search  current discussion  categories  safety - misc 

safety issue: "make-up" air (was: electric kiln)

updated sat 10 jul 04


Ken Nowicki on fri 9 jul 04

Something that I think needs to discussed here is the safety issue of
providing "make-up" air for your room ventilation in a situation where you have a
kiln in an enclosed space. Even if you have the proper kiln ventilation system
(Orton vent, EnviroVent, VentSure, etc.) installed on your kiln, exhausting the
nasties outdoors (away from any open windows)... and... you have some sort of
room ventilation system in the enclosed space to keep the room from getting
exceedingly hot... you still need to think about where your "make-up" air is
going to come from.

I've been directly involved with this issue recently as I too am installing a
kiln in my "boiler room" of my basement in my home... so this topic is
forefront in my mind... and I am taking all the measures I can to make this
installation very safe... after all... I have my whole house above it all... not to
mention the safety of my family at stake.

If, for example, you have an exhaust system in place for the room
ventilation, whether it be an exhaust fan mounted in a window or whatever... IF there is
NOT ENOUGH "make-up" air (fresh air to replace the air being sucked out of the
room)... it will create a vacuum effect... and the fan will begin drawing air
from any available source it can find as the vacuum pressure increases. This
could potentially pose a fatal accident, as my electrical contractor recently
reminded me with this tragic true story (see following paragraph).

A doctor here on Long Island a few years ago was in his basement "boiler
room" changing the filter on his furnace/fau unit. Newer units have new safety
measures that when you pop off the grill to access the filter, a button pops out
and shuts off they system. Unfortunately his was an older model that didn't
have this safety feature. He proceeded to take off the grill setting it aside,
then took out his dirty air filter. He apparently realized he didn't have
another clean filter handy, or was distracted or whatever... but either way... he
left the room with the system open and filter missing... closed the door to the
boiler room and left. The furnace unit continued to run. Without the grill
and filter in place the volume of air being sucked into the furnace was
increased enough to create a vacuum in the room. The vacuum created caused the flue
gasses from the nearby water heater to back down the water heater's exhaust pipe
pumping carbon monoxide into the boiler room. Even worse, the doctor had a
battery powered carbon monoxide detector nearby, but apparently it had been
beeping to tell the user that the batteries were low... and he disconnected the
thing and never put fresh batteries in it. The carbon monoxide built up enough
to seep upstairs into his home where it tragically ended up killing his wife
and three children while in their beds sleeping... apparently he wasn't home at
the time. Imagine having to live with that the rest of your life.

So... the moral of this story is... make sure you have (a) plenty of
available "make-up" air for your ventilation system, and (b) a working carbon monoxide
detector nearby... at the very least.

In my situation, I thought at first that I would just get a powerful enough
exhaust fan from Grainger or something and place it in one of the windows in my
boiler room, and then open the other window for my "make-up" air.
Fortunately, my electrician is extremely knowledgeable about HVAC and other types of
ventilation issues as well... and his first response was... "I don't like it...
When are you planning on firing this kiln... how often? Year 'round? What are
you going to do in the winter months when it's freezing or below outside... open
that window?" Hell... hadn't even thought about THAT... sheesh. He said...
"open that window when it's in the 20s here and you could freeze your pipes
down here." He came up with a brilliant solution. He is going to be cutting a
rectangular hole on one of the concrete walls, and installing a room ventilation
system with a 'heat exchanger'... the until fit snugly into the hole... and
circulate the air in the room X times per minute/hour (I forget the details
right now) but... this is the kicker... when the outside air temperature drops
below 40 degrees, the heat exchanger will preheat the incoming "make-up" air
coming into the room so that it won't get too cold down there. For those of you
living in more temperate climates, this is probably a non-issue, but for me,
living here on Long Island, New York... it's something I need to contend with in
the winter months. He said this unit takes up about as much space as a small
air conditioner, like the kind people mount in their windows. Fine with me. It
also frees up being able to use those two windows again in the warmer months
if I like.

He is also going to hard-wire a carbon-monoxide detector in the boiler room
for me as well. When I asked if he thought that it might be prematurely
tripping all the time being so close to the kiln area (I've heard those things are
notorious for being ultra sensitive) he said that he didn't think it would be a
problem, that he has had many successful installations next to industrial
applications, such as large boilers and furnaces.

Anyway, I felt that this was an extremely important topic for consideration
while planning on any kiln installations in enclosed areas, especially
basements and the like. With the deadly nature of carbon monoxide, we can never be too

Best wishes,

- Ken

Kenneth J. Nowicki
Port Washington, NY
Charter Member/Potters Council

On Thu, 8 Jul 2004, Patrice Murtha wrote:

>I Am finally getting around to building a studio in my basement. Can
>I safely install an electric kiln down there? This kiln would be
>going into what I call my slop room area- It's located under my porch
>away from the rest of the basement near a window where it can easily
>be vented-- on a cement floor with fireboard around it. I guess I'm
>wondering if anyone else out there has their electric kiln in their
>basement and if you do can you give me some tips what you did to make
>it as safe as possible.