Hello everyone,
Since I’m having trouble communicating with my heating installer, I’m asking you all:
What exactly is a “modulating heat pump”?
The Brötje BWL Neo 8 installed in our home is described by the manufacturer as modulating. However, since its commissioning in November 2023, it has been running at full heating capacity: about 7 kW. Although it operates with a good COP (average over the last two months is 4.4), that doesn’t help me much. Currently, it consumes a huge amount of electricity (sometimes well over 30 kWh per day). That doesn’t seem normal for a new build...
The installer says the pump only modulates the flow rates, not the output power. That can’t be right, can it?
I’ve noticed in this forum that @Alessandro has the same pump. However, his posts are somewhat old. Could someone help me out here?
To keep this post concise, I’m leaving out detailed information about the hydraulics and settings for now. These will follow if needed.
Since I’m having trouble communicating with my heating installer, I’m asking you all:
What exactly is a “modulating heat pump”?
The Brötje BWL Neo 8 installed in our home is described by the manufacturer as modulating. However, since its commissioning in November 2023, it has been running at full heating capacity: about 7 kW. Although it operates with a good COP (average over the last two months is 4.4), that doesn’t help me much. Currently, it consumes a huge amount of electricity (sometimes well over 30 kWh per day). That doesn’t seem normal for a new build...
The installer says the pump only modulates the flow rates, not the output power. That can’t be right, can it?
I’ve noticed in this forum that @Alessandro has the same pump. However, his posts are somewhat old. Could someone help me out here?
To keep this post concise, I’m leaving out detailed information about the hydraulics and settings for now. These will follow if needed.
R
RotorMotor19 Dec 2024 16:51How do you come to the conclusion that it always runs at 7kW?
And what do you mean by that?
Is the heating element active?
And what do you mean by that?
Is the heating element active?
RotorMotor schrieb:
Why do you think it is always running at 7kW?
And what do you mean by that?
Is the electric heater active?I see that in the settings. Currently 6.7kW (about 22,700 BTU/h) with a COP of 4.9 = approx. 1400W (1.4kW) electrical input. It never runs below 6.5kW (about 22,200 BTU/h).The electric heater has never been active.
R
RotorMotor19 Dec 2024 17:08Unfortunately, the performance charts only start at W35.
But it seems it cannot handle less than 1400W.
You can at least be glad that the COP is quite high.
It’s definitely the wrong unit for your house.
These kinds of systems are usually installed in unrenovated old buildings.
There’s not much you can do to prevent short cycling.
However, the energy consumption of 30 kWh is really high.
Are windows kept open continuously?
But it seems it cannot handle less than 1400W.
You can at least be glad that the COP is quite high.
It’s definitely the wrong unit for your house.
These kinds of systems are usually installed in unrenovated old buildings.
There’s not much you can do to prevent short cycling.
However, the energy consumption of 30 kWh is really high.
Are windows kept open continuously?
A
Alessandro20 Dec 2024 08:33It is already modulating as it should.
The display "WMZ_Leistung" is confusing. It decreases with falling outdoor temperatures, so it is not the heat pump’s output!
Don’t worry about the cycling. Even if it cycles 15 times per day throughout the year (which it doesn’t, because it only heats domestic hot water in summer), the compressor is rated for 150,000 starts and will last 25 years!
The hysteresis is also different compared to other manufacturers, so it needs to be understood differently.
I’m happy to help you again in two weeks, as I will be on vacation myself ;-)
The display "WMZ_Leistung" is confusing. It decreases with falling outdoor temperatures, so it is not the heat pump’s output!
Don’t worry about the cycling. Even if it cycles 15 times per day throughout the year (which it doesn’t, because it only heats domestic hot water in summer), the compressor is rated for 150,000 starts and will last 25 years!
The hysteresis is also different compared to other manufacturers, so it needs to be understood differently.
I’m happy to help you again in two weeks, as I will be on vacation myself ;-)
A
Alessandro20 Dec 2024 09:23Here are my data during the heating cycle at 4°C (39°F) outdoor temperature.
Heating circuit pump at 66%
Compressor at 22% power
These are the compressor factory settings via the heating curve
Heating circuit pump at 66%
Compressor at 22% power
These are the compressor factory settings via the heating curve