Can I run the furnace blower to recirculate air

[carlsbad]

Originally Posted by Johnfort

That's what I thought. No Joy.

How about this: two new switches. The first is a simple inline that disconnects the fan from the thermostat and control board and the new manual switch. Kind of a failsafe.

Just thinking out loud.

[Johnfort]

I tried this with a STDP switch which acts as two seperate switches in the same housing. Again, No Joy.

[rockfordroo]

Originally Posted by Johnfort

rockfordroo and quicky06, thanks for entering the challenge. In the cold gray light of dawn, I looked over your well thought out drawing, and realized that it looked familiar. I tried that exact circuit, as well as some modifications of same earlier.

This circuit worked the best, but there was a fatal flaw. When the stat was satified in the normal furnace mode, the fan "after run" to cool the combustion chamber did not work. It stopped immediately when the stat shut off, leaveing excessive heat lingering in the chamber. Not safe I think.

Another iteration of this circuit would only allow 1 heat cycle if you were in the fan on mode, then not recycle.

I'm not privy to the logic of the board, and my old Navy aviation electronics theory has failed me years ago, but I think the circuit board innards is the road block here.

I'd really like to see this work in both modes, but it seems to be above my pay grade.

I did mke this work on a pre-circuit board furnace with relays years ago, so the concept does work.

Did you use a SPDT relay as I show, or a SPST relay as quicky06 showed? With the SPST allowing 12VDC to go backwards into the control board, that could be why it didn't work with the T-stat.

[Johnfort]

Nope. Used the relay as you suggested.

[rockfordroo]

Very curious.

[Johnfort]

Ditto

[Wolverine 1945]

I once installed carpet in some folks home where the furnace/AC fan ran 24 - 7 !!!
They said there was no way to shut it off ??? Very Strange !!!

It would be nice if RV fan was like House unit,,, fan on or auto !!!

[Johnfort]

Actually there is a way to shut it off, they just haven't found it. Their HVAC tech can figure it out. Someone may have replaced the T-stat with the wrong one. It's a fan circulation mode that keeps the air moving for more even comfort. It's good for multi-level homes. I've had mine running on low for 21 years except for maintenance down time. Nice thing is you hardly ever hear or feel the ac or heat cycle on. Costs less than $100 a year.

[Wolverine 1945]

Originally Posted by Johnfort

Actually there is a way to shut it off, they just haven't found it. Their HVAC tech can figure it out. Someone may have replaced the T-stat with the wrong one. It's a fan circulation mode that keeps the air moving for more even comfort. It's good for multi-level homes. I've had mine running on low for 21 years except for maintenance down time. Nice thing is you hardly ever hear or feel the ac or heat cycle on. Costs less than $100 a year.

And you never had to replace your Blower Motor ???

[Johnfort]

No, it runs on low. I ckeck/lube the bearings and clean the fan every 2-3 years. The startup 15-20 times a day is harder on the motor than constantly running on low.

[Wolverine 1945]

Preventive maintenance is the trick !!!
Not all blower motors can be lubed !!!
How often do you change your filter ???

[Johnfort]

But if they can, 1 or 2 drops of Dad's 3 in 1 oil does the trick.

I use 2 AprilAire media filters. They are about 2' x 3' x 6", made out of pleated filter paper for high surface area.

I carefully blow them out once a year, and replace every two years.

The house stays very dust free. Saves a ton of time on cleaning and dusting.

[Wolverine 1945]

Originally Posted by Johnfort

But if they can, 1 or 2 drops of Dad's 3 in 1 oil does the trick.

I use 2 AprilAire media filters. They are about 2' x 3' x 6", made out of pleated filter paper for high surface area.

I carefully blow them out once a year, and replace every two years.

The house stays very dust free. Saves a ton of time on cleaning and dusting.

I would think you would need to replace them once a Month ???
I use a pleated filter,,, 2X16X20 replace them every 6 month !!!

[Johnfort]

Mine are 6" x 2 x 3. (X2) They have a magnitude of 10 x the surface area of yours. I check them after a year with a manometer and they are within 5% of starting flow rate.

