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!
D
driver55a13 Nov 2022 16:32junijulibaut schrieb:
Our project:
2 full floors
No basement
148 sqm (1593 sq ft)
KFW55Based on these data, something around 4 kW... (unless you’re building on the Zugspitze...)junijulibaut schrieb:
Our energy demand calculation suggests a 6 kW air-to-water heat pump.This document is practically useless...junijulibaut schrieb:
However, the heating load calculation shows an 8 kW air-to-air heat pump in the plan.And with a “proper” heating load calculation, there is no heat pump specified at all, only the heating load of the individual rooms and the total heating load.I would steer clear of this.
Out of curiosity: How many heating circuits does the “house” have?
J
junijulibaut13 Nov 2022 17:12That's right, there are two documents; attached to the heat load calculation is the "solution," a printout from the heating solutions navigator. It suggests the Daikin 8kW.
We have 13 heating circuits, one for each room. Even the hallway downstairs and the corridor upstairs each have their own. The open-plan area with kitchen, dining, and living spaces has three heating circuits. The bathrooms each have only one circuit, but they are designed more closely spaced and extend into the shower area.
Which parts would you specifically avoid?
We have 13 heating circuits, one for each room. Even the hallway downstairs and the corridor upstairs each have their own. The open-plan area with kitchen, dining, and living spaces has three heating circuits. The bathrooms each have only one circuit, but they are designed more closely spaced and extend into the shower area.
Which parts would you specifically avoid?
D
driver55a13 Nov 2022 21:54junijulibaut schrieb:
The open-plan area including kitchen, dining, and living has 3 heating circuits That’s probably about 50-60 sqm (540-645 sq ft), so having 3 heating circuits is quite “manageable”...
You might actually need a larger heat pump because the pipe spacing is “relatively” wide.
What is the flow temperature in each room?
What target/desired temperature did you specify?
What is the wall construction?
junijulibaut schrieb:
What exactly would you advise to avoid? Taking care of the heat pump myself...
J
junijulibaut13 Nov 2022 22:17The installation spacing is 15cm (6 inches), and in the bathrooms 5–10cm (2–4 inches). This is estimated based on photos; we do not have any document specifying the installation spacing.
Our open-plan living area is 42sqm (452 sqft), including kitchen, dining, and living spaces.
The target temperature was set at 20°C (68°F), and 24°C (75°F) in the bathrooms. In addition, electric heaters are used there as supplementary heating.
Wall construction: lightweight expanded clay concrete precast elements for external walls and load-bearing interior walls are 15cm (6 inches) thick; non-load-bearing interior walls are 12cm (5 inches) thick.
The external insulation consists of mineral wool carrier boards, 16cm (6 inches) thick, with a thermal conductivity rating (WLG) of 35.
In the heating load calculation, a standard heating load is calculated for each room, plus an additional charge for the heat-up capacity. All combined, the standard heating load results in 6233 W.
Interestingly, the heating load for the entrance and hallway is even negative, meaning these areas are warmed by adjacent rooms?
Reference outdoor temperature is –12°C (10°F).
Our open-plan living area is 42sqm (452 sqft), including kitchen, dining, and living spaces.
The target temperature was set at 20°C (68°F), and 24°C (75°F) in the bathrooms. In addition, electric heaters are used there as supplementary heating.
Wall construction: lightweight expanded clay concrete precast elements for external walls and load-bearing interior walls are 15cm (6 inches) thick; non-load-bearing interior walls are 12cm (5 inches) thick.
The external insulation consists of mineral wool carrier boards, 16cm (6 inches) thick, with a thermal conductivity rating (WLG) of 35.
In the heating load calculation, a standard heating load is calculated for each room, plus an additional charge for the heat-up capacity. All combined, the standard heating load results in 6233 W.
Interestingly, the heating load for the entrance and hallway is even negative, meaning these areas are warmed by adjacent rooms?
Reference outdoor temperature is –12°C (10°F).
X
xMisterDx14 Nov 2022 00:23The installation spacing can be estimated quite easily. When taking pictures, you will probably have already "stepped in" there at some point.
I wear size 46 shoes, so with a 10cm (4 inch) spacing, you really have to be precise to step between the pipes. At 15cm (6 inch), there is plenty of room to walk around.
Regarding the planned provision of the heat pump or even the complete installation done on your own, you can look at it any way you want. If you do everything yourself through your own installer, you bear sole responsibility for everything that follows. The general contractor (GC) will always assume that they installed everything correctly and that your installer made mistakes if there is any damage.
The same applies if you supply the heat pump yourself to the GC. How could they guarantee it then?
Either way, you lose any claims under a construction time warranty.
Also, the plan is not very realistic. Where do you expect to get a heat pump faster in the current situation than your GC or their installer?
If you knew an installer well enough to get one for you, you wouldn’t be asking these questions here 😉
So, let the GC handle it. You won’t get it done faster on your own.
I wear size 46 shoes, so with a 10cm (4 inch) spacing, you really have to be precise to step between the pipes. At 15cm (6 inch), there is plenty of room to walk around.
Regarding the planned provision of the heat pump or even the complete installation done on your own, you can look at it any way you want. If you do everything yourself through your own installer, you bear sole responsibility for everything that follows. The general contractor (GC) will always assume that they installed everything correctly and that your installer made mistakes if there is any damage.
The same applies if you supply the heat pump yourself to the GC. How could they guarantee it then?
Either way, you lose any claims under a construction time warranty.
Also, the plan is not very realistic. Where do you expect to get a heat pump faster in the current situation than your GC or their installer?
If you knew an installer well enough to get one for you, you wouldn’t be asking these questions here 😉
So, let the GC handle it. You won’t get it done faster on your own.
X
xMisterDx14 Nov 2022 00:40And in the worst case, you might even end up in a dispute with your general contractor over change orders because your "owner’s work" has delayed the construction schedule.
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