Over Pressure (Part Two)

Welcome back! In Part One we talked about how steam pressure gets too much attention. Controlling pressure for its own sake should never be the end goal—steam pressure is just a means to an end. In this post we’ll discuss one way that controlling steam pressure can be useful—where it can help you balance the system, control the temperature, and yes, save energy.

Two-pipe Steam

The biggest issue plaguing two-pipe steam heating systems are steam traps. Steam traps are supposed to do just that—trap steam—keeping the pressurized steam on the supply side of the system and allowing air and water (i.e., condensate) to pass through into the returns. Keeping the supplies and returns separate is critical, but steam traps are too failure prone to accomplish this reliably.

Radiator steam “trap” failed open

Radiator steam “trap” failed open

At the start of any heating cycle, the system is full of air, which must be removed for steam to enter the heaters. In most two-pipe systems, the steam pushes the air out of the heaters, through the traps, and into the return piping where it eventually exits the system through a vent in a vacuum or condensate tank. That’s what happens when the traps are working. But a failed open trap is no trap at all. It lets the steam flow into the return piping and, with pressure on both the supply and return sides, air is trapped in the system. This affects those farthest from the boiler—the heaters near the ends of the mains and on the top floors—the most.  (And with air trapped inside keeping the metal cold, are they even heaters?)

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Electrify Everything? Part 1

So in utility and policy circles, electrification is all the rage. Grid electricity is getting cleaner (i.e. resulting in lower CO2 emissions), on-site renewables are taking off (sometimes even with storage), and heat pump technologies are getting better. More regional and utility initiatives are encouraging building owners/designers/developers to forego onsite fossil fuels entirely (or at least mostly) to help meet CO2 emission reduction goals. But is electricity really more sustainable than natural gas? Is it cheaper? Which is better, really?

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Tech Notes: Meeting the Accessibility Criteria for Horizontal Exit Doors

Getting out of a building during a smoke or fire event can be traumatic for anyone. But, just imagine how traumatic it can be for a person who uses an assistive device, such as a wheelchair? If proper maneuvering clearance is not provided at doorways, then a person can become trapped.

Building code requirements for accessible means of egress have been developed to ensure that people with disabilities can exit buildings safely in the event of a fire. These requirements, found in chapter 10 of the International Building Code (IBC), establish proper maneuvering clearances at certain doors to safeguard against the potential for entrapment. Horizontal exit doors are an example of such doors.

Horizontal Exit Doors

horizontal exitWe’ve all seen them; in a hospital corridor, at the school cafeteria, or near the elevator lobby in a high-rise apartment building. They are doors that are held open most commonly by magnetic locks, which are connected to the building’s fire alarm system. When the building’s fire alarm is triggered, the magnetic hold-open device releases, and the doors close to contain smoke and flames.

 

The 2015 IBC defines a horizontal exit as:

“An exit component consisting of fire-resistance-rated construction and opening protectives intended to compartmentalize portions of a building thereby creating refuge areas that afford safety from the fire and smoke from the area of fire origin.”

 

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Does Your Exhaust Fan Suck? Part 1

You most likely don’t even think about it when using the bathroom. Flip the switch, hear the exhaust fan, and everything is working as it is intended…right? Far too often, the answer is NO, and it is no fault of the user. Sure, homeowners should take a minute each year to vacuum the inside of the exhaust fan housing, but otherwise, these fans should just work. So why don’t they? Hint…it all depends on how it was sized and installed.

Background

The purpose of exhaust ventilation is to remove contaminants (including moisture) that can compromise health, comfort, and durability. Exhaust fans are amongst the simplest mechanical systems in your home, but decades of experience working in homes has shown us that even the easiest things can get screwed up. Far too often, exhaust fans rated for 50 or 80 cubic feet per minute (cfm) of air removal are actually operating at less than 20 cfm. In theory, the exhaust fan should be installed in a suitable location and then ducted to the outside via the most direct path possible. However, the installation of an exhaust fan can involve up to three trades: an electrician typically installs and wires the unit; an HVAC contractor supplies the ductwork; and, the builder/sider/roofer may install the end cap termination. What could go wrong?

As energy efficiency standards and construction techniques have improved over time, new and retrofitted buildings have become more and more air-tight. If not properly addressed, this air-tightness can lead to moisture issues. Quickly removing moisture generated from showers is a key component of any moisture management strategy. While manufacturers have made significant advancements in the performance, durability, and controls of exhaust fans, these improvements can all be side-stepped by a poor installation.

So how do you correct this issue? Read more

Trends in Healthcare: Patient Check-in Kiosks

“Trends in Healthcare” is a recurring series that focuses on exciting new designs and technologies we’re seeing in healthcare projects and provides best practices on how to ensure that these latest trends are accessible to persons with disabilities. We build on the wealth of knowledge we gain from working with healthcare design teams, construction crews, and practitioners to provide practical solutions for achieving accessible healthcare environments.

And now for our first installment…Patient Check-in Kiosks!


Check-in kiosks are becoming prevalent in state-of-the-art healthcare facilities. Where provided, at least one of each type of kiosk must be accessible.

Imagine that you are walking into the waiting room of your doctor’s office for your annual checkup. The waiting room is overflowing with people and the receptionists are answering phone calls, entering information into the computer, and taking care of the long line of patients ahead of you. That’s when, out of the corner of your eye, you see several touch screens located on a nearby counter. You’ve grown accustomed to self check-in kiosks at airports and theaters, but not at your doctor’s office. Eager to skip the long line, you make your way toward the digital devices. Hooray! Patient check-in kiosks have arrived!

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