X10 Community Forum
🔌General Home Automation => Automating Your House => Troubleshooting Automation Problems => Topic started by: wheelsea on September 02, 2006, 03:41:16 PM
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I am trying to control the 24 volts power into a thermostat , so that when there is a power outage the a/c unit will shut down and stay shut when the power returns. I want to be able to either manually turn it back on or give it a command thru AH software. My house is on a generator that will not handle the a/c load. Will the UM506 do this or will it stay latched on in a power failure?
Appreciate any comments or another way to work around this.
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Did a test with a UM506. In the Continuous mode. If it is on and the power is removed; I unplugged it; the switch in it stays on and will be on; at power return. The only thing that does not come back on is the Beeper if it was enabled and on at power loss.
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Although I can't claim to be familiar with every single one of them all the appliance modules I am familiar with are latching and remember their previous status after a power failure.
On the other hand lamp modules don't remember their pre power failure status. Unfortunately they are not recommended for non lamp loads, although many people use them that way. Try powering your 24 volt HVAC transformer with one but do it so that nothing, including you, will be harmed if it blows or overheats.
If that works make sure the thermostat won't trigger the module on when it's off by playing with the temperature setting. If it does trigger it try my 22k bypass resistor suggestion posted elsewhere here.
If you've gotten this far then you need to worry about accidental dimming of the module. I'd suggest putting it on its own house code and, if you're going to control it with AHP, use an applance module icon instead of a lamp module icon.
If anything about this worries you don't do it but do tell us what your level of electronic fabrication experience is. There are none X10 solutions to this problem that could be used with an X10 module but you'd need to build the device yourself.
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I think you would be safest with a latching relay that you could reset manually or by X10.
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I think your best bet is to wire a double pole relay (with 24V coil) so that one contact is wired to "self-latch" the relay so long as it's powered up, but will drop out once power is lost (and stay off when power is restored). Then wire a UM506 in _momentary mode_ across this contact to actuate the relay.
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I think your best bet is to wire a double pole relay (with 24V coil) so that one contact is wired to "self-latch" the relay so long as it's powered up, but will drop out once power is lost (and stay off when power is restored). Then wire a UM506 in _momentary mode_ across this contact to actuate the relay.
Funny you should happen to post that while I was working on my crude drawing.
Ok here's one one my crude drawing showing how you could do it with a 24V double pole relay.
o
o-----------o
! \ o--------------------o
!
2 ! o
4 o-----------------o
V \ o---------+---o * ---> To AC
-----mmmm------!
! 24V relay
!
o-----+--------------------------------o
*Reset point - You can connect a universal module here in momentary mode to reset relay.
Relay is powered through one of its own contacts and stays on only while power is on. When power fails, a reset is required to latch the relay again.
BTW...Does you generator power all your outlets. i.e. Are any not on the generator? If so they could be be used to automate a reset when power returned. Does X10 run when outlets are powered by the generator?
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Since it sounds like it's going to be a "hack" anyway, here is my suggestion:
Use a double-pole 24 volt relay.
Connect one pole in series with the 24 volt thermostat so that the thermostat gets power when the relay is energized.
Connect the other pole in series between the positive 24 volt supply and the relay coil so that the coil will connect to the positive 24 volt supply when the relay is energized.
Connect the other end of the relay coil to the negative (or ground) side of the 24 volt supply.
Connect a momentary normally-open push-button between the positive 24 volt supply and the positive side of the relay coil.
When power is first applied, the relay will be de-energized, and no power will flow to the thermostat.
When you press the push-button the relay will be energized, supplying power to the thermostat and to the relay coil, holding it energized until the 24 volt supply is cut off (like in a power outage).
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Looks like great minds think alike Charles and steven r! :)
But you were quicker on the trigger.
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Looks like great minds think alike Charles! :)
But you were quicker on the trigger.
I bet I started my drawing before he posted. ;)
He just sneaked in while I was trying to make all my lines meet.
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Looks like great minds think alike Charles! :)
But you were quicker on the trigger.
I bet I started my drawing before he posted. ;)
He just sneaked in while I was trying to make all my lines meet.
Yeah, but my text description makes your drawing easier to follow. ;)
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...Yeah, but my text description makes your drawing easier to follow. ;)
Both Charles's summary and your technical manual do help my crude illustration.
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...Yeah, but my text description makes your drawing easier to follow. ;)
Both Charles's summary and your technical manual do help my crude illustration.
Hey, at least you made an illustration, I gave up on that and just used text!
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...Hey, at least you made an illustration, I gave up on that and just used text!
Well if a picture is worth a 1000 words, do I win? ;D
I don't have a way to really draw a diagram and post it so I have to be creative to make my crude drawing. Your description definitely helps clarify my drawing.
Hopefully its clear enough for wheelsea.
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Hopefully its clear enough for wheelsea.
That's the important part.
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Hey everyone thanks for the info so far. One thing I just thought of would be to replace my service switch at the A/C air handler with an XPS2 switch, since the transformer for the thermostat side of A/C receives power through this.Am I correct to assume that the XPS2 will behave like a lamp module and stay off until I either manually turn it on or turn back on with a command from AHPro.
