"Mark" wrote in message
...
Hoping someone can offer some guidance. I do want to state that I will not
be doing the work myself but will have a licensed electrician replace the
motor in my unit heater if it is a good option.
Not hard to do for a DIY. I used to run the assembly line for unit heaters
that compete with Reznor.
I am asking here instead of
playing phone tag with the electrician and waiting two weeks for a call
back
plus I know there are a lot of experienced folks here that can tell me if
I'm thinking in the right direction.
Here's the question:
What I'd like to do is put a larger motor on it to
try and increase the cfm's to use more of the heat that appears to be
available. Doing the also may increase air circulation in the room to
spread
the heat around a bit more also. Does this sound like a good or a bad
idea
?
Bad idea.
Changing the motor is not going to give more CFM unless it turns at a higher
rpm. A 1/30 hp motor at 1550 will give the same volume of air as a 1/2 hp
motor at 1550 with the same fan blade. I cannot speak for Reznor, but we
used to offer two fans on a given model, one had a higher output. There
were still limits as to the amount of heat that a given coil will produce.
Increasing the flow of air over the coil is not necessarily going to extract
more heat. You need a certain amount of "residence time" for the moving air
to pick up the heat from the surface area of the coil/fins. It may move it
to other sections of the room, but it is not going to give off more heat.
You can get the same result by putting a secondary fan to help move the air
to where it is needed.
In truth, you can get more heat from the coil with lesser air flow. That
gives the air more time to pick up the heat. What it also does is reduce
the circulation. It will be much hotter at the heater, but much cooler in
the far areas of the room.
When I worked for the Nesbitt Company years ago, we had some pretty smart
engineers trying to wring out as much heat as possible from a given heater
design. You need some balance between air flow and temperature. I'm sure
Reznor did the same.
If you want to get more heat out of the water line in the room, add more
surface area. After the heater add sections of finned tube. Or add a
second heater with blower.
Ed
http://pages.cthome.net/edhome