Under Floor Heating connections

[Guy King]

I'm going to take the feed to the conservatory's UFH back to the airing cupboard where the pump is so I can run at as a seperate circuit so it can come on earlier in the morning. I have an existing Y-plan heating system.

Two questions.

Is there a well tried pattern to connect the UHF in, so I don't have to reinvent the wheel? I was thinking of a two-port valve before the existing one, tapping off to the UFH and a second timer driving it.

Do I need to plumb the return in all the way back or can I pick it up nearby? There's a radiator very close to where I want it which would simplify the piping and leave rather more timber holding the floor up.

[The Natural Philosopher]

Oh dear. You do know that UFH not only needs a spearate circuit, but it has to run at a lower temp than the CH to avoid screed cracking, and it probably needs its own pump as well as well as a temp reduction valve, and that means a separate channel and relay for all that..and thermostat?

[<me9]

I would scrap the Y plan and go for 3 zones on an S plan. I found a (modified) Y plan with 3 zones ate microswitches. You /should/ also be running your UFH at a lower temperature than the other zones, so another pump & mixing valve may be necessary.

That could cause phantom circulation backflowing where i isn't needed. If you have to do it fit some check valves.

[Guy King]

The message from The Natural Philosopher contains these words:

The system from Hepworth that I've used specifically says it's intended to be connected to existing CH systems. There's a return temperature thermostat included, and yes, it does specify a maximum input temperature with which I can already comply.

What I want to know is that given I'm going to feed it seperately from the existing CH do I need a seperate return or can I just pick up a return that's going that way anyway?

[The Natural Philosopher]

Well any old return will do.

As long as you have a pathway...if its separately zoned just make sure the motorized valve doesn't end up controlling the ordinary heating and vice versa, and that the contacts for the boiler/pump are paralleled so calling for UFH heat does indeed fire up the boiler..

[John Stumbles]

No don't tap in: you're liable to get reverse circulation and heating of bits of the circuit you don't want (been there, done that :-().

[Guy King]

The message from John Stumbles contains these words:

I had a feeling that would be the answer.

It's not the end of the world, but the preferred route back to the airing cupboard is already stuffed full of ringmains, lighting circuits and 22mm main pipes for the heating. And the phone cables, the cable cables, the network cables, the alarm cables, the thermostat cable. And shortly the conservatory lighting and sockets cables and the conservatory phone and network cables.

And maybe a mains water pipe for an outdoor tap.

[<me9]

You could always put some check valves in (that reminds me of my summer jobs).