house fan control

[cully]

I have a triple vent fan in the loft servicing three wet rooms with each room giving switched live (via room light) to control the fan.
I am replacing this fan (not working correctly) with a Envirovent Spider MEVS-H that has one sw live into the fan.
Is there a product available that accepts multiple 240V live connections in and probably through a relay gives one 240V out?
Thanks

 

[ericmark]

I will be interested in replies, with my central heating with similar situation I used a bank of relays, each zone valve runs a pump and the central heating so want the central heating to run when zone valve opens but not to open other zone valve.

With the original Part P in a bathroom with non opening windows it wanted the ability for fan to be turned on without lights, requirement now dropped, but the method was to use double pole switches for lights and pneumatic timed switches for the fan so either would switch on fan but the push button would not turn on lights.

But wait in case there is a better method.

 

[Taylortwocities]

I rather suspect that the existing fan also has only one switched live into the fan. With DP switches etc in the rooms.
How is the connection made to the fan?

 

[AndyPRK]

I will be interested in replies, with my central heating with similar situation I used a bank of relays, each zone valve runs a pump and the central heating so want the central heating to run when zone valve opens but not to open other zone valve.

The normal way to do this is to use the motorized valve as a relay.
The thermostat operates the motor.
The motor end switch then commands the boiler and pump on.


As for the OP, use dual pole pull switches

 

[cully]

The original fan "Silavent triple vent" has three switched live connections at the fan, one from each wet room
The Envirovent "Spider" has nine extract spigots and one to exhaust. The fan also has an additional three sw. live connections to the PCB but to gain access I have to go through the casing and this could invalidate the warranty not being one of their installers.

 

[ericmark]

Using a PIC or PLC yes you can do that, but programming a PIC is not that easy, so likely need relays.

The normal way to do this is to use the motorized valve as a relay.
The thermostat operates the motor.
The motor end switch then commands the boiler and pump on.


As for the OP, use dual pole pull switches

The programmer sends power to thermostat, the thermostat sends power to motorised valve and motorised valve sends power to pump. But how do you run two independent pumps where if either runs the boiler fires up? And the pumps are independent.

You would need twin micro switches in the motorised valve. One pump and one boiler easy, two pumps and one boiler only way is a relay on pump supply so when pump runs boiler runs, but no back feed.

Easy was is DC control, switch, diode, fan so no back feed, however the problem is that will result in DC through the RCD so would need type B RCD fitting, so relay is only way I can think of unless using double pole light switches.

Double pole light switch means fan supply does not need to come from lights, and relay also fan supply does not need to come from lights.

 

[Lectrician]

Use relays in an enclosure.

 

[cully]

Thanks Lectrician
So each of the wetroom switched lives would supply power to it's own non latching relay (in an enclosure) and the output of all the relays would give a common feed into the fan?

 

[Taylortwocities]

Thanks Lectrician
So each of the wetroom switched lives would supply power to it's own non latching relay (in an enclosure) and the output of all the relays would give a common feed into the fan?

yes, that’s the way. Have all three relays at the fan site, you already have the Three switched lives there.

 

[cully]

Thanks for all the advice, I will talk to RS re; what relays are suitable for my situation

 

[SimonH2]

Another consideration (as long as all the lights are on teh same circuit) would be a zone controller as used in wet UFH installations. You wouldn't be using all of it, but you get ready assembled a device that takes multiple AC inputs and has a relay that turns on when any of the inputs is live. The inputs are only diode logic, hence the "as long as all the lights on one circuit" bit, but that would save time building something.

To expand a bit, these zone controller panels are like a bit wiring centre. For each zone, there's an AC output that goes to a wall stat, and terminals to link the returning switched live to connections for a thermo-hydraulic valve on each zone control valve. The stat returns are diode OR'd together, and control a relay to control the boiler.
For this application, you'd just connect each light's switched live to the stat return terminal, and use the boiler relay to control the fan.

 

[cully]

Thanks Simon, the lights are on two different circuits

 

[SimonH2]

DIY with relays then.

 

[Taylortwocities]

Get three of these

put them in a suitable enclosure with a DIN rail fixing.

 

[Lectrician]

This enclosure

Three of these bases

Three of these relays