Just out of curiosity, to better understand the slope of the heating curve, what flow temperatures do you typically run at 0°C (32°F) outdoor temperature, given a certain indoor temperature and insulation level, when using a combination of underfloor heating and a heat pump?
Background of the question:
My logic tells me that if I want, for example, 22°C (72°F) room temperature, the flow temperature must be at least 22°C (72°F) or higher, since I learned that there needs to be a temperature difference for heat transfer to occur.
So if my heating system turns on at 12°C (54°F) outdoor temperature, my flow temperature should logically start somewhere around 22°C–25°C (72°F–77°F). Accordingly, at only 5°C (41°F) outside, it should be around 27°C (81°F), and at 0°C (32°F) close to 30°C (86°F).
The system design usually takes the location and outdoor temperature down to about –12°C (10°F). If at 0°C (32°F) flow temperature is already 30°C (86°F) according to my logic, then at –12°C (10°F) the flow temperature should be about 40°C (104°F). But most underfloor heating designs for heat pumps are based on a maximum flow temperature of 35°C (95°F).
Of course, the insulation of the house and the indoor temperatures still play a role. Or is the increase in flow temperature actually so gradual that it only rises by about 0.5–1°C (1–2°F) for outdoor temperature drops in 0–5°C (0–9°F) increments?
Background of the question:
My logic tells me that if I want, for example, 22°C (72°F) room temperature, the flow temperature must be at least 22°C (72°F) or higher, since I learned that there needs to be a temperature difference for heat transfer to occur.
So if my heating system turns on at 12°C (54°F) outdoor temperature, my flow temperature should logically start somewhere around 22°C–25°C (72°F–77°F). Accordingly, at only 5°C (41°F) outside, it should be around 27°C (81°F), and at 0°C (32°F) close to 30°C (86°F).
The system design usually takes the location and outdoor temperature down to about –12°C (10°F). If at 0°C (32°F) flow temperature is already 30°C (86°F) according to my logic, then at –12°C (10°F) the flow temperature should be about 40°C (104°F). But most underfloor heating designs for heat pumps are based on a maximum flow temperature of 35°C (95°F).
Of course, the insulation of the house and the indoor temperatures still play a role. Or is the increase in flow temperature actually so gradual that it only rises by about 0.5–1°C (1–2°F) for outdoor temperature drops in 0–5°C (0–9°F) increments?
KingJulien schrieb:
Those are magnetic compasses, read from a photo taken at the wrong angle.
I trust the flow meter on the circulation pump more. That may be true, but zero remains essentially zero, even with parallax error.
I will adjust the flow rates on the heating circuit distributor again this evening.
By the way, the minimum flow rate of the heat pump is 310 liters and the nominal flow rate is 540 liters.
I will also check the pump capacity again this evening when I have access to the system.
Based on this, if I calculate backwards, the maximum flow rate would be 540 L/h : 60 = 9 L/min, which would have to be divided among the number of heating circuits.
So, 9 L/min : 14 heating circuits = 0.64 L/min if all heating circuits were to receive the same flow rate, which is not actually the case.
By the way, the minimum flow rate of the heat pump is 310 liters and the nominal flow rate is 540 liters.
I will also check the pump capacity again this evening when I have access to the system.
Based on this, if I calculate backwards, the maximum flow rate would be 540 L/h : 60 = 9 L/min, which would have to be divided among the number of heating circuits.
So, 9 L/min : 14 heating circuits = 0.64 L/min if all heating circuits were to receive the same flow rate, which is not actually the case.
lesmue79 schrieb:
So 9 L/min (2.4 gallons/min): 14 heating circuits = 0.64 L/min (0.17 gallons/min) if all heating circuits had to receive the same flow rate, which is not the case.That’s why the question was raised earlier: what exactly was calculated?
KingJulien25 Oct 2021 06:49Maybe you have also throttled too much, and the difference comes from some still passing through the pressure relief valve.
I think it’s the same as in my case. Unfortunately, you can’t fully close it but only set it to maximum response pressure.
The calculation is really rough. Mine were also set according to the calculation. Without exception, all circuits were heavily throttled. Great calculation.
In my opinion, the most sensible approach is to start fully open and adjust gradually.
I think it’s the same as in my case. Unfortunately, you can’t fully close it but only set it to maximum response pressure.
The calculation is really rough. Mine were also set according to the calculation. Without exception, all circuits were heavily throttled. Great calculation.
In my opinion, the most sensible approach is to start fully open and adjust gradually.
KingJulien schrieb:
In my opinion, it makes the most sense to start by fully opening everything and then adjust step by step. To be honest, that’s exactly what I did. I set the flow to maximum everywhere and observed how the temperature level stabilized. If a room became too warm, I reduced the flow there and that was it.
In the end, nothing needed to be reduced; the flow remained at maximum everywhere. We have a consistent 22.0 - 22.3 degrees Celsius (71.6 - 72.1 °F) throughout the house, and that’s that.
KingJulien25 Oct 2021 07:07@guckuck2 Lucky you. Did you have a good plumber?