Furnace bump timer

[amdx]

I put this circuit together over twelve years ago.
I have it installed on my furnace/air condition control.
I have a momentary switch near the thermostat, when I
push the switch the furnace or air will come on for about
4 minutes (plus or minus). I move an alligator clip
depending on season, you can put in a switch.
I use it rather than turning the heat/air up and down,
for a short comfort adjustment.
It runs from a 9 volt battery and has very low standby current,
about 80 nanoamps. The battery lasts two or three years.
Others can modify for different purposes. If you think of another
use, please post it.
MikeK
http://i395.photobucket.com/albums/pp37/Qmavam/Furnacebumpcircuit.jpg

 

[Jamie]

I put this circuit together over twelve years ago.
I have it installed on my furnace/air condition control.
I have a momentary switch near the thermostat, when I
push the switch the furnace or air will come on for about
4 minutes (plus or minus). I move an alligator clip
depending on season, you can put in a switch.
I use it rather than turning the heat/air up and down,
for a short comfort adjustment.
It runs from a 9 volt battery and has very low standby current,
about 80 nanoamps. The battery lasts two or three years.
Others can modify for different purposes. If you think of another
use, please post it.
MikeK
http://i395.photobucket.com/albums/pp37/Qmavam/Furnacebumpcircuit.jpg

Something tells me a capacitor across the coil (1,5) should be added to
aid in making sure the armature gets fully moved over with out chatter
on the contacts.

That's just me... ignore me otherwise.

Jamie

 

[Josepi]

Very nice idea and good logic.

I can't help but think the circuit is way over designed with too many
components. It doesn't matter to you because you have it built now.

I would have thought a UJT transistor with a simple RC ramp generator
but....wait! Yeah another contact on the relay would go a long way to
accommodate much simpler circuitry. probably not happening on a latching
relay.

Here is something ese you may consider...steal power from the furnace
circuit. Hook your common to the one side of the contact and to the other
side of the contact make a simple trickle charge circuit with.

furnace connection -> diode -> resistor (say 1K) -> capacitor to common (say
1000uf) -> 9v input.

If the voltage is critical you could insert a 7809 regulator to setady the
voltage at 9 volts from the 30 you may get off the trickle voltage stealing
circuit or you could use a parallel resistor across the ripple capacitor to
drop the voltage down to 9-12 volts. The trickle current has to be light and
the cap. big enough to carry the relay coil snaps.

I have discovered the timer input on my HRV system and gor PB to activate it
for 20-40-60 by holding it down longer for one, two or three blinks of the
feedbak LED on the wall. Short shots of ventilation stuff is nice. You get
it when you want it but don't have to find it running your wallet down a
month later.




I put this circuit together over twelve years ago.
I have it installed on my furnace/air condition control.
I have a momentary switch near the thermostat, when I
push the switch the furnace or air will come on for about
4 minutes (plus or minus). I move an alligator clip
depending on season, you can put in a switch.
I use it rather than turning the heat/air up and down,
for a short comfort adjustment.
It runs from a 9 volt battery and has very low standby current,
about 80 nanoamps. The battery lasts two or three years.
Others can modify for different purposes. If you think of another
use, please post it.
MikeK
http://i395.photobucket.com/albums/pp37/Qmavam/Furnacebumpcircuit.jpg

 

[Tom Biasi]

"amdx" wrote in message
I put this circuit together over twelve years ago.
I have it installed on my furnace/air condition control.
I have a momentary switch near the thermostat, when I
push the switch the furnace or air will come on for about
4 minutes (plus or minus). I move an alligator clip
depending on season, you can put in a switch.
I use it rather than turning the heat/air up and down,
for a short comfort adjustment.
It runs from a 9 volt battery and has very low standby current,
about 80 nanoamps. The battery lasts two or three years.
Others can modify for different purposes. If you think of another
use, please post it.
MikeK
http://i395.photobucket.com/albums/pp37/Qmavam/Furnacebumpcircuit.jpg

You have explained and documented your project rather nicely.
Good job.

Tom

 

[amdx]

Something tells me a capacitor across the coil (1,5) should be added to
aid in making sure the armature gets fully moved over with out chatter
on the contacts.

That's just me... ignore me otherwise.

