ᐅ HvH combines an air-source heat pump with panel radiators – what about the temperature settings?
Created on: 17 Nov 2015 22:42 ölschlamm
Hello community,
I just had a conversation with my regional manager from Heinz von Heiden. The houses now typically use an air-source heat pump combined with conventional radiators operating at a flow temperature of 55°C (131°F).
Doesn't this basically mean a seasonal performance factor below 2 is inevitable?
From my intuitive assessment, I would say that a flow temperature of 40°C (104°F) is sufficient for almost all days of the year. But even that is still way too high for a heat pump.
What do you think?
I just had a conversation with my regional manager from Heinz von Heiden. The houses now typically use an air-source heat pump combined with conventional radiators operating at a flow temperature of 55°C (131°F).
Doesn't this basically mean a seasonal performance factor below 2 is inevitable?
From my intuitive assessment, I would say that a flow temperature of 40°C (104°F) is sufficient for almost all days of the year. But even that is still way too high for a heat pump.
What do you think?
Hello Michael,
One more tip: Just call the information hotlines of various air-to-water heat pump manufacturers next week and discuss this with them. The experts there will surely have an idea whether an air-to-water heat pump plus underfloor heating works, what the limitations are, and how significant these limitations might be.
Regarding your arguments about the gas (tank): Fully agree. My father has such a tank in his garden. The costs are high, overall not a good solution.
Off-topic: I laughed at the term “spruce mopeds.” Well, so far I only have one spruce moped. Spruce moped riding is fun .
Yes, my wood stove has a large glass surface (and even a baking compartment, which I definitely need to try out).
The stove is rated at 3.3 kW - 7 kW, maximum 9 kW. In other words, it’s actually too big for the house. Because I don’t run it at partial load for the reasons mentioned.
However – the stove has a soapstone casing and therefore some heat storage capacity. Occasionally I put in 2-3 brown coal briquettes, and it stays warm for hours. It can be done.
Best regards, Thorsten
One more tip: Just call the information hotlines of various air-to-water heat pump manufacturers next week and discuss this with them. The experts there will surely have an idea whether an air-to-water heat pump plus underfloor heating works, what the limitations are, and how significant these limitations might be.
Regarding your arguments about the gas (tank): Fully agree. My father has such a tank in his garden. The costs are high, overall not a good solution.
Off-topic: I laughed at the term “spruce mopeds.” Well, so far I only have one spruce moped. Spruce moped riding is fun .
Yes, my wood stove has a large glass surface (and even a baking compartment, which I definitely need to try out).
The stove is rated at 3.3 kW - 7 kW, maximum 9 kW. In other words, it’s actually too big for the house. Because I don’t run it at partial load for the reasons mentioned.
However – the stove has a soapstone casing and therefore some heat storage capacity. Occasionally I put in 2-3 brown coal briquettes, and it stays warm for hours. It can be done.
Best regards, Thorsten
Addition: I just looked into it a bit more because I was curious.
There are "low-temperature radiators." You might want to look them up. Various manufacturers offer them.
The systems I have seen operate with supply temperatures below 40 degrees Celsius (104°F), but they include small fans (in the watt range) and a control unit (meaning a socket near the radiator is required).
However, these radiators are far from inexpensive (well over 500 euros per unit).
Additionally, I came across an air-to-water heat pump from a well-known manufacturer in Hesse, specifically designed for supply temperatures exceeding 60 degrees Celsius (140°F) at an outdoor temperature of -10 degrees Celsius (14°F), as well as hot water up to 55 degrees Celsius (131°F). I haven’t looked into the details, but this probably affects the seasonal performance factor. Nevertheless, solutions like this exist. On the manufacturer’s website, there was also a “contact for advice” button to request more information. You can quickly find this system via Google by searching for "air-to-water heat pump for high supply temperature."
There are "low-temperature radiators." You might want to look them up. Various manufacturers offer them.
The systems I have seen operate with supply temperatures below 40 degrees Celsius (104°F), but they include small fans (in the watt range) and a control unit (meaning a socket near the radiator is required).
However, these radiators are far from inexpensive (well over 500 euros per unit).
