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?
Alessandro schrieb:
However, the throttle reduces the total flow rate, which in turn causes cycling.
Giving more than 3L/min (0.8 gallons per minute) to the bathroom and guest toilet doesn’t make any sense at all.
3L (0.8 gallons) is actually already a design mistake...Not entirely correct. As long as you reduce the volume flow without going below the pump’s required minimum flow, you will achieve better heat emission.Malz1902 schrieb:
The question here is whether more energy is used by having a slightly higher heating curve while reducing the other zones, or by keeping the heating curve as is and using an electric radiator in the bathroom. I can somewhat answer this, as we have a fairly efficient heat pump and electric towel warmers in both bathrooms, controlled via KNX with consumption measurement.
My previous measurements and subsequent cost estimate showed that using the towel warmer once daily would increase heating expenses by 15-20%.
We use them as (expensive) towel racks, but we don’t actually heat with them. If it gets too cold, I would first try increasing the flow temperature of the underfloor heating.
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Alessandro8 Nov 2021 11:07tomtom79 schrieb:
Not entirely correct. As long as you reduce the flow rate but do not go below the pump’s required minimum flow, you will achieve better heat output.How do you arrive at better heat output? The temperature difference increases. My heating circuit pump regulates to a temperature difference of 5°C (9°F), which means it would then push even more water into the system...
How I come to this: I read it in the forum, and if I write the name now, I will get the next warning. But I'll send you the link.
For understanding, if the water flows slower through the pipes, you get better heat transfer and efficiency.
By the way, we tried to achieve a temperature difference of 6°C (11°F) in my heating system. I simply trust the professionals on this, and I don’t mean the heating installers.
For understanding, if the water flows slower through the pipes, you get better heat transfer and efficiency.
By the way, we tried to achieve a temperature difference of 6°C (11°F) in my heating system. I simply trust the professionals on this, and I don’t mean the heating installers.
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Alessandro8 Nov 2021 11:58That doesn’t make any sense at all. According to that, I would have to reduce the airflow the most in the rooms I want to be the warmest...
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