The Effect of Hydronic Balancing on Room Temperature and Heat Pump Efficiency of a Building with Underfloor Heating

Martin Thalfeldt*, Raimo Simson, Jarek Kurnitski

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

5 Citations (Scopus)
179 Downloads (Pure)


Underfloor heating is a common solution in single-family houses and a suitable solution for nearly zero-energy buildings as a low temperature heating system. According to general practice, the underfloor heating systems should be balanced to assure stable room temperatures and avoid under heating in rooms with higher heat losses. The purpose of the presented study was to analyze the effect of hydronic balancing on the room temperature fluctuations and heat pump performance. The tests were performed at full-scale nearly zero-energy building test facility with under floor heating and an air-to-water heat pump. We measured room and floor temperatures and monitored the heat pump electricity use and heat output. The heat balance of rooms was disturbed with internal gains introduced to several rooms in cycles. The results showed that room temperature fluctuations slightly increased of an unbalanced system, however during all tests, the average temperature fluctuations during night time were below 0.2 °C, so both systems performed well. We identified a negative effect of balancing on the heat pump performance as higher COP was measured in case of an unbalanced system. The results allow to conclude that in the case of studied system with one manifold and relatively small loop length differences the balancing had negligible effect on system performance. However, the topic should be studied further in more unfavorable conditions.

Original languageEnglish
Title of host publicationSB16 Tallinn and Helsinki Conference
Subtitle of host publicationBuild Green and Renovate Deep, 5-7 October 2016, Tallinn and Helsinki
Number of pages11
Publication statusPublished - 2016
MoE publication typeA4 Article in a conference publication
EventSustainable Built Environment Tallinn and Helsinki Conference: Build Green and Renovate Deep - Tallinn, Estonia
Duration: 5 Oct 20167 Oct 2016

Publication series

ISSN (Electronic)1876-6102


ConferenceSustainable Built Environment Tallinn and Helsinki Conference
Abbreviated titleSBE


  • heat pumps
  • hydronic balancing
  • indoor climate
  • underfloor heating


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