I've been using an Mport made by Ubiquiti to datalog monitor and alert me on the wood boiler's condition to avoid trips to the boiler and increase efficiency.
I'm not a re-seller or any ting like that I just like the device. Here is a link to the device
https://www.ubnt.com/mfi/mport/ I have it to setup TXT me if it's out of wood, too hot, too cold and when the blower kicks on to make more heat.
The only down side the device requires the Mfi software to be running on a PC all of the time but I'm looking to move the software over to a raspberry Pi and put the Pi up in the boiler so it's self contained. The software is accessible VIA a web site with full access on a PC and has a mobile friendly view with limited access.
Check out the pics.
2 are from my phone and the 3 others are from my PC.