Think Cummins 650 HP tractor air filter, vs Briggs nd Stratton lawn mower filter.

[ben31]

Originally Posted by Johnfort

Actually there is a way to shut it off, they just haven't found it. Their HVAC tech can figure it out. Someone may have replaced the T-stat with the wrong one. It's a fan circulation mode that keeps the air moving for more even comfort. It's good for multi-level homes. I've had mine running on low for 21 years except for maintenance down time. Nice thing is you hardly ever hear or feel the ac or heat cycle on. Costs less than $100 a year.

Ok, a little off topic.

We do the same thing in our house and camper. We leave the air conditioner fan on to circulate the air. It helps keep the whole house/camper close to the same temperature (no hot/cold spots).

In the camper, we have a ducted ac system with two units. In the winter, we leave the secondary (bedroom) unit's fan on low. We run the fireplace heat (set on 70 degrees). If it is really cold outside (below about 45), we also set the furnace to about 63-65 (depending on the DW's hot flashes ). This setup keeps the air moving and closer to the same temperature throughout the camper. It also provides some white noise at night to block out noises outside (road, other campers, etc.). With the bedroom fan on, (while sleeping in the bedroom) we can't even hear the furnace come on (in the living room area), so don't need to release my fingernails from the ceiling.

Side note: The Dometic thermostat has separate independent zones. The main zone has furnace, fan, or ac, and secondary zone (bedroom) has fan or ac.

We have been running our ac fan in our house for 15 years straight. Our HVAC person says it is actually better for it than the starting and stopping. We just need to replace the two pleated filtrete filters about every 60 days. It also keeps the dust down in the house.

[Johnfort]

That would be perfect for me. I'm trying to mask tinnitus, and mask the furnace fan on and off that wakes me every time.

[Wolverine 1945]

Originally Posted by Johnfort

Mine are 6" x 2 x 3. (X2) They have a magnitude of 10 x the surface area of yours. I check them after a year with a manometer and they are within 5% of starting flow rate.

Think Cummins 650 HP tractor air filter, vs Briggs nd Stratton lawn mower filter.

Sounds like a great system,,, what year,,, and brand is it ???

[MillMitch]

Originally Posted by Johnfort

quicky06, to answer your "original question", yes, simply put an on off switch with a fuse between B+ and the blower motor. You can use a two spade terminal adapter from Home Depot to tie into the B+ and blower terminal right on the board. Then mount the switch in a handy place. The furnace heat mode will not work, or it may work one cycle.

As long as you understand this, you'll accomplish some circulation.

Question regarding a non-electric solution. Why can't I put a small fan on the ground blowing into my furnace intake vent? do the ducts close off when not in use? or would the fan blow air through the underbelly and furnace ducts? might have to put some foam around the fan to create a better seal, but I would think this would work (not well granted, but it should push some air into the underbelly).
thanks

[5picker]

Originally Posted by MillMitch

Question regarding a non-electric solution. Why can't I put a small fan on the ground blowing into my furnace intake vent? do the ducts close off when not in use? or would the fan blow air through the underbelly and furnace ducts? might have to put some foam around the fan to create a better seal, but I would think this would work (not well granted, but it should push some air into the underbelly).
thanks

Unless you somehow sealed the fan to the furnace housing it wouldn't push much (if any) air through. Think about how little flow the furnace's internal fan pushes out the vents from factory and it's designed to do so. A fan pointed at the intake would be futile.

[Wolverine 1945]

Originally Posted by MillMitch

Question regarding a non-electric solution. Why can't I put a small fan on the ground blowing into my furnace intake vent? do the ducts close off when not in use? or would the fan blow air through the underbelly and furnace ducts? might have to put some foam around the fan to create a better seal, but I would think this would work (not well granted, but it should push some air into the underbelly).
thanks

I think you have to totally block off the intake,,, other than an opening for the fan,,, and it would take a pretty good fan !!!
And there is a very good chance that the air would not get passed the furnace !