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
OWLer schrieb:
If he meant 30°C (86°F) flow temperature, then that should mean the floor would be that warm. You can’t control what goes into the heating pipes. He completely misunderstood everything we have discussed (and documented) so far. I find this statement alone shocking coming from a general contractor. I mean, okay, he’s not carrying out the trade work himself, but if you’re offering housebuilding services professionally, you should at least have some basic knowledge about everything related to construction.
A general contractor always refers me directly to their heating specialist. My heating guy also prefers a flow temperature of about 35°C (95°F). I’m still not sure how to convince him I want it differently.
He’s the type who thinks he knows everything and that what’s written on internet forums is nonsense.
Is there any reliable source about low flow temperatures and pipe spacing other than the usual forums? Something I could maybe use to persuade him?
Thanks and regards
Tolentino
D
Daniel-Sp9 Sep 2020 11:21Commission a heating load calculation including the design calculation for the underfloor heating with your desired flow temperature and then present the calculation clearly... You don’t need to mention that you commissioned the calculation online.
T
T_im_Norden9 Sep 2020 12:25You pay, so you decide what you want.
I have the calculation in front of me. Apparently, we have purchased "poor" walls. A supply temperature of 30°C (86°F) is not achievable. According to the calculation, several rooms lack the required heating capacity. It’s interesting how much the brick veneer and the many windows conflict with our desired temperatures. I don’t think our neighbors with external insulation systems (ETICS / EIFS) are experiencing similar issues.
Most likely, the underfloor heating will now be designed for 33°C (91°F) – even then, the bathroom remains critical and will either need additional electric heating or I will have to convince my heating contractor to install wall heating.
Fortunately, both my general contractor and the heating contractor have experience installing wall heating systems. Although the heating contractor didn’t sound enthusiastic and didn’t want to comment on the additional costs, I’m taking that as a good sign.
Most likely, the underfloor heating will now be designed for 33°C (91°F) – even then, the bathroom remains critical and will either need additional electric heating or I will have to convince my heating contractor to install wall heating.
Fortunately, both my general contractor and the heating contractor have experience installing wall heating systems. Although the heating contractor didn’t sound enthusiastic and didn’t want to comment on the additional costs, I’m taking that as a good sign.
Yes, this is not uncommon. There are situations where underfloor heating reaches its limits, regardless of whether you reduce the spacing or make other adjustments. The rooms do not achieve the required heating output according to calculations, for example due to the number, size, or type of windows, as well as the wall construction and other factors.
In such cases, you need to consider other options, such as using wall heating systems, installing perimeter heating zones, improving insulation values, and so on.
However, theory can differ somewhat from practice, and it may turn out that occupants perceive the temperatures differently once living there, and that the heating is sufficient for their needs. Especially since temperatures of -20°C (-4°F) or lower are rare here. Although, with proper installation, such conditions usually do not pose a problem.
In such cases, you need to consider other options, such as using wall heating systems, installing perimeter heating zones, improving insulation values, and so on.
However, theory can differ somewhat from practice, and it may turn out that occupants perceive the temperatures differently once living there, and that the heating is sufficient for their needs. Especially since temperatures of -20°C (-4°F) or lower are rare here. Although, with proper installation, such conditions usually do not pose a problem.
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