Shower light with extractor fan - heat loss & air leaks

[renovator123]

Hi.

 

We are in the process of renovating with the aim of getting close to EnerPHit standard.

 

We have a large bathroom with small shower extractor fan extracting through loft area to gable end wall, and would like to keep shower light. Currently the room has fairly new argon-filled double glazing with 2 air vents (the only ones in the house), and we slightly open windows during or after showers to reduce condensation. We also sometimes use an other bath clothes drier with air vents open.

 

Main concerns are:

* low budget

* reducing condensation after bath/shower or when drying laundry, without heat loss

* reducing heat loss from shower extractor fan into attic

 

What are the options here? I have seen decentralized heat recovery units for walls, but can these be combined with existing shower fan? Are they safe to place in shower enclosure, which is by far the main area of condensation? Any concerns about length of ducting? Removing the fan from the shower light but adding an additional ceiling extractor fan using existing ducting might work.

 

Shower fan is perhaps 60cm from gable wall of house (plus about 60cm thick wall), plus there is attic ducting, mainly above level of insulation due to avoiding fan overheating plus height of external hole/grill.

 

Outside temperature is almost always above 0C in the day in winter, rarely below -10C overnight.

 

Tumble drier is out of the question and laundry is dried on washing line when possible, but it's a rainy climate.

 

(We will not be doing a single/whole house MVHR due to difficulty with layout/age of house/disruption).

[Nickfromwales]

Single room MVHR units ( through wall ) per bathroom / utility room? Sound good on paper, but results are not amazing. 

 

Edited November 6, 2022 by Nickfromwales

[Radian]

IMO, the expense of a heat exchanger for a single extraction point would take a long time to be offset by the relatively small amount of energy lost through just dumping the warm air with its moisture outside.  Given the low SHC of air, heating the replacement fresh air will not be particularly energy intensive. When you mention keeping the shower light, do you mean you have a combined extractor/light in the shower ceiling? I've got one of those and find it very efficient when coupled to an inline extraction fan. I went through the same thought process and came up with the above conclusion.

[renovator123]

I think we will have to see on MHVR after windows are in, depending on air tightness given it's retrofit. Thank you all.

[ProDave]

If you want that level of performance go for MVHR.  Use the shower light fitting as the MVHR extract in the bathroom if you want to keep the light fitting.