Steam has been widely used as the source of heating in commercial buildings and industries throughout the twentieth century. Even though contemporary designers have moved to hot water as the primary choice for heating, a large number of facilities still use steam for heating. Medical campuses with on-site steam generation and extensive distribution systems often serve a number of buildings designed prior to the mid-1980s. The steam is typically used for preheat as its high thermal content helps in heating the air faster and prevents coils from freezing in locations with extreme weather conditions during winter. The present work provides a comprehensive description of the various types of steam heating systems, steam coils, and valves to facilitate the engineer's understanding of these steam systems. A large percentage of the steam coils used in buildings are provided with medium pressure steam. Veterans Integrated Service Network and Army Medical Command Medical Facilities are examples which use medium pressure steam for heating. The current design manual for these medical facilities recommends steam at 30psig be provided to these coils. In certain cases although the steam heating coil is designed for a 5psig steam pressure, it is observed that higher pressure steam is supplied at the coil. A higher steam pressure may lead to excessive heating, system inefficiency due to increased heat loss, simultaneous heating and cooling, and increased maintenance cost. Field experiments were conducted to evaluate the effect of lowering steam pressure on the system performance. A 16% reduction in temperature rise across the coil was found when the steam pressure in the coil was reduced from 15psig to 5psig. The rise in temperature with lower pressure steam was sufficient to prevent coil freeze-up even in the most severe weather conditions. Additional benefits of reduced steam pressure are reduced flash steam losses (flash steam is vapor or secondary steam formed when hot condensate from the coil is discharged into a lower pressure area, i.e., the condensate return line) and radiation losses, increased flow of air through the coil thereby reducing air stratification and reduced energy losses in the event of actuator failure. The work also involved evaluating the existing control strategies for the steam heating system. New control strategies were developed and tested to address the short comings of existing sequences. Improved temperature control and occupant comfort; elimination of valve hunting and reduced energy consumption were benefits realized by implementing these measures.

I flerbostadshus är radiatorer det vanligaste uppvärmningssystemet. Inte alls många har golvvärme i deras lägenheter. I dagens nyproduktion av flerbostadshus bygger man för det mesta husen med radiatorer och har elburen golvvärme som komfortvärme i badrummen. I villor är det däremot mycket vanligare att man använder sig av vattenburen golvvärme över större delen av huset. Detta examensarbete undersöker varför det inte används golvvärme lika mycket i flerbostadshus, det undersöker även intresset för privatpersoner att ha golvvärme i lägenheter samt om dessa personer isåfall hade kunnat tänka sig betala mer pengar om de fick vattenburen golvvärme installerat vid nyproduktion.Resultaten har fåtts fram genom en enkätundersökning samt intervjuer där vi intervjuat kunniga inom området. Våra resultat visar att nästan 40% av de enkät intervjuade hade velat ha endast golvvärme som uppvärmningssystem medan ungefär 55% hade velat ha både radiatorer och golvvärme som ett gemensamt uppvärmningssystem. De flesta hade då velat ha golvvärme i bland annat toalett, badrum, hall, kök, vardagsrum och sovrum. Resultaten visar även att nästan hälften av de enkät besvarande hade kunnat tänka sig betala mer för en bostad med golvvärme medan den större delen av den andra hälften var osäkra och förmodligen behövde mer tid för att tänka. Resultaten gällande varför man inte använder vattenburen golvvärme i lägenheten lika ofta som man använder radiatorer visade sig variera lite mellan de intervjuade vilket vi tror har med erfarenheter att göra men att ett golvvärmesystem var installationsmässigt dyrare än ett radiatorsystem verkade vara huvudsaken. / In prefabricated apartment blocks the most common thing people have in their homes is radiators as their waterborne heating system but very few have underfloor heating in their apartments. Nowadays the most usual thing to do is to install radiators and have underfloor electric heating in the bathrooms. Most residentials however usually have waterborne underfloor heating across the bigger part of the house. This report digs into why underfloor heating isn’t being used as often in apartment buildings, it also investigates people’s interest to have underfloor heating in apartment buildings plus if they then would be interested in paying more for a new apartment with waterborne underfloor heating.The outcome from our results has been achieved through a survey and interviews where we have questioned competent persons within the sector. Our results show that 40% of the people in the survey would like to have only underfloor heating as their waterborne system while 55% of the people would like to have a combined system with both radiators and underfloor heating. Most of them preferred to have underfloor heating in their toilets, bathrooms, entrance hall, kitchen, living room and bedroom. The results also show that almost half the persons in the survey could pay more money for a place with underfloor heating while the bigger part of the other half weren’t sure and probably needed more time to think. Our outcome on why waterborne underfloor heating in apartment buildings isn’t being used as often as radiators showed to differ between the interviewed persons which we assume have to do with their different backgrounds and experience but the main reason seemed to do with the part that a waterborne underfloor heating system in an installation point of view is more expensive than a radiator system.