wood boiler tweaking with underfloor heating

Avice

Hello, i want to tweak this:


Maybe possible run it with only one pump?
Now both pump work on lowest level (5 wats consume).
With this schema boiler temp always ~70*C ~ 75*C
Any ideas?
Thanks for any advice

Paul Pollets

John Siegenthaler has written extensively on proper piping and setup when using wood boilers or pellet boilers. I suggest you spend some time reading them and get familiar with how to do it correctly, so there's no fire or explosion hazzards.

Avice

thanks.
now i have questions about one thing

Do i need a non-return valve in this place? i mark it with arrow? or it's not good idea to place it here?

leonz

you do not require a check valve.

GroundUp

No check valve, but a 3 way thermostatic mixing valve will never work properly unless there is a circ pump pulling from the mixed port. If the one in your diagram is thermostatic, that is.

STEVEusaPA

https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_10_0.pdf

Avice

both mixing valves are thermostatic. i want run it with only one pump if it possible.
Now it work like this: (yellow color is how water flow.)



But i want like this:



It will works if i install check valve in place where i marked `Here` with arrow.?

GroundUp

No, and no. You can do it with one pump, one mixing valve, and zero check valves unless boiler protection is an issue which is likely. In which case, you either need a 4 way valve or 2 pumps and a primary/secondary piping arrangement. If boiler protection is not an issue, the one pump needs to go between the mixed port of the mixing valve and the radiant, pushing toward the radiant and pulling from the valve.

Avice

GroundUp said:

No, and no. You can do it with one pump, one mixing valve, and zero check valves unless boiler protection is an issue which is likely. In which case, you either need a 4 way valve or 2 pumps and a primary/secondary piping arrangement. If boiler protection is not an issue, the one pump needs to go between the mixed port of the mixing valve and the radiant, pushing toward the radiant and pulling from the valve.

Thanks.

so me schema (first image) is good and don't need any changes?
for boiler protection im using this valve (https://www.regulus.eu/en/dbv1-thermal-relief-valve-insulated).

Zman

You need to have a circulator inside the mixed temp loop. If you do not, the flow rate in the loop varies and you do not get even distribution.

GroundUp

No, the first drawing will not work as we already told you

Avice

GroundUp said:

No, the first drawing will not work as we already told you

im confused
u mean this drawing?
(avoid condensation mode)

here are 2 pumps one for floor and other for small circle.

Now reading some articles and found scheme like this: (diverting mode)


which one is better?

Zman

Why not use a taco iseries mixing valve with outdoor reset and condensation protection on the radiant side and lose the other mixing valve and circ?
The iseries valve will throttle back when the boiler return temp drops.

Zman

That is assuming the owb has no minimum flow requirements.

Zman

If you need both loops to satisfy minimum boiler flows, the loops should be piped primary/secondary so that one loop will not interfere with the other

Zman

Is your wood boiler pressurized? If not, what is it's elevation in relation to the floor it is heating?

Avice

Zman said:

Is your wood boiler pressurized? If not, what is it's elevation in relation to the floor it is heating?

about 2 meters, anyway system under pressure always ~1 Bar.

i just read this article https://www.pmmag.com/articles/88035-the-do-s-and-don-ts-of-three-way-thermostatic-valves-br-john-siegenthaler-pe
if it applicable and for wood boiler

with this loops not interfere with each other. if I understood correctly.

http://prntscr.com/1szbji5

Zman

You getting the idea. This solution is much simpler and accomplishes the same thing. You also get outdoor reset which, IMO is mandatory in a radiant heat system.

Avice

Zman, thanks for help.