UFH vs radiators manifolds

[justwondering]

I am doing heavy house renovation and want to have ufh (multizone) at the ground floor and radiators on upper floors.

I want to have consistent controls, with manifolds feeding both the ufh loops and radiators, and the same type thermostats controlling both (depending on the room, the thermostat will actuate different manifold valves - either ufh or radiators).

I plan to have buffer tank with 50C water maintained by a heat pump.

I keep hearing that the systems for radiators and ufh need to be different, but nobody can properly explain why. Is not it just down to temperature? So if I have blending valves on both manifolds (radiators and ufh) set to different temperatures (say, 28 for ufh and 40 for radiators - I can size them to any temperature at this point) - can't I have identical set ups? And have both manifolds fed from the same flow/return connected to the buffer tank?...

Why would the systems be different?

Thanks!

 

[IND_Nick]

If you are at the early stages and plan it properly, there's no reason why you can do what you have outlined. We often use manifolds for rads on 1st floor, just make sure radiators are sized correctly.

We often use the Heatmiser wiring setup and thermostats to control the lot.

 

[John.g]

With a buffer does then entail separate pumps for the UFH & Rads?, two pumps in all for the UFH, one to supply HW to the TMV and a manifold mixing pump and one for the Rads? 4 in all, including the primary (boiler) flow circ pump.

 

[Ric2013]

The temperature you need for the UFH will be dictated by the maximum for the type of system you are choosing to install, whereas the radiators are, yes, better cooler in terms of heat pump COP, but only if the heat pump is running at a lower temperature. Not sure what advantage there would be in blending the radiator flow temperature down to below that output by the heat pump.

You may need a secondary pump for the UFH manifold to get sufficient flow and pressure for a number of loops of high resistance (16mm and long length) pipework, but if it's a separate flow from the storage tank, I don't really see the problem.

No reason not to run multiple zone valves from a manifold for the radiators. That's basically an S plan plus design and can work quite nicely, although, depending on the house and how you end up using it, such level of complexity MAY be unnecessary.