Extractor siting woes

[Grout Expectations]

Hi all
Hoping you might be able to solve a dilemma.
I moved into a new house last year. Although the previous owners had had the kitchen and bathroom redone in the previous two months they had not put extractors in either of them.

The bathroom seemed like an easy job as there is a plastic grill on the inside covering the channel to the original 7x7inch airbrick. So my plan was to:
Remove internal grill
Core drill a hole in the air brick
Fit 6 inch fan and external vent
Job done

However (it's never that easy is it?)
When I removed the internal grill it turned out that a tile covered half the channel behind it.
Also, although the channel itself was clear, when the rear of the house was re-rendered (again before we bought it, they had damp and had the rear of the house Lime rendered) they've rendered over half the air brick. It's clearly intentional as there's a brick been put on the rear of the air brick to render against.

The only thing I can think is that they intended to put a 4 inch fan in so covered any space they wouldn't need then never gotten the fan.

My plan is to put in a 6 inch humidistat extractor in to get decent air changes as the house (1930s/fireplaces covered/double glazed/roof 'insulated' with expanding foam) is, unsurprisingly prone to condensation so I want to make sure there's the welly to clear damp air swiftly

So, my questions are:

1. The air brick channel is next to the shower making it zone 1 (so only 12v) and directly opposite the door but as its a) already a hole in the wall and b) there's a shower screen between door and airbrick so the passage of air will not be direct, is it still the best place to site an extractor (if the hole wasn't there I'd be putting it at the end of the bath, furthest from the door but it's only 10m3 so as I say, with the shower screen in the way I would have thought the air will move enough?
Is it ok siting there rather than ducting through the ceiling at the end of the bath?

2. If I do go for it, will I be ok to core drill through the air brick to fit the exhaust for the fan (after attempting to diamond angle-grind the tile on the bathroom side without breaking it)?
3. The soil pipe partially covers the air brick on the outside so my intention is to rotate the pipe slightly so it is to the left of the extractor outlet. Assuming that's ok?
4. Am I being stupid and I should just bite the bullet, fit a 4 inch fan that meets building regs and stop worrying about number of air changes?

Thanks for any advice

 

[JohnD]

"The air brick channel is next to the shower making it zone 1"
Is it directly above the shower tray or bath? How high is it above floor level (be precise)?

I can't easily see your pictures. You can C&P them into your post, or use "Media" "Add Media" (top of screen).

Some of us have short attention spans, so if you find a way to use fewer words, you will get better response.

 

[Grout Expectations]

Thanks for such a quick reply.
The air brick is directly over the shower/bath approx 6.5ft / 2m above floor level

Pics imbedded.

Point taken re brevity. Not my strong point and wanted to be clear.must try harder

Bathroom air brick access

• Grout Expectations
• 4 Jul 2016

Airbrick external

• Grout Expectations
• 4 Jul 2016

 

[JohnD]

Pity it is right over the bath.

The ELV fans I have seen are pretty weedy. If you can find a powerful one, that's great.

For example, cheap, weedy builders fans are usually (nominally) about 80cu.m/hr. Get more than that.

Modern ones can be very quiet, with ball-bearing motors. Rather than a humidstat, I prefer it to come on automatically with the lightswitch, and a delay timer to run on. If it is a quiet fan this is no hardship. Not all bathroom activities involve steam.

I do not think the soil pipe is of any consequence.

 

[jj4091]

You could put an external fan on the outside of the vent, they are expensive & I'm not sure how efficient they are, but an inline fan in the loft & vented out through the soffit would seem an easier & less expensive option.

 

[Grout Expectations]

Thanks both. I know what you mean about SELV fans but I have found some that go a little higher.
For instance the Vent Axia lo Carbon svara goes up to over 100m/hr on boost.

Great that there's no problem with soil pipe. So core drill out air brick doable or should I really seal the hole and go through the ceiling?

 

[Grout Expectations]

Thanks both. I know what you mean about SELV fans but I have found some that go a little higher.
For instance the Vent Axia lo Carbon svara goes up to over 100m/hr on boost.

Great that there's no problem with soil pipe. So core drill out air brick doable or should I really seal the hole and go through the ceiling?

 

[JohnD]

If you were to go through the ceiling, and duct out through the loft wall or eaves, you could have a much more powerful and quieter mains voltage Inline fan. They are IMO much better than wall fans.

For example 160m3/hr
https://www.tlc-direct.co.uk/Products/SLTDK160T.html
and you can get others up to 240m3/hr

Up to you if you want to do that work and are agile enough. I rather regret that I didn't, but due to height of house would need scaffolding and I don't think it's worth it now.