Thanks, look forward to your thoughts on this approach.
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Hey everyone thanks for the info so far. One thing I just thought of would be to replace my service switch at the A/C air handler with an XPS2 switch, since the transformer for the thermostat side of A/C receives power through this.Am I correct to assume that the XPS2 will behave like a lamp module and stay off until I either manually turn it on or turn back on with a command from AHPro.
Thanks, look forward to your thoughts on this approach.
I don't see any specification about latching/non-latching for the XPS2 on the X10Pro website, and I don't know of any appliance-type modules which aren't latching. So without further info I'd assume that the XPS2 does in fact have a latching relay.
You could try calling the X10Pro Tech Support line and inquiring. These techs seem to be a cut above the ones in standard X10 Tech Support.
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wheelsea
I am pretty certain Charles is correct, the XPS2 remains in the same state it was, when power is interupted. I do not have any XPS2, but do use PAM04 for 240 V pumps. I believe the PAM04 and the XPS2 are same animal, inside.
FWIW
The 24V latching relay is the simplest way to go on this. I use 120V coil relays for similar purpose to delay returning power to my home control computer. I use a $5 timing module (electronic surplus price) to relatch the relay 5 minutes after power returns, which (in theory) eliminates all the "flicker and flash" we usaually have as Duke Power brings up the local grid. Works good.
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Charles, Dave: you are both right . X10Pro support at first gave some conflicting advice on this but then retested and yes it reverts back to the previous state it was on. Any brand/model # on the 24 volt latching relay and 120 volt coil?
Thanks.
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Charles, Dave: you are both right . X10Pro support at first gave some conflicting advice on this but then retested and yes it reverts back to the previous state it was on. Any brand/model # on the 24 volt latching relay and 120 volt coil?
Thanks.
Lest we've confused you about this: The relay we're talking about for your application will be a regular DPST-NO (Normally Open) relay with a current and voltage contact rating sufficient for your Air Conditioner but with a coil designed to pull in with 24 Volts. It is NOT a "latching" relay, but a normal relay wired so as to keep itself turned on once it is actuated by a momentary contact and as long as the power is on. A lot of suitable relays will have DPDT contacts, which is fine. The 120 V coil Dave mentioned was for a different application.
BTW, this assumes that your Air Conditioner runs off 120V single phase. If its a 230V unit you would normall want to switch both hot leads to it, and would therefore require a THREE-pole relay.
There are lots of relays that will fill the bill; the usual problem is how to connect to them and how to enclose them so someone won't get zapped. Quick connect insulated connectors that you crimp to the wires usually work well for relays which have those terminals.
Take a look at Magnecraft W92S7D22-24 in their catalog page at http://www.magnecraft.com/products/e104_sec1_pg40_42.pdf
It's got 30 Amp, DPST-NO contacts and a 24VDC coil. Quick connect terminals and a mounting flange. It's listed in a July 2005 Mouser catalog I have as Mouser stock number 528-92722-24, $8.74 + S&H. (Price is probably different now - check on-line at http://www.mouser.com) You'll still need to put it in an enclosure of some sort and acquire a 24VDC wall-wart power supply and a UM506.
Disclaimer: I suggested a part out of a catalog which looks OK to me, but I'm NOT a licensed engineer or electrician and it may be totally unsuited for your application. If you're not familiar with wiring and safety practises for power line work, please consult a licensed electrician or someone with experience.
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I sense that this kind of wiring is not your forte but, with the caveat that the final responsibility is yours, I'd suggest you use FROOGLE which is part of GOOGLE under "More" on their search window to look up
"24Vac relay DPDT" and order the results from lowest price to highest. You'll get lots of hits if you do.
I'm concerned that we may not really understand how your 24 volt thermostat control circuit operates. Charles Sullivan, for example, obviously has a different visualization of it than I do. The 24 V HVAC thermostat circuits I'm familiar with operate a relay built into the AC or furnace that in turn control the high amperage circuits of the device itself so the relay you're going to add is handling very low current.
Feel free to give us more info as you go along with the hope we can be of more help.
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I'm concerned that we may not really understand how your 24 volt thermostat control circuit operates. Charles Sullivan, for example, obviously has a different visualization of it than I do. The 24 V HVAC thermostat circuits I'm familiar with operate a relay built into the AC or furnace that in turn control the high amperage circuits of the device itself so the relay you're going to add is handling very low current.
This "Old Tinkerer" agrees with the Oldtimer ;D - based solely on my experience with strictly heating (oil at my folks, gas for me furnaces).
You can either interrupt the 120VAC input or the 24VAC output of the transformer that forms a low-current SERIES circuit with the thermostat and the relay (inside a Honeywell Aquastat in my case) whose 24VAC coil, when energized, pulls in the contacts for the 120VAC circulator pump (and another pair for the millivolt feed to the gas valve).
EDIT: How many other "Old Geezer's" besides me find that Spell Checkers DON'T HELP much when you correctly spell the WRONG WORD!!! :-[ (i.e. gas value instead of gas valve - it even LOOKS right the first time around... ::) )
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You're right Oldtimer and TTA.
Somehow when I got this far down into the thread I ended up with a window AC unit in my mind.