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?
KingJulien19 Nov 2021 00:37Controllers and control loops are really a topic on their own.
I completely agree with @RotorMotor; too much theory just confuses things.
When it comes to setting up a controller, I believe in the approach: try first, then study the effects afterwards 😉
What still helps me a lot is keeping in mind what the proportional (P) and integral (I) parts of a controller actually do.
A picture is worth a thousand words in this case.
Unfortunately, I can’t upload attachments from my phone 🙄
Just try searching for "step response PI controller".
I completely agree with @RotorMotor; too much theory just confuses things.
When it comes to setting up a controller, I believe in the approach: try first, then study the effects afterwards 😉
What still helps me a lot is keeping in mind what the proportional (P) and integral (I) parts of a controller actually do.
A picture is worth a thousand words in this case.
Unfortunately, I can’t upload attachments from my phone 🙄
Just try searching for "step response PI controller".
A different question: I lowered my heating curve slightly, from 0.16 to 0.1. Now the heat pump cycles 15 times in 24 hours at an average outdoor temperature of 7°C (45°F). With the heating curve at 0.16 and the same outdoor temperature, it only cycled 3-4 times. Which is better: a lower heating curve with more cycling, or a slightly higher heating curve with less cycling?
R
RotorMotor19 Nov 2021 07:45That cannot be compared.
By lowering the heating curve, you make it cooler.
To achieve this, the heat pump has to run less often or for shorter periods.
This will consume less energy, but the heat pump may not last as long as a result.
By lowering the heating curve, you make it cooler.
To achieve this, the heat pump has to run less often or for shorter periods.
This will consume less energy, but the heat pump may not last as long as a result.
Malz1902 schrieb:
. Which is better? A lower heating curve with more cycling, or a slightly higher heating curve with less cycling?What is the hysteresis of your heat pump?tomtom79 schrieb:
What is the hysteresis of your heat pump? I can’t adjust that on my heat pump.
There are only the heating curve slope and the heating curve shift settings. The slope is set to 0.1 and the shift is at 0.
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