ᐅ Central room temperature controller for the fan coil unit (FCU) of the underfloor heating system
Created on: 23 Jun 2020 11:34
M
micric3
Hello,
Is there a way to control the ERR centrally on one device, so that, for example, the children cannot adjust the underfloor heating control (heating circuit)? Also, I don’t mind not having a thermostat with a controller in every room. What would be the alternative? Are there sensor-only devices that, for example, send the temperature wirelessly to the central unit, or does a separate fixed setting for the respective heating circuit also count as an ERR?
Good luck
M
Is there a way to control the ERR centrally on one device, so that, for example, the children cannot adjust the underfloor heating control (heating circuit)? Also, I don’t mind not having a thermostat with a controller in every room. What would be the alternative? Are there sensor-only devices that, for example, send the temperature wirelessly to the central unit, or does a separate fixed setting for the respective heating circuit also count as an ERR?
Good luck
M
T_im_Norden schrieb:
Yes, you have a misunderstanding.
..
The only point where the temperature should be controlled after a successful hydraulic balancing is the heating curve of the heat pump. Since the ERR is required by the energy regulations, it will also be installed by the general contractor. This means that, according to the regulations, controllers/sensors must be installed in every room!
I can also perform the hydraulic balancing using wireless thermostats (or simply deactivate them and do it manually) and then disable or decouple them.
T
T_im_Norden8 Jul 2020 15:28@ Alessandro
You set the flow rate for each room at the manifold of the underfloor heating so that each room reaches its desired temperature.
Look up "hydraulic balancing" to fully understand the process.
Assuming your target temperature is 21°C (70°F), as in your example, and the room has also reached 21°C (70°F),
the simplified process is as follows:
The heating water arrives at the correct supply temperature. Since the room is already at 21°C (70°F), the water cannot transfer any more heat to the room and returns at the same temperature.
The water returns to the heat pump with almost no temperature drop.
The water can either be redirected to another room to be used there, or the heat pump detects that there is no heat demand and reduces its output.
The goal with a heat pump is always to run it as long as possible at the lowest possible power.
If you control this via thermostats, the simplified process is:
Heating water flows, thermostat reduces flow,
The flow rate is significantly lowered because at least one room is not calling for heat.
This can cause the heat pump to trigger an error due to insufficient minimum flow.
The heat pump switches off because no heat is being drawn.
The thermostat senses the room temperature is dropping and allows flow again. The heat pump starts at full power, runs for 2-3 minutes, and is then throttled again by the thermostat.
This results in a heat pump that cycles on and off many times a day, leading to faster wear.
The best control method is always the integrated control of the heat pump or the condensing boiler.
You set the flow rate for each room at the manifold of the underfloor heating so that each room reaches its desired temperature.
Look up "hydraulic balancing" to fully understand the process.
Assuming your target temperature is 21°C (70°F), as in your example, and the room has also reached 21°C (70°F),
the simplified process is as follows:
The heating water arrives at the correct supply temperature. Since the room is already at 21°C (70°F), the water cannot transfer any more heat to the room and returns at the same temperature.
The water returns to the heat pump with almost no temperature drop.
The water can either be redirected to another room to be used there, or the heat pump detects that there is no heat demand and reduces its output.
The goal with a heat pump is always to run it as long as possible at the lowest possible power.
If you control this via thermostats, the simplified process is:
Heating water flows, thermostat reduces flow,
The flow rate is significantly lowered because at least one room is not calling for heat.
This can cause the heat pump to trigger an error due to insufficient minimum flow.
The heat pump switches off because no heat is being drawn.
The thermostat senses the room temperature is dropping and allows flow again. The heat pump starts at full power, runs for 2-3 minutes, and is then throttled again by the thermostat.
This results in a heat pump that cycles on and off many times a day, leading to faster wear.
The best control method is always the integrated control of the heat pump or the condensing boiler.
Thanks for the explanation!
As a reference, here is an older post from you as well: https://www.hausbau-forum.de/threads/heizungseinstellungen-sowie-raumtemperaturmessung.34808/page-2#post-400533
edit: asked again, how could I disable the ERR?
As a reference, here is an older post from you as well: https://www.hausbau-forum.de/threads/heizungseinstellungen-sowie-raumtemperaturmessung.34808/page-2#post-400533
edit: asked again, how could I disable the ERR?
T
T_im_Norden8 Jul 2020 15:32Yes, ERR must be installed if you do not have an exemption, but you do not have to use them.
Unscrew the actuators, adjust the flow once, and then control it using the heating curve.
Unscrew the actuators, adjust the flow once, and then control it using the heating curve.
A
Alessandro8 Jul 2020 16:26@T_im_Norden
That all makes sense to me. However, during transitional periods, I often experience varying temperatures caused by external influences in the rooms, which leads to unnecessary energy loss when the heat pump provides too high supply temperatures at low outdoor temperatures. This happens quite regularly, especially in modern new buildings with very large window areas.
I don’t understand your explanation that the heat pump goes into fault mode if the minimum flow rate is not reached. According to this, the same would happen when the heat pump only heats domestic hot water in summer or when the 3-way valve completely shuts off the heating circuit. It wouldn’t make much sense to require a flow monitoring device that regularly triggers a fault on the heat pump due to not reaching the minimum flow rate, for example if all bedrooms do not demand heat and the heating circuit valves are closed. The heat pump also does not run at full power if the room thermostat signals a delta-T of 0.5°C (0.9°F).
Permanent flow through open valves also means the pump can never operate at a lower performance level.
Of course, a flow monitoring device never offers the same advantage in underfloor heating as it does in radiator or fan coil systems, but it still has its justification—especially during transitional periods with large fluctuations in outdoor temperature.
That all makes sense to me. However, during transitional periods, I often experience varying temperatures caused by external influences in the rooms, which leads to unnecessary energy loss when the heat pump provides too high supply temperatures at low outdoor temperatures. This happens quite regularly, especially in modern new buildings with very large window areas.
I don’t understand your explanation that the heat pump goes into fault mode if the minimum flow rate is not reached. According to this, the same would happen when the heat pump only heats domestic hot water in summer or when the 3-way valve completely shuts off the heating circuit. It wouldn’t make much sense to require a flow monitoring device that regularly triggers a fault on the heat pump due to not reaching the minimum flow rate, for example if all bedrooms do not demand heat and the heating circuit valves are closed. The heat pump also does not run at full power if the room thermostat signals a delta-T of 0.5°C (0.9°F).
Permanent flow through open valves also means the pump can never operate at a lower performance level.
Of course, a flow monitoring device never offers the same advantage in underfloor heating as it does in radiator or fan coil systems, but it still has its justification—especially during transitional periods with large fluctuations in outdoor temperature.
T
T_im_Norden8 Jul 2020 16:44That is why most manufacturers recommend buffer tanks with heat pumps.
Have you tried adjusting the heating curve during the transitional season?
That often helps.
Pumps today are usually automatically controlled, and the flow rate should be properly sized to match the heat pump.
For domestic hot water, heat pumps typically have a high flow rate.
Have you tried adjusting the heating curve during the transitional season?
That often helps.
Pumps today are usually automatically controlled, and the flow rate should be properly sized to match the heat pump.
For domestic hot water, heat pumps typically have a high flow rate.
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