Upgrading Wirsbo SYSTEMPro 311 to Tekmar 374

jdperlow

Hi, my Wirsbo 311 controller is on the fritz and I purchased a Tekmar 374 to replace it. The house has in-floor radiant heat for the main living spaces and wall-mounted radiators for the basement. The in-floor radiant heat is connected to the mix loop using a mixing device, mix demand, and a mix pump. The basement radiators are connected to a separate boiler loop using the boiler demand and a boiler demand pump.

The Tekmar 374 doesn't seem to have a high-temperature boiler demand function like the 311. Instead it has two mix demands and something called a "setpoint demand". I am wondering which should be used for the basement radiators. If I use the Mix2 function, will something go wrong if there isn't actually a mix device for the loop? Would I need to install a mixing valve? On the other hand, the "setpoint demand" doesn't appear to have a relay to control a separate pump. So it's not clear to me which way to go.

Any advice here would be appreciate. Thanks.

EdTheHeaterMan

It is difficult to tell becaust there are so many ways to connect these controls based on what features you are using. In the I/O manual starting on page 92 thru 99 there are different wiring diagrams based on whet features your system requires. https://www.manualslib.com/manual/1493267/Uponor-Systempro-311.html?page=1#manual. If you can describe what your system actually has connected, perhaps I might be able to help. This is an example of a wiring diagram on the manual

109A_5

Hello @jdperlow,
Looking at the manual, it looks like the "setpoint demand" just overrides the Warm Weather Shut Down and Outdoor Reset features for whatever other input is being called. Like a DHW call in the summer but with its own independent temperature setpoint. I think it is assumed (if needed) the setpoint pump or valve is powered and controlled by the 'other' equipment needing this functionality. Or if a Mix 1 or Mix 2 is used it just overrides the Warm Weather Shut Down and Outdoor Reset features.

See Setpoint modes page 13
https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Tekmar-374-User-Guide.pdf

EdTheHeaterMan

From what I can tell the pump that is connected to:
6 and 8 on the Wirsbo 311 is connected to 16 and neutral on the Tekmar 374. that is the boiler pump
9 and 10 to neutral on 311 is connected to 13 and neutral on 374. No other pump operates on this call.
This is operated by a call for heat from 25 to 26 by a thermostat or other device as in a zone control relay.
This will offer high temperature since no mixing device is connected. Select mix mode 0 when setup for mix 1 setting to turn off mixing.

11 and 12 to neutral on 311 is connected to 17 to neutral on 374. Mix pump operates on call for this pump
17 and 19 to neutral on 311 is connected to 5 to neutral on 374 and is the mix pump for above pump.
This will provide mixed temperature water when there is a call for heat from 26 and 27.
The sensor on 23 to 24 on the 311 is connected to 10 and 12 on the 374
Select Mix mode 1 on setup for Mix 2 in setup for following the reset curve on the low temp zone
You will want to verify these facts and compare them to your actual system components.

I believe all the other items are self explained.

That is were I would start if I were you

jdperlow

That is were I would start if I were you

Ah, that makes sense. The part I was missing is that I could use one of the Mix Demands as a high-temperature zone. I was interpreting the Mix Mode 0 Mixing Device is Off" as disabling the entire mix-demand loop. But your interpretation that it only disables the mixing device makes a lot more sense. I'll give that a try. Thank you!