240 to 24v

[The Baker]

I have to provide a controller for a boiler that has 240V at the room stat terminals, to reduce work/cost to the customer I would like to convert to 24v for the connection from the boiler position to the switch within the battery powered room stat.

I seem to remember an electrician installing some thing which resembled a MCB/relay on a DIN rail, which acted as a switch for the 240V but had a low/no volts connection on the front of it that connected to a switch on the wall in a damp/humid area else where in the building.

Can any one help me with this?

Thanks in advance.

Tim

 

[holmslaw]

..

 

[mikhailfaradayski]

I have to provide a controller for a boiler that has 240V at the room stat terminals, to reduce work/cost to the customer I would like to convert to 24v for the connection from the boiler position to the switch within the battery powered room stat.

How is faffing about with din rail enclosures and relays ever going to reduce the amount of work or cost involved?

I seem to remember an electrician installing some thing which resembled a MCB/relay on a DIN rail, which acted as a switch for the 240V but had a low/no volts connection on the front of it that connected to a switch on the wall in a damp/humid area else where in the building.

Can any one help me with this?

I'm sure a competent electrician would be able to do this instead of you. Its probably better for the customer

Thanks in advance.

Tim

Are you charging the customer for this work?

Does the customer think they have employed the services of someone who knows what they are doing?

 

[flameport]

I have to provide a controller for a boiler that has 240V at the room stat terminals, to reduce work/cost to the customer I would like to convert to 24v for the connection from the boiler position to the switch within the battery powered room stat.

How does any of that reduce costs for the customer?

240v stat = no batteries required, no extra wiring, no work required at all.
Battery stat - wiring alterations, expensive additional equipment, far more to go wrong, new batteries required every year, inconvenience when batteries run down.

Battery thermostats are tools of the devil and should never be installed. They only exist for a. lazy people who can't be bothered to install a cable to the thermostat position (as in wireless types) or b. to increase the profits of thermostat manufacturers, as installing a battery box is cheaper than a voltage converter.

 

[HH1]

To answer the original post (and if you are hell bent on going down that road)

Search for "Relay" within the Maplin website
http://www.maplin.co.uk/
Should give you an idea of what's available.

Although may be wise to heed the advice in previous posts.

 

[The Baker]

Thanks for the replies.

Let me start again,

1st the bloke does not want Radio Frequency (he has had enough of that thanks)

2nd, it’s a Baxi Duotec with 240V at the room stat terminals, not a live and neutral, just a 240V live which is currently connected by a link.

Usually the battery powered programmerble room stat volt free terminals are used to switch on/off the boiler at its set point.

I would like to fit a bit of electrical equipment in a small box next to the boiler.

The function of this electrical box is to act as a switch/interface between the room stat and the boiler. It needs to use 240V from the boiler to power it self, it needs to act as a switch to open/close the 240V room stat circuit within the boiler circuitry, and most importantly it has to be able to have low/no voltage connections for connecting through the volt free switch of the battery powered room stat.

Thanks in advance.

Tim

PS a sparky I spoke to today thinks the thing I am talking about is a DIN Rail modular Transformer, I am contacting a suppliers tech help line to see if it does what he/I want it to.

PSS I will only be getting paid for installing the thing he is happy with.

 

[holmslaw]

..

 

[fireman22]

hi Baker, your losing everyone i`m sure.
on that boiler the link for the central heating, if its fitted, the boiler fires and pumps the water around the rads.
if the link is out the boiler doesnt pump around the rads.
if you connect a cheap simple switch room stat across the link terminals on a two core cable job done.

 

[fireman22]

if you are hell bent on using a battery room stat connect the two core cable from the "link" terminals across the battery room stat terminals, job done, again

 

[flameport]

The function of this electrical box is to act as a switch/interface between the room stat and the boiler. It needs to use 240V from the boiler to power it self, it needs to act as a switch to open/close the 240V room stat circuit within the boiler circuitry, and most importantly it has to be able to have low/no voltage connections for connecting through the volt free switch of the battery powered room stat.

This is complete waste of time.

There are a pair of terminals in the boiler.
There are a pair of terminals on the thermostat.
A cable between the boiler and thermostat is all that is needed. Nothing else.

'Volt free contacts' are exactly that - contacts which are not connected to any power within the device, so can be used for any purpose you choose.
It does NOT mean that they are only suitable for ELV.

 

[The Baker]

There are a pair of terminals in the boiler.

I agree.

There are a pair of terminals on the thermostat.

I agree with that as well.


A cable between the boiler and thermostat is all that is needed. Nothing else

Now that’s the bit that is the problem,

running a cable be it surface mounted or in trunking is difficult in this property,

where as a mutli stranded screened cable carrying a “low voltage“ can so easily be hidden away and will reduce the cost to this Customer.

This Boiler, a Baxi Duotec, comes with 240V at the room stat terminals

All of the Central Heating boilers I install have what the Manufacturers call “low voltage terminals” for the Installer to utilise to run a programmable room stat, or have opentherm built into the PCB.

Thanks for advice received.

Apologies for not getting the message across as clearly as it should have been, but spanner men like me iant good at the writen stuff.

Tim

PS

Will call in at Maplins.

 

[fireman22]

hi Baker, got the whole picture now, i will have a quick look and report back
just thinking you may be able to use bell trans that can be clipped on a din rail and a relay with bell trans voltage coil and 230 volt rated contacts again din rail mountable

 

[fireman22]

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2019157
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=7150929

these will do the job or any simular trans & relay. are you ok with the wiring? its just the feed off the trans switched via the room stat to operate the relay, then the link terminals of the boiler go across the relay switch contacts these are voltage free just a switch.

 

[bernardgreen]

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2019157

has a 12 volt AC output

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=7150929

has DC coil. The relay may operate but it might just make a loud buzzing noise when the thermostat demands heating.

Choose a relay with an AC coil.

 

[The Baker]

Thanks for the info, I will give it a go.

Tim