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Old 04-09-2012, 01:54 AM   #1
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Automatic Fresh Air System, help...


First, thanks for the previous help! As I continue to improve our HVAC system some more input would be appreciated.

I would like to install a fresh air system (we have none) and would like to do it as affordably as possible.

At a minimum, I will connect a 10ft piece of 6" flex duct to our existing intake duct and run outdoors. It would have a hood and screen and be about ten feet off the ground.

Now for the challenge.

1) I would like to install some sort of automatic damper that could be used in conjuntion with a tstat otherwise outdoor temp monitoring device/switch.

It would be nice if it could monitor the outdoor conditions and bypass a/c mode and use the fan only when outdoor conditions are satisfactory. I found something like that HERE but know nothing of the cost or feasibility? I think that unit is for heat pumps whereas I have an a/c with heat.

2) Mostly, I just want to introduce a little fresh air to our house with little to no efficiency loss. I prefer it run through the central duct system, even if I have to add a second high efficiency fan inline. Our existing blower only operates at one speed, it's not a variable type.

Thanks, Ralph


Last edited by Ralph III; 04-09-2012 at 01:58 AM.
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Old 04-09-2012, 03:58 AM   #2
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Automatic Fresh Air System, help...


Google air to air heat exchanger.
Pulls in outside air and exhausts inside air without sending your heat out with the stale air.

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Old 04-09-2012, 01:30 PM   #3
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Automatic Fresh Air System, help...


Quote:
Originally Posted by Evstarr View Post
Google air to air heat exchanger.
Pulls in outside air and exhausts inside air without sending your heat out with the stale air.
Your talking about an ERV or HRV, correct? Do those work for a/c mode also? I'd like to add one of those in the future but for now want something simple/affordable.

What issues are involved if I just connect some 6" flex duct to the homes return duct and run outdoors? I have a manual damper and could adjust for minimal fresh air flow until I'm able to do something more permanent.

Ralph
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Old 04-09-2012, 01:56 PM   #4
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Automatic Fresh Air System, help...


Model 216
Model 216

Make-up Air Control for forced air heating systems



Make-up Air Control for forced air heating systems

Last edited by hvac5646; 04-09-2012 at 02:38 PM.
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Old 04-09-2012, 02:38 PM   #5
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Automatic Fresh Air System, help...


Quote:
Originally Posted by hvac5646 View Post
Model 216

Make-up Air Control for forced air heating systems
Thanks Hvac5646,
I was conteplating using a dryer vent but this is excellent. Should I use this in conjunction with a manual damper which would be used to limit the amount of fresh air intake? I would not be able to adjust the damper, minus going into the attic, so am wondering if it should be tempered some in order to avoid an increase in electric bill.

An automatic damper/tstat will eventually solve that by allowing me to control when I want fresh air, otherwise ERV unit.

Thanks, Ralph
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Old 04-09-2012, 04:45 PM   #6
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Automatic Fresh Air System, help...


I prefer Aprilaire's 8126 system, but you gotta buy the intake hood separate.
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Old 04-09-2012, 05:48 PM   #7
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Automatic Fresh Air System, help...


Quote:
Originally Posted by beenthere View Post
I prefer Aprilaire's 8126 system, but you gotta buy the intake hood separate.
That looks to be exactly what I want.

1) Does the Aprilaire system also control the volume of fresh air coming in at any given moment by controlling the damper door position -or- does it simply just fully open/close the damper?

2) Does the Aprilaire take control of your existing tstat/HVAC in any fashion, such as controlling the fan at times, or does it just control the fresh air aspect? I don't understand the timer feature? I mean does it affect your A/C or Heat modes or just work around them, with the timer just controlling the fan? If the later, does it recognize when the last time the fan ran so as not to start the fan soon after it just cycled off?

Thanks, Ralph
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Old 04-09-2012, 06:43 PM   #8
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Automatic Fresh Air System, help...


