UFH wiring to a combi with built in time controls!

[Martynrosscampbell]

Hi, I'm hoping someone may have some experience with this!
I've been asked to connect The electrical side of a single zone John guest UFH kit to a biasi s.p.a combi boiler. The combi has built in time controls so the only terminals inside are the main live, neutral and earth terminal and the volt free room stat terminals.
There is also a new zone valve for the existing rad circuit so the new system can run independently.
I need to know how I can take a feed and a switch return from the boiler to supply the UFH kit and a new time clock and room stat for rad circuit.
Any help will be greatly received!!

 

[matt1e]

time clock and stats will control the individual zone valves (rads and UFH)
the zone valves end switches will fire the boiler via its volt free terminals

Matt

 

[Agile]

Its not clear on what basis you are going to do this wiring.

Its not difficult to wire up volt free controls but as you seem unsure how to do it then I would say that its very risky. If you make a mistake you can damage the boiler's PCB and they can cost up to £200 plus fitting!

In any case you will need seperate time controls on the UFH and the rads so the boiler time clock will be set on constant and all timing will be from the external controls.

Some would do all the wiring at 230v and use a relay to isolate the boiler volt free contacts.

Tony

 

[Dan Robinson]

Its not clear on what basis you are going to do this wiring.

Its not difficult to wire up volt free controls but as you seem unsure how to do it then I would say that its very risky. If you make a mistake you can damage the boiler's PCB and they can cost up to £200 plus fitting!

In any case you will need seperate time controls on the UFH and the rads so the boiler time clock will be set on constant and all timing will be from the external controls.

Some would do all the wiring at 230v and use a relay to isolate the boiler volt free contacts.

Tony

Or not...

2 zone valves using internal microswitch for volt free to boiler.

Two programmable room stats (single UFH zone?).

Easy peasy.

 

[Martynrosscampbell]

Thanks for the help so far guys.
Been thinking about it today and the only way which i can get my head around doing it is with the relay. wiring everything in 240 and having the orange wire from the rad circuit or switch live from the UFH wiring centre switching the relay and completeing the 24v circuit?????
I dont know enough about way the zone valves work to know what the micro switch is all about. feel free to enlighten me on that!!!
Let me know your opinions on the relay!
Thanks,
Martyn

 

[Martynrosscampbell]

If you do think the relay will work, will this do the trick. been a while since ive had to use a relay
http://www.tlc-direct.co.uk/Products/SR501.html

 

[DeltaT2]

Its not clear on what basis you are going to do this wiring.

Its not difficult to wire up volt free controls but as you seem unsure how to do it then I would say that its very risky. If you make a mistake you can damage the boiler's PCB and they can cost up to £200 plus fitting!

In any case you will need seperate time controls on the UFH and the rads so the boiler time clock will be set on constant and all timing will be from the external controls.

Some would do all the wiring at 230v and use a relay to isolate the boiler volt free contacts.

Tony

Or not...

2 zone valves using internal microswitch for volt free to boiler.

Two programmable room stats (single UFH zone?).

Easy peasy.

Dan as always is on the money, do as he as stated & you'll not go far wrong. Take it from someone that's done it 100 of times.

 

[Dan Robinson]

It amazes me how people can over think things, then ignore simple solutions.

Untitled

• Dan Robinson
• 26 Jan 2012
• 2

Not a relay in sight, yet above this lot, a 40kW combi. There are two rad circuits, an UFH system further split into 4 zones, plus an Unvented cylinder and towel rail cicuit (which encompasses the frost protection for the externally housed cylinder).

All mains powered controls, mixed wireless and hard wired. Yet the boiler is switched at low voltage.

All off the shelf Honeywell controls.

Please forgive the state of the build site... it was chaos there. All looking very swish now though. Cables and gas meter all tidied up now.

 

[Martynrosscampbell]

So your obviously the man in the know Dan!

I wasnt ignoring your advice at all, just couldn't and still cant quite get my head around how that would actually be connected up! im sure its simple enough, but feel free to explain it further!

A little more about the job if it helps!!

UFH wiring centre has volt free in and out terminals so that side will be easy enough if we go down that route. the bit i dont understand is how the supply for the programmer, timeclock and zone valve will switch the volt free contacts in the boiler without using a relay? I will probably go with a wireless programmable room stat rather than seperate wired units if that changes anything!

Really appriciate the help.

Martyn

 

[picasso]

The grey and the orange on 2 port valves are connected to a microswitch that makes when the valve opens, you need 240v to make the valve open but you can use the grey and orange to switch any voltage you like,

so if you put 24vdc on the grey wire the orange will have 24vdc on it when the valve opens.

 

[Dan Robinson]

Just as Picasso said.. the microswith is standalone. The controls just power the brown wire.

 

[Martynrosscampbell]

Job done!

Shame there was a dodgy push fit T on the water main feeding the boiler. it blew off and flooded the place as soon as i touched it! Lucky i keep a few spare fittings!

Appriciate the help anyway!!