Here’s an app note from MAXIM integrated on using the time-to-digital converter chip MAX35101 for heat meters. Link is here
Heating and cooling a living space is often the greatest contributor to energy consumption in both commercial and residential applications. It is for this reason that many conservation efforts focus on adding insulation and sealing air leaks in older buildings, and sponsoring public service campaigns to remind utility customers to set their thermostats warmer in the summer and cooler in the winter. Customers who fail to take these measures will see their energy bill inevitably rise.
In multi-unit dwellings, it is not uncommon for heat to be provided by radiators sourced by heated water. There are several reasons for this: heating a large quantity of water and distributing it to radiators in the living spaces is an efficient way to provide heat. Water is an inexpensive working fluid, has a relatively high capacity to carry heat, and the technology for building water radiators, pumps, and distribution systems is mature.
But providing individual billing is more difficult with water-sourced radiator heat than with direct electrical heat or direct gas- or oil-fired heat. With these latter heat sources, it is easy to measure energy usage: just measure the number of kilowatt-hours of electricity or the volume of gas or oil consumed. The radiator is different, because there are two components to the energy usage, the amount of water flowing through the radiator and the temperature drop as the water flows through the radiator.
In this application note, we will show how Maxim Integrated’s MAX35101 time measurement chip makes an ideal metering device for water-sourced radiator designs.