It will run the fan when the timer calls for a fresh air cycle. The damper won't open if the outdoor temp between 0 and 20 degrees unless there is a heat call, it won't open at all if the outdoor temp is 0 or below, nor if the outdoor temp is 100 degrees or higher weather or not a cooling call exist. It also won't open if the outdoor humidity is too high, that it would raise your indoor humidity above 55%.

You choose your ventilation time schedule, 1,2,3, or 4 hours, also choose how long you want the vent time to be. 1 to 60 minutes, but the damper is either open or closed, no modulation of it.
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Old 04-10-2012, 06:46 PM   #9
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Automatic Fresh Air System, help...


Quote:
Originally Posted by beenthere View Post
It will run the fan when the timer calls for a fresh air cycle. The damper won't open if the outdoor temp between 0 and 20 degrees unless there is a heat call, it won't open at all if the outdoor temp is 0 or below, nor if the outdoor temp is 100 degrees or higher weather or not a cooling call exist. It also won't open if the outdoor humidity is too high, that it would raise your indoor humidity above 55%.

You choose your ventilation time schedule, 1,2,3, or 4 hours, also choose how long you want the vent time to be. 1 to 60 minutes, but the damper is either open or closed, no modulation of it.
Hello Beenthere,
I took your advice and purchased a Aprilaire 8126 (got a good deal, btw) but may need your help with a few things when time comes to install.

A few questions up front:

1) I didn't realize the controller mounted within the duct itself as a set and forget. I assumed it could be mounted/used like a thermostat. Anyhow, do you ever install a convenient switch or tstat in having full control over the unit? I don't know that I want fresh air coming in when let's say it's under 36 degree's.

2) I don't have any means of determining my "ventilation requirements" or "fresh air delivery rate" as per instructions. I have no fresh air at all at the moment. Is that really necessary or just for precise installation purposes? I do have a thermo anemometer which can give some air flow rates....

My fresh air line will be 6" flex duct about 9 ft total in length. That is from air handler return duct to fresh air inlet. We have a 4 ton system.

3) Should I build/install a duct box with a replaceable filter near the fresh air inlet? Otherwise, it will be entering my duct system unfiltered?

God Bless
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Old 04-10-2012, 07:22 PM   #10
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Automatic Fresh Air System, help...


In homes that have a standard themostat, I just leave the Aprilaires control handle everything. Sometimes if they have a VS blower, I use the IAQ thermostat(YTH9421) to control them.

I would start out at once every 2 hours, for 5 minutes. If thats not enough, then increase to 7.5 or 10 minutes. If once every 2 hours, for 5 minutes is too much, go to once every 3 hours. Trail and error is ok.

You can make a filter for it if you want. most of the time it is not needed.
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Old 04-12-2012, 01:14 AM   #11
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Automatic Fresh Air System, help...


Thanks Beenthere,

Now with Controller wiring questions.
A) I know the outdoor temp sensor goes on the "T" and "T" terminals and the automatic damper connects to the "D" and "D" terminals.

--------This is where I need some help------

B) It appears I am to remove the green tstat wire from my air handlers Relay and connect that to the "GSTAT" on the Controller. I then run a wire from the Controller "GHVAC" back to the Relay #1 (where green tstat wire was).

C) I am unsure however where I am supposed to run the wires from terminals "C" + "R" to HVAC and the "W" wire? It states to connect those to the corresponding terminals on the HVAC control board but I have no such thing. I'm assuming those are for heat, air and maybe common?

I've attached a previous pic of my air handler wiring but may need to run down other tstat wiring? Anyhow, "g" goes to Relay #1, I think #3 is supposed to be a 24 volt common and comes of the Sequencer, #2 and #4 are hot legs, and #5 goes to Sequencer as well. Our tstat is very basic Maple/Chase 09500 which must be Robertshaw now, see pdf (I cannot link to pdf but if you Google Robertshaw 9500 you'll get it). Our setup is shown on pg.10 "Heat/Cool 4 wire" but again I would have to trace exactly how wires hookup in air handler.

