# Air exchanger. Replace room switches with timers?



## yuri (Nov 29, 2008)

Is the unit a HRV, heat recovery ventilator? Post the brand name and model # and some pics of it. HRVs have circuit boards and need a matching timer from their manufacturer, not generic ones.


----------



## murray59 (Jul 11, 2007)

yuri said:


> Is the unit a HRV, heat recovery ventilator? Post the brand name and model # and some pics of it. HRVs have circuit boards and need a matching timer from their manufacturer, not generic ones.


I'm at work right now but later tonight I'll get that info. Thanks.


----------



## murray59 (Jul 11, 2007)

Okay I phoned home and got the following information. The house was built in 1995 indicating the age of the unit.

Lifebreath HRV
Nutech Energy Systems
Mod. 200max

There's an instruction sticker on the side and one part says:

Optional Remote Devices
-digital electronic timer
-digital programmable timer
-Air Sentry air quality sensor-
-dehumidistat remote
-mechanical timer device

I pulled one of the switches in the bathroom. (it's just a regular house light switch)The wires are thin low voltage but I can't see on the unit what the switch voltage is. ?24volt


----------



## murray59 (Jul 11, 2007)

Here's some more info. I stopped at a local wholesaler and got some Vanee switches. You hit the switch and the HRV runs on high for 15 minutes. Didn't come with a wiring diagram. At the bathroom end there is a black wire and a red wire running to the old switch and a green wire attached to the ground screw in the box. Downstairs on the HRV unit there are two terminals on the terminal block on the side of the unit where the blk and red wires go. The green wire is just grounded to a screw on the case. Beside those two terminals, separated by a small space there are two other unused terminals on the unit (perhaps to integrate it with the furnace?) 

So the new Vannee switch has three terminals. OL, OC and I. I hooked up the blk and red to two, hit the button and the unit goes on high for about 10 seconds before it shuts off, telling me it's only getting connected for the brief second I push the switch. (the unit has a delay before it shuts off). I took the green ground wire off at the box and hooked it up to the 3rd terminal and a little light comes on on the Vanee switch. I tried various ways hooking it up and can't get it to time on for 15 minutes. It goes for 10 seconds and shuts off.

I went to the website for Lifebreath and they sell a similar timer for $49. (no wiring diagram) The Vanee switches are $20 so I'd like to use them if possible because I have 5 locations to do in the house. I also found the installation manual but it doesn't say anything about the terminal block on the unit or how to hook up override switches.


----------



## Yoyizit (Jul 11, 2008)

If you get solid state switches that do not use electromechanical relays make sure they work at your voltage and with your [motor] load.


----------



## yuri (Nov 29, 2008)

You need to get the proper Lifebreath timers B4 you damage the circuit board. I replaced a Venmar/VanEE with a Lifebreath and had to replace the timers also. You have an older setup and may need 3 wires for the newer timers because of the light. I would contact Lifebreath as the timers change with the changes in models and years they were built and have to match properly. Yours are part of an older "Legacy" series.


----------



## spark plug (May 5, 2009)

yuri said:


> You need to get the proper Lifebreath timers B4 you damage the circuit board. I replaced a Venmar/VanEE with a Lifebreath and had to replace the timers also. You have an older setup and may need 3 wires for the newer timers because of the light. I would contact Lifebreath as the timers change with the changes in models and years they were built and have to match properly. Yours are part of an older "Legacy" series.


Yes. Like you and Poster "Yoizit" said that with the newer, electronic circuit boards, you need to get a timer with matching Voltage and load capacity (Amps.). But some units have (on the board) a "Dry contact". Meaning that the terminals do not supply power and they only close and open the circuit. (N/O) or (N/C). In that case, you can connect ANY type of switch. Including a mechanical (Spring wound) timer. (As distinct from a time switch that needs an independent power supply.) Also. An electrical rating on a manual switch in terms of Voltage and Amps. means not to exceed that voltage or current load. But it will work fine on a lower voltage and current draw.:yes::thumbsup:!


----------



## murray59 (Jul 11, 2007)

I'm thinking the only option I have is to use the spring wound style that don't require any voltage to operate.


----------



## spark plug (May 5, 2009)

murray59 said:


> I'm thinking the only option I have is to use the spring wound style that don't require any voltage to operate.


But, again. Be certain that it's a DRY CONTACT. Otherwise, (where there's voltage present on the contacts in the board) you can damage the entire control unit and it will have to be replaced (Probably at a fairly high cost.)
p.s.: For someone who is not well versed in the workings of electrical and electronic systems, it's kind of difficult to understand the concept of supplied power switching and dry contact.:yes::no: (The ultimate symbol of confusion.):thumbsup: (Symbol of hope and best wishes.)


----------



## Yoyizit (Jul 11, 2008)

Dry circuit switching has voltages and currents so low that the contacts don't self-clean from the arcing. 
The problem then is that the slightest tarnish gives intermittent operation and so the contacts are enclosed in dry nitrogen or some other inert gas.


----------



## murray59 (Jul 11, 2007)

Okay for the last 16 years they used regular light switches. Are they dry circuit switches? 
Also what are the chances that the $19 spring wound timers at HDepot are dry circuit?


----------



## Yoyizit (Jul 11, 2008)

No and ~zero.


----------



## beenthere (Oct 11, 2008)

murray59 said:


> Okay for the last 16 years they used regular light switches. Are they dry circuit switches?
> Also what are the chances that the $19 spring wound timers at HDepot are dry circuit?


Regular single pole switches used for lights. Are dry contact switches.

The spring wind timer switches at HD, are also dry contact.


----------



## Yoyizit (Jul 11, 2008)

?
http://en.wikipedia.org/wiki/Dry_contact
http://www.google.com/search?client=safari&rls=en&q="dry+circuit+switching"&ie=UTF-8&oe=UTF-8


----------



## spark plug (May 5, 2009)

beenthere said:


> Regular single pole switches used for lights. Are dry contact switches.
> 
> The spring wind timer switches at HD, are also dry contact.


Now the question remains if the switching contact/s on the control board are dry contacts (a/o powered switching), too. But even if the control board switching terminals are not dry contact type, it'll still work. Only the voltage and amp. rating (of the switches) must be compatible.:yes::no:!


----------



## beenthere (Oct 11, 2008)

The terminals that you connect a switch to. Can't be dry contacts. 
if they were. then nothing would work. Since there would be no power/electric for the switch to control.


----------



## spark plug (May 5, 2009)

beenthere said:


> The terminals that you connect a switch to. Can't be dry contacts.
> if they were. then nothing would work. Since there would be no power/electric for the switch to control.


I withdraw that statement on a/c control. But in intercom systems manufactured by Aiphone (this is not meant as an endorsement. Just for useful information purposes. M.K.) where you can control an independently powered entry door buzzer system from the IC unit. those terminals are Dry Contact. Yes. I see the distinction. Thank You.:thumbsup:!


----------

