Vacuum Reservoir Plumbing Help Needed

Check the vacumm line on the hot water valve in the engine compartment. With engine running, there should be no vacumm on that line in heat position.
If there is vac, you have a control problem. If there is no vac, and still no hot water flow, you have a valve problem. The valve could be bad, or it might be the wrong valve. These type valves come in two configurations, one is open with vac, the other is closed with vac. you need closed with vac.
If you wish send me a PM, and I will give you my phone number, and can posibly explain better.