Multi vent Bathroom extraction

[JRJ]

Anyone have any experience of these systems?

Considering something similar to a vent-axia multi room to extract 2 ensuite and a bathroom through one vented tile, rather than having to hire scaffolding to drill 2 extra holes.

From what I can see they run constantly but speed up if they sense humidity in the ