Air-water heat pump underfloor heating and domestic hot water heat pump separate

Hello, today for the first time at a heating company. I was given an offer for an air-water heat pump Fujitsu WPYA 100LA 10kw, and separately a hot water heat pump washing machine Feinwerk 270/200LS. It was new to me that there is no buffer tank for underfloor heating. Are these heat pumps okay?? And are separate heat pumps recommended or is it better to have them combined?? I thank you for any information as I am a total layman in this field Single-family house 170m² ground floor, upper floor +85m² basement Best regards

Hello,

.... I was offered an air-to-water heat pump Fujitsu WPYA 100LA 10kw, and a separate hot water heat pump washing machine Feinwerk 270/200LS. ....

In most cases, a separate hot water heat pump is pointless!

.... I was unaware that there is no buffer tank for underfloor heating....

In well-designed systems, no additional buffer tank is usually needed for heating operation. However, as always, there are exceptions.

.... Are these heat pumps okay??

How should one reliably answer that without knowledge of the required boundary conditions?
Counter question:
What power is needed for heating and what for hot water preparation? That is, what is the standardized heating load and what are the room heating loads? How was the underfloor heating designed (volume flows, flow temperature, temperature spread)?
What is the actual annual energy demand for heating and hot water?

Best regards,

NB: Manufacturer’s performance specifications of air heat pumps never refer to the necessary design point of the individual construction project!

Thank you for the answer, so separate air-water heat pump heating and heat pump hot water does not make sense, then combined after all, did I understand that correctly?? Then, for example, the air-water heat pump would always run for the shower water, right? Instead of just the smaller heat pump for domestic hot water. As I said, I am not an expert in this field )

Well, of course there are probably a few tricks on how to optimize the heat pump for higher temperatures, but you have double the technology. We use a normal air-to-water heat pump with two buffer tanks (1x 300l hot water + 1x 350l separation tank). The purpose of the separation tank is that when the heat pump has finished heating the hot water, it can heat or cool the separation tank if there is still energy being supplied from the photovoltaic system. Additionally, the separation tank reduces the switching frequency of the heat pump, meaning the separation tank is heated up to 37 or 38°, and when it drops to 33°, the heat pump starts again. This way, the heating circuit is hydraulically decoupled from the heat generator and hot water circuit. As far as efficiency goes, if I'm not completely wrong, it’s worse than without a separation tank because it also has losses. But that doesn’t matter to me since the heat pump is located on the ground floor in a heated room.

Hi, is 270 liters actually sufficient for a family of 4, maybe 5 people someday?? What is the advantage of an integrated air-water heat pump and domestic hot water storage??

...In addition, the buffer tank reduces the switching frequency of the heat pump, i.e. the buffer tank is brought up to 37 or 38°, then when it goes down to 33, the heat pump starts again....

What is a buffer tank? Buffer tanks in the heating circuit, except for serial ones, are real efficiency killers and should be avoided if possible, which in most cases is achieved with proper sizing.

...Thus, the heating circuit is hydraulically decoupled from the heat generator and domestic hot water circuit.

Why should this be necessary here?

....In terms of efficiency, if I'm not completely wrong, it is worse than without a buffer tank, since it also has losses. But it doesn't matter for me, since the heat pump is located in a heated room on the ground floor.

Standby losses play a minor role as long as the tank is within the thermal envelope. From a balance perspective, this is accounted for as heating energy credit. For this, take a look at the Energy Saving Ordinance or KfW certificate! Critical are the significantly higher heating medium supply temperatures compared to a proper design. The achievable annual performance factors of such botched systems are rather modest. Higher investment, lower benefit! A rather unfavorable combination.

Best regards.