Is an additional heater recommended in the bathroom with underfloor heating?

Yes, as a rule, that is how it is...

I think Lexmaul is right. With heat pumps, much more attention simply has to be paid to keeping the flow temperature as low as possible, and the design and spacing per room need to be planned more precisely. Every incorrect design or each degree more costs more electricity and unnecessarily increases heating costs.

With gas or pellets, it’s not as bad, because the water can generally be heated to high temperatures much more easily and with less effort than with a heat pump. So if, for example, the bathroom is too cold, you don’t pay as much heating cost compared to heat pumps if you simply turn up the flow temperature a bit.

But after the discussion here, I don’t know again what to choose now?? Infrared is not that great, or only useful for a short time to have a little warmth. Towel radiators connected only to underfloor heating are dust catchers and supposedly hardly bring any benefit...

I find it strange, though, why underfloor heating is supposed to work but the towel radiator is said to bring no benefit? It runs at the same temperature all day long, so wouldn’t it simply add 2m² more if it measures 1 m x 2 m??

Or what would be the alternative now with a heat pump and underfloor heating?

Yes, Lex is right - just as an example for our bathroom on the ground floor:

Heat loss at -12° C [W]: 140
Design temperature [°C]: 24
Heatable area [m²]: 3.7
Theoretically required W/m²: 37.84
Laying distance at 30°/26° [cm]: 5 cm -> results in 13 W/m² (cannot do more)
Notes: Heatable area -> 4.7 m² minus shower

You should keep in mind that 30/26 is extremely low for the calculation and -12° only happens every 10 years. Furthermore, the 13 W assume that there is a carpet on it and the air cannot circulate freely.
Here the area simply is not enough - even at 5 cm laying distance.

If you were to include the towel radiator here, as "underfloor heating," would that help?
But the necessary W/m²: 37.84 compared to existing underfloor heating heat of: 13 W/m² is already extreme....

Hello,

our bathroom has a floor area of a little over 18 sqm - about 4 sqm of that (shower and bathtub) are not equipped with underfloor heating.

The underfloor heating in the bathroom is laid closer together than in the other rooms, but at a flow temperature of 29° C it is easily sufficient to bring the bathroom to 24°C.

We only use our towel radiator (with an electric heating cartridge and an area of about 1.6 sqm (0.90 m x 1.80 m)) to preheat the towels – purely as a comfort feature.

However, we once forgot to switch it off again after showering in the evening (immediately after moving in – it was not programmed yet ) – the next morning we then had a tired 32°C in the bathroom despite the presence of an exhaust opening of the Controlled Residential Ventilation...

With a suitable heating cartridge, such a device can definitely be used as an additional heater – but I’d rather not see the electricity bill for that...

Regards,

Dirk

Thank you Dirk, that sounds more reassuring again!

What does "enger" mean? 5 cm installation spacing or 7.5?

But he also has a bad size, which is very unusual - then there is no problem of insufficient heating area