water underfloor heating

Postby waterman » Sun Aug 09, 2009 11:48 am

hi i am in the process of fitting water underfloor heating in my coservatory,i have a junction box next to my underfloor heating manifold where the cables from the 2 port valve the room programmer and manifold pump,and mains are terminated.i have run a 3 core cable from this junction box back to my condensing combi boiler,can anyone tell me where to make the connection at my boiler this is so when the floor heating calls for heat it fires the boiler so the floor heating works independent from the central heating,i now this is a switched live but where do i make connection.my boiler is controled by a wireless programmer which is in my hall,and there is a reciever box under the boiler so i assume the connection will be made inside this box,the wireless system is honeywell.can anyone help.thanks
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Joined: Sun Aug 09, 2009 11:27 am


Simply Build It

Postby htg engineer » Mon Aug 10, 2009 7:23 pm

Before we go down the route of wiring, can you explain the set-up.

For a standard underfloor system, the two port valve would be to isolate this section when the stat reaches temp - or is turned down. The way you're going to set it up, a two port valve is no use - you need a three port valve, where AB will be flow A will be central heating and B will be underfloor heating. And the wiring wont be as simple as you think.

The manifold pump ?? when you put power to the combi the pump will run - why do you need another pump ? not needed, if you get one pumping against the other - one will pack up.

Why do you want the conservatory heating on and not the rest of the house ?

The easiest set-up, is tee into flow and return like you would if installing another radiator - connect two port valve with thermostat, stat down or temp met - valve closes, undefloor heating off. But it will only work if the heating is on for the rest of the house.

htg engineer
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Postby waterman » Tue Aug 11, 2009 5:59 pm

hi htg engineer,
thanks for your reply.i have just purchased this single zone kit,as i want to run the floor heating independant from the central heating,this is what the manufacturer recommended,i have teed into the flow and return near the boiler and before the central heating take off's for radiators as they recommended.the 2 port valve is in the flow from boiler adjacent to the manifold.i think you have misunderstood me about the pump,i dont want 2 pumps,i have the manifold pump and the boiler pump,the system came with cad drawings and instuction book,but it is not very clear as to where on the boiler i connect the switched live that runs from junction box near manifold.hope this is a bit more helpful to you.thanks .waterman.
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Joined: Sun Aug 09, 2009 11:27 am

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