<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31377089</termId><termName>vacuum heating</termName><termType>PT</termType><termNote><![CDATA[ Steam heating systems that include vacuum pumps that separate air from condensation in the return main of the system, maintaining the pressure at a constant level and accelerating the circulation of steam. ]]></termNote><termCreatedDate>2026-03-30 20:41:42</termCreatedDate><relation><relationType>UF</relationType><termId>31377090</termId><termName>heating systems, vacuum</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377091</termId><termName>heating, vacuum</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377092</termId><termName>return systems, vacuum</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377093</termId><termName>systems, vacuum heating</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377094</termId><termName>systems, vacuum return</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377095</termId><termName>vacuum heating systems</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31377096</termId><termName>vacuum return systems</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31346567</termId><termName>steam heating</termName><termType>PT</termType></relation></term>  </Zthes>