Ralph
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Last edited by Ralph III; 04-12-2012 at 01:33 AM.
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Old 04-12-2012, 06:06 AM   #12
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Automatic Fresh Air System, help...


R and C can come from your transformer. W is just a pigtail wire from your stat that calls for heat is connected. So just make sue which wire from the stat calls for heat.
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Old 04-15-2012, 11:04 PM   #13
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Automatic Fresh Air System, help...


Ok Beenthere, please confirm the wiring on the Aprilaire system for me so I don't screw anything up.

controller:

1) Terminals "T & T" go to outdoor temp sensor
2) Terminals "A & A" (also denoted D & D) will go to the Aprilaire transformer and then on to the automatic damper. This is wired in series.
3) Terminal "24vac" (also denoted C & R) will wire directly to the 24 volt wires on my air handler step-down transformer? I have a blue and yellow wire coming from the step-down transformer (see pics) that supplies everything to air handler and condenser.
4) Terminal "GSTAT" will go to my air handlers Relay. It will replace the existing green wire, which will now go to the terminal "GHVAC" on the controller.
5) Terminal "W" will wire to whichever 24 volt tstat wire that calls for heat mode. That should be the "white" wire coming from the tstat wires, as I have denoted. That wire connects to a tan/black and tan/blue, both connect to the Sequencer.

----------------------------------------------------------------------------------

Just FYI,
The "yellow" tstat wire is wire nutted to the condensers blue wire (so must be for cool).
The "red" tstat wire is wire nutted with the large "Yellow" transformer (power?) wire.
The "brown" tstat wire pigtails together with the condensers "white" wire, the large "Blue" transformer wire (neutral/ground?), and three brown wires. Two of the brown wires go to the Sequencer whereas the third is grounded.

The brown tstat wire actually isn't hooked up within the tstat itself, so don't know why they bothered wiring it with others?

Also, instructions don't say where to mount the Aprilaire transformer nor how? The screw is bent so how does that attach?

Thanks, Ralph
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Last edited by Ralph III; 04-15-2012 at 11:09 PM.
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Old 04-16-2012, 05:20 AM   #14
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Automatic Fresh Air System, help...


Quote:
1) Terminals "T & T" go to outdoor temp sensor Correct
2) Terminals "A & A" (also denoted D & D) will go to the Aprilaire transformer and then on to the automatic damper. This is wired in series. Correct
3) Terminal "24vac" (also denoted C & R) will wire directly to the 24 volt wires on my air handler step-down transformer? I have a blue and yellow wire coming from the step-down transformer (see pics) that supplies everything to air handler and condenser. Correct
4) Terminal "GSTAT" will go to my air handlers Relay. It will replace the existing green wire, which will now go to the terminal "GHVAC" on the controller. GSTAT gets the wire from the thermostat that controls the fan. GHVAC wires to the air handle where the thermostat use to wire to for fan control.
5) Terminal "W" will wire to whichever 24 volt tstat wire that calls for heat mode. That should be the "white" wire coming from the tstat wires, as I have denoted. That wire connects to a tan/black and tan/blue, both connect to the Sequencer.
W is correct.
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Old 04-16-2012, 10:20 AM   #15
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Automatic Fresh Air System, help...


Quote:
Beenthere; "4)..."GSTAT gets the wire from the thermostat that controls the fan. GHVAC wires to the air handle where the thermostat use to wire to for fan control.".

OOOps, that's what I meant to say. The thermostats green wire (currently runs to Relay for fan control) will now go to Aprilaire Controller "GSTAT". The "GHVAC" will then go to air handlers Relay (fan control).

Should I just attach the Aprilaire transformer within the air handler somewhere?

I appreciated your help and suggestions!

God Bless

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