Remote control of a device

[Little Bill]

A customer had a vent exhaust fan installed in a remodeled house. The exhaust does up, through a wall and down into the basement. It was discovered that the fan needs a booster fan in the basement to aid the air flow. They want the booster fan to come on when the main fan is turned on. The vent fan has both manual push button switches, off-low-med-high, and a remote to operate it. I'm trying to help figure a way to turn on the booster when the main fan turns on but I don't want to mess with any of the fan's internal wiring to avoid warranty problems.
I can think of how a relay would work but can't figure how to trigger the relay. Any thoughts on this?

 

[Buck Parrish]

Have you ever used or thought of a pressure switch?

. https://www.homedepot.com/p/Vortex-...-Fan-with-Pressure-Switch-VTX400PSW/204262757

Probably going to have to make sure their bath fan is pushing enough air to turn it on or off.

 

[wwhitney]

Is the issue how to detect whether the primary fan is running? For that there are airflow switches that can get installed in the duct. Or there are CT sensors that require no external power and will close contacts when the circuit is (sufficiently) energized. Of course if the hood has lights as well and you put it somewhere that it sees the lighting current, the lights may trigger the CT as well.

Or is the issue how to get that signal from the primary fan location to the booster fan location to control the booster fan? I'm sure there are wireless solutions if running wiring is a problem, but wouldn't know what to recommend.

Cheers, Wayne

 

[Little Bill]

Have you ever used or thought of a pressure switch?

. https://www.homedepot.com/p/Vortex-...-Fan-with-Pressure-Switch-VTX400PSW/204262757

Probably going to have to make sure their bath fan is pushing enough air to turn it on or off.

That sounds interesting, I will look into that

Is the issue how to detect whether the primary fan is running? For that there are airflow switches that can get installed in the duct. Or there are CT sensors that require no external power and will close contacts when the circuit is (sufficiently) energized. Of course if the hood has lights as well and you put it somewhere that it sees the lighting current, the lights may trigger the CT as well.

Or is the issue how to get that signal from the primary fan location to the booster fan location to control the booster fan? I'm sure there are wireless solutions if running wiring is a problem, but wouldn't know what to recommend.

Cheers, Wayne

I just need it detect when the primary fan is running.

 

[brantmacga]

Have you ever used or thought of a pressure switch?

. https://www.homedepot.com/p/Vortex-...-Fan-with-Pressure-Switch-VTX400PSW/204262757

Probably going to have to make sure their bath fan is pushing enough air to turn it on or off.

I think that’s a good idea.


Here’s a link to a pressure switch that can be installed in the duct and connected to the booster fan they have .

Tjernlund 6.5 in. x 6.5 in. Activating Pressure Switch Duct Booster Steel Fan PS1503 - The Home Depot

Senses duct pressure via hole in duct between main blower and Duct Booster Fan. Pressure from main blower actuates switch to operate Duct Booster fan automatically. 120-Volt, 15 Amp max. Makes on pressure

www.homedepot.com

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[tom baker]

I suggest a current monitoring relay. When your Ef turns on relay closes to start booster fan. I would suggest Zoro or Grainger for sourcing

 

[MTW]

I would suggest an air differential sensing pressure switch, one that has a wide range of adjustment. Has a high and low pressure sensing ports. Uses 1/4" po[y or copper sensing tubes and is remote mounted. Using both tubes will make it the most sensitive. It can work with just one tube if the fan pressure is high enough. Low pressure to the fan inlet side or (atmospheric pressure) and the hi pressure to the exhaust duct. I have used these for years on paint booths to control an air solenoid for atomizing air, wired directly.

Air Sensing Switch, HVAC/General Purpose Type, 0.02 to 0.8 Differential (In. WC), SPDT American made economical price​

You don't mention what your fan is for, what static pressure it operates at, how many CFM is has, or what the duct size is. These can have an effect on the booster fan sizing. I like the Fantech Inline duct fans, operate in any mounting position, and have a long quiet life. I have used one for 20 years with no issues. Here is a sample selection, for comparison.

Duct Fans

 

[ptonsparky]

AD offers a small current switch that will work for you. That and a small relay.

https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/current_-a-_voltage_sensors_(ac_-a-_dc)/current_switches_-a-_indicators/single_range_ac_current_operated_switches/acsn100-ae-f

 

[tom baker]

A second on fantech for in line booster.

 

[retirede]

I’d be careful with trying to sense either pressure or flow since the booster itself will cause fluctuations in both as it turns on and off. For example, if you sense flow, there could still be enough flow from the booster even when the primary fan shuts off to keep the booster running.

Sensing the current flow to the primary fan would be most reliable.

