Villavent heat recovery ventilation system vm-400 ev

[Gabriel]

A friend has this Villavent Systemair heat recovery ventilation system which is partly working - I put an arow on the failled output -everything else is working.

I want to start with the relays,how can I test these without connecting this to 230V ?

Schrack RP330012 relay @RS

[budm]

Re: Villavent heat recovery ventilation system vm-400 ev

Since you do have the pin out of the relay, you can at least check the contact resistance between C (Common) and the N.C. (Normally close contact). Then you can check the Coil resistance to see if they all read the same Ohms. The bottom line will be that you will need to apply the power to see if you do get the DC voltage to the relay coil or not.

[Gabriel]

Re: Villavent heat recovery ventilation system vm-400 ev

Between point 5 and 6 I get 266 ohm on these relays.

Between 1 and 3 , 2 and 4 I get 1ohm to 1.3ohms, same as other relay.

Between 1 and 2, 3 and 4 I get 10, 20 30 Mohm and then OL - only this relay 'counts up' and then shows OL.

[budm]

Re: Villavent heat recovery ventilation system vm-400 ev

OK, the one you have labeled is 1 form a (1 NO). normally open contact, PIN 1 & 3 are tied together, PIN 2 & 4 are also tied together per relay spec), the other relays I can see some of them are 1 FORM C (1 CO).
That Gray connector with 2 pins, is one of the pin connected to relay Pin1 or Pin 2, and another pin of the connector goes some where else?
At this point you will need to apply 12VDC to the relay coil pin 5 &6 but the polarity applied to the coil must be correct or it will damage the relay coil back EMF protection Diode. I do not know at this point if the voltage relay coil is Source or Sink switching, need to get the DATA SHEET of those two relay drive IC and trace out the circuit.
If what you gave me is correct, if you jump pin 1 and 2 (to simulate relay turn on) of the relay as marked in your picture, what ever is connected to that gray terminal should come on, but you have to be careful since we do not know how each relay should be sequence on.

[Elysarian]

Re: Villavent heat recovery ventilation system vm-400 ev

looks to me like those are either spst (or dpst relays with the poles wired together).

being as the coil resistance sounds good (points 5 to 6 on your pic) then the next thing would be to see if the 12v is getting to those points when the relay is supposed to be energised.

you could test the relay itself with a 12v dc power supply but you'd be better taking it off the board for that to avoid damaging whatever is driving it.

[budm]

Re: Villavent heat recovery ventilation system vm-400 ev

OK, after looking at the spec of the relay driver IC, it is Sink switching setup, one end of the coil is connected to +12V power source, the other end of the coil is connected to ground through the transistor inside the IC.