Straw Hall Hydronics

The BBHSP community meeting space is called “Straw Hall” because it has walls and insulation partially made from rice straw. The floor is made from very thick NHL (Natural Hydraulic Lime Plaster), and includes insulating layering, structural rebar, and a network of Pex pipe for the hydronic radiant floor heating system. We plan to connect the system’s heat-exchanger to a geothermal source, but for now, the systems operates using it’s “back-up” heat source: a tankless propane water heater (AKA “boiler”). This web page is intended to store information about the hydronic in-floor heating system, as we work out the bugs and improve its functionality and efficiency.

The water heater boiler unit is a propane Noritz Always Hot Model NC1991-DVC.

The “Back Up System” Propane Boiler, used when geothermal heat exchange is not working

Exterior Vent Pipe Clearance:

No Problem- Adequate Clearance!

**Building Inspector wrote: “WH (Water Heater) exhaust within 2 feet of eave vents. Consult Install Guide, as needed” -DONE!

The exterior vent pipe termination outlet from the boiler is just over two feet clearance (2′ 2.5″) from the soffit venting above the termination. The boiler’s manual and relevant building codes call for at least two feet of clearance, so the installation was done correctly.

Exhaust vent from propane water heater, has over two feet of clearance to soffit under eaves
Installation Guide calls for at least two feet of clearance from soffit
Turns out it was installed properly, with plenty of clearance.

When we have our GPP (Geothermal Power Plant) up and running, it might make sense to replace the existing propane-powered boiler with an electric tankless water heater, since we will have an abundance of “green”eletricity generated on site.

Other Concerns and Questions:
Increasing Effectiveness of Room Heating: Floor (made of Natural Hydraulic Lime) is so thick that pipes are not near surface, and the floor is not heating up very well with standard settings on boiler and pumps. Can the water heater be turned up to solve this problem, so working fluid running through floor pipes is hotter? Would a higher heat be easier, more difficult, or about the same to achieve with an electric tankless water heater?

Can this Remote Controller (below) be turned up? What does it do?
What is the maximum setting?

Also… What is the function of this mixing controller (below), and can it be turned up to make circulating fluid (and the floor) hotter?

Mixing Controller for Hydronic System
This entry was posted in Uncategorized. Bookmark the permalink.