Quote:
Originally Posted by Marc_NL
...Also those thermal wax valves do consume considerable power...
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I'm not sure that I know what a 'thermal wax valve' is? I know that there are temperature-control valves that control bath and shower water temperature, that use paraffin's high thermal expansion rate as a regulatory mechanism, but they use no external power. Sounds like you are talking about something different.
Quote:
Originally Posted by Marc_NL
...I still have some work ahead on the heat recovery ventilation as well. The idea is to run brine through a water to air heat exchanger for air entering the house.
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I don't think that brine is being used much in North America. I'd like to know more about your interest in it, and what its advantages are.
Quote:
Originally Posted by Marc_NL
This should prevent the heat recovery system from freezing during the cold winter days. For extra (quick) heating to take care of sudden thermal changes it would be good to have such a heat exchanger after the heat recovery unit and power it with the output of the GSHP. In summer this one could aid in passive cooling.
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This sounds like a wonderful idea. There is a house here in my city of Portland that was very advanced for it's time, called
The Rose House (full architect drawings are
HERE), and it uses a very high-efficiency HRV followed by a water-to-air HX, for the very same purpose that you have in mind. Their HRV is similar to
THIS_ONE. I have become friends with the owners, and they have been kind enough to let me peek into every technical aspect of their house. The house was a Zero Energy project partly funded by the state Oregon. The house has many excellent features:
- optimum orientation to the sun
- optimized roof overhang
- very intelligent architectural design
- super efficient HRV followed by water-to-air HX
- good insulation from the ground
- good insulation in the walls
- good, 2x glass windows
- windows that were each specifically designed for it's position in the house (different glass formulations & different coatings)
- Large thermal storage tank inside the conditioned envelope
- PV panels on the roof
- ASHP that took advantage of the heat from the back side of the PV panels for it's input air
- Solar water heating
- Custom designed controller to balance all of the energy resources
I went to see them a few months ago (my second visit) and I had with me all of the documentation that was available, with underlines and questions, so they realized that my interest was very serious, and they were very candid with me regarding their experience of having lived there for ten years...
First, they were utterly satisfied with the architectural aspects of the house, particularly, how the light and space were crafted to provide a home that was resonant with their lives. They repeatedly mentioned the light and space.
They were proud of the energy efficient aspects, and proudly pointed out the various parts and the role they played in the overall house.
However, toward the end of my extended visit, they became more open about their dissatisfactions. The custom controller that was designed specifically for their house, to balance all the various heat-gains and to apportion out the energy to the various heat requirements (house heat via HRV HX, radiant floor in bathroom, etc.), quickly became a total failure. It was so complex that even the firm that designed and built it were unable to make it function as it was intended. Therefore, the unusual days when it was too cold or too warm had to be dealt with by having the owner (82 years old) climb a ladder into the small attic utility room and adjust the water flow to the HRV by hand. He performed other aspects of control to the system also, but I wasn't able to witness him doing it. So, in other words, an 82 year old man is now serving the function of system balancing. His wife of 68 yrs is concerned, because her husband is the only person who understands the system.
Also, they are having trouble with the amount of heat that is being lost through the larger front windows. (3X glass would help here. I want to work with them toward a Multi Layer Insulation window shade solution). I don't think that reducing the window area is the solution, because it is the natural light that makes the house so satisfying.
Looking at the drawings for the house, I think that more attention should have been given to insulate the foundation from the ground.
I think that thicker walls would have been better.
There are many lessons to learn from all of this. Not the least of which are:
- Pay great attention to the architectural aesthetics, and how they affect the occupants.
- Design the thermal aspects of the house (especially windows), giving the "mechanicals" a smaller role.
- Pay greater attention to the foundation and floor insulation.
- If a controller is required, try to find a commodity controller, should controllers fail, or owners change.
By the way, I have been following this house with great enthusiasm, since it was built. There were many detailed pages on the Internet relating to this house, that have mostly disappeared. However, greedy EcoRenovator that I am, I have in my archives everything that was ever published about this house.
Best,
-AC