TODAY I took another look at a key section of the Historic Structure Report (HSR), namely its comprehensive analysis of the mechanical (air handling) system in the Social Hall, as of 20 years ago. Potentially good news there, with regard to our being able to provide decent ventilation in the era of covid-19, at least when the weather is mild. It may be practical for us to safely use the room, after all!
 |
| (As usual, click/tap on an image to enlarge it.) |
What I hadn’t realized before is that even though the Social Hall’s furnace no longer works, the supply fan might still be able to provide ventilation to the hall and kitchen.
Executive Summary
According to the HSR, the Social Hall has a working ventilation system in place:
- A supply fan draws outside air from the play area.
- Ductwork distributes the air throughout the Social Hall.
- The air is exhausted back outside via vents in the kitchen.
At the time, the supply fan was estimated to have at least 2 years of remaining life, and apparently it has not been used at all since then. So with lubrication, and with the cleaning of fan blades, louvers, grilles, and ducts, the system may still work for some time to come. The introduction of a modest filter should also be considered, to reduce the level of dust introduced into the room.
I’m inclined to suggest that we call in a mechanical contractor for an updated evaluation.
Existing Condition of the HVAC System (2003)
Excerpted from the engineering report by Donald F. Dickerson Associates in the HSR. Emphasis added; relevant passages highlighted.
Mechanical System: Social Hall – Basement Level
a. The social hall is served by [a] heating ventilation system which consists of a gas furnace, supply air fan and related ductwork. The system is 100% outside air [i.e., no return ducts that recycle the inside air]. Air is supplied through supply air grilles located in upper portion of the east wall. An outside air grille is located on the east exterior wall. Air is relieved through a relief air grille located in the meat/parve and dairy kitchens.
b. The gas furnace located in the southeast room … is in very poor condition and has not been operational for some time. … The gas furnace must be replaced as soon as possible to provide heating to the basement, in order to meet Uniform Mechanical Code requirements.
c. The supply fan is located in the southeast fan room [see B-04B in the floor plan, above].… Supply fan is in poor condition and rusted but is currently operational. Life expectancy is 2 to 5 years.
d. There is a manual air damper between the gas furnace and fan room. Damper is rusted and has not been operational. Needs to have rust removed and repair damper.
e. The ductwork has been recently installed and in good condition. The life expectancy is 15 to 20 years.
f. Outside air louver … needs to have rust removed and [be] repainted.
g. Supply air grilles … are in fair condition. Need to be cleaned and repainted.
PROPOSED REPAIR RECOMMENDATIONS
[when the supply fan does reach the end of its useful life]
Install new supply fan with associated ductwork and support. Provide filter,
60% efficiency. [Estimated cost in 2003:] $6,000
 |
| Supply fan (about 4' tall and wide), with its motor in the background |
 |
| Inlet grille for Social Hall ventilation, at landing at top of the fire escape stairs, under the shed roof, just off the play yard |
APPENDIX:
How Long Does Ductwork Typically Last?
I’d not realized before that air ducts need occasional maintenance and have a predictably limited lifetime. The following excerpt from an HVAC contractor’s website discusses a residential system, but the principles should apply in our case, as well.
Most ductwork will last for 10–15 years before you need to consider repairing or replacing it. It usually has a maximum lifespan of 20–25 years. It often begins to deteriorate much sooner than that.
Deterioration happens over time because ductwork moves. It expands in winter when it is used for heating and then contracts in summer when it is used for cooling. In addition to the expansion and contraction caused by the change in the temperature, vibrations from the fans pushing air through the house can cause damage.
While the movement of the air ducts is largely unnoticeable, it does actually have an effect on the duct system. Over time seams will pull apart, creating leaks. This makes the HVAC system far less efficient, as the cool or warm air that it is trying to direct into your home leaks into your attic or crawlspace.
The metal in the system can also rust. This happens mainly during the summer, when the cool air running through the ducts causes condensation to collect on the metal. That rust can corrode the metal until it has created holes in the work, further reducing the efficiency of the HVAC system.
Leaks can also affect air quality. If the system runs through the attic, they can allow dust into your system. If they run through the crawlspace, they can pull in the dirt, mold spores, and other particles into the ductwork. Since these contaminants will essentially be bypassing your air filter, they can significantly degrade the air quality in your home.
In other words, every 10 years, Mishkon should have its school building’s ducts inspected by a contractor for leaks, and the same for our temple building every 15 years. The leaks can then get fixed with duct tape (!). Because our school building’s HVAC system runs 5 days a week, all day long, it ought to be inspected more often than our temple building’s system. But what is the starting point — how long has it been since either set of ducts was inspected?
No comments:
Post a Comment