ᐅ Inside the house is 10°C warmer than outside – how is that possible?
Created on: 5 Jun 2021 17:44
K
kati1337
Hello!
We are beginners at living in a newly built house, and this first spring is raising some questions.
Our heating system (Tecalor THZ 504) has already decided, based on the outside temperature—which is currently around 20°C (68°F)—that it is in summer mode. In other words, the heating is turned off.
The system information still shows the flow temperature at just under 30°C (86°F), but the flow rate has dropped to zero.
The ventilation is still running, and I suspect our heat recovery unit is causing the issue—because what’s the point of exchanging indoor air with outside air if it blows the air back inside at almost the same warm temperature as it took out?
We only have an outdoor temperature sensor. The device doesn’t handle the indoor temperature very well. It claims the current indoor temperature is 20°C (68°F), but it seems to detect (through measuring) that the exhaust air temperature is about 28°C (82°F). This matches what our various thermometers around the house show.
The question remains: why do we have 28°C (82°F) inside at all? Where is the heat coming from?
Could it be caused solely by sunlight coming through the windows?
We have air conditioning, but I’d rather not run it yet when it’s only about 20°C (68°F) outside and raining.
How do you other new build owners handle this issue? Do you use shading? Something else? Or do you not have this problem at all and maybe there is something wrong with our building services?
We are beginners at living in a newly built house, and this first spring is raising some questions.
Our heating system (Tecalor THZ 504) has already decided, based on the outside temperature—which is currently around 20°C (68°F)—that it is in summer mode. In other words, the heating is turned off.
The system information still shows the flow temperature at just under 30°C (86°F), but the flow rate has dropped to zero.
The ventilation is still running, and I suspect our heat recovery unit is causing the issue—because what’s the point of exchanging indoor air with outside air if it blows the air back inside at almost the same warm temperature as it took out?
We only have an outdoor temperature sensor. The device doesn’t handle the indoor temperature very well. It claims the current indoor temperature is 20°C (68°F), but it seems to detect (through measuring) that the exhaust air temperature is about 28°C (82°F). This matches what our various thermometers around the house show.
The question remains: why do we have 28°C (82°F) inside at all? Where is the heat coming from?
Could it be caused solely by sunlight coming through the windows?
We have air conditioning, but I’d rather not run it yet when it’s only about 20°C (68°F) outside and raining.
How do you other new build owners handle this issue? Do you use shading? Something else? Or do you not have this problem at all and maybe there is something wrong with our building services?
kati1337 schrieb:
Because what use is exchanging air with the outside if it pushes the air back inside at almost the same temperature as it was expelled? If the system were that simple, you would have freezing drafts in winter.
kati1337 schrieb:
Could that be caused just by solar radiation through the windows? Yep. I already mentioned that here on the forum when the first sun rays appeared recently.
kati1337 schrieb:
How do you other new homeowners solve this problem? Shading? For example, yes. Or just enjoy the warmth 😉 With this kind of weather, you barely notice what’s going on inside :p
kati1337 schrieb:
But we have roller shutters that we could close if needed. Would that help? ... why not try it?!
I put it in the box from the summer cassette and that’s it. It doesn’t look so delicate that it would just break like that.
We have a thermometer in the room. We have the LWZ 604 air. Up to the connection to the underfloor heating, it’s quite similar. Beyond that, I’m not sure.
Check where the system gets the 20 degrees from and whether the zero point has been adjusted. In our case, the system always assumed 4 degrees higher. Wow, it was really cold in winter until the mistake was found.
We have a thermometer in the room. We have the LWZ 604 air. Up to the connection to the underfloor heating, it’s quite similar. Beyond that, I’m not sure.
Check where the system gets the 20 degrees from and whether the zero point has been adjusted. In our case, the system always assumed 4 degrees higher. Wow, it was really cold in winter until the mistake was found.
G
Grobmutant5 Jun 2021 20:31I'm not an expert, but in your image from the first post, it shows that the "Setpoint HK2" is at 29.5°C (85°F). The target room temperature for HK2 is also set to 25°C (77°F). Is this intentional? Could the heating system actually be heating this circuit further?
