Hello everyone,
I have the following description from the general contractor. I notice that the domestic hot water storage tank is much smaller than in other examples here in the forum. Does this make sense?
Are there any experiences with this type of unit(s)?
Is a circulation system necessary?
Which screed is recommended for underfloor heating?
(About the house: 166 m² (1786 sq ft), approx. 9 x 11 m (30 x 36 ft), KFW 55)
Heating system
Vaillant system:
Gas condensing boiler with integrated solar system according to DIN/EN 677, auroCOMPACT series in compliance with the energy saving regulation, featuring a stainless steel heat exchanger. Rated heating output is approximately 3.3 to 14.7 kW. Depending on the outdoor temperature, a weather-compensated solar system controller type multiMATIC regulates the temperature level. Heating cycles and domestic hot water production can be programmed individually via a timer.
Air/exhaust system:
The air/exhaust system for the sealed combustion condensing units is a concentric air/flue pipe system routed through the roof.
Domestic hot water
Vaillant system:
The house’s domestic hot water supply is central without circulation pipes. For supplying the bathroom, guest toilet, and kitchen, the described gas condensing boiler with integrated 190 L (50 US gallons) stratified hot water storage tank is combined with three system-matched flat-plate solar collectors of type auroTHERM VFK 145 V/H, mounted on the roof with a total collector area of about 7.5 m² (81 sq ft). A thermostatic mixing valve is provisioned to prevent scalding.
Underfloor heating:
Warm water underfloor heating designed based on heating demand calculation, using plastic piping on insulation boards with room temperature control (surface-mounted thermostat).
Depending on the contractor’s choice, either a cement or anhydrite screed will be installed.
One heating circuit manifold per floor is planned, which will be installed flush with the wall.
Thank you,
h4nnes
I have the following description from the general contractor. I notice that the domestic hot water storage tank is much smaller than in other examples here in the forum. Does this make sense?
Are there any experiences with this type of unit(s)?
Is a circulation system necessary?
Which screed is recommended for underfloor heating?
(About the house: 166 m² (1786 sq ft), approx. 9 x 11 m (30 x 36 ft), KFW 55)
Heating system
Vaillant system:
Gas condensing boiler with integrated solar system according to DIN/EN 677, auroCOMPACT series in compliance with the energy saving regulation, featuring a stainless steel heat exchanger. Rated heating output is approximately 3.3 to 14.7 kW. Depending on the outdoor temperature, a weather-compensated solar system controller type multiMATIC regulates the temperature level. Heating cycles and domestic hot water production can be programmed individually via a timer.
Air/exhaust system:
The air/exhaust system for the sealed combustion condensing units is a concentric air/flue pipe system routed through the roof.
Domestic hot water
Vaillant system:
The house’s domestic hot water supply is central without circulation pipes. For supplying the bathroom, guest toilet, and kitchen, the described gas condensing boiler with integrated 190 L (50 US gallons) stratified hot water storage tank is combined with three system-matched flat-plate solar collectors of type auroTHERM VFK 145 V/H, mounted on the roof with a total collector area of about 7.5 m² (81 sq ft). A thermostatic mixing valve is provisioned to prevent scalding.
Underfloor heating:
Warm water underfloor heating designed based on heating demand calculation, using plastic piping on insulation boards with room temperature control (surface-mounted thermostat).
Depending on the contractor’s choice, either a cement or anhydrite screed will be installed.
One heating circuit manifold per floor is planned, which will be installed flush with the wall.
Thank you,
h4nnes
h4nnes schrieb:
Are these systems really that "stupid" and unable to handle excess energy in any other way? As mentioned before, if it is a drainback system, the collectors empty as soon as the preset maximum storage temperature is reached. So, no problem.
If it is a conventional pressurized system, the solar fluid will eventually evaporate at high temperatures and move into the solar expansion tank. Initially, nothing serious happens, but if this process repeats frequently during summer, the solar mixture can degrade and may clog the system. Additionally, the mixture of water and propylene glycol breaks down, and frost protection is no longer consistently guaranteed. Therefore, with pressurized systems: when in doubt, use fewer collector panels.
h4nnes schrieb:
Wouldn’t the unit override my set desired temperature and keep heating if there is an oversupply of energy? What exactly happens? No, the gas unit’s sensor is positioned above the solar system’s sensor. Typically, the gas unit is set to a target temperature of about 50°C (122°F) +/- some variance; if the solar system has already heated the storage to over 50°C (122°F) (the solar heat exchanger is located at the bottom of the tank), the gas unit won’t activate at all.
h4nnes schrieb:
What about heating support through solar thermal? Does it make sense? See Nordlys, it doesn’t help much—especially with your roof: solar thermal used for heating support in your house only makes sense, if at all, with a collector tilt between 45° and 60°. During the heating season, the sun shines not only for shorter periods but also at a lower angle.
My advice remains: ideally, choose a 300-liter (79 gallons) storage tank (not much more expensive than a 190-liter (50 gallons) one) and just 2 collectors—you will likely meet the KfW requirements and, with a pressurized system (which is the most common type in Germany), minimize the risk of overheating during summer.
Nordlys schrieb:
Well, you don’t die from it…..Energy Saving Ordinance nonsense.The real problem is the extra costs for solar thermal systems. Aside from that, saving energy is not nonsense at all. No one would build more calcium silicate brick walls without insulation and uninsulated roofs anymore.
However, the approach taken by lawmakers is questionable and, unfortunately, in many parts, essentially a huge subsidy program...
Joe, don’t get me wrong. I know how to save money and energy as well. But I think the way the energy saving regulations promote uneconomical use of technology and excessive insulation is wrong. The preference for electric heating systems over gas or even oil, while ignoring stoves, etc.
Joedreck schrieb:
This is all simply due to the decision to go with gas. You have to accept some drawbacks. We have gas WITHOUT solar and with the planned controlled residential ventilation system with heat recovery. This means no additional costs for solar thermal systems. Also, no issues with scalding, maintenance of an unnecessary system, summer overheating, and so on...
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