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Humidity, or lack thereof... is my heat pump making rooms drier?

Air Source Heat Pumps (ASHPs)

Last Post by Majordennisbloodnok 4 hours ago

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AndrewJ

(@andrewj)

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Topic starter 19/02/2026 9:05 pm

The humidity in my house is very low since the heat pump started providing heating - most rooms are somewhere between 30% and 40%. Bathroom is higher after a shower obviously and some of hat persists during the day but is down around 45% by the end of the day.

Is this something that is common? What do you do?

This topic was modified 6 hours ago by Mars

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Deltona

(@deltona)

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19/02/2026 9:16 pm

What makes you think it's too low?

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trebor12345

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19/02/2026 9:25 pm

Posted by: @andrewj

↑

The humidity in my house is very low since the heat pump started providing heating - most rooms are somewhere between 30% and 40%. Bathroom is higher after a shower obviously and some of hat persists during the day but is down around 45% by the end of the day.

Is this something that is common? What do you do?

I am currently at 37% RH and it's been at that level for most of the winter season. I believe it comes from the underfloor heating being on 24/7.

My previous houses would have been some 60/70%.

Hitachi Yutaki SCombi Heat Pump
(Indoor Unit ) RWD-3.0RW1E-220S-K
(Outdoor Unit) RAS-3WHVRP1

2024 build bungalow
Southern england
179 m2
High level of insulation
Underfloor heating
All 12 circuits are fully open all the time
1 thermostat in family room
7KW heat pump
50 litre buffer tank (4 port)
3.6KW solar panels
Energy used by heating 2527 KWh - 7527 KWh (SCOP 3.5 approx)

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AndrewJ

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Topic starter 19/02/2026 9:44 pm

@deltona I always thought a range of 40% to 50% was a good level to have. It can feel a little dry sometimes and I wonder if it’s good for wooden furniture.

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Majordennisbloodnok

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19/02/2026 11:36 pm

Posted by: @andrewj

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@deltona I always thought a range of 40% to 50% was a good level to have. It can feel a little dry sometimes and I wonder if it’s good for wooden furniture.

Actually, it’s better for wooden furniture – or at least the consistency is. It’s the swings in humidity that cause the problems unless the furniture is well designed.

As for people, guidelines vary; 30-50%, 40-60% and the NHS’s own 50-55%, so the 30-40% you mention is on the low side but definitely better than being too high. @andrewj, how many house plants have you? They’re a well proven way to gently raise humidity; 5-6 medium ones can raise it by 10-15%.

This post was modified 4 hours ago by Majordennisbloodnok

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"

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