ᐅ Adjusting the Flow Rate of Underfloor Heating with an Air Source Heat Pump
Created on: 27 Dec 2025 15:28
D
delbauHello everyone,
We have been living for some time now in our well-insulated house with an air source heat pump and underfloor heating. We have properly set up the air source heat pump and have turned off the thermostats.
However, one room is always too warm while another is too cold.
Therefore, I would like to slightly adjust the flow rate of the underfloor heating.
That means increasing it in the cold room and decreasing it in the warm room.
It seems that this can be done using the small tubes on the supply line.
One of the tubes had the square section broken off at the top from the start, which was done by the heating installer.
I have now carefully tried to adjust the flow by turning it, but the tube does not move, and I am worried about breaking it.
Am I correct in assuming that the tube must really be turned using the square section?
Can it be damaged mechanically like that? I would rather avoid causing a water leak :-)
We have been living for some time now in our well-insulated house with an air source heat pump and underfloor heating. We have properly set up the air source heat pump and have turned off the thermostats.
However, one room is always too warm while another is too cold.
Therefore, I would like to slightly adjust the flow rate of the underfloor heating.
That means increasing it in the cold room and decreasing it in the warm room.
It seems that this can be done using the small tubes on the supply line.
One of the tubes had the square section broken off at the top from the start, which was done by the heating installer.
I have now carefully tried to adjust the flow by turning it, but the tube does not move, and I am worried about breaking it.
Am I correct in assuming that the tube must really be turned using the square section?
Can it be damaged mechanically like that? I would rather avoid causing a water leak :-)
R
RotorMotor27 Dec 2025 16:25Normally, this is adjusted at the valves and not at the sight glasses.
R
RotorMotor27 Dec 2025 16:34That might work with some distribution boards as well. How well it worked with yours was already demonstrated by the heating technician for the office.
I have now found my manifold and a corresponding instruction manual.
It seems you can actually close the loops using the flow meter, but according to the instructions below, this is not intended as a permanent setting.
An adjustment should be made directly at the valve.
In my case, the thermostatic radiator valves are attached to the valves.
Is it allowed to unscrew these while the system is running and adjust the flow at the valve?
I am not sure if this is permitted – that’s why I replaced the h in https with an asterisk.
watts.eu/dfsmedia/0533DBBA-1771-4B1A-B581-AB07A4CBB521/639403-source/638417005400000000/MuB_10018992_HKV2013A_DE_EN_FR_IT_ES_RU_2020_05.pdf
It seems you can actually close the loops using the flow meter, but according to the instructions below, this is not intended as a permanent setting.
An adjustment should be made directly at the valve.
In my case, the thermostatic radiator valves are attached to the valves.
Is it allowed to unscrew these while the system is running and adjust the flow at the valve?
I am not sure if this is permitted – that’s why I replaced the h in https with an asterisk.
watts.eu/dfsmedia/0533DBBA-1771-4B1A-B581-AB07A4CBB521/639403-source/638417005400000000/MuB_10018992_HKV2013A_DE_EN_FR_IT_ES_RU_2020_05.pdf
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