naughty pump

[Marcin G.]

I’m looking for a pump (for forced hot water heating system) that would not let return water flow whenever thermostat is set to “low”. Presently the way the system is designed in the condo building (6 units), the pump might still allow for the water to flow (even if the pump is not working, being off) if the other pumps push the water up. As a result the unit gets constant heat and it’s hard to control it. The other solution is to install zone valve before the pump. I would like to replace the pump with the right kind of pump that would push water (when it’s cold in the apartment) and stops water completely (when it’s hot). do you know of any product that stops/pushes the water and could be used for that purpose ?thanks