CV Terminal box with reheat/ Control Valve from thermostat

[xnetfly]

We are looking at controlling a room with a CV terminal box (venturi) and trying to figure out how to most cost effectively control the reheat valve. From my surface level search it seems there are thermostats that provide a 4-20 mA signal to control a valve. What are the cost implications? Shouldn't this option be cheaper than having a controller on the terminal box that controls both dampers and valves? The mechanical contractor is saying that the cost from going from a VAV terminal box with reheat to a constant volume with only control to the valve on the controls side is a wash... I would think we would save some money here.

Can anyone point me to a good solution for the Alerton system and what the cost of each thermostat might be to just control a valve?

Thanks in advance!

 

[SAK9]

You are on the right track for cost reduction.Go for a system pressure powered CV box like the one Trox offers.There is no actuator or wiring required.The thermo stat can then directly control the reheater valve