Hello everyone,
We are currently dealing with heating. It will come down to a ground source heat pump. The underfloor heating and the pump now need to be optimally configured. The Energy Performance Certificate (EPC) here is more for official purposes rather than active use. So a proper hydraulic balancing is definitely mandatory.
Now it’s about the sizing of the heating system. For example, Stiebel Eltron offers a heating load calculation. However, this is probably not a "room heating load" calculation. I think it is more of an overall calculation. What is the difference between heating load and room heating load? Do both need to be calculated independently, or how should this be handled? Is it enough to have just a room heating load calculated?
I would appreciate some clarity in this jungle, thanks!
We are currently dealing with heating. It will come down to a ground source heat pump. The underfloor heating and the pump now need to be optimally configured. The Energy Performance Certificate (EPC) here is more for official purposes rather than active use. So a proper hydraulic balancing is definitely mandatory.
Now it’s about the sizing of the heating system. For example, Stiebel Eltron offers a heating load calculation. However, this is probably not a "room heating load" calculation. I think it is more of an overall calculation. What is the difference between heating load and room heating load? Do both need to be calculated independently, or how should this be handled? Is it enough to have just a room heating load calculated?
I would appreciate some clarity in this jungle, thanks!
MKK_SE92 schrieb:
The response was: "Yes, heating load according to DIN EN 12831 is calculated by our system technician." Is this a room-by-room calculation or something general that applies to the entire house? Although it’s a prefabricated house, the floor plan is customized for us, so it’s unique. Is there a general statement on this? I would include in my contract: "Design and installation of underfloor heating based on a supply temperature of 30°C (86°F) according to room-by-room heating load calculation per DIN 12831."
That should be enough, right?
Unfortunately, nothing regarding this is mentioned in the contract.
Neither in the contract with the prefab house company nor in the "contract" with the plumbing company. It is only described that I will receive an air-to-water heat pump with integrated controlled residential ventilation (as mentioned on request, Tecalor 5.5 eco) combined with underfloor heating.
Can anyone make sense of this statement from the plumber, especially regarding the DIN standard? I specifically asked whether the heat load calculation is done room by room.
Good luck
Neither in the contract with the prefab house company nor in the "contract" with the plumbing company. It is only described that I will receive an air-to-water heat pump with integrated controlled residential ventilation (as mentioned on request, Tecalor 5.5 eco) combined with underfloor heating.
Can anyone make sense of this statement from the plumber, especially regarding the DIN standard? I specifically asked whether the heat load calculation is done room by room.
Good luck
In general, prefabricated house companies are very inflexible when it comes to external changes to their planning.
Or to put it another way: Although you are the client and pay for everything, ultimately the heating installer is a subcontractor of the prefabricated house company, gets paid by them, and will want to continue being paid by the company in the future.
But asking doesn’t cost anything — you might get lucky. You can only avoid the energy requirements regulation (ERR) by submitting a formal exemption request, which has to be filed together with the building permit / planning permission application.
Typically, the heating installer will have the heating load and underfloor heating design calculated by an underfloor heating manufacturer. That was also the case for me — I received a summary of the heating load and the underfloor heating design. Upon request, I got the detailed printout broken down by individual rooms.
Based on the heating load, Tecalor/Stiebel Eltron will recommend the size of the heat pump along with the ventilation system. For the ventilation system, a quick design calculation according to DIN 1946 for controlled residential ventilation will be provided, and that’s it.
I would try to have the underfloor heating designed for a maximum flow temperature of 30°C (86°F) at natural heat demand, with the smallest possible pipe spacing — 5cm (2 inches) or at most 10cm (4 inches).
For the heating load calculation, I would specify room temperatures of maximum 21–22°C (70–72°F) since you won’t realistically achieve larger temperature differences between individual rooms.
If the contract includes a towel warmer, have it operated electrically only and do not connect it to the water circuit of the underfloor heating.
If there are complaints that the heating load in the bathrooms isn’t met at 24°C (75°F), argue that the underfloor heating is intended to provide 20°C (68°F) with 30°C (86°F) flow temperature and 5cm (2 inches) or max. 10cm (4 inches) pipe spacing, and that if you really want 24°C (75°F), you can switch on the electric towel warmer.
And insist on the smallest possible heat pump — don’t let anyone convince you to buy a larger heat pump for the same price.
Or to put it another way: Although you are the client and pay for everything, ultimately the heating installer is a subcontractor of the prefabricated house company, gets paid by them, and will want to continue being paid by the company in the future.
But asking doesn’t cost anything — you might get lucky. You can only avoid the energy requirements regulation (ERR) by submitting a formal exemption request, which has to be filed together with the building permit / planning permission application.
