Diverting or mixing valve in underfloor heating ??

cacko85

Hello
Need help for UFH, what to use, what is better, diverting or mixing valve ?? I have Oventrop "Tri-CTR", can be use as diverting or mixing valve, what is better ??
The supply will be buffer tank and pellet stove.
Thanks in advance.

psb75

Describe more: "pellet stove." Please.

cacko85

Sorry Pellet boiler, doesn't matter what the heat source is, but here it is

https://www.thermoflux.ba/en/pellet-boiler/interio/

psb75

Thank you for that clarification on boiler. I install pellet boiler systems. I am not familiar with this version.
I'm troubled by the colored schematic and your hand-drawing. They don't correspond. Confusing. Could you perhaps provide a complete schematic of your planned system? You will get a better response from more people. More information = more better. You are on site. We are not.

Ironman

Is the floor a slab or a wooden staple up application?
Can you give some info on the design criteria? Tubing size, length, spacing? Insulation, heat transfer plates (if staple up)? Piping layout and pump size?

cacko85

Ok thanks. I try to clarify better.
First forget the pellet boiler, we will talk later about connection with buffer tank, it dosen't matter what the heat source is.
The discusion is about the mixing/diverting valve, in this case I have Oventrop Tri-CTR , here it is manual for the valve from official website.
Look on page 3, picture 2, it says:
"System illustration - Three-way valve “Tri-CTR” as diverting valve for the control of underfloor heating systems"
When the probe is cold, the flow is beetween B<>AB, when the probe is heating it open "A" then the wather is diverted or mixed.
But the vlave can be placed as mixing valve, if it placed on supply (hot side), like my hand drawing, I
try to draw better.
The question is witch solution is better, the one valve is placed as diverting (like in pdf doc.) or mixing (as on my hand drawing)

hot_rod

Mixing, like your drawing. Be aware of the Cv if you have a high flow requirement 

cacko85

hot_rod said:

.......Be aware of the Cv if you have a high flow requirement 

Sorry what is Cv ??
tnx

Ironman said:

Is the floor a slab or a wooden staple up application?
Can you give some info on the design criteria? Tubing size, length, spacing? Insulation, heat transfer plates (if staple up)? Piping layout and pump size?

It's the slab, with floor tile, but that it not the problem, and it already done.

Am confused about the valve (mixing or diverting), seeing different solution on web.

EBEBRATT-Ed

A diverting valve has two outlets and one inlet. The flow goes in one port and then either to the return back to the boiler or through the radiation and back to the boiler 100% flow to either or in some mixed position depending on the valve actuator. AB port always has water flowing through it.

A Mixing valve has 2 inlets and 1 outlet. Since the outlet always has water going through it the outlet is AB.

1 inlet to a mixing valve is water supply, the other inlet is return water from the radiation and the common AB port returns to the boiler.

The way I remember how these are piped is that a mixing valve mounts in the return line (return water from the radiation entering the valve and return water going to the boiler).

Weather you use the valve one way or the other I can't think it has much difference as long as it is properly applied

Most commercial jobs I have seen use mixing valves

epmiller

Either method of installing the valve will accomplish the same thing. The "mixing" configuration will run hotter because any supply water from the boiler will go through the valve. The "diverter" installation, like in the original picture from the valve manual, will have cooler temperature water running through it because the boiler supply is being mixed in at a pipe tee instead of inside the valve. Install it in the easiest way to service it.

Ironman

If you have a slab, you really should use a smart mixing valve like Taco’s I series or variable speed injection mixing, not a thermostatic valve.
The reason for this is that the high mass of the slab will continue to emit heat for a long time after the call for heat is satisfied and the circulator has stopped. The space will overheat (often by several degrees) because the slab is still giving off heat. It’s called the “flywheel effect”. The remedy is to use a mixing method that varies the SWT to the slab based upon out door temp and the actual heating load.
Both of the methods  that I mentioned above provide out door reset (ODR) to accomplish this. Variable speed injection mixing requires an additional pump, but eliminates the Cv issue that Hot Rod mentioned.

cacko85

Ironman said:

.....use a smart mixing valve like Taco’s I series or variable speed injection mixing..........“flywheel effect”....

Thanks folks.
I already bought this, I'll try with this, the ufh manifold is designed with electric actuator and room thermostat, I hope that gonna slow the “flywheel effect”, if not then I'll buy smart mixing valve.

Can someone check this drawing about connecting buffer tank and pellet boiler ??

and the buffer tank:

Zman

Why do you need coils in the buffer tank? Creating 2 separate loops adds some unnecessary complications.

cacko85

The buffer coil will be connected to solar panels (via solar pump stations), for additional heating.

Ironman

If you got a buffer tank with coils, you’re gonna need an additional fill/backflow preventer, relief valve, expansion tank and air separator on the floor side.

You’ll need all of those in each separate circuit of the system.

cacko85

It’s buffer with one coil, coil will be connected with solar panels.
The others are inputs/outputs from the “barrel”