R-G fan drive

[producteng]

Looking for tech info on Tstat/furnace connections. If I put an external set of contacts across R & G to drive the fan independent of a call for heat, will I somehow be forcing the compressor to run? (Fan switch is in AUTO position.) Or is this possibly Yes, possibly NO depending on one Tstat to the next? Found some literature that seems to suggest this, but need some schematic info to show me why this is.

[Toolpusher]

Your back feeding voltage through the t-stat subbase to the "y" circuit.
The "y" circuit energizes the A/C mode.

If you put the Stat in the "fan on" mode, your stat by-passes the "y" circuit by itself.

[producteng]

So I'd have to disconnect Y if I want to leave the fan switch in AUTO?

[Toolpusher]

Yes or the "g"

remove either one and jumper the "r to g" at the furnace,
and the blower will run.

What are you trying to accomplish ?

[djken]

Use a spdt relay at the unit to close r-g at the unit and open the g signal from tstat to unit.

[Edited by djken on 02-16-2005 at 12:22 PM]

[MikeJ]

Originally posted by Toolpusher
Yes or the "g"


What are you trying to accomplish ?

He's an engineer with time on his hands. An awful situation.

[producteng]

I want to be able to run a humidifier even if there's not a call for heat.

[Toolpusher]

All you have to do is install a transformer, Line side of transformer to line side of furnace.

Load side or low voltage side of transformer. 1 wire goes to 1 wire on humidistat, other humidistat wire goes to solinoid valve on humidifer, other solinoid wire goes to low voltage side of transformer. Completing the circuit.

You don't want to disturbe the fan circuit control wires.

If you run the humidifier during no call for heat, what are you hopeing to achieve ?

[producteng]

If I understand you correctly that will open the solenoid valve when the humidistat contacts close. That might be OK for a wet-pad type humidifier, but I'm working with a steam type humidifier, which will generate however much moisture it's told to generate, regardless of ambient temp or RH. I just need to make sure the fan is running when it's making steam.

I still want the Tstat to be able to turn on the fan as usual too, so it looks like the best approach would be to disconnect the Y terminal during the heating season.

[sir fix alot]

I find the only time its worth yor wild to run the fan without the heat is with steam humidifers skuttle #60 etc.just kinda shooting yourself in the foot with a bypass humidifer aprilair etc. they work better with heat on.than off.only downfall tosteam it will rust your duct-work....but is worth it.

[Toolpusher]

What a long way around robinhoods barn just to reach the front door,

Meaning, If you would say what your trying to achieve the first post.
You would have gotten answere without the back and forth part.

[producteng]

I'm not interested in discussing the pros and cons of humidification, which is why I specifically left that out of my first post. What I AM interested in is what happens when you put a second set of contacts in parallel across R & G, which is exactly what I DID ask in my first post.

Thanks anyway.

[billva]

make sure high voltage of humidifier is wired constant hot.

use a current sensing relay on blower common wire to humidistat.

turn fan to "on" at stat.

problem solved.

[sir fix alot]

my precious humidifaction i'll die without you...

[mark beiser]

Have you purchased your steam humidifier yet?
I know EWC's Autoflow brand steam humidifiers will turn the system fan on themselves when himidification is needed, and isolate the call to the G terminal of the equipment from G on the thermostat.

They also give instructions for how to set up a fan failure safety lockout.

http://www.ewccontrols.com/steam_humidifier.htm

[pipedope]

Originally posted by producteng
I'm not interested in discussing the pros and cons of humidification, which is why I specifically left that out of my first post. What I AM interested in is what happens when you put a second set of contacts in parallel across R & G, which is exactly what I DID ask in my first post.

Thanks anyway.

I'm an idiot and need your help, But I also want to be a smart a$$ with reply's like above. Take a jumper from R-C if you see a spark it will work fine..

[beenthere]

Yes you'll back feed the Y terminal to the outdoor unit.
Check the vision pro stat, the 1 model has fan recycle ability, and may be just what you want.

[filterchanger]

24 volts at humidastat,which energizes coil and closes to sets of contacts,one set is humidafier and the other set is 24 volt to g terminal in airhandler,,,,,,,,,will it work?

[filterchanger]

nevermind!!