Hello everyone,
we bought a house with a heat pump, so we inherited all the settings from the previous owners.
I’m not very familiar with this yet, so please feel free to question anything I say, but I have a feeling that not everything is ideally configured. Several things caught my attention or aren’t clear to me, so let’s see if it all fits into one thread.
We have a Dimplex heat pump installed, model LA17TU. In the basement, there is a Hydrotower HWK 332 Econ with a heat pump manager. It would be great if someone is familiar with this system.
First question: In the advanced settings, there is an option to set a limit value for the second heat source (i.e., the electric heating element).
The manual explains: “Depending on the dimensioning of the heat pump, the second heat source is only required below a certain limit temperature. The second heat source will only activate at temperatures below the set limit temperature.”
The limit temperature is set to -5°C (23°F). That would mean the heating element runs whenever the temperature is below -5°C (23°F), right? Isn’t that set too high? At -5°C (23°F), the heat pump should still be able to perform sufficiently without needing the high-consumption heating element. On the other hand, the manual specifies a setting range from -20°C (-4°F) to +20°C (68°F), with -5°C (23°F) in bold, which makes it look like a default value.
Second question concerns the heating curve.
The manual contains a section on optimizing the heating curve. According to this, the heat pump is controlled based on the return temperature. In the settings menu, under the heating circuit options, you can select the temperature sensor as either “supply” or “return.” Currently, “supply” is selected. Doesn’t this contradict the statement that the control is based on the return temperature? Or could it mean something else?
Also, the endpoint of the heating curve puzzles me. According to online information, our local reference outdoor temperature is -14°C (7°F). Is the heating curve endpoint really only dependent on the reference outdoor temperature and not on the building’s construction?
When I look at the tables and curves in the manual, a reference outdoor temperature of -14°C (7°F) corresponds to a required return temperature of 28°C (82°F), which results in a heating curve endpoint of 29°C (84°F) to be set on the device. The actual indoor temperature level is then adjusted by shifting the curve in parallel. However, the currently set heating curve endpoint is 45°C (113°F). I’m hesitant to make such a big change without knowing exactly what it will affect. Are building-specific conditions possibly important here?
Regards,
TObi
we bought a house with a heat pump, so we inherited all the settings from the previous owners.
I’m not very familiar with this yet, so please feel free to question anything I say, but I have a feeling that not everything is ideally configured. Several things caught my attention or aren’t clear to me, so let’s see if it all fits into one thread.
We have a Dimplex heat pump installed, model LA17TU. In the basement, there is a Hydrotower HWK 332 Econ with a heat pump manager. It would be great if someone is familiar with this system.
First question: In the advanced settings, there is an option to set a limit value for the second heat source (i.e., the electric heating element).
The manual explains: “Depending on the dimensioning of the heat pump, the second heat source is only required below a certain limit temperature. The second heat source will only activate at temperatures below the set limit temperature.”
The limit temperature is set to -5°C (23°F). That would mean the heating element runs whenever the temperature is below -5°C (23°F), right? Isn’t that set too high? At -5°C (23°F), the heat pump should still be able to perform sufficiently without needing the high-consumption heating element. On the other hand, the manual specifies a setting range from -20°C (-4°F) to +20°C (68°F), with -5°C (23°F) in bold, which makes it look like a default value.
Second question concerns the heating curve.
The manual contains a section on optimizing the heating curve. According to this, the heat pump is controlled based on the return temperature. In the settings menu, under the heating circuit options, you can select the temperature sensor as either “supply” or “return.” Currently, “supply” is selected. Doesn’t this contradict the statement that the control is based on the return temperature? Or could it mean something else?
Also, the endpoint of the heating curve puzzles me. According to online information, our local reference outdoor temperature is -14°C (7°F). Is the heating curve endpoint really only dependent on the reference outdoor temperature and not on the building’s construction?
When I look at the tables and curves in the manual, a reference outdoor temperature of -14°C (7°F) corresponds to a required return temperature of 28°C (82°F), which results in a heating curve endpoint of 29°C (84°F) to be set on the device. The actual indoor temperature level is then adjusted by shifting the curve in parallel. However, the currently set heating curve endpoint is 45°C (113°F). I’m hesitant to make such a big change without knowing exactly what it will affect. Are building-specific conditions possibly important here?
Regards,
TObi
Does anyone have an idea about this?
One thing I noticed: This year we waited quite a while to switch the heat pump from summer mode. The indoor and outdoor temperatures were relatively cold at that time. Room temperature was about 17°C (63°F), outside maybe 12°C (54°F), I don’t remember exactly. When I just set it to Auto, which is the winter mode, it didn’t start at all. Only after I manually increased the temperature setting significantly did something happen.
Right now, the setpoint for the underfloor heating circuit (I'm not 100% sure if it shows the supply or return temperature, but logically it should be the return?) is around 28°C (82°F). The heat pump heats up to this setpoint once, then switches off. The actual temperature then drops quite a bit over time, down to about 20°C (68°F), which means water below the setpoint is circulated through the pipes. It then takes a relatively long time before a new heating cycle brings the temperature back up to the setpoint. Does this make sense? I don’t think so. The temperature inside the house is okay though.
One thing I noticed: This year we waited quite a while to switch the heat pump from summer mode. The indoor and outdoor temperatures were relatively cold at that time. Room temperature was about 17°C (63°F), outside maybe 12°C (54°F), I don’t remember exactly. When I just set it to Auto, which is the winter mode, it didn’t start at all. Only after I manually increased the temperature setting significantly did something happen.
