Multi room extract fan

[sythai]

Hi Guys

Got a full refurb job coming up which includes x3 first floor bathrooms, each to have extraction.

Currently have priced 1 x 4" wall mounted unit/ per Bathroom.

On this occasion Client has asked if I can run all x3 bathrooms off x1 unit in the loft.
Never run x3 rooms off x1 fan to be honest.
Fitted tons of loft mount units though and preferred choice being Vortice lineo 100t (255meter cubed/per hr)

I could position the unit in middle of loft with around a 5meter run to each bathroom and roof vent to go directly above.

Couple of things want to check out and any pointers appreciated as usual ;-)

- Any reason I couldn't all these off x1 inline fan ?

- With the wiring if they want triggered with lights, suppose best way would be to fit a double pole light switch at each bathroom?

Cheers Sy

 

[radiohead]

All 3 bathrooms will be extracted just because one is in use. Daft idea .
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Avoid roof vents for bathroom fans, you'll be back sorting out the huge amount of condensation which forms in the duct in winter, long ducts will amplify the problem.

 

[sythai]

All 3 bathrooms will be extracted just because one is in use. Daft idea

Any better ideas then ?

 

[bill01803]

Work out the correct size fan for each room and fit separately.
A 100T will not be enough assuming ceiling height of 2.4m
255/2.4=106
106/3=35.3 each room 35.3/8(air changes per hour)=4.4m2
square root 4.4= 2.1m square max per room with no losses allowed

 

[radiohead]

Any better ideas then ?

Er….how about a fan in each room operated by the light in each room, or is that to radical?

 

[Vortigern]

I have fitted multivent. There is the problem of switching the fan as it had only one trigger. However saying that it was not so bad. It does not hurt that the other bathrooms get ventilated. There is always a low passive ventilation on with the vent axia I used. They are pretty pricey though. The up side is that it is almost silent. As well there would be enough extracts to vent the bedroom (or two) as well. It is still only one fan being triggered so it is not so much a waste of electricity. Of course the only problem is it wont trigger in the other two bathrooms when the light is switched on.
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Vent Axia Lo-Carbon MVDC Multivent c/w Humidity | Vent Axia (443298A)

Although I see here they now have a separate controller

 

[radiohead]

It does not hurt that the other bathrooms get ventilated.

In winter it will be drawing out heat that has been paid for unecessarily.
I'd still go with three fans. I can only see disadvantages with cutting corners here.

 

[Vortigern]

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That sorts out the heating extraction though.

 

[Zerax]

MVHR would be my preferred route... makes so much sense, especially now whilst the major refurb is being done.

 

[Marvo]

There's several complications to address. I assume all 3 bathrooms are in the same dwelling.... if it's separate flats then forget it, rather go with one fan per bathroom.

Triggering varies with different fans, if it's triggered by a switched live then all 3 bathroom lights should be on the same lighting cct and d/pole switches would be needed in each bathroom.

Most of the problems are mechanical rather than electrical. You'd need dampers in each duct branch or adjustable diffusers in each bathroom to be able to adjust the air volume at each bathroom in order to balance the system. Duct check valves should also be installed to prevent air crossover between the rooms when the fan isn't running. Sometimes there's also privacy issues where they will be able to hear other rooms via the common ducting in which case sonic attenuation (sound dampers) will also be required.

I'd suspect that with all things considered using a single fan will be a more complex installation and no cheaper than using one fan per room.

 

[AJshep]

Intermittent extract fans will very rarely comply in a modern property with double glazing as you physically cant get enough trickle vents into the windows to let fresh air in.

We use these quite often.

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They run at a constant low speed then boost when it gets humid, you can install a series of retractive switches (in series) in each room for a boost facility if needed.
There pretty easy to install but take a bit of time, to do it properly your need an airflow meter (anemometer) the grills will need to adjustable so you can wind the grills in or out to get the right extraction rates in each room.
If the ductwork runs in the lofted area then it will all need insulating too (unless it's a warm roof and the insulated under the felt).
Your supposed to keep flexible ducting to a max of 300mm to so ductwork should be mostly solid too.
Usually an extra couple of days work.

 

[sythai]

All sorted..... gone for x1 in-line loft unit/ per bathroom.

Keeps it simple and not a a great deal more in the grand scheme of things ;-)

More pricey than a 'little' wall fan, but decent amount of airflow.

Client didn't want to go down MVHR route, he's watching the budget.

 

[davesparks]

Intermittent extract fans will very rarely comply in a modern property with double glazing as you physically cant get enough trickle vents into the windows to let fresh air in.

We use these quite often.

404 Error Page | Greenwood

www.greenwood.co.uk

They run at a constant low speed then boost when it gets humid, you can install a series of retractive switches (in series) in each room for a boost facility if needed.

That is the ridiculous thing about modern properties, they have to be sealed up so tight to stop airflow and then have mechanical ventilation installed to replace the lost airflow from sealing them up!

Shouldn't the retroactive switches be in parallel? Or are they normally closed?

 

[AJshep]

That is the ridiculous thing about modern properties, they have to be sealed up so tight to stop airflow and then have mechanical ventilation installed to replace the lost airflow from sealing them up!

Shouldn't the retroactive switches be in parallel? Or are they normally closed?

Sorry! yes, your correct Retractive switches in parallel.