What can I use for steam valves?

Water heater valves are activated by pressure and/or temp. You can buy relief valves that will lift at any given pressure as well. steam temp can be easily plotted with pressure. A relief valve is nothing more than a diaphragm that works with system pressure to overcome a spring which can be adjusted to give at any given pressure you pick. Sporlan valve can make you any valve you need just be willing to pay for it. You can look for a contact in their company at www.sporlan.com