Hello,

 I have 2 separate warmup mats and a Potterton Performa 24 boiler. I would like to control these via the brick.

 
Heating Mats: The two mats draw 1.01 and 2.97 Amps respectively so the simplest thing would be to connect them to the brick but that is 4 AMPS, sure, within in the 6.4A fuse but I would like a bit more headroom as I will be attaching lights to the other circuits. My analogue outs are all used up so ideally I need a relay that will flick between on and off on the high voltage side but the relay circuit has to operate in response to the digital outs as that is all i have left on the brick - any ideas of the spec / i need to be looking for?
 

Boiler: Potterton Performa 24 Combi. This boiler has a separate 240 volt circuit that ships with a loopback wire in it. With the wire in and the boiler set to continuous central heating the heating will be on. Therefore the external controller just breaks or closes this circuit. The brick manual mentions something about relay circuits, not sure if these are 240 rated or whether I should be looking for the same type of relay that i will get for the underfloor heating.

Anyone been here before?

thanks,

Leon.


 

 Leon

   a) Use the open collector outputs to close 12v relays and use the contacts to drive the heating mats.

   b) Bond a temp sensors in to the floors to directly read the floor temperature

   c) Use temp sensors for room temp (reg say that should be between 400-1200mm but anywhere off the floor is good)

   d) Use the Triacs to drive the boiler.

Regards

Andy


 

Hi Andy,

Thanks for your help on this.

a) Use the open collector outputs to close 12v relays and use the contacts to drive the heating mats.

Ok - excellent - i have 2 x finder relays already that I think are 12v -24 so I will hook them up to the OCs and see what happens 

   b) Bond a temp sensors in to the floors to directly read the floor temperature

Already under the tiles!  

   c) Use temp sensors for room temp (reg say that should be between 400-1200mm but anywhere off the floor is good)

Already under the tiles 

   d) Use the Triacs to drive the boiler.

- I will add a picture of the diagram on the boiler later but I think it looks like I should use the same technique as the underfloor heating as the boilet is not expecting a 240 circuit to be passed through it - the circuit is from the boiler. Picture to be posted when i get home.

L.

OK, Here is the diagram - a 240v circuit coming from the boiler. So it looks like i should be using a relay to do a simple switch?

Hi Leon,

Your boiler is a (primitive) Britsh device and as such is designed to work within a 240v high(relative) current enviroment.  Use a relay between terms 1&2 or connect terminal 2 to a triac output, both will work.

Boring safety bit - if you opt for the triac then you should make sure that the boiler power isolator isolates the triac line as well. You can achive this by:

1.  feeding the bolier from the same live supply as the brick and isolating the boiler and brick 240v side together  (not suitable if the brick is not adjacent to boiler)

2. changing the boiler isolator (typically a switched fused conection unit)to a tripple pole type like a fan isolator (adding an unswitched FCU where necesarry) and running the live/neutral/triac lines via this.

If you do not do this any uninitiated Corgi guy servicing your boiler will switch it off at the normal isolator and stick his mucky paws straight on your (potentially) live triac feed! Also if your house wiring setup is anything other than standard you need to be sure where your neutral and earth are coming from for the two separate bits of equipment.

And don't forget that Part P registration :-)

Leon

  Simon is right here, there needs to be local isolation.  Which brings us onto the bigger issue of servicing etc.

  Just to let you know that we are manufacturing a switch that can do isolation as well as [auto-manual] control so that any service techician can get the boiler into the state(s) they need for work.

Regards

Andy

 

 Simon and Andy,

Before I posted the original email I already sent 240v from the triacs into connect 2 - the RCD for the whole tripped instantly I switched it on the from the brick so I don't intened to be doing that again. I have wired connectors 1 and 2 to a relay and it has a manual advance swich so I am using that to turn the heating on and off at the moment - i will wire the relay section to the 12v from the brick PSU and then into the OCs as recommened. This way boiler off = no current from anywhere else and Mr. Gasman won't kill himself.

 
I inted to power 3 of these relays from the brick PSU and into 3 OCs ponits. 1 for the boiler and 2 for heating mats.
 

Leon.

 

Before I posted the original email I already sent 240v from the triacs into connect 2 - the RCD for the whole tripped instantly I switched it on the from the brick so I don't intened to be doing that again.
 

The different live and neutral path lengths together with a (relative) low  loop impeadance (which is good!) cause this. An excellant example of why taking just phase or just neutral between diffferent final circuits is not clever!  And why option 1 would be to feed the whole heating system with the brick - anyway you have already sussed the less fraught solution :-)

Sussed but not installed yet, I'm getting there. When I'm done I think I will make notes for others and post. "How to get most out of a WebBrick in a 1 bedroom flat"

L.