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?
S
Saruss
21 Nov 2015 21:14
In the manual for the mentioned heat pump, you can find the important data after 5 seconds on page 23. The COP is about 2 to 2.5 at a source temperature of 0°C (32°F) and a supply temperature of 55°C (131°F). The seasonal performance factor is usually slightly lower. So, it’s feasible, but the electricity consumption is considerable. We won’t even talk about the COP below 0°C (32°F).
T
T21150
21 Nov 2015 21:17
Saruss schrieb:
In the manual for the mentioned heat pump, on page 23 after 5 seconds, you can find the important data. The COP is about 2 to 2.5 at 0 degrees source temperature and 55°C (131°F) supply temperature. The performance factor is usually slightly lower. So it’s doable, but the electricity consumption is significant. We’re not even talking about the COP below 0°C (32°F).

OMG. Not good numbers... Generally, we have 3 to 4 months with temperatures around 0°C (32°F) or lower... This will get expensive (electricity).
wrobel22 Nov 2015 05:05
T21150 schrieb:


Modern flat panel radiators have the advantage over traditional radiators in that 70-80% of the heat is emitted through radiation. After more than one heating season, I can say: They work very well and provide comfortable warmth.


Olli

Hello

For both flat panel radiators and traditional radiators, about 70-80% of the heat is actually transferred by convection rather than radiation.


Olli
T
T21150
22 Nov 2015 08:58
Hello Olli,

I have different information.

The flat panel radiator can emit up to 70% of its heat through radiation.
Whether it is 70% or 50%, it’s not worth debating. Either way, it is noticeably more than older, traditional radiators.

Best regards, Thorsten
wrobel22 Nov 2015 11:22
Hello Thorsten,

that is not quite correct.
If you look at your radiator, you will find convection fins between the panels.
These are there to improve the convection of the radiator.
According to your statement, the output would only increase marginally by extending to 2 or 3 panels.
Try placing, for example, a wooden board over the entire radiator up to the wall behind it.
The heat output and the difference between the supply and return temperatures will then change significantly.

Olli
T
T21150
22 Nov 2015 11:26
Hello Olli,

I’m happy to be proven wrong!

You’re the expert. I’m not.

Let’s put it this way: I’m also very familiar with the old finned radiators. In fact, quite well.
Personally, I find the heat output from the flat-panel radiators in the house much more comfortable overall in comparison. However, this might also be because I operate them at a relatively low supply temperature, so the radiators don’t get extremely hot...

Best regards,
Thorsten