using a line-voltage thermostat to drive a blower
 

Hello,

does anybody have experience using a line-voltage thermostat
to drive something other than a heater? I would like to use one
to drive a 1/4 HP 115V electric motor, but I am concerned that
it might not work. The specs for most of them (for instance,
the Honeywell T4700) specify "resistive load only" and
furthermore they have a minimum power requirement of
500W. I am afraid that the power supply of the thermostat
itself relies on a certain amount of current flowing through
the wire.

Thanks
Luigi

P.S. What's the deal with alt.hvac? Is it exclusively for people
who make a living out of HVAC installation/repair?

These things work in series with the load. I assume the 500w minimum is a
calculation about where you won't be powering a significant part of the load
simply to drive the thermostat. It does sound high for any solid state device.
Personally I think I would go with a low voltage thermostst and a relay/starter
for the motor.

wrote in message
oups.com...

P.S. What's the deal with alt.hvac? Is it exclusively for people
who make a living out of HVAC installation/repair?


Yup
Greg

wrote in message
oups.com...
Hello,

does anybody have experience using a line-voltage thermostat
to drive something other than a heater? I would like to use one
to drive a 1/4 HP 115V electric motor, but I am concerned that
it might not work. The specs for most of them (for instance,
the Honeywell T4700) specify "resistive load only" and
furthermore they have a minimum power requirement of
500W. I am afraid that the power supply of the thermostat
itself relies on a certain amount of current flowing through
the wire.

Thanks
Luigi

P.S. What's the deal with alt.hvac? Is it exclusively for people
who make a living out of HVAC installation/repair?


This is Turtle.

I think your tring to hook a light weight thermostat to a heavy weight electric
load. I think you need to rethink this and go here.

For the price of a Honeywell T-4700 thermostat you can buy a Honeywell
T-6031A-1029 and run a 1 horse motor and do fine. Or maybe a White Rogers
1609-105 which is the same thing in White Rogers. Also the starting amps of the
1/4 H.P. motor will be working on the T-4700 thermostat a good bite.

Now to your P.S. Question. We're Crazy / Somewhat but we would like to think
that.

TURTLE

wrote in message
oups.com...
Hello,

does anybody have experience using a line-voltage thermostat
to drive something other than a heater? I would like to use one
to drive a 1/4 HP 115V electric motor, but I am concerned that
it might not work. The specs for most of them (for instance,
the Honeywell T4700) specify "resistive load only" and
furthermore they have a minimum power requirement of
500W. I am afraid that the power supply of the thermostat
itself relies on a certain amount of current flowing through
the wire.


From some of your other posts it sounds like you may have part of what could
be a really nice system in place, I suggest you should get a hold of a
contractor that specializes in industrial HVAC control systems and have him
add contactors and some kind of a low voltage zonal control system.


P.S. What's the deal with alt.hvac? Is it exclusively for people
who make a living out of HVAC installation/repair?


Not exactly true, but for all practical purposes close enough........

===

For example, if you wanted me to open up shop after hours and discuss
modifications or fabricate repair parts on the cheap for your gyrocopter,
wood chipper, dirt bike, ect. etc; then you had better at least bring along
some good beer......

....BUT...

If theres 'any' doubt in my mind whatsoever you are wanting me to do
something that may present a hazard yourself or others, I'm NOT gonna TOUCH
it with a ten foot pole.....and at this point it dont matter how much cash
you bring along, whether its during regular business hours or
otherwise......

--

SVL

Thank you for all the suggestions.

I have been using a contractor (Reid Heating and Energy in Marin
County) for the major work, but it's not clear to me that the extra
cost is justifiable for small, simple things that I can do myself
almost as fast. Hydronics contractors are quite expensive. I figure I
have being paying for labor at something like $200/hour. That's a fine
pay for myself (no taxes either) and right now I have the extra time.

Using a 24V thermostat requires running 24V power to the switch, but it
does seem like the cleanest solution. I'll have to cave in an break the
walls. Only once I hope!

Thanks again.

"Greg O" wrote in message
...

wrote in message
oups.com...

P.S. What's the deal with alt.hvac? Is it exclusively for people
who make a living out of HVAC installation/repair?


Yup
Greg

Second that!

~kjpro~

wrote in message
oups.com...
Thank you for all the suggestions.

I have been using a contractor (Reid Heating and Energy in Marin
County) for the major work, but it's not clear to me that the extra
cost is justifiable for small, simple things that I can do myself
almost as fast. Hydronics contractors are quite expensive. I figure I
have being paying for labor at something like $200/hour. That's a fine
pay for myself (no taxes either) and right now I have the extra time.

Using a 24V thermostat requires running 24V power to the switch, but it
does seem like the cleanest solution. I'll have to cave in an break the
walls. Only once I hope!

Thanks again.


This is Turtle.

Running a line voltage to a thermostat in your home is dangerous to have 120
volts or 220 volt service hanging on a wall in your home. A kid can get up on a
chair and pull the cover off and start playing with high voltage to kill him
with. If you run a 24 volt system to control the pumps or water system it will
be set up to do anything else you want later when changing things over to a new
type system or control system. Set up a 24 volt control system is really simple
to do.

TURTLE