Underfloor heating and rads

[WillC91]

I am wondering about running a loop for ufh and a loop for rads from a single boiler.
The boiler I’m dealing with is Weil-Mclain eco tec 150h.
A thermostat controls the rads which heat most of the house.
Both loops have their own pump but the ufh never circulates if the rads are programmed to come on for heat demand.
I’m thinking I need a separate thermostat for the ufh loop. There is a thermocouple on the return side of the ufh loop but the boiler doesn’t seem to be able to use it to control the pump.
Is there a way to make it work where the pump operates until the thermocouple reads 30C (86F)? Also trying to avoid separating the loops with a heat exchanger as this boiler is apparently able to control multiple pumps.
Thanks for an insight

 

[John Gayewski]

Is your system piped for primary secondary systems? The boiler should be on its own loop with its own pump. Then the rads with their own poop and pump. Then the radiant with its own poop and pump.

If it's not piped for this then the loops can't run together

 

[Sponsor]

 

[Fitter30]

Need to know how the boiler is piped? What water temp are you running? Take a few pics of boiler and piping. Radiators don't start heating till 140° supply,floor heat depends on floor covering. Wood floor 80°

 

[WillC91]

Thanks
There's an example attached of how it might be piped where each end has its own pump. I plan to have temps around that, maybe even higher for the rads.

 

[Fitter30]

Thanks
There's an example attached of how it might be piped where each end has its own pump. I plan to have temps around that, maybe even higher for the rads.

Have any idea how long the two 1/2" pex loops are? Boiler is it a combi supplying dhw. Boiler can only control supply water temperature. What water temp are you running ? Boiler have outdoor reset?

 

[WillC91]

Have any idea how long the two 1/2" pex loops are? Boiler is it a combi supplying dhw. Boiler can only control supply water temperature. What water temp are you running ? Boiler have outdoor reset?

On the lengths I’m not sure, there are 4 pex loops off the manifold that cover around 300 sqft. total. The boiler doesn’t feed the hot water it’s just for heating. It’s set to 75C rads and 30C floors. It has a sensor outdoors

 

[Fitter30]

On the lengths I’m not sure, there are 4 pex loops off the manifold that cover around 300 sqft. total. The boiler doesn’t feed the hot water it’s just for heating. It’s set to 75C rads and 30C floors. It has a sensor outdoors

How are the different temps piped? Pencil diagram is fine.

 

[WillC91]

Basically like the image attached. Both loops would have their own pump. On the underfloor heating loop a sensor on the return side would run the pump if the temp dropped below 30C. I'm wondering if this is possible without a heat exchanger type setup. I know it would pull potentially 75C through the floor but some have said this boiler is capable of such a system.