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Utvärdering av termisk VVC

Paulsson, Anna LU and Svensson, Madelene LU (2016) MVK920 20161
Department of Energy Sciences
Abstract (Swedish)
Studiens målsättning har varit att ur ett energibesparingsperspektiv samt ekonomiskt perspektiv utvärdera termostatiska cirkulationsventiler (termiska ventiler) som används i varmvattencirkulation (VVC). De frågeställningar som belystes i studien var hur värmeförluster från VVC med termiska respektive fasta ventiler varierar, om det är ekonomiskt lönsamt att installera termiska ventiler jämfört med fasta ventiler, hur temperaturen på VVC-returen skiljer sig mellan termiska och fasta ventiler samt hur returtemperaturen i VVC:n påverkas om börvärdet på framledningstemperaturen ändras. Som medel för att besvara dessa frågeställningar har skillnader i värmeförluster från VVC och kostnader mellan termiska och fasta ventiler jämförts. Genom en... (More)
Studiens målsättning har varit att ur ett energibesparingsperspektiv samt ekonomiskt perspektiv utvärdera termostatiska cirkulationsventiler (termiska ventiler) som används i varmvattencirkulation (VVC). De frågeställningar som belystes i studien var hur värmeförluster från VVC med termiska respektive fasta ventiler varierar, om det är ekonomiskt lönsamt att installera termiska ventiler jämfört med fasta ventiler, hur temperaturen på VVC-returen skiljer sig mellan termiska och fasta ventiler samt hur returtemperaturen i VVC:n påverkas om börvärdet på framledningstemperaturen ändras. Som medel för att besvara dessa frågeställningar har skillnader i värmeförluster från VVC och kostnader mellan termiska och fasta ventiler jämförts. Genom en fallstudie på två hus med i stort sett identisk byggkonstruktion har energi- och temperaturmätningar gjorts. Det ena husets VVC har utrustats med termiska ventiler och det andra med fasta ventiler. För den ekonomiska jämförelsen har livscykelkostnader för de båda ventiltyperna beräknats.

Utöver detta har även en intervjustudie genomförts för att få en bild av hur de praktiska erfarenheterna ser ut från användning av termiska och fasta ventiler samt för att få bättre kunskap om hur ventilerna fungerar under hela deras livslängd. För att få ett brett perspektiv på åsikter vände vi oss till aktörer inom fyra områden; tillverkning, installation, injustering och underhåll. Frågeformulär sammanställdes och mailades ut till aktörer, med varierande kunskap och erfarenheter om ventiler i VVC, inom varje område.

Resultatet från energiberäkningarna visade att det ur ett energibesparingsperspektiv inte finns några större skillnader mellan de båda ventiltyperna. Värmeförlusterna från det termiska VVC- systemet var av samma storlek som förlusterna från VVC med fasta ventiler, ca 10 W/m. Inte heller den utförda livscykelkostnadsanalysen (LCC:n), baserad på ett basscenario samt ett "best- case"- och "worst-case"-scenario, visade på några betydande skillnader. De termsika ventilerna har en LCC som är cirka 1 000 kr högre än LCC:n för de fasta ventilerna. Den känslighetsanalys som utfördes visade dock att en kortare livslängd, än den som uppskattats i basscenariot, för de termiska ventilerna leder till en ökad LCC och därmed en större skillnad mellan ventiltyperna. Temperaturen på VVC-returen hölls relativt jämn av de termiska ventilerna men för de fasta ventilerna var det dock svårt att dra någon slutsats utifrån resultatet detta eftersom de påverkades av den något sämre varmvattenregleringen i det hus de installerats i. Vid en ändring av framledningstemperaturen, även kallad VV-temperaturen, hade det förväntade beteendet från termiska ventiler varit att temperaturen på VVC-returen var samma som tidigare eftersom de är dynamiska och ska reglera sig själva. Men resultatet av studien visade att de termiska ventilerna inte svarade på en förändring av VV-temperaturens börvärde så som man kunde förvänta sig utan man kunde se samma förändring i temperaturen för VVC-returen som för VV- temperaturen.

Sammanställning av intervjuerna visade på att fasta ventiler i många fall föredras framför termiska. Ofta beror det på att många väljer det som är bekant och man har störst erfarenhet av fasta ventiler. Termiska ventiler i VVC har inte fått samma genomslag som fasta ventiler, varför erfarenheten av termiska ventiler inte är lika stor. (Less)
Abstract
The study's objective was, from an energy-saving and economical perspective, evaluate thermostatic circulation valves (thermal valves) used in hot water circulation (HWC). The issues that have been highlighted in the study were how the heat losses from HWC with thermal valves varies from HWC with fixed valves, whether it is economically viable to install thermal valves compared to fixed valves, if the temperature of the HWC return between thermal and fixed valves is different and how the return temperature in HWC is affected if the setpoint of the HWC supply temperature is changed. As means to address these issues, the differences in heat loss from the HWC and cost between thermal and fixed valves have been compared. Through a case study... (More)
The study's objective was, from an energy-saving and economical perspective, evaluate thermostatic circulation valves (thermal valves) used in hot water circulation (HWC). The issues that have been highlighted in the study were how the heat losses from HWC with thermal valves varies from HWC with fixed valves, whether it is economically viable to install thermal valves compared to fixed valves, if the temperature of the HWC return between thermal and fixed valves is different and how the return temperature in HWC is affected if the setpoint of the HWC supply temperature is changed. As means to address these issues, the differences in heat loss from the HWC and cost between thermal and fixed valves have been compared. Through a case study on two houses with virtually identical building construction, energy and temperature measurements were made. The HWC in one of the houses was equipped with thermal valves and the other with fixed valves. For economic comparison, the life cycle costs of the two valve types have been calculated.