Right now, the setpoint for the underfloor heating circuit (I'm not 100% sure if it shows the supply or return temperature, but logically it should be the return?) is around 28°C (82°F). The heat pump heats up to this setpoint once, then switches off. The actual temperature then drops quite a bit over time, down to about 20°C (68°F), which means water below the setpoint is circulated through the pipes. It then takes a relatively long time before a new heating cycle brings the temperature back up to the setpoint. Does this make sense? I don’t think so. The temperature inside the house is okay though.
M
Matthias4513 Oct 2022 15:40The hysteresis is probably set too wide!
I have a Dimplex li9tu running in my house myself. So far, the additional heating element has never been used here! However, the domestic hot water is never heated above 50°C (122°F), and the heating water is a maximum of 35°C (95°F) when it's -20°C (-4°F) outside.
@Tobibi if you want, we can exchange ideas.
I have a Dimplex li9tu running in my house myself. So far, the additional heating element has never been used here! However, the domestic hot water is never heated above 50°C (122°F), and the heating water is a maximum of 35°C (95°F) when it's -20°C (-4°F) outside.
@Tobibi if you want, we can exchange ideas.
KingJulien13 Oct 2022 15:41In general:
I’m not familiar with your heating system. You’ll need to do some research. The manual usually explains a lot (including the one for the installers, if available).
Also, everything depends on the hydraulics. Have you done a balancing? Is the EER deactivated / continuously open? Is the safety valve (if present) closed?
Just try it. What could happen? If it’s 10°C (50°F) for two weeks and the compressor can’t handle it, you simply turn it back on.
So, deactivate the heating element.
I run with 100% return flow; that seems more reasonable to me since it is the more sluggish control variable.
Just experiment with that as well.
Same here. Does that set the slope? If so, just try it. It can only get too warm or too cold. You have to get the hang of it yourself. Watch, understand, adjust.
Generally, long heating cycles are desirable. For that, you need a slow (or inert) control system.
The downside is that if it’s too slow, you get large fluctuations in indoor temperature.
You need to find the right setting for yourself here.
I’m not familiar with your heating system. You’ll need to do some research. The manual usually explains a lot (including the one for the installers, if available).
Also, everything depends on the hydraulics. Have you done a balancing? Is the EER deactivated / continuously open? Is the safety valve (if present) closed?
Tobibi schrieb:
First question
Just try it. What could happen? If it’s 10°C (50°F) for two weeks and the compressor can’t handle it, you simply turn it back on.
So, deactivate the heating element.
Tobibi schrieb:
Second question
I run with 100% return flow; that seems more reasonable to me since it is the more sluggish control variable.
Just experiment with that as well.
Tobibi schrieb:
The endpoint of the heating curve also puzzles me.
Same here. Does that set the slope? If so, just try it. It can only get too warm or too cold. You have to get the hang of it yourself. Watch, understand, adjust.
Tobibi schrieb:
One more thing I noticed
Generally, long heating cycles are desirable. For that, you need a slow (or inert) control system.
The downside is that if it’s too slow, you get large fluctuations in indoor temperature.
You need to find the right setting for yourself here.
Tobibi schrieb:
When I look at the table and the set of curves in the manual, a NAT of -14°C corresponds to a required return temperature of 28°C (82°F), which then results in a heating curve endpoint of 29°C (84°F) that needs to be set on the device. The actual temperature level in the house should then be adjusted by shifting the curve in parallel. However, the heating curve endpoint is actually set at 45°C (113°F). I hesitate to make such a large change without knowing exactly what it will do. Are there possibly building-related conditions that need to be considered here? 45°C (113°F) is far too high. I have a Dimplex brine heat pump, and my heating curve endpoint is set at 32°C (90°F). The interaction between endpoint and parallel shift needs to be experimented with, but the manual explains quite well under which circumstances which value should be changed.
Deactivate the electric heater and see what happens. If the heat pump really can’t manage it at some point, you can manually reactivate it within one minute.
Return flow control is usually correct. Perhaps your observation comes from having no or too short a (heating circuit) pump lead time set.
Thanks for the answers.
@Matthias45 happy to share information.
I have now set the curve endpoint to 30°C (86°F). However, it is currently too warm outside to do much testing. There is a second small heating circuit with a few radiators connected, where I also lowered the endpoint.
I set the threshold for the second heat generator to -15°C (5°F), so if this is the setting that controls when the electric heating element activates, it should now only run very rarely.
I should mention, we have a large house with 200sqm (2,150 sq ft) of living space built in the 1980s, which is insulated as poorly as was typical at the time. In recent years, we have used 12,000 kWh of heating electricity.
I am also working on improving the insulation, but I have the impression that adjusting the heating system settings can also save energy.
@Matthias45 happy to share information.
I have now set the curve endpoint to 30°C (86°F). However, it is currently too warm outside to do much testing. There is a second small heating circuit with a few radiators connected, where I also lowered the endpoint.
I set the threshold for the second heat generator to -15°C (5°F), so if this is the setting that controls when the electric heating element activates, it should now only run very rarely.
I should mention, we have a large house with 200sqm (2,150 sq ft) of living space built in the 1980s, which is insulated as poorly as was typical at the time. In recent years, we have used 12,000 kWh of heating electricity.
I am also working on improving the insulation, but I have the impression that adjusting the heating system settings can also save energy.
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