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[steven r]

This is a request for a hardware device to
detect a temperature and close a contact
monetarily. I want to trigger a universal
module when the temperature drops below 40.
The trick is it can't stay on and must just
be a momentary on.

Any ideas?

[Noam]

You could use a timing circuit. Radio shack
a chip for this. You can set it to close
the "output" contacts for a moment when
the "input" contacts get closed, but won't
reset until the "input" contacts are opened
again.

[steven r]

My idea is trigger a hot water recycler to
keep pipes warm if the temperature should
approach freezing. What I need is a small
simple sensor that could be attached to the
hot water pipe that closed when the
temperature dropped below 40. That should
work fine. The warming of the pipe would
serve as a reset for the sensor.

Check out
http://www.chilipepperapp.com/Default.htm
for the hot water recycler I'm planning to
install.

[Gil Shultz]

The interface is very easy to make, a Op-
AMP a few resistors and a thermistor will
do the trick.  I have several working in my
house controlling heating, cooling and the
instant hot water system.  Many Op-Amps can
directly drive an opto interface.  What
does the output need to look like.  I tend
to use Wall Warts to power these systems
and put them in a standard 4” electrical
box.
Gil

[steven r]

"What does the output need to look like?"

It needs to close a contact on universal
module.

Thanks!

[steven r]

"What does the output need to look like?"
Basically it needs to close a contact.

Now that I think about it, my previous
answer must of been a bit confusing since
the universal module isn't an input device.
I'll be connecting the sensor to a hot
water recycler. See
http://www.chilipepperapp.com/Default.htm
for specifications. My confusing previous
post was because I plan to have the
universal module also connected to the hot
water recycler.

I can use a soldering iron but would need a
bit of "hand holding" regarding what parts
to get. i.e. A schematic would be a great
help.

[Gil Shultz]

In my house I installed what is called
instant hot where the hot water is pumped
from the far end of the house to the bottom
of the hot water heater (about 80 feet each
way of ¾” tubing).  Initially this worked
just fine with convection but when we added
the California room it quit working.  I
installed a small (size 00) Taco
recirculation pump and put a grounded line
cord on the pump and plugged it into an
appliance module.

I put motion sensors in the halls near each
bathroom, kitchen sink, laundry sink and
the bar sink.  These are all set for
minimum time (1 minute).  When anybody
approaches any of these sinks, the pump
starts.  The result is that they get hot
water instantly when turned on, this works
very well on the lines with a return and
fairly well on the others. Worse case delay
for hot water is about two seconds instead
of the original 30.  When we have a bunch
of people over it seems the pump never to
stops so I added a thermistor (10K) Put it
in shrink tubing and placed on hot water
return.  With an OP-AMP (LM358) a few
resistors, a wall wart, surplus solid-state
relay and a few other minor parts.  Now
when somebody gets near any of the
appropriate points the appliance module
still comes on but the pump doesn’t start
if the return is above about 110F.

You would need to be handy with a soldering
iron etc to build this one, but it does
work quite nicely. It may be possible to do
it with a motion sensor such as the MS12
and replace the photo sensor CDS1 with a
thermistor.  I have not taken the time to
work out the circuit.

Hope this helps.
Gil

[Gil Shultz]

In my house I installed what is called
instant hot where the hot water is pumped
from the far end of the house to the bottom
of the hot water heater (about 80 feet each
way of ¾” tubing).  Initially this worked
just fine with convection but when we added
the California room it quit working.  I
installed a small (size 00) Taco
recirculation pump and put a grounded line
cord on the pump and plugged it into an
appliance module.

I put motion sensors in the halls near each
bathroom, kitchen sink, laundry sink and
the bar sink.  These are all set for
minimum time (1 minute).  When anybody
approaches any of these sinks, the pump
starts.  The result is that they get hot
water instantly when turned on, this works
very well on the lines with a return and
fairly well on the others. Worse case delay
for hot water is about two seconds instead
of the original 30.  When we have a bunch
of people over it seems the pump never to
stops so I added a thermistor (10K) Put it
in shrink tubing and placed on hot water
return.  With an OP-AMP (LM358) a few
resistors, a wall wart, surplus solid-state
relay and a few other minor parts.  Now
when somebody gets near any of the
appropriate points the appliance module
still comes on but the pump doesn’t start
if the return is above about 110F.

You would need to be handy with a soldering
iron etc to build this one, but it does
work quite nicely. It may be possible to do
it with a motion sensor such as the MS12
and replace the photo sensor CDS1 with a
thermistor.  I have not taken the time to
work out the circuit.

Hope this helps.
Gil

[steven r]

Gil
The motion detector sounds like a nice
touch. For my aplication I plan to use a
push button to trigger it most of the time.
My idea of the temperature sensor was to
trigger if the pipe temperature dropped
below 40. By having the sensor attached to
the pipe, it would "reset" when it warmed.
It sounds like your idea could work for me.
Could you email or post wiring plans. I am
comfortable with a soldering iron.

[steven r]

Gil
I've posted my request at
http://forums.accessx10.com/showthread.php?
s=&threadid=81 also. (As usual remove any
forum added spaces from link.)

If you would be so kind as to access it
there I can email you directly through that
forum for details.

I don't like posting my email on forums. I
get enough spam as it is and don't care to
feed the spy bots. That forum will allow
attachments also if you can work up a
schematic.

Thanks!

[Brian H]

Maybe overkill but Smarhome has a Templinc
module. It can be programed [need a
controller that can send house and unit
codes with no function codes like a Maxi-
Controller] to send a X10 ON code when a
temperature is below the set temperature and
an OFF code 2 degrees higher. Can also be
polled for temperature or to send changes as
they happen. Model 1625