How have you connected your cooker hood (electrically)?

[phatboy]

Hi all,

 

I will soon be installing my Vent Axia Kinetic BH unit up.

 

It has multiple volt-free connections.  I have a PIR that I have set to volt-free mode for the bathroom, but unsure of the best approach for the kitchen extractor to set the system to boost.

 

There is a LS input on the unit, but this expects a 240v input.  If the cooker fan is set to anything but full power, I'd expect the voltage to be lower and so not activate this circuit.

 

Alternatively, I may need to rig up some sort of relay from the supply to the hood extractor fan, that feeds to a set of the volt-free terminals.  but I don't think these connections have an over-run facility.

 

Interested in how other people have dealt with this.

 

Cheers

Tim

Edited March 5, 2019 by phatboy

[phatboy]

Hi, I'd appreciate any feedback from anyone who has experience of this, before I floor the loft and make cable runs a whole lot more difficult!

 

Thanks
Tim

[Nickfromwales]

On 05/03/2019 at 11:22, phatboy said:

Hi all,

 

I will soon be installing my Vent Axia Kinetic BH unit up.

 

It has multiple volt-free connections.  I have a PIR that I have set to volt-free mode for the bathroom, but unsure of the best approach for the kitchen extractor to set the system to boost.

 

There is a LS input on the unit, but this expects a 240v input.  If the cooker fan is set to anything but full power, I'd expect the voltage to be lower and so not activate this circuit.

 

Alternatively, I may need to rig up some sort of relay from the supply to the hood extractor fan, that feeds to a set of the volt-free terminals.  but I don't think these connections have an over-run facility.

 

Interested in how other people have dealt with this.

 

Cheers

Tim

Can you give a little more detail on how / why you need the boost to work please?

I would imagine ( yet to fit my first unit ) that the boost goes into overrun itself so any external trigger / feed should only need to be momentary.  

[phatboy]

@Nickfromwales I need to boost when the extractor is turned on to help purge the cooking smells and moisture.

 

From what I can tell, the various inputs on my unit are not momentary, and rely on an input for the duration of the boost.  Momentary would also not be great, as it could turn off boost whilst cooking was still happening.  An over-run built in though would be good, so it boosts for x minutes after the trigger has gone.....

[ProDave]

We opted for the "keep it simple" idea.  We have a timed boost available from a button on the wall in the kitchen that you press when you are going to be cooking.  You could link it to the cooker hood, but you might not always use that so that is not foolproof.

[Nickfromwales]

You can simply add something like this and set the overrun to suit. Boost will stay on until the hood is turned off, and then it falls back to overrun timer which you set to suit.

Link

[phatboy]

Thanks Nick,  that looks positive!  The variable input voltage will do the trick.  I'll probably not bother with a railed enclosure, just put it in a plastic box with a screw on lid, as once its set i should never need to touch it again.

 

Many thanks

Tim

[phatboy]

On 11/03/2019 at 15:55, ProDave said:

We opted for the "keep it simple" idea.  We have a timed boost available from a button on the wall in the kitchen that you press when you are going to be cooking.  You could link it to the cooker hood, but you might not always use that so that is not foolproof.

 

I could have got away with that if I'd considered MHRV at the refurbishment stage, but I am 2 - 3 years on now and would end up dead if the wife caught me with a length of trunking in her kitchen

 

We are fairly disciplined with using the cooker hood fortunately.

[phatboy]

Hi again all,

 

I ordered the relay as suggested by @Nickfromwales, and the time has come to install it.  The wiring isn't quite as I am used to, so hopefully I can run by my understanding of it to you all?  Schematic is shown here https://www.ebay.co.uk/itm/GIC-1CMDT0-Multi-Function-12-230Vac-dc-SPCO/323787573022?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

A1 - Permanent live from hood (240v)

A2 - Neutral from hood

B1 - Switching live from good (voltage will vary)

 

16 - Volt free + from MHRV unit

18 - Volt free - from MHRV unit  (I think this is the NO terminal)

Relay mode - sf

Any confirmations or corrections gratefully received

Tim

[PeterW]

11 hours ago, phatboy said:

A1 - Permanent live from hood (240v)

A2 - Neutral from hood

B1 - Switching live from good (voltage will vary)

 

16 - Volt free + from MHRV unit

18 - Volt free - from MHRV unit  (I think this is the NO

 

B1 isn’t needed - just use a feed from the switch output (ie when it’s on) to the A1 connection and then connect 15/18 as the connection. 15 is common, 18 is NO

[phatboy]

40 minutes ago, PeterW said:

 

B1 isn’t needed - just use a feed from the switch output (ie when it’s on) to the A1 connection and then connect 15/18 as the connection. 15 is common, 18 is NO

 

Thanks Peter,

 

If I only send a switching supply to it, what will control the over-run timer?

[PeterW]

17 minutes ago, phatboy said:

 

Thanks Peter,

 

If I only send a switching supply to it, what will control the over-run timer?

 

Capacitor on the control board

[phatboy]

On 06/07/2019 at 09:00, PeterW said:

 

B1 isn’t needed - just use a feed from the switch output (ie when it’s on) to the A1 connection and then connect 15/18 as the connection. 15 is common, 18 is NO

 

In the end, after much tampering, I got this working.

 

I had to connect as below:

 

A1 - permanent live 

B1 - switching live (variable voltage)

A2 - neutral

 

15 - volt-free + from HMRV unit

18 - volt free - from MHRV unit

 

Between the relay unit and the cooker hood (next to the MHRV unit), I have added a 3-pole fan isolator switch, as a means of local isolation.

 

@PeterW's guidance didn't entirely work for some reason, luckily I had routed a permanent live there and not chopped it back yet