Jamie

Hi Jamie,
I noted I have a diode on one coil but not on the other.
I don't remember if the diode was added to correct a problem or
if it was put in as general good practice and just forgot on the other coil.
But the circuit is drawn as has been working for 12 years.
MikeK

 

[amdx]

Very nice idea and good logic.

I can't take credit for the design, I just put it together.

I can't help but think the circuit is way over designed with too many
components. It doesn't matter to you because you have it built now.

I would have thought a UJT transistor with a simple RC ramp generator
but....wait! Yeah another contact on the relay would go a long way to
accommodate much simpler circuitry. probably not happening on a latching
relay.

I'd like to see your design!

Here is something ese you may consider...steal power from the furnace
circuit. Hook your common to the one side of the contact and to the other
side of the contact make a simple trickle charge circuit with.

furnace connection -> diode -> resistor (say 1K) -> capacitor to common
(say
1000uf) -> 9v input.

If the voltage is critical you could insert a 7809 regulator to setady the
voltage at 9 volts from the 30 you may get off the trickle voltage
stealing
circuit or you could use a parallel resistor across the ripple capacitor
to
drop the voltage down to 9-12 volts. The trickle current has to be light
and
the cap. big enough to carry the relay coil snaps.

I have discovered the timer input on my HRV system and gor PB to activate
it
for 20-40-60 by holding it down longer for one, two or three blinks of the
feedbak LED on the wall. Short shots of ventilation stuff is nice. You get
it when you want it but don't have to find it running your wallet down a
month later.

Thanks, MikeK

 

[amdx]

I do the same thing by having a humidity sensor(Aprilaire)
wired for switch closure on humidity RISE, inserted into the
red wire to the thermostat.
That way, when I come in from grass cutting or whatever,
I just breathe a warm, wet breath into it, and the A/C kicks
on promptly, runs for about 15 minutes.
And since the thermostat/humidistat is in the hallway near
the bathroom door, when someone finishes taking a shower
and opens the door, the A/C will kick on within 45 seconds
and clear the humidity from the area and remove it from
the air in the house. That beats trying to remember to turn
the bathroom vent fan off.
This arrangement causes the A/C unit to be a whole-house
dehumidifier, rather than trying to get a certain temperature.
With a 'baseline' humidity setpoint of 35%. My wife no longer
gets up in the morning with dry throat and eyes.
That makes a big difference to our utility bill in the summer,


since a dry 83 degrees is far more comfortable than a muggy
73 degrees.

Amen to that, I bought a dehumidifier to run just to bring humidity
down to 40%. I can run the temp 5 degrees higher and be more
comfortable than with lower temp and higher humidity.
It is not the solution though, the dehumidifier produces a lot of heat
and wherever room it is is gets hot.
New SEER 15 installed recently, won't know till summer how it does
with the humidity/temp issue.
Cool idea with the humidistat wired into the cooling circuit.
Or is that a dry idea?
MikeK

 

[amdx]

"amdx" wrote in message I put this circuit together over twelve years ago.
I have it installed on my furnace/air condition control.
I have a momentary switch near the thermostat, when I
push the switch the furnace or air will come on for about
4 minutes (plus or minus). I move an alligator clip
depending on season, you can put in a switch.
I use it rather than turning the heat/air up and down,
for a short comfort adjustment.
It runs from a 9 volt battery and has very low standby current,
about 80 nanoamps. The battery lasts two or three years.
Others can modify for different purposes. If you think of another
use, please post it.
MikeK
http://i395.photobucket.com/albums/pp37/Qmavam/Furnacebumpcircuit.jpg

You have explained and documented your project rather nicely.
Good job.

Tom

Well thanks,
I use paint for schematics, although it could have a few extra features
that would really help.
Such as when you want a six sided object like this,
http://i395.photobucket.com/albums/pp37/Qmavam/3DcoilFormerDrawingSANSWire.jpg
I worked around it, but "draw a line at angle xx" would be nice.
MikeK

 

[Jamie]

Hi Jamie,
I noted I have a diode on one coil but not on the other.
I don't remember if the diode was added to correct a problem or
if it was put in as general good practice and just forgot on the other coil.
But the circuit is drawn as has been working for 12 years.
MikeK

It's most likely the relay you are using has it's mechanics designed
to get past the load swing point of no return before the contacts that
is maintaining the coil current opens. My thoughts were to have a cap
on the opening coil to help it give a little more time to make sure it
gets over the hump.

