I'm looking for a natural gas, sealed combustion, forced air garage heater
for my 20' X 20' insulated garage workshop (which also has to house our two
cars). From my research so far I can only find a Reznor unit that meets the
above specifications. From what I can tell the Modine Hot Dawg units do not
have sealed combustion chambers. I have already decided that I want a
sealed unit and also that I don't want radiant heat. One contractor that
has come to my house gave me an estimate of around $2000 to install even the
30,000 Btu Reznor sealed unit (which apparently is about the right size for
my installation). I wasn't under the impression that Reznor would sell
direct to customers, but I would certainly consider self-installation, as my
brother-in-law is an electrical contractor and has a "gas guy" that would do
the natural gas work for only the cost of materials. I'm a little
concerned, though, about making sure the whole installation is to code and
safe. My questions are...
* Are there any other brands other than Reznor that provide the type of unit
I'm looking for?
* Is there a place where I could buy one of these heaters direct?
* Would the installation and especially the venting be a difficult thing to
it is not rocket science but does have to be done right. I would check
with the local inspector (assuming you are going to get it inspected)
and see if he has specifice requirement. they may actually have a spec
sheet that will give you THEIR clearence requirement and slops and all that.
As for the heater, I can't help you their, I just have a none vented
Denver Woody wrote:
It looks like their "unit heaters" are from a company called Dayton, which I
had not heard of. From what is displayed in the Grainger catalog (limited
information), it does not seem to me that these heaters are sealed unit
heaters. I tried to Google for "Dayton heaters" and several variations, but
I could find no company homepage to give me more information.
I looked at the same thing for my 20x20 shop and ended up with the Reznor FT
25. Nope, it's not a sealed unit but I did get the stainless steel heat
exchanger as I figured the unit may undergo condensing at night when I
turned the heat down. Initially I wanted a sealed unit but was talked out of
it by the rep and by several engineers. The theory being that the volume of
dust in the air to even begin thinking about an explosion would mean that
the place would not be habitable to begin with. Keep in mind that the rep
actually "down sold" me and lost a larger sale because of this.
I hung the unit myself with a little help from a "gas guy". The elec was a
simple 110VAC feed and a pair of thermostat wires. The worst part was lining
up the vent with the back of the unit when I cut the hole in the wall. I ran
the unit for the time I was in the shop (have since sold it) and I know it's
still running now and being used every day.
$2000 is too much money. you should be able to do it for 1/3 to 1/2 that.
So that opens up the possibility of running one of those Hot Dawg units as
well (if a sealed unit is not all that necessary). I don't know if they're
any lower cost than the Reznor units. I get the impression in my research
that Reznor commands a premium price. Did you ever stain or polyurethane in
your garage or have the concern of igniting those vapors?
I've had a 45,000 BTU propane Hot Dawg in my shop for almost two years with
no problem. As someone else suggested, the air quality would have to be
uninhabitable before the heater exhaust becomes a concern. The cost of my
heater with installation and shipping was about $550. I installed the heater
and the propane company installed their tank, lines and fittings. I bought
my heater from
http://www6.mailordercentral.com/igcusastore/departments.asp?dept 09. All
the info you need is available at the site. I ordered on a Thursday and it
arrived the following Tuesday. I bought the thermostat, type B vent pipe and
cap locally. I vented out a side wall rather than going up.
If you have further questions, email me. I can send you photos if you would
I stain what I term as small items, up to half a sheet of plywood, in my
shop with a non vented propane heater. there is not enough solvent in
the air for an ignition. In order to do larger pieces, or poly, I move
to the garage (unheated). the major problem being space and the air
would not be breathable in the shop for days after. My shop is fairly
tight to help with the heat and AC so i try and poly outside of it.
If you are going to vent the shop properly, to finish in there, then you
will exhaust all the solvent (along with the heat) so it wouldn't matter.
Denver Woody wrote:
I have a Reznor; it uses a co-axial flue to get cold combustion air in
and exhaust out. Mine is vented out the side of my garage instead of
going up. Since moisture is a by-product of combustion and the
exhaust tube is surrounded by a cold air coming in, the water tends to
condense on inside of the exhaust flue and run downhill. Initially
that meant back into my house and into a storage shelf!
The heating company made good and fixed it, now the chimney tubes are
all sealed with high temperature caulk and the inner tube is tilted
slightly so the water runs out of the house. I often have a 4 to 6
foot ice stalagtite under my heater's exhaust. If you have one of
these units installed, make sure you know where the water will go.
I didn't realize how much more the sealed units would be over the non-sealed
types. Do you think that the airborne wood dust, or stain or polyurethane
present a flammable hazard? I'm starting to wonder myself...
I would hazard a guess that most of the regular posters here do not have
a sealed unit. The concentration of either dust or solvent has to be
fairly high before there will be a problem. I am guessing that you
would not be able to be in the shop at those levels.
I expect that there will be a huge posting by someone with a story about
a friend of a cousin that made 3 cuts on his table saw and the heater
cut on and the whole place burned down but I really doubt those stories.
Falls into the same category as grounding your PVC dust collection
pipe (don't start that here! email me directly).
I use an unvented heater and there are many postings ranting about not
doing that because of all the water vapor generated and your tools will
rust in hours. Well I do get some rust on my tools, year round, I'm in
the south and the humidity is always high, that's just life.
I've been reading this and other news groups for a long time (back when
we go them via UUCP!) and the best advice I can give you is to look at
the postings, throw out the ones that say "you HAVE to do it this way",
the ones that say "you CAN't do it that way" and look for the folks in
Denver Woody wrote:
I bought Reznor 45,000 BTU sealed unit for my shop, having also looked
at the Hot Dawg. The heater itself was around $1k from the distributor
and installation and chimney and other parts added close to another
$1k. Like you say, the Reznor model in question has sealed combustion
and takes its combustion air from outside via a pipe, not the shop.
The Hot Dawg is not sealed and takes its combustion air from the
surrounding space. Both of them pipe their exhaust products to the
Even though the Hot Dawg is much cheaper and seems to have lots of
sastified users, I still went with the sealed Reznor, based on advice
from the local distributor (who sells both types) and reading the
product literature closely.
First, the sealed Reznor unit is specifically designed and warranteed
to operate trouble-free in dusty woodworking shop conditions. The Hot
Dawg is marketed and warranteed as a garage heater. Obviously, both
these heaters work by blowing large amounts of (more or less dusty)
room air across a heat exchanger then back out into the shop. Given
how complex the burners and sensors and electronics located in the
same cabinet look to be, it seems reasonable that a sealed combustion
system should hold up better over the long haul. Second, the Hot Dawg
has certain ventilation requirements for use in some confined, tightly
built spaces that do not apply to the Reznor which takes its
combustion air from outside.
...If you haven't already, download the full installation and owners
manual for both units (not just the consumer brochures or spec
sheets). IIRC, both address these points in detail, includuing the
presence of dust and wood dust as operational and/or warranty issues
Whatever you go with, I think you will be very pleased with how well
these heaters work. Being able to walk in and crank the thermostat to
any temperature you want and have a toasty shop makes a huge
Thanks for the detailed response. I think the key to satisfaction with the
Hot Dawg may be to keep my garage dust-free, which is difficult when I've
already got a ton of mobile-base-equipped tools and two compact cars in
there. Fitting something for dust collection will require some ingenuity.
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