Hello everyone,
we are planning a prefabricated house using timber frame construction. It will have 180 sqm (1,937 sq ft) of living space with underfloor heating, and about 230 sqm (2,475 sq ft) of usable area.
So far, the offer included an air-to-water heat pump from Daikin (Altherma 3R, formerly Rotex HPSU compact Ultra).
Now it seems that this unit might not have enough capacity (?) and as an alternative (additional cost around 4,000) we have been offered a "Wolf heat pump CHC Monoblock 10/300-35".
The Daikin is available in the 4-9 kW version—would that really be insufficient for this size? And what do you think about this offer?
I have the energy-saving regulation heat protection certification and a renewable energy heat law document available, if any information from those is needed.
Thank you very much!
Best regards
we are planning a prefabricated house using timber frame construction. It will have 180 sqm (1,937 sq ft) of living space with underfloor heating, and about 230 sqm (2,475 sq ft) of usable area.
So far, the offer included an air-to-water heat pump from Daikin (Altherma 3R, formerly Rotex HPSU compact Ultra).
Now it seems that this unit might not have enough capacity (?) and as an alternative (additional cost around 4,000) we have been offered a "Wolf heat pump CHC Monoblock 10/300-35".
The Daikin is available in the 4-9 kW version—would that really be insufficient for this size? And what do you think about this offer?
I have the energy-saving regulation heat protection certification and a renewable energy heat law document available, if any information from those is needed.
Thank you very much!
Best regards
S
Strahleman10 Aug 2020 11:30Pixelsurium schrieb:
Hi, I found something in the thermal insulation calculation. Is this the Ht value??? The Ht value isn’t exactly impressive for a timber frame house. It should actually be better. The better you insulate your house, the more you relieve the ground source heat pump in the end. With A-7/W35 and A2/W35 conditions, neither of these air-to-water heat pumps show good COP values.
Pixelsurium schrieb:
So, would you prefer the Wolf CHC Monoblock over the Daikin 8kW if I can get it in the 7kW version instead of the 10kW? 10kW is too much. Whether 7kW or 8kW is less decisive. The Wolf has slightly better COP values, but offers very little buffer if you (or your tenant) want the indoor temperature 1-2 °C (2-4 °F) warmer than you currently expect.
T
T_im_Norden10 Aug 2020 12:30If it needs to get warmer, you increase the supply temperature or the flow rate; you only need the maximum output at A-7°C (19°F) or NAT or worse.
In extreme cases, the electric heating element will kick in.
In extreme cases, the electric heating element will kick in.
tomtom79 schrieb:
You reduce the required room temperature to lower the heating load? If 20°C (68°F) is not enough, you'll end up with a cold house and a heat pump running at almost 99% capacity. It’s better to set the pipe spacing to 7cm (3 inches) or even 5cm (2 inches) everywhere and then throttle down the heating circuit. I lived for 40 years until recently in a moderately insulated older building, maintaining a room temperature of 20°C (68°F), so 20°C is more than sufficient for us. As mentioned, there will also be an electric heater added, so if I lack 1-2°C (2-4°F) in the bathroom, that will cover it. If needed, you can still adjust the heating curve or slightly raise the flow temperature by 1-2°C (2-4°F).
An important point here is to ensure an appropriate flow rate for the heat pump, which depends on the pipe diameter and the length of the piping runs. For example, if your installer uses 25cm (10 inches) pipe spacing with 14mm (0.55 inch) pipes and the electronic radiator control (ERR) also shuts off some heating circuits, the minimum required flow rate can become a problem.
Tolentino schrieb:
@tomtom79 For me (at least), it’s a tactic to get the heating installer indirectly to set a lower supply temperature (VT) and then design the system accordingly. So if they already say we won’t get below 35°C (95°F) supply temperature, I want to know how I can present other parameters to them so that I can still set the VT to 30°C (86°F) later and achieve my desired temperatures.
For example, 20°C (68°F) would be too cold for me. It might even be better for me to say, okay, just do 35°C (95°F), but definitely no higher, and I want 23°C (73°F) everywhere.
@Joedreck
I can’t directly agree on anything contractually with the heating installer. All I can do is communicate my wishes (temperature) or special requests (upgrades)...
I’m not sure if I can specify exactly how they must design the system. Supposedly, they do room-by-room heat loss calculations (HLB), but I suspect they have the manufacturer do that... Sorry, I wrote this in the wrong context. This is more about BEFORE signing the contract with the general contractor. It’s definitely a good idea to negotiate as much as possible beforehand. That would be a point I would personally include.
D
Daniel-Sp10 Aug 2020 14:55Joedreck schrieb:
- Room-by-room heating load calculation according to DIN standard
- 30/27/21 (supply temperature/return temperature/room temperature) or 30/27/23 in the bathroom
- Heating circuit length fixed at 80m (260 feet) per circuit ±10%
Is it realistic to get this included in the contract with every general contractor? It’s probably rather the exception that a general contractor agrees to such specific terms contractually, or they will charge a premium for it. Asking the group—what are your experiences with this?
Daniel-Sp schrieb:
Is it possible to get that included in the contract with every general contractor? It will probably be the exception that a general contractor agrees to such a binding commitment in the contract, or they will charge a high price for it. Question to the group: what are your experiences with this? There probably isn’t much experience with this. But it’s true, not many will agree to it. For that reason, I generally tend to prefer smaller general contractors or direct contracting of individual trades.
It’s similar with, for example, electrical outlets. The common phrase here has often been: they discuss that individually with the electrician after signing the contract… For me, that’s a disaster and one reason I prefer renovation over building new.
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