Additionally, I came across an air-to-water heat pump from a well-known manufacturer in Hesse, specifically designed for supply temperatures exceeding 60 degrees Celsius (140°F) at an outdoor temperature of -10 degrees Celsius (14°F), as well as hot water up to 55 degrees Celsius (131°F). I haven’t looked into the details, but this probably affects the seasonal performance factor. Nevertheless, solutions like this exist. On the manufacturer’s website, there was also a “contact for advice” button to request more information. You can quickly find this system via Google by searching for "air-to-water heat pump for high supply temperature."
No way with low-temperature radiators. I already ruled that out right from the start. Just a reminder: Heinz von Heiden offers products in the budget segment. So standard 22mm (7/8 inch) radiators and heat load calculations based on 55°C (131°F) flow temperature. That was actually my initial question as well. You can forget about your soapstone as a heat storage (from another post). No offense, but try to consider the physics. It’s mainly about the appearance.
But I guess I’ll have to follow your advice about the manufacturers—there’s not much experience in this area. The risk is they’ll tell me all sorts of things...
Or do you think they’d say, "It won’t work… no way"?
But I guess I’ll have to follow your advice about the manufacturers—there’s not much experience in this area. The risk is they’ll tell me all sorts of things...
Or do you think they’d say, "It won’t work… no way"?
Regarding the off-topic point: I am aware of the soapstone, which is why I wrote "some thermal mass." It’s not much, but it’s sufficient for the house. My dream, however, would have been a real fireplace instead of a wood-burning stove. You can’t have everything in life anyway. The most important thing is health.
I don’t believe the manufacturers say it’s not possible.
Based on my research this afternoon, it is possible with the right heat pump designed for these conditions.
The question then is: What system does Heinz von Heiden install? A standard air-to-water heat pump won’t simply deliver 55°C (131°F) supply temperature on its own. If you know the type of system, you can check.
Do you trust the heating load calculation? Is it plausible? If you know the types and sizes of radiators in each room, you can find their performance curves online and in datasheets—and understand their output at lower supply temperatures. From that, you can quickly determine whether there are any reserves and, if so, what kind. Heinz von Heiden should provide you with a clear and detailed power requirement in watts for each room. If they want to, they can do that. It will make things easier for you.
The bathroom is often the problem.
I had the same situation. Under warranty, a larger radiator was installed because the previous one could not reach more than 21.5°C (70.7°F) at 0°C (32°F) outside temperature even with a 60°C (140°F) supply.
My neighbor across the street is building with Heinz von Heiden as well, but with underfloor heating and an air-to-water heat pump. So asking them probably wouldn’t help much here.
I don’t believe the manufacturers say it’s not possible.
Based on my research this afternoon, it is possible with the right heat pump designed for these conditions.
The question then is: What system does Heinz von Heiden install? A standard air-to-water heat pump won’t simply deliver 55°C (131°F) supply temperature on its own. If you know the type of system, you can check.
Do you trust the heating load calculation? Is it plausible? If you know the types and sizes of radiators in each room, you can find their performance curves online and in datasheets—and understand their output at lower supply temperatures. From that, you can quickly determine whether there are any reserves and, if so, what kind. Heinz von Heiden should provide you with a clear and detailed power requirement in watts for each room. If they want to, they can do that. It will make things easier for you.
The bathroom is often the problem.
I had the same situation. Under warranty, a larger radiator was installed because the previous one could not reach more than 21.5°C (70.7°F) at 0°C (32°F) outside temperature even with a 60°C (140°F) supply.
My neighbor across the street is building with Heinz von Heiden as well, but with underfloor heating and an air-to-water heat pump. So asking them probably wouldn’t help much here.
Hi Thorsten,
nice that you replied so quickly. It would be a Siemens Novelan LAD 7. Do I trust the heating load calculation? Probably not, but what other option is there?
And on the other hand: Even if you know all the radiators, you can only say whether their sizing was calculated correctly—but only in relation to the assumed heating load. And whether that is accurate... see above.
What kind of experience does your neighbor have with Heinz von Heiden—just in general?
Regards
michael
nice that you replied so quickly. It would be a Siemens Novelan LAD 7. Do I trust the heating load calculation? Probably not, but what other option is there?
And on the other hand: Even if you know all the radiators, you can only say whether their sizing was calculated correctly—but only in relation to the assumed heating load. And whether that is accurate... see above.
