TRV

I have used the TRV valves in two pipe steam system and also in the one pipe steam system.  I have the control on the wall next to the radiator and they work very well.  Controls temperatures in the individual rooms nicely.  We have a old 3 story building with several bedrooms in it.  The heating system is hot water with a thermostat on the wall and air control to the valve that should open and shut as the thermostat controls the valve with air as it need heat.  Nothing works anymore valves bad and some thermostats bad.  Can not get the valves anymore and they have been trying to control the heat by turning the boiler on and off as needed.  Some rooms stay cold and other rooms are 90 to 100degreess.  Can you use or do they make a TRV that works with hot water system that would start and stop the flow of hot water as needed.  This would be much cheaper fix and easier than having to redo the whole system.