xcel, we can supply our energy Carbon Neutral - no carbon dioxide contribution to global warming.
The downside is reduced maximum flow rate compared to gas systems (max 3.1GPM @45F) and need for an updated electrical service with very large breakers (120amp holy &!@# ) to supply the electric heater.
http://www.e-tankless.com/gas-vs-electric.php
An initial electric search brings up: e-tankless 27kw….3.1GPM @ 45 F
Taking Energy Sustainability to the Next Step: Solar Hot Water:
A solar hot water heater is certainly the most sustainable option, but also the most unknown. The only winter solar access at the co-op is on the roof of our garage 50ft to the west of the house. Thus, a solar setup at the Co-op would require an insulated trench from the garage to house (a trench is also needed for a new garage electrical system).
If you combined:
- Solar water heating (Sizing a solar system)
- An indoor storage tank & heat exchanger
- A tankless electric water heater
We would be able to reliably, efficently heat our water…and be Carbon Neutral (w/ purched wind power electricity & our solar pannels)!!
An initial solar search brings up: All in-one solar water system
Economic & Energy Savings Estimate
My initial thought is that an electric tankless water heater seems like a good idea for our hot water replacement. It would be probably 1-2k less then a gas system install, but the heating flow rate is about half as much (3gpm vs. 6gpm at 45F). I remember in the off-grid house Chris and I saw last year, the owner had an indoor storage tank that would store 80 gallons at room temperature. Room temp storage would give 6gpm with the electric system, and be quite efficient! With the tax rebate for tankless heates an electric heater would cost around, $500! and we could probably install it ourselves with plubing assistance.The next step is building in solar & radiant heating into our hot water supply system to achive maximum energy efficency and sustinability.
To be continued….
