The water pump moves the coolant around the system so the heat can be transferred inside.
The pump that moves hot water through a hot water heater is the recirculation pump. This pump moves the water through the heater and back through the intake line.
Generally, the upper heater hose leads to the water pump.
a bad water pump could cause low heat. The heater uses the coolant from the pump to generate heat.
Yes, coolant has to flow correctly for the heater to function.
What you have to do, is replace the heater core itself
If the water pump is bad ussually the heater will stop giving hot air .
water pump
through a cracked heater core - possible.
Your pool pump needs to be pushing the water through your solar system
It depends on what kind of car and engine you have. Some don't connect to the water pump but to the radiator.
On a 2003 Bonneville, the hose to the water pump that is the heater inlet hose is the top hose coming from the radiator. This is also the hose that holds the thermostat.
It could be like my 95 F250. The fan tips on the water pump were rusted off. It would keep the engine cool but the pump could not push water up to the heater. Replace water pump. Took me 2 hrs to replace water pump and 100.00.