ᐅ Increased Supply Temperature of Underfloor Heating During Ventilation
Created on: 28 Oct 2019 21:10
G
Geisti
Hello,
I know that you should simply keep the underfloor heating running when airing out the rooms, and that nowadays lowering the temperature at night doesn’t really help anymore. This is partly explained by the higher energy required to heat the system back up afterwards, as opposed to heating constantly; similar to a car journey.
However, when I keep the underfloor heating running during ventilation, I notice in the system settings of my air-to-water heat pump that the target flow temperature increases as the indoor air temperature drops—for example, from 22°C (72°F) to 30°C (86°F). In my view, this seems counterproductive because the underfloor heating starts heating up again precisely when it was supposed to maintain a constant temperature.
I can’t figure out where my thinking is going wrong...
I would appreciate any clarification!
Best regards,
Geisti
I know that you should simply keep the underfloor heating running when airing out the rooms, and that nowadays lowering the temperature at night doesn’t really help anymore. This is partly explained by the higher energy required to heat the system back up afterwards, as opposed to heating constantly; similar to a car journey.
However, when I keep the underfloor heating running during ventilation, I notice in the system settings of my air-to-water heat pump that the target flow temperature increases as the indoor air temperature drops—for example, from 22°C (72°F) to 30°C (86°F). In my view, this seems counterproductive because the underfloor heating starts heating up again precisely when it was supposed to maintain a constant temperature.
I can’t figure out where my thinking is going wrong...
I would appreciate any clarification!
Best regards,
Geisti
michert schrieb:
The screed stores significantly more energy than the indoor air.
By the way, this is also the reason why heat recovery ventilation systems are rarely cost-effective. However, the issue here is less about constant storage and more about the dynamics, that is, the time-dependent change of these quantities.
And the screed indeed loses less heat than a column of indoor air, which is in constant exchange with the outside environment.
Since the ventilation system primarily serves a comfort purpose, the additional cost for actual heat recovery is almost negligible. Even saving about 25% of the heating demand in a KfW 70 building (typically around 100 to 150 euros) adds up over the years.
H
hampshire29 Oct 2019 14:06Geisti schrieb:
I would appreciate some clarification!I am familiar with this phenomenon from our old house, and it was indeed due to the room temperature sensors being exposed relatively quickly to fresh, cold air during ventilation, as @boxandroof had already suspected. You can try the following test: isolate the temperature sensors from the room air volume with a bag or container while you ventilate. If the phenomenon does not recur under this setup, you have found the cause—quickly reacting sensors linked in a less-than-ideal way to a slow-reacting system.
In our house, the effect was inconvenient because rooms could overheat sometime after ventilation; however, this floor heating system was from 2001 and certainly not close to the standards of today’s systems.