HTP Munchkin 926 0-10v control

Teemok

Has anyone used this kit 7250-374. I'm guessing it is just a $230 wiring change kit were the return sensor is dropped for a 0-10v input. I found this below 926 instructions for the Elite boiler that doesn't seem to need a kit due to a jumper on a sub-board. I know I need to change programing option 17 in the 926

I'm investigating replacing a failed vision3 board with the Tekmar 294. The dirty way is converting all the boilers to 0-10v and running individual wire pairs for each 0-10v modulation signal.

Or the clean way, using the factory A+B+ground RS485 BUS wiring and the tekmar modbus output. I'm not confident the Tekmar 294 (rs485 capable) will talk correctly to the 926 boards like the vision3 RS485.

Any thoughts or experiences?

mattmia2

I use a 10v crestron dimmer on the 10v input of my uft-100 to call it for some zones that are controlled by a crestron processor. the 10v is unlikely to break with a firmware change on something and much easier to troubleshoot than serial.

Teemok

@mattmia2 I expect I'll be going the 0-10v route. That means I need conversion "kits" for the boilers. I'd like to know exactly what's in kit 7250P-374. I may just pull some molex plug pins from a parts bin and test out my theory with a lightly fused 9v battery. If the kits turn out to be $230 for $5 of pins and instructions valued at $225. I'll make my own "kits" The tekmar Rs485 either works or doesn't. I'm not going down the "why" rabbit hole. 0-10v also means I can start replacing Munchkins as they fail and the system will work with a mix of new and old boilers.

mattmia2

If you can find a picture of the kit that will tell you if it is some electronics or just a breakout. I'd use resistors instead of a fuse that way it will limit the current instead of shorting something then blowing the fuse because it shorted (although a 9v doesn't have much current available so it damaging something is unlikely)

Teemok

No pics I can find. Two descriptions: wiring harness, control box and…. interface adapter kit.

Both sound vague. Likely the harness is a couple wires with a pins/ connector for the control box and instruction to cut and cap x8-7 and how to change the settings.