We've worked with those kind of dual coil latching relays before and
had issues when the applied duty cycle of DC current to the coil was
not always long enough and the relay would either switch back or
sometimes get stuck in the middle. The fix was to place a cap across the
coil with a blocking diode. I've seen some that come with these
components already in them.

If it works, that is all that matters.

Jamie.

 

[Winston]

I put this circuit together over twelve years ago.
I have it installed on my furnace/air condition control.
I have a momentary switch near the thermostat, when I
push the switch the furnace or air will come on for about
4 minutes (plus or minus). I move an alligator clip
depending on season, you can put in a switch.
I use it rather than turning the heat/air up and down,
for a short comfort adjustment.
It runs from a 9 volt battery and has very low standby current,
about 80 nanoamps. The battery lasts two or three years.
Others can modify for different purposes. If you think of another
use, please post it.
MikeK
http://i395.photobucket.com/albums/pp37/Qmavam/Furnacebumpcircuit.jpg

This has even lower standby current:
http://www.acehardwareoutlet.com/productDetails.aspx?SKU=3299195

--Winston

 

[amdx]

This has even lower standby current:
http://www.acehardwareoutlet.com/productDetails.aspx?SKU=3299195

--Winston

That's a great idea Winston!
Only down side is cutting the hole in the wall
for the box.
Thanks, Mikek

 

[Winston]

(...)


That's a great idea Winston!
Only down side is cutting the hole in the wall
for the box.
Thanks, Mikek

That's easy.

This is a 'low voltage' use, so you don't need an official stud-
mounted box in most jurisdictions. Locate studs in the wall
and outline the location of your new switch between them.

Drill 3/8" holes to define the inside corners of the box and
use your keyhole saw to cut out the plug in the middle of the
outline.

Use a respirator and have a vacuum ready. This is dusty business.

Fold the tabs of one of these nifty 'box eliminators' into
the hole and use two sheetrock screws to secure the end of
the tabs so that they grip the edges of the opening.

http://www.firefold.com//Low-Voltage-Device-Box-Eliminator-Ring-One-Gang-P1477.aspx

Use your fish tape or fish rod to pull the cable from the opening
into the wall and attic. Connect both ends of the cable and drop
a generous 12" service loop of cable into the wall behind the
switch. Affix your switch and cover plate to your box eliminator.

Use a slightly damp cloth to clean the area of sheetrock dust.

Hey Presto! A clean looking custom installation!

Piece of cake.

--Winston

 

[vaughn]

Drill 3/8" holes to define the inside corners of the box and
use your keyhole saw to cut out the plug in the middle of the
outline.

If that's still too big of a hole, use one of those plastic "pancake" surface
mount boxes. Then all you need is screw holes and a small hole for the wire.

Vaughn

 

[Winston]

If that's still too big of a hole, use one of those plastic "pancake" surface
mount boxes. Then all you need is screw holes and a small hole for the wire.

But check clearance first!

The timer switch is fairly deep.
<http://www.ccixpress.com/cci/Marketing/Woods_US_Timer_Instructions/TM_59711_InstrMan.pdf>


This might work, but it has been "whomped with the 'ugly stick'":

<http://www.legrand.us/Ortronics/Cop...rface-Mount-Box/Universal/OR-40300185-13.aspx>

<http://www.legrand.us/Ortronics/Cop...~/media/6A590E1437CF45AE9DCFDBE387764E33.ashx>

--Winston

 

[Winston]

Winston wrote:
(...)



For drywall?

Draw the outline and use a utility knife to cut a deep grove along the
lines. Then cut groves to opposite corners. Whack with a hammer and
peel out the scrap. VERY little dust created.

The paper backing would tear out the back side
of the drywall in the corners. It wouldn't be
visible but it would be a weakness in the 'rock
where a crack could form. Filleted corners
reduce the chances of cracking.

--Winston <-- In Earthquake country

 

[Winston]

Winston wrote:
(...)



So everyone was wrong for generations?

Yes. Other examples abound.

You can't trim the backing
with the knife?

In a way, yes.
I let the drill and the saw cut all the way through
both paper layers and the 'rock.

It's fast and it works a treat.



--Winston