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Author Topic: 20-40-60 minutes timer switch  (Read 935 times)

Offline TurboLed

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20-40-60 minutes timer switch
« on: November 17, 2016, 06:52:36 AM »
Hi all,
I'm an electronic hobbyist and I'm trying to install a 20-40-60 minutes push-button timer for my ERV. I ordered the RTS3 control from Fantech but I can't get it to work with my ERV, even though some links suggested that this control works using 24V.  I have a 24VAC transformer and a dry-contact to turn on my ERV. But if I tried many ways to power the RTS3 with 24V, its light never turn on.
I also found online that other manufacturers seem to be using a very similar design for their 20-40-60 minutes push controls, namely Venmar and VanEE. But I haven't found any specs for inputs/outputs voltage and internal diagrams.

I came across this forum hoping to find some detailed schematics diagrams for the ERVs that use the 20-40-60 controls, most importantly how the signal on the OC, OL and I connectors of the Venmar and VanEE ERV works? On the Fantech, these are named DEH+, DEH- and C.

I was hoping that this switch would work as a relay taking 24V on two of the  contacts and outputing switched 24V on the remaining contact. But this is not the case :(

Thanks




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Re: 20-40-60 minutes timer switch
« Reply #1 on: November 17, 2016, 11:43:46 AM »
What is the model of your ERV?

Is this ERV dedicated and used to ventilate the bathroom or just a simplified installation?  The Vanee OL, OC and I terminals are used for a dedicated bathroom control.  Use the Y, G and B terminals on a Vanee for a main control.  I'm not sure what the C, DEH+ and DEH- terminals are when dealing with Y, G and B.

Also most ERV's don't supply 24VAC.

Offline TurboLed

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Re: 20-40-60 minutes timer switch
« Reply #2 on: November 17, 2016, 01:32:03 PM »
Hi,
Thanks for replying.
My ERV is a Renewaire EV130 but I don't want to focus on that because I'm supplying my own 24 VAC transformer and I successfully connected a humidistat/dehumidistat to it (the Honeywell H6062). I want to replace the mechanical timer in my bathroom with an electronic one.

I haven't found a one-size-fits-all solution except DewStop which seemed to produce a universal control (FS-3300) using 24V but only the 110V version is available. Renewaire makes their own control but I don't like it as it require an additional PTL control (percentage timer). Many timers on the mass-market exists for 110V already but I want to re-use the existing low-voltage wiring.

So it came down to the Fantech RTS3 for which this website states it works using 24V: https://www.zoro.com/fantech-timer-control-push-button-24-volt-rts3/i/G7507911/
I took a risk by ordering it without knowing if I could make it work.

I assume the DEH+ and DEH- are equivalent to the OC and OL terminals of the VanEE/Venmar. With an ohmmeter, I cannot find any continuity between any terminals of the timer but I do see some current flowing. I'm in the dark here because there's no schematics, no specifications about what kind of signal should be on which input. I expected simple on/off logic so that's why I'm asking for you help.

Thanks




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Re: 20-40-60 minutes timer switch
« Reply #3 on: November 18, 2016, 01:09:34 PM »
The problem is the ERV doesn't use 24V.  It simply sends a communicating signal from the control to the HRV unit.  It's not something you can measure with a voltmeter.  The only times an ERV uses 24V is when it's interlocked with the furnace fan.  But the ERV really only uses a relay and gets 24V from the furnace R terminal then send it back to G.

I think I'm still confused with what you're trying to do exactly.  But the ERV sends a signal to the control, and if the control is on it gets sent back to the ERV and then starts. 

The EV130 manual says,

Quote
Do not connect power to the units external control terminals: this will damage the unit. The external terminals are for use only with un-powered controls designed for low-voltage operation.

Offline TurboLed

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Re: 20-40-60 minutes timer switch
« Reply #4 on: November 18, 2016, 01:37:29 PM »
Do you have any insight about the implementation of the "communicating signal" ? I wonder why they chose the complicated way, that means each ERV control needs to have a complex micro-controller inside and they can sell them for 80-150$. So we're stuck with the old-time, noisy/ugly dry-contact mechanical controls...


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Re: 20-40-60 minutes timer switch
« Reply #5 on: November 18, 2016, 02:00:32 PM »
If you remove the DEH- and DEH+ wires, from the existing control, and touch them together does the ERV start?  Really any control with dry contacts should work.

Look at the Vanee Lite-Touch  Bronze Wall Control,

http://www.vanee.ca/en/accessory/37-lite-touch-bronze-wall-control.html

I know the Y terminal is what powers the LED lights on the control.  Earlier models of the touch control had to wire Y to the ERV/HRV OC terminal.  The newer controls wire Y to the Y terminal on the ERV/HRV.

I'm not familiar with your manufacturer.  I attached a picture below.  Does your existing control have 3 wires?  What are the terminals labeled on the ERV?

Offline TurboLed

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Re: 20-40-60 minutes timer switch
« Reply #6 on: November 18, 2016, 02:23:31 PM »
My problem is not with the ERV contact, but how to power the Fantech timer switch I'm trying to retrofit. I was mistaken by the Zoro website which was stating 24V because that's what I need.
I have added my own 24Vac transformer to power a Honeywell H6062 (de)humidistat which has a dry-contact output. I'm using the dry-contact output of this dehumidistat to turn on my ERV, all is good. I'm looking for the exact same thing but in a nice electronic timer switch package for a bathroom wall control.
I couldn't find anything except the Fantech RTS3 and some equivalent controls from Venmar/VanEE. Impossible to find out how these controls work, they all seem to use a proprietary signal...
The control you sent is the Renewaire one which require a PTL control, it's even worse because it's in series (2-wires, not 3) and I would not be able to re-use my current 24V humidistat wiring.

Offline TurboLed

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Re: 20-40-60 minutes timer switch
« Reply #7 on: November 21, 2016, 07:39:18 AM »
I got some luck by connecting DEH+ and COM to +12Vdc or +5Vdc. It just doesn't work with AC. With +24Vdc the regulator gets very hot, so it's really not intended for 24V.
Now the LED turns on and I can step through the 20/40/60 minutes setting (the LED turns green/orange/red), and I see the DEH- output has some voltage when the switch is on. So I know the microcontroller is working.
The only remaining problem is how the switch is supposed to turn off. I waited the whole night and the LED just stays green all the time :(