In addition an interview were conducted to get a picture of how the practical experience looks from the use of thermal and fixed valves, and to get a better understanding of how the valves work throughout their lifetimes. To get a wide perspective on the opinions we turned to operators in four areas; manufacture, installation, hydronic balancing and maintenance. Questionnaires were compiled and e-mailed to stakeholders, which had varying knowledge and experience of valves in HWC, in every area.

The results of the energy calculations showed that, from an energy-saving point of view, there were no major differences between the two valve types. Heat losses from the HWC system with thermal valves were of the same size as the losses from HWC with fixed valves, about 10 W/m. None of the performed life cycle cost calculations, based on a baseline scenario, a “best-case” – and a “worst-case” scenario, showed any significant differences. The life cycle cost (LCC) for the thermal valves were about 1 000 SEK higher compared to the LCC for the fixed valves. The sensitivity analysis conducted showed that a shorter life time, than that estimated in the baseline scenario, for the thermal valves lead to an increased LCC hence a greater difference between the valves. The temperature of the HWC return was held relatively steady in the system with thermal valves. The result for the fixed valves was affected by the slightly poorer regulation of the hot water in the house where they were installed, making it difficult to draw any conclusions from the result. The expected behavior of thermal valves when the supply temperature was increased would have been that the temperature of the HWC return would remain the same because they are dynamic and should be self regulated. But the results of the study showed that the thermal valves did not respond to a change in the supply temperature setpoint in the manner one might expect. Instead an equal change in the temperature of the HWC return corresponding to the change in supply temperature could be seen.

Summary of the interviews revealed that fixed valves in many instances are preferred over thermal. Oftentimes this is due to that many choose what they are familiar with and have most experience of. Thermal valves have not had the same break throught as fixed valves, which has lead to that the experience of thermal valves are lower. (Less)
Please use this url to cite or link to this publication:
author
Paulsson, Anna LU and Svensson, Madelene LU
supervisor
organization
alternative title
En fallstudie på Kämnärsvägen i Lund
course
MVK920 20161
year
type
H2 - Master's Degree (Two Years)
subject
keywords
LCC, Termisk VVC, Ventiler, Värmeförluster
report number
ISRN LUTMDN/TMHP-16/5364-SE
ISSN
0282-1990
language
Swedish
id
8883689
date added to LUP
2016-06-21 10:37:47
date last changed
2016-06-22 04:08:13
@misc{8883689,
  abstract     = {The study's objective was, from an energy-saving and economical perspective, evaluate thermostatic circulation valves (thermal valves) used in hot water circulation (HWC). The issues that have been highlighted in the study were how the heat losses from HWC with thermal valves varies from HWC with fixed valves, whether it is economically viable to install thermal valves compared to fixed valves, if the temperature of the HWC return between thermal and fixed valves is different and how the return temperature in HWC is affected if the setpoint of the HWC supply temperature is changed. As means to address these issues, the differences in heat loss from the HWC and cost between thermal and fixed valves have been compared. Through a case study on two houses with virtually identical building construction, energy and temperature measurements were made. The HWC in one of the houses was equipped with thermal valves and the other with fixed valves. For economic comparison, the life cycle costs of the two valve types have been calculated.

In addition an interview were conducted to get a picture of how the practical experience looks from the use of thermal and fixed valves, and to get a better understanding of how the valves work throughout their lifetimes. To get a wide perspective on the opinions we turned to operators in four areas; manufacture, installation, hydronic balancing and maintenance. Questionnaires were compiled and e-mailed to stakeholders, which had varying knowledge and experience of valves in HWC, in every area.

The results of the energy calculations showed that, from an energy-saving point of view, there were no major differences between the two valve types. Heat losses from the HWC system with thermal valves were of the same size as the losses from HWC with fixed valves, about 10 W/m. None of the performed life cycle cost calculations, based on a baseline scenario, a “best-case” – and a “worst-case” scenario, showed any significant differences. The life cycle cost (LCC) for the thermal valves were about 1 000 SEK higher compared to the LCC for the fixed valves. The sensitivity analysis conducted showed that a shorter life time, than that estimated in the baseline scenario, for the thermal valves lead to an increased LCC hence a greater difference between the valves. The temperature of the HWC return was held relatively steady in the system with thermal valves. The result for the fixed valves was affected by the slightly poorer regulation of the hot water in the house where they were installed, making it difficult to draw any conclusions from the result. The expected behavior of thermal valves when the supply temperature was increased would have been that the temperature of the HWC return would remain the same because they are dynamic and should be self regulated. But the results of the study showed that the thermal valves did not respond to a change in the supply temperature setpoint in the manner one might expect. Instead an equal change in the temperature of the HWC return corresponding to the change in supply temperature could be seen.

Summary of the interviews revealed that fixed valves in many instances are preferred over thermal. Oftentimes this is due to that many choose what they are familiar with and have most experience of. Thermal valves have not had the same break throught as fixed valves, which has lead to that the experience of thermal valves are lower.},
  author       = {Paulsson, Anna and Svensson, Madelene},
  issn         = {0282-1990},
  keyword      = {LCC,Termisk VVC,Ventiler,Värmeförluster},
  language     = {swe},
  note         = {Student Paper},
  title        = {Utvärdering av termisk VVC},
  year         = {2016},
}