Underfloor heating and mechanical ventilation with heat recovery (MVHR), replacement of ordinary radiators

A gas boiler is offered in the bb. Since the prices and the potentially high operating costs of a heat pump still deter me, I will stick with gas. Maybe a heat pump will be more interesting someday.

How is it with underfloor heating? I once read that you should keep underfloor heating running constantly in winter because it reacts sluggishly. Is that correct? Does that also apply to kfw xx houses?

Hello,

what types of heat pumps are offered, and at what price differences? Which potentially high operating costs? Is your house being built to energy saving ordinance standard, or better? Many factors count to be able to compare an offer... Heat pumps are a thing of their own anyway. Often mistakes are made by the installers here, e.g. buffer storage with brine heat pumps, active individual room control, etc.

Underfloor heating: System-related, it naturally reacts sluggishly, but that also has its advantages. Underfloor heating is a surface heating system and generates a nice even warmth, and that at low flow temperatures. At minus 20 degrees in February, we had 33 degrees flow temperature. With normal radiators, you have 60 degrees. Right, setback hardly pays off (saving about 3% I believe I read). You have a nice self-regulating effect – the entire floor is basically the heat storage. You have an even room climate, especially in combination with controlled residential ventilation/heat recovery, as there is a permanent air exchange here. In my opinion, the only real disadvantage: you cannot have 15 degrees in the bedroom if it should be 22 degrees next door in the kids’ room.

Definitely install underfloor heating. As already said, if it is laid accordingly, you can still switch to a heat pump later.

By the way: we have a KFW70 house with controlled residential ventilation/heat recovery and a brine heat pump. We basically saved the chimney and the gas connection – however, this advantage was partly consumed by approval fees for the deep drilling. At the moment, for a household of 4 people (2 adults, 2 kids), our daily consumption (24h) for hot water (showers) is 1.7 - 2.1 kWh, so not even 40 cents per day. I can’t say more right now, as we only moved in in January.

I hope I could help you a bit.

Regards...

...In our house planning, a controlled residential ventilation system with heat recovery is to be installed....

The controlled residential ventilation system is only indirectly related to the heating surfaces (heat recovery). It does not matter whether underfloor heating, radiators, or convectors are used! The main thing is that the room heating loads are ensured. The choice of heating surfaces depends on many factors. In extreme cases (poorly to moderately insulated, or very well insulated (PH)), radiators are more advantageous; in the transitional range, underfloor heating or convectors are more favorable. The intended heat generator also has an influence. Heat pumps, for example, require low flow temperatures, so in the transitional range usually larger heating surfaces => underfloor heating, convectors often also a combination of both.
Best regards.

What types of heat pumps are offered, and at what price differences? What possibly high operating costs? Is your house built to Energy Saving Ordinance standard, or better? Many facts count in order to compare an offer...

No offer is available. It is from a general BB of a certain FH manufacturer.
The energy standard is supposed to be Kfw 70 or 55.
By high operating costs, I mean the electricity costs for the heat pump. You really need true professionals for that, otherwise it can get pretty expensive.

In my opinion, the only true disadvantage: you cannot have 15 degrees in the bedroom if 22 degrees are wanted next door in the children’s room.

Why is that not possible? They are probably separate heating circuits after all. You can control those individually.

However, this advantage was partially offset by permit fees for the deep drilling.

I have also heard that the drillings are very expensive. 15,000 euros or so are quite common. You can heat with gas for a long time with that.
I once looked into air-to-water heat pumps, but I have still heard too many negative opinions.

Currently, with a 4-person household (2 adults, 2 kids), we have a daily consumption (24h) for hot water (showers) of 1.7 - 2.1 kWh, so not even 40 cents per day.

That only concerns hot water now. What about heating if it actually runs constantly in winter? How high will the consumption probably be?

So we decided on HK for two reasons... we don't like underfloor heating because of "warm feet" and a heat pump would have cost us 12,000 more. But as always, that is individual and we also got a special deal that made gas a bit cheaper. And a third fact: we love cooking on gas.... so we killed several birds with one stone

So the prices always seem to be very different. The drilling (2x60m) cost me €4000. The gas connection was omitted with about €2000 and the alibi ST system is also omitted! And the warm feet with underfloor heating are also from times when the underfloor heating ran with high supply temperatures!

...By high operating costs I mean the electricity costs for the heat pump. You really need true professionals for that, otherwise it can get quite expensive.

What exactly are high operating costs?

...I've also heard that the drilling can be very expensive. €15k or so is to be expected. I can heat with gas for a long time for that.

Vertical drilling is certainly not negligible in terms of costs. How high exactly depends, among other things, on the required extraction capacity and energy. As long as this has not been determined, it is pure speculation. There are also other forms of source development in brine heat pumps. One should also consider that with conventional heat generators such as gas condensing boilers, consumption is always higher than demand. With heat pumps, it is the other way around! With the latter, in combination with photovoltaics, heating and hot water preparation is sometimes possible virtually at "zero cost".

...I once dealt with air-to-water heat pumps, but I heard too many negative opinions about them.

That only applies if exact dimensioning and design were neglected.

...What about heating if it actually runs constantly in winter? How high will consumption probably be?

This question is pointless because every building project is completely specific. What A consumes does not apply at all to B, even if it is an identical building!

Best regards.