 

[Jraef]

+1 on a Current Sensing Relay (CSR). Get a "split core" so you don't have to cut any wires, you just clamp it around the power wire for the exhaust fan and as soon as current flows to that fan, the relay closes and turns on the booster. I would have the booster fan run off of a little relay that is driven by the CSR, because that relay is easier to replace if something goes south on the booster fan.

$22, split core link.

 

[DrSparks]

A customer had a vent exhaust fan installed in a remodeled house. The exhaust does up, through a wall and down into the basement. It was discovered that the fan needs a booster fan in the basement to aid the air flow. They want the booster fan to come on when the main fan is turned on. The vent fan has both manual push button switches, off-low-med-high, and a remote to operate it. I'm trying to help figure a way to turn on the booster when the main fan turns on but I don't want to mess with any of the fan's internal wiring to avoid warranty problems.
I can think of how a relay would work but can't figure how to trigger the relay. Any thoughts on this?

Maybe an airflow proving switch?

Switch,Duct Pressure https://www.amazon.com/dp/B002EC1O0C/ref=cm_sw_r_apan_glt_fabc_MR0E31ZYVSYGEHT7784P

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[wwhitney]

But as others have commented, if using an airflow/pressure switch, starting the primary fan starts the booster, and when the primary fan is turned off, the booster fan alone may be enough to keep the airflow/pressure switch in the "on" state, causing the booster never to turn off.

Cheers, Wayne

 

[DrSparks]

But as others have commented, if using an airflow/pressure switch, starting the primary fan starts the booster, and when the primary fan is turned off, the booster fan alone may be enough to keep the airflow/pressure switch in the "on" state, causing the booster never to turn off.

Cheers, Wayne

True. Very true. Perhaps a current sensing switch then?

Current Sensing Switch, Normally Open Current Sensing Relay Adjustable AC 0.2A -30A (SZC23-NO-AL-CH Model) https://www.amazon.com/dp/B07N1P6TWL/ref=cm_sw_r_apan_glt_fabc_S2H0ZK88FM29Z2CANQ4B

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[wwhitney]

True. Very true. Perhaps a current sensing switch then?

Yes, that is the other option that has been suggested multiple times in this thread. : - )

Cheers, Wayne

 

[DrSparks]

Yes, that is the other option that has been suggested multiple times in this thread. : - )

Cheers, Wayne

Lol sorry. My bad for not reading all the posts. I'd be interested in knowing the OPs solution and how it worked out. Keep us posted.

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[oldsparky52]

A customer had a vent exhaust fan installed in a remodeled house. The exhaust does up, through a wall and down into the basement. It was discovered that the fan needs a booster fan in the basement to aid the air flow. They want the booster fan to come on when the main fan is turned on. The vent fan has both manual push button switches, off-low-med-high, and a remote to operate it. I'm trying to help figure a way to turn on the booster when the main fan turns on but I don't want to mess with any of the fan's internal wiring to avoid warranty problems.
I can think of how a relay would work but can't figure how to trigger the relay. Any thoughts on this?

Lots of good ideas, but I'm confused as to what you have access to? Is there an attic this fan is accessible from? Can you get another cable to the switchbox (enough room?)?

Basically, what conditions are you working under?

 

[Little Bill]

Lots of good ideas, but I'm confused as to what you have access to? Is there an attic this fan is accessible from? Can you get another cable to the switchbox (enough room?)?

Basically, what conditions are you working under?

I thought I mentioned it, but apparently I didn't. It's a kitchen exhaust fan similar to a down draft. As I said, it goes through the wall and down into the basement and then piped on outside.

I haven't actually seen it. We wired for it but the fan wasn't installed yet. This was just sprung on us when the appliances were installed.

 

[hillbilly1]

Maybe this: https://www.zoro.com/functional-dev...ansmitter-spdt-120vac-ribw01b-en3/i/G1601026/

May be an issue to wire directly to the hood fan since it’s three speed, but you may be able to wire it to a current sensor as others have mentioned. Would save having to run a control wire back to the panel or the booster fan directly. Zoro is a heck of a lot cheaper as someone said in another post, Grainger was $300+ for the same relay!

 

[Little Bill]

Maybe this: https://www.zoro.com/functional-dev...ansmitter-spdt-120vac-ribw01b-en3/i/G1601026/

May be an issue to wire directly to the hood fan since it’s three speed, but you may be able to wire it to a current sensor as others have mentioned. Would save having to run a control wire back to the panel or the booster fan directly. Zoro is a heck of a lot cheaper as someone said in another post, Grainger was $300+ for the same relay!

I'm trying to figure how this is wireless and how it works. Maybe because I spent 8 hours on a ladder today and my brain is still on the ladder!