Integral device Stibel Eltron LWZ 504 with central supply air

We are getting the LWZ304 for our Kfw55 144m² house. It will be installed next week. Experience reports will probably follow only by winter.

What exactly is the difference to the LWZ504?

Hi,

so we have been operating the THZ304 (from Tecalor, identical to the LWZ304) for almost 2 years now and are very satisfied with it so far.
The difference between the 304 and the 505 is, according to my layman’s understanding, mainly that the 504 has a higher heat output and energy efficiency and is slightly larger in size.
For our house (154m² with 1 heating circuit for underfloor heating) the 304 is absolutely sufficient, so we did not see the additional cost as worthwhile.

@ Daniela and ares:
Regarding the noise, I just wanted to let you know that a large part of the noise is caused by the ventilation. The fact that the system is quiet without ventilation operation therefore means nothing. Unfortunately, it gets a bit louder when the ventilation is turned on.

We reprogrammed the system over the weekend so that the ventilation is now off during the day and runs at level 2 at night.
Why?
When it is warm outside during the day, unfortunately the ventilation brings the warm air into the house, and because of the tight building envelope, it is very difficult to get it out again, which makes the house much too warm in summer.
Last summer we could hardly sleep at night because it was so warm inside, so this summer we want to try another method and not let the warm air in during the day at all.

After we reprogrammed the system, we were quite surprised how quiet the heat pump actually is without the ventilation. Now it can hardly be heard anymore, except of course when it is heating up hot water; before it was humming constantly.

However, I don’t want to scare you, just to take away a bit of the illusion that the heat pump is really as quiet as Daniela had assumed so far.
Even with the ventilation turned on, the system does not bother us in everyday life. When we close the door to the utility room (a completely normal room door, on the ground floor) we can hardly hear the system on the ground floor, and in the attic it is not audible at all.

Hello everyone,

thanks for your feedback!

:
So the difference between the LWZ 304 and the LWZ 504 is mainly the inverter technology. It regulates the power better. I’ll put it in layman’s terms as I understood it. While another heat pump only heats at "full throttle or off," the inverter technology operates with the amount currently needed. Maybe this is better understood from the product description text on the Stiebel Eltron website:

"The compact ventilation integral system LWZ 504 with Passive House certification offers all the living comfort worthy of an energy-saving house. The system draws energy for pleasant room temperatures and hot water from the outside air. The modern ventilation management ensures that the heat stays inside the house. It recovers up to 90% of the heat from the exhaust air. A pleasant, healthy atmosphere and high efficiency can thus be excellently combined. The power-regulating inverter technology also ensures high efficiency. It produces exactly the amount of heat currently needed. Even at low temperatures, high performance values can be achieved this way.

A modern high-efficiency heating circulation pump and excellent insulation of the hot water tank ensure economical energy use. Those who want to be even more independent from rising energy prices can operate the LWZ 504 with self-generated photovoltaic electricity with the right accessories (ISG plus). The large, intuitively operated matrix display ensures that modern technology in the award-winning design is easy to use."

Regarding the noise level, I will report soon when the ventilation system has been put into operation. Also, how the cooling works. Because it was important to us that we can lower the temperatures by a few degrees so that it does not get too warm. It is also important to take certain things into account from the start regarding insulation and the installation of ventilation ducts so that they are not noisy or audible. Our specialist craftsman said that a well-built ventilation system should not be heard or only minimally.

: The 304 can also cool, right? At least that’s what the website says. Or did you not want to use that? Especially since it’s too warm for you, that would be a good thing.

For us, the 160 sqm are on one level. The LWZ 504 is in the utility room. It is important to ensure that the screed is decoupled accordingly in terms of sound. In addition, we chose a soundproof door to the living area because I wanted to be sure not to hear any of the appliances. We don’t even hear the washing machine when it’s running at full power, which is great.

Best regards,
Daniela

huhu,

may I ask if you have applied for funding for the LWZ504? If yes, how much was granted?

Regards
D.Gerner

The heat in summer should not be an issue with an (automatic) bypass. Or does the system not have that? That would be a dealbreaker for me.

When installing the LWZ 504, you receive a new construction subsidy of 1,500 euros. Our craftsman took care of this together with us. Important, this must definitely be done before the start of construction, so make sure to arrange it in time! I got some initial information here (MAP-Fördermittelrechner) and it also showed 1,500 euros, so that was correct.

Best regards Daniela