Abstract: A thermostatically operated valve uses a valve insert screwed into a tube-shaped stud at a valve housing. The valve insert comprises two spaced-apart valve seats which are located on opposite walls of a chamber provided within the valve insert series-connected in a flow direction with one seat forming a control valve seat and the other seat forming a shut-off valve seat. Between the valve seats, a valve closing body is arranged within the chamber for temperature control operation by a thermostat device. The outlet of the valve is connected to a chamber downstream of the shut-off valve seat and a throttling bore connects the chamber between both valve seats with the outlet of the valve. A removal of the thermostat device allows the valve closing body to be urged against the shut-off valve seat by a spring within the valve insert while maintaining a flow through the throttling bore.

Abstract: In order to protect a boiler against overheating a boiler draft control device comprises a safety thermostat in addition to the regular control thermostat. The control thermostat is provided with a supporting tube in order to limit its length reduction in the event of its failure. The safety thermostat is designed in such a manner that its working element only provides a displacement when the control range of the control thermostat is exceeded. Furthermore the safety thermostat has a very steep displacement/temperature characteristic and its maximum stroke is equal or greater than the stroke being given by an operable control thermostat over its total control range. A latch means is provided to prevent that an air inlet flap closed according to the response of the safety thermostat may be opened again with the cooling down of the boiler.