What kind of experience does your neighbor have with Heinz von Heiden—just in general?
Regards
michael
Hi Michael,
A quick check shows that the Novelan should handle supply temperatures up to 62 degrees Celsius (144°F), definitely 55 degrees Celsius (131°F). I’ll take a closer look tomorrow. At 55 degrees Celsius (131°F), you are already in a good range. So, from a very brief glance, the system doesn’t seem fundamentally wrong.
The heating load calculation is usually done by computer nowadays at modern companies. If the parameters are entered correctly, the results are very likely to be accurate. You should be able to recognize basic values like heat transfer coefficients from the product specifications.
Different rooms have different requirements—a bathroom might need x, the living room y, and so on. The result of what I consider a meaningful heating load calculation is essentially this conclusion: in room xy, I need a heat source with a maximum output of w watts. This refers to a reference, for example a practically chosen minimum outside temperature, which in our climate is somewhere between -15 and -20 degrees Celsius (5°F and -4°F).
If you know the radiators that will be installed in each room and their required output, you can quickly check based on the radiator parameters whether the target supply temperature will achieve the necessary power, or which supply temperature is needed to meet the calculated output.
The heat pump manufacturer will certainly provide data on the system’s annual performance factor (seasonal coefficient of performance) linked to outdoor temperature and required supply temperatures—that’s what their tables are for.
That’s the point I want to make. And that’s what I would “fix” Heinz von Heiden on in this case.
The Heinz von Heiden townhouse near my almost-neighbor isn’t finished yet. Visually, it’s a dream, a beautiful house, inside and out. If I interpret my neighbor correctly, he would be happier if the construction had progressed faster. Other building projects nearby are moving ahead more quickly overall. He’s asked me for advice a few times—I think I would know if anything major or out of the ordinary had gone wrong. So it seems everything is fairly okay. Fairly okay means, from my perspective, a good outcome, which you have to achieve first when building…
But be careful: every building project is unique. No single opinion can represent a definitive statement. The core and key point remains the building owner: how they act and how they take control. And my conclusion is this: a relaxed approach will always lead to disaster… you’re building…
Best regards,
Thorsten
A quick check shows that the Novelan should handle supply temperatures up to 62 degrees Celsius (144°F), definitely 55 degrees Celsius (131°F). I’ll take a closer look tomorrow. At 55 degrees Celsius (131°F), you are already in a good range. So, from a very brief glance, the system doesn’t seem fundamentally wrong.
The heating load calculation is usually done by computer nowadays at modern companies. If the parameters are entered correctly, the results are very likely to be accurate. You should be able to recognize basic values like heat transfer coefficients from the product specifications.
Different rooms have different requirements—a bathroom might need x, the living room y, and so on. The result of what I consider a meaningful heating load calculation is essentially this conclusion: in room xy, I need a heat source with a maximum output of w watts. This refers to a reference, for example a practically chosen minimum outside temperature, which in our climate is somewhere between -15 and -20 degrees Celsius (5°F and -4°F).
If you know the radiators that will be installed in each room and their required output, you can quickly check based on the radiator parameters whether the target supply temperature will achieve the necessary power, or which supply temperature is needed to meet the calculated output.
The heat pump manufacturer will certainly provide data on the system’s annual performance factor (seasonal coefficient of performance) linked to outdoor temperature and required supply temperatures—that’s what their tables are for.
That’s the point I want to make. And that’s what I would “fix” Heinz von Heiden on in this case.
The Heinz von Heiden townhouse near my almost-neighbor isn’t finished yet. Visually, it’s a dream, a beautiful house, inside and out. If I interpret my neighbor correctly, he would be happier if the construction had progressed faster. Other building projects nearby are moving ahead more quickly overall. He’s asked me for advice a few times—I think I would know if anything major or out of the ordinary had gone wrong. So it seems everything is fairly okay. Fairly okay means, from my perspective, a good outcome, which you have to achieve first when building…
But be careful: every building project is unique. No single opinion can represent a definitive statement. The core and key point remains the building owner: how they act and how they take control. And my conclusion is this: a relaxed approach will always lead to disaster… you’re building…
Best regards,
Thorsten
Similar topics