Baseboard heater parts or accessories are sold by large home improvement stores such as Lowe's and Home Depot, as well as smaller home improvement stores. Parts such as vacuum breakers, switching relays and zone valves are available for purchase online at companies like SupplyHouse.com.
There are many different brands of baseboard heaters, so it is important to find the brand or model number of the baseboard heater before purchasing replacement parts. The brand name makes it easier to find a store that carries the parts needed. Many home improvement stores can order parts if they are not currently in stock.