Dear heat pump experts and experienced home builders,
I would like to better understand what heat pump capacity we actually need.
Our project:
2 full floors
No basement
148 sqm (1,593 sq ft)
KFW55 standard
In our energy demand calculation, a 6 kW air-to-water heat pump is recommended.
However, the heating load calculation in the plan specifies an 8 kW air-to-air heat pump.
Both calculations seem to follow a standard procedure, as this is a developer project.
Which figures in both documents should I focus on?
To me, 8 kW seems quite high, but this is just a feeling formed by reading here in the forum.
The underfloor heating is already installed, also standard, and the screed has been curing for 4 weeks, waiting for the system to be heated up.
But there is no heat pump installed yet.
The builder would credit us €15,000 if we handle the purchase and installation of the heat pump ourselves.
All these questions are overwhelming us.
Is this even possible? Can we choose a different model or manufacturer?
Is it worthwhile, is €15,000 a reasonable amount?
Is 6 kW enough? ...
We need solid information to stand our ground with the builder.
Help!
Thanks!
I would like to better understand what heat pump capacity we actually need.
Our project:
2 full floors
No basement
148 sqm (1,593 sq ft)
KFW55 standard
In our energy demand calculation, a 6 kW air-to-water heat pump is recommended.
However, the heating load calculation in the plan specifies an 8 kW air-to-air heat pump.
Both calculations seem to follow a standard procedure, as this is a developer project.
Which figures in both documents should I focus on?
To me, 8 kW seems quite high, but this is just a feeling formed by reading here in the forum.
The underfloor heating is already installed, also standard, and the screed has been curing for 4 weeks, waiting for the system to be heated up.
But there is no heat pump installed yet.
The builder would credit us €15,000 if we handle the purchase and installation of the heat pump ourselves.
All these questions are overwhelming us.
Is this even possible? Can we choose a different model or manufacturer?
Is it worthwhile, is €15,000 a reasonable amount?
Is 6 kW enough? ...
We need solid information to stand our ground with the builder.
Help!
Thanks!
A
Alessandro12 Dec 2022 11:47parcus schrieb:
Alessandro
Technical FAQ item 2.03
For a KfW Efficiency House 55 based on reference values, there is a requirement to install a ventilation system in the building. This also applies, for example, to the installation of centralized apartment ventilation systems in multi-family houses, which therefore must be installed in at least all apartments.For KfW 55, a ventilation system is not mandatory. You can quote whatever you want 😉
My brother-in-law is currently building a KfW 55 single-family house without an automatic ventilation system...
D
Daniel-Sp12 Dec 2022 11:48parcus schrieb:
Daniel-Sp no problem, you probably won’t be doing any MEP calculations either,... No, that’s not my profession either. But I did calculate the sizing of my underfloor heating myself, and the heating technician installed it accordingly.
I’ve read enough on the subject to confidently say that your statement, taken as an absolute, is not correct, and that’s why I don’t understand it.
Have a nice day everyone, I don’t think I’ve greeted you all yet today, sorry.
@parcus: What do you mean exactly by system? The one installed at the operator’s site? Or a specific heat pump model?
My Arotherm plus can operate monovalently, but I still have an electric heating element installed (bivalent), which doesn’t engage during normal operation but only when it reaches -12°C (10°F).
So, what do I actually have?
My Arotherm plus can operate monovalently, but I still have an electric heating element installed (bivalent), which doesn’t engage during normal operation but only when it reaches -12°C (10°F).
So, what do I actually have?
The problem with the KfW definition is that it indirectly relies on the VdZ ventilation concept tool, which is based on DIN 1946-6, a standard that generally does not allow for manual ventilation anymore. Clearly, an industry lobby influence.
Tolentino
System = heat generator. I use the term system because domestic hot water production is often combined with space heating, and sometimes there are even two heat generators involved.
Specific models are more commonly found in Austria or Switzerland, where monovalent heat pumps have been installed for a longer time and test data is publicly available.
Here in this region, it mostly concerns specific models from Daikin and Panasonic, possibly also Lambda.
You can tell what you have by whether the refrigeration circuit / refrigerant exists only outside the building. The system concept is simply different.
Alright, I have to do other things now, bye
Tolentino
System = heat generator. I use the term system because domestic hot water production is often combined with space heating, and sometimes there are even two heat generators involved.
Specific models are more commonly found in Austria or Switzerland, where monovalent heat pumps have been installed for a longer time and test data is publicly available.
Here in this region, it mostly concerns specific models from Daikin and Panasonic, possibly also Lambda.
You can tell what you have by whether the refrigeration circuit / refrigerant exists only outside the building. The system concept is simply different.
Alright, I have to do other things now, bye
parcus schrieb:
You can tell by whether the cooling circuit/refrigerant only exists outside the building.Okay, I think parcus means something completely different. It’s possible that in some professional circles there’s a different definition for mono- and bivalent, somewhat like how “moment” or “sufficient” can vary.@parcus That’s the case with my Vaillant system. And by the way, in my opinion, that would be the definition of a monoblock unit. Nevertheless, I can also operate it bivalently. So it seems you might be mixing things up. Or you mean something else that, according to your sources, is described as monovalent or is confusingly associated with the characteristic of a monoblock.
What we mean by bivalent: There are two possible heat generators in the installation. For example: heat pump + electric heating element. Or gas boiler + solar thermal system. Or...
Edit: Your quoted definition above doesn’t really make sense conceptually, since there are also indoor heat pumps. Those would never be monovalent, regardless of the rest of the installation...
parcus schrieb:
The pipe lengths should be listed for each room in the HVAC calculation, which is why it is called room heating load. That means the heating load, like for underfloor heating and hydraulic balancing, is determined for each room. U-values of interior walls, interior wall assemblies, It should maybe be included, but it’s not. Our HVAC planner can do really great things.
Pacmansh schrieb:
The good thing is: I feel the same way, and you don’t have to worry about it either. I think the consensus (for the majority) is that the heat pump is oversized, and I’m keeping my fingers crossed that you find a better solution somehow. Thanks, some balm for my soul.
Many thanks also to @face26, I have learned a lot from your posts.
But no use, apparently the 11 kW monster will still arrive at the beginning of January.
That also nullifies the offer for a credit and removal.
The outdoor unit is model ERLA11DAW1.
Does anyone know how far it can modulate down?
What can we expect from our monster?
Higher electricity consumption? How much more?
Increased cycling, faster wear-out of the heat pump?
What else?
Maybe it will break down within five years.
That would be karma.
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