Is it worth fitting HR ventilation in a bathroom?

[Edders]

I've got 2 existing bathrooms and I plan to have another built.

They don't have any ventilation, save for the windows.

 

Is it worth fitting HR ventilation in a bathroom?

I was originally planning to get in-line extractors fitted in the loft and vented at the soffits.

[Marvin]

Well that's a question with many answers. Are you talking about Mechanical Ventilation Heat Recovery?  MVHR

 

 

Edited May 18, 2021 by Marvin
minor change.

[Edders]

Something like this:

[Olf]

If it is a refurb you need to judge how easy it is to run at least 5 ducts (out, in, 2 x bathroom extracts and at least 1 supply).

Depending on how insulated and airtight you are, you need to judge how much money can you get from recovering heat vs what you pay upfront for the MVHR system.

Have you considered single room MVHRs?

[Edders]

3 minutes ago, Olf said:

If it is a refurb you need to judge how easy it is to run at least 5 ducts (out, in, 2 x bathroom extracts and at least 1 supply).

Depending on how insulated and airtight you are, you need to judge how much money can you get from recovering heat vs what you pay upfront for the MVHR system.

Have you considered single room MVHRs?

Yes, then I saw a multi room isn't much more.

Originally I was going to get two extractors fitted, which are a lot cheaper,

but I was wondering if it was worth getting something that'll recover some of the heat and provide ventilation as 

the bathroom ceilings have gone mouldy.

 

[Marvin]

Up stairs bathroom ceiling?

 

[Olf]

4 minutes ago, Edders said:

then I saw a multi room isn't much more

Unit only yes, but add cost of ducting and installing it.

If you can run it via the loft, either straight to the bathrooms, or with some easy boxing if going lower, then cetral unit will indeed be a better idea.

[Edders]

Yes, it'll be just for the 1st floor bathrooms, they're about 8m apart, all accessible via the loft. I've got plastic soffits etc. 

[Edders]

Yes - just for the 1st floor bathrooms. Loft is directly above.

No more holes than 2 x single-room units, but more ducting.

Is it a good idea to mix different humidity intakes? i.e 2 bathrooms and a landing?

[Marvin]

Hi Edders

 

You can go for single unit or a whole house unit, you can go for individual humidity levels, one single humidity sensor, you can just stick fans in or open a window. All these choices work.

 

It would be knowing the building design, use ( and sometimes location if exceptional), materials, thermal resistance and air tightness that will give a holistic evaluation to choice.

 

No point sticking draft excluder on a barn door if there's no roof. 

 

More details would help.

 

Marvin

 

[SteamyTea]

If this is for a bathroom, you want an Enthalpy heat recovery unit.  There is energy in that moist air.

 

https://www.engineeringtoolbox.com/heat-recovery-efficiency-d_201.html

 

Don't guess, calculate.

[Olf]

I disagree, If this is a bathroom with mouldy ceiling, you do not want an enthalpy heat recovery unit. 

You keep more heat, but you also keep nearly all the moisture inside.

With a standard heat exchanger you get drier air in winter, so lower dew point and less chance of condensation on cold wall/ceiling - what feeds the mould.

Anyway, moot point as you won't find them in units in this price bracket, the upgrade itself costs what you're willing to pay for the whole unit.

By the way, think about how to improve insulation, (top up in the loft) and/or check if you have some draughts at the junctions making the ceiling cold enough to promote growth.

[Edders]

There's 300mm of loft insulation directly above the bathrooms.

It's the lack of ventilation and the love of long, hot showers.

As a minimum it needs an extractor.

If a MVHR brings additional benefits, then I'll get one of those fitted with ducting going to the 2 bathrooms.

If it's marginal, then it'll be 2 x standard in-line extractors venting via the soffits.