T
T_im_Norden5 Jun 2021 21:13kati1337 schrieb:
Okay, I guess we'll have to get used to that. I'm just surprised it's this bad today. It’s been pouring all day, and outside it’s a maximum of 20°C (68°F).Well, thanks to good insulation, it just takes longer.kati1337 schrieb:
I have the option to activate "Bypass." Should I do that? Currently, it’s set to "Exhaust." Otherwise, I could choose: "Off, Supply air, Bypass," or "Summer cassette" (which we don’t have).You should check the manual to see if it operates automatically.kati1337 schrieb:
I don’t understand that—what does it mean?It means the heating circuit has taken the ground temperature, and the heat pump is showing you that temperature. You could measure the ground temperature yourself for comparison.kati1337 schrieb:
“Our system only has an outdoor sensor and consistently maintains 24°C (75°F) indoors for a setpoint of 20°C (68°F), so that doesn’t match.”I’ve explained before that the 20°C (68°F) the heat pump shows as indoor temperature is not a measured value but a theoretical figure used to calculate the heating curve.
haydee schrieb:
Check where the system gets the 20 degrees from and whether the zero point has been set. In our case, the system always assumed 4 degrees higher. Man, it was really cold during winter until we found the error. That’s a good point, I can ask the heating engineer about it. It’s always a bit tricky to convert (meaning you have to know that the 20°C (68°F) shown by the heat pump is actually 24°C (75°F) and always calculate from there). But we never really had any issues with the temperature because of it; we just kept lowering it further. At first, it was way too warm because we set the temperature we wanted directly on the heat pump. Then the heating specialist explained it to us—T_im_Norden also mentioned—that the displayed value isn’t the actual measured temperature but rather serves as a reference. So we slowly reduced it until the temperature felt right.
Grobmutant schrieb:
I’m not an expert, but your image from the first post shows that the “target value HK2” is set to 29.5 degrees.
Also, the target room temperature for HK2 is set to 25 degrees.
Is that intentional? Could the heating system really still be heating that circuit? Anything shown or listed under HK2 can be ignored. We only have one heating circuit.
T_im_Norden schrieb:
You should check the manual to see if it operates automatically. The manual doesn’t mention any of that passive cooling or bypass stuff at all. I can only see it in the web interface; maybe that menu option isn’t on the heat pump itself, I’d have to check. But I can’t find any information about it in the manual, not even in the installation guide.
T_im_Norden schrieb:
I’ve already explained that the 20 degrees the heat pump shows as indoor temperature is not a measured value but rather a theoretical figure used for calculating the heating curve. Yes, I know, but it still confuses me that it deviates so much from the actual current temperature and that you can’t adjust it. I could use a thermometer, measure the room temperature, and tell the system “it’s currently X degrees,” then you wouldn’t have to convert anything all the time.
KingJulien6 Jun 2021 05:57As far as I know, Tecalor is the no-name brand of Stiebel Eltron. That’s why the menu navigation is almost exactly the same as ours.
Regarding the bypass, the question is whether one is installed or not. Since you have a compact unit, possibly not.
You can put the cassette in yourself, no problem. Why would the heat recovery ventilator (HRV) get damaged if it’s stored in a box instead of being installed? As long as no pets or children tamper with it. 😉
Regarding summer operation, I would check the settings again. At the moment, it’s too warm inside. But once you reach a comfortable temperature indoors, it might happen that the heating turns on during a cold night, even if it’s 30°C (86°F) again during the day.
Otherwise, this might be interesting for you:
https://www.hausbau-forum.de/threads/Zehnder-q350-optimale-sommer-einstellungen.39421/
Regarding the bypass, the question is whether one is installed or not. Since you have a compact unit, possibly not.
You can put the cassette in yourself, no problem. Why would the heat recovery ventilator (HRV) get damaged if it’s stored in a box instead of being installed? As long as no pets or children tamper with it. 😉
Regarding summer operation, I would check the settings again. At the moment, it’s too warm inside. But once you reach a comfortable temperature indoors, it might happen that the heating turns on during a cold night, even if it’s 30°C (86°F) again during the day.
Otherwise, this might be interesting for you:
https://www.hausbau-forum.de/threads/Zehnder-q350-optimale-sommer-einstellungen.39421/
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