Typically, the heating installer will have the heating load and underfloor heating design calculated by an underfloor heating manufacturer. That was also the case for me — I received a summary of the heating load and the underfloor heating design. Upon request, I got the detailed printout broken down by individual rooms.
Based on the heating load, Tecalor/Stiebel Eltron will recommend the size of the heat pump along with the ventilation system. For the ventilation system, a quick design calculation according to DIN 1946 for controlled residential ventilation will be provided, and that’s it.
I would try to have the underfloor heating designed for a maximum flow temperature of 30°C (86°F) at natural heat demand, with the smallest possible pipe spacing — 5cm (2 inches) or at most 10cm (4 inches).
For the heating load calculation, I would specify room temperatures of maximum 21–22°C (70–72°F) since you won’t realistically achieve larger temperature differences between individual rooms.
If the contract includes a towel warmer, have it operated electrically only and do not connect it to the water circuit of the underfloor heating.
If there are complaints that the heating load in the bathrooms isn’t met at 24°C (75°F), argue that the underfloor heating is intended to provide 20°C (68°F) with 30°C (86°F) flow temperature and 5cm (2 inches) or max. 10cm (4 inches) pipe spacing, and that if you really want 24°C (75°F), you can switch on the electric towel warmer.
And insist on the smallest possible heat pump — don’t let anyone convince you to buy a larger heat pump for the same price.
B
Bauherr am L4 Jun 2020 09:15I just received a quote for a heat load calculation and the design of the underfloor heating system. 2,000 euros net from a locally based building services planning office...
Is my impression correct that this is way too expensive?
@lesmue79
Am I understanding you correctly that you would design all rooms within the insulation for 21-22 degrees Celsius (70-72°F), including the bathrooms? Why is the technical reasoning behind not targeting 24 degrees Celsius (75°F) in the bathroom?
Is my impression correct that this is way too expensive?
@lesmue79
Am I understanding you correctly that you would design all rooms within the insulation for 21-22 degrees Celsius (70-72°F), including the bathrooms? Why is the technical reasoning behind not targeting 24 degrees Celsius (75°F) in the bathroom?
T
T_im_Norden4 Jun 2020 09:50A heat pump should operate with a low supply temperature, around 30°C (86°F).
However, this also means you need a large surface area for the underfloor heating.
This surface area is usually not available in most bathrooms, so achieving 24°C (75°F) is unlikely.
Solutions:
Increase the supply temperature -> Leads to higher heat pump costs
Increase the surface area with wall heating -> Additional costs and many heating installers are reluctant to do this.
Additional electric heating:
Infrared mirror -> Additional costs but quickly heats the room and prevents mirror fogging
Electric radiators -> Extra costs, slow to warm up, and not very efficient.
However, this also means you need a large surface area for the underfloor heating.
This surface area is usually not available in most bathrooms, so achieving 24°C (75°F) is unlikely.
Solutions:
Increase the supply temperature -> Leads to higher heat pump costs
Increase the surface area with wall heating -> Additional costs and many heating installers are reluctant to do this.
Additional electric heating:
Infrared mirror -> Additional costs but quickly heats the room and prevents mirror fogging
Electric radiators -> Extra costs, slow to warm up, and not very efficient.
I had my entire house designed for 20°C (68°F) and am using the lowest heating curve available, yet I still have 23-24°C (73-75°F) everywhere (unless I reduce the output via the ERR), partly due to various external heat sources.
(And this does not refer to current outdoor temperatures with open windows.) This means that the heating load calculated by the typical heating installer/wholesaler/underfloor heating manufacturer still has a significant safety margin.
For me, a heating load of just under 3.2 kW was calculated at an outdoor temperature of minus 12°C (10°F). External gains from solar radiation and the ventilation system were not taken into account, so my actual heating load is probably around 2.5-2.8 kW.
Originally, the general contractor wanted to install a 5 kW heat pump, on the assumption that this would provide enough reserve capacity.
At my insistence, the 3 kW system was installed instead...
I should mention that I haven’t been able to perform a proper system balancing yet because the system hasn’t been in operation for very long.
(And this does not refer to current outdoor temperatures with open windows.) This means that the heating load calculated by the typical heating installer/wholesaler/underfloor heating manufacturer still has a significant safety margin.
For me, a heating load of just under 3.2 kW was calculated at an outdoor temperature of minus 12°C (10°F). External gains from solar radiation and the ventilation system were not taken into account, so my actual heating load is probably around 2.5-2.8 kW.
Originally, the general contractor wanted to install a 5 kW heat pump, on the assumption that this would provide enough reserve capacity.
At my insistence, the 3 kW system was installed instead...
I should mention that I haven’t been able to perform a proper system balancing yet because the system hasn’t been in operation for very long.
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