IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Dilemma
Topic Summary:
Created On: 27 November 2012 05:37 PM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 27 November 2012 05:37 PM
User is offline View Users Profile Print this message


Avatar for OldSparky.
OldSparky

Posts: 592
Joined: 28 June 2011

Hello peeps

i have got my self into a dilemma, and i should have just gone with plan A instead of thinking about it.

this is problem.

i am currently wiring a new 5 bed house, a luxury one. The customer has bought a air handling unit that reclaims the heat from the house, you guys know the type of thing.

he wants the boost controls connected, this is a 240v signal from any of the bathroom light switches which have been operated.

Now would you A) take the boost feed from the light switch/ switch wire or B) take a 2 core cable from the AHU control box to a double pole switch, so one side would operate the light the other would operate the boost fan..

either way at either end i would have 2 supplies, which would you guys think is the better option.

My first thoughts were to rely on the signal coming from the lighting switch wire, this way i can connect them through an isolator adjacent the AHU labeled warning of 2 supplies..

have i made sense
 27 November 2012 06:02 PM
User is offline View Users Profile Print this message


Avatar for OMS.
OMS

Posts: 19668
Joined: 23 March 2004

If it's a luxury house why isn't there controls for the lighting rather than 230v switches - just so last decade - you could just pick up the supply via a programmable relay -

Assuming no controls, if you link the switch wires from several bathrooms, you'll back feed onto the lights.

a simple realy box with a relay per bathroom wired in parallel with the boost supply direct through all the relays will bring on the fan boost when any bathroom light is operated.

I wouldn't beat yourself up over more than one supply - we do it in multigang switches without batting an eye (even on different phases) - just bang a label on it so the next guy fault findinghas a sporting chance - for ad hoc fiddling, then a spark would test before touching - for everyone else - darwinian selection takes over.

regards

OMS

-------------------------
Failure is always an option
 27 November 2012 06:29 PM
User is offline View Users Profile Print this message


Avatar for Legh.
Legh

Posts: 3488
Joined: 17 December 2004

just bang a label on it so the next guy fault findinghas a sporting chance - for ad hoc fiddling, then a spark would test before touching - for everyone else - darwinian selection takes over.


Lol, Labels! Ah now I understand, something to do with lack of ambiguity perhaps?

I would have thought that Oldsparky was reasonably proficient to test his own work

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 27 November 2012 06:34 PM
User is offline View Users Profile Print this message


Avatar for OMS.
OMS

Posts: 19668
Joined: 23 March 2004

Originally posted by: Legh

just bang a label on it so the next guy fault findinghas a sporting chance - for ad hoc fiddling, then a spark would test before touching - for everyone else - darwinian selection takes over.




Lol, Labels! Ah now I understand, something to do with lack of ambiguity perhaps?

Exactly - ambiguity and testing are certainly not the same thing Legh ?


I would have thought that Oldsparky was reasonably proficient to test his own work

I'm sure he is - but if he's Old Skool, hell know in his water if it's OK to bang test it, as he installed it -


Legh


regards

OMS

-------------------------
Failure is always an option
 27 November 2012 06:41 PM
User is offline View Users Profile Print this message


Avatar for OldSparky.
OldSparky

Posts: 592
Joined: 28 June 2011

OMS

i take note on the back feed issue.. they wont be any there is a special box thingy they supply to stop this

i agree with the old darwin selection tho ;
 27 November 2012 06:48 PM
User is offline View Users Profile Print this message


Avatar for OMS.
OMS

Posts: 19668
Joined: 23 March 2004

OK - so I guess you have a supply to the AHU via an isolator and then you terminate an extended switch wire into the "special box thingy" from each bathroom that the AHU serves.

Job done - anyone taking the lid off the "special box thingy" will be expecting live lines even with the AHU isolator "off".

I imagine the "special box thingy" is just a box of relays as I suggested then -

Regards

OMS

-------------------------
Failure is always an option
 27 November 2012 06:52 PM
User is offline View Users Profile Print this message



impvan

Posts: 768
Joined: 07 September 2005

A hotel I look after has something similar - one fan with a shared ducting to a block of 8 bedrooms. Any bathroom light brings on the fan.

The way it's wired (1960's) is that the bathroom light switch is a double-pole gridswitch... one pole does the light, the other pole is paralleled with all the other bathrooms and then on to the fan.
 27 November 2012 09:36 PM
User is offline View Users Profile Print this message


Avatar for OldSparky.
OldSparky

Posts: 592
Joined: 28 June 2011

the way i look at it is.. i feel its safer to take the feed from the light switch because you can isolate the supplies via an multi pole isolator ..

thank you for your input guys..
 27 November 2012 10:13 PM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11462
Joined: 13 August 2003

The customer has bought a air handling unit that reclaims the heat from the house, you guys know the type of thing.

he wants the boost controls connected, this is a 240v signal from any of the bathroom light switches which have been operated.


Not a Vent-Axia Sentinel Kinetic by any chance?

he wants the boost controls connected, this is a 240v signal from any of the bathroom light switches which have been operated.

Sounds slightly sub-optimal, unless none of the bathrooms have windows... (is moist air only generated at night?)

Some types have the option of proportional control by a humidity sensor in the extract airflow - so increases the fan speed when the air's damp - might be a better option. (Although you might still want some other means of dealing with other 'air quality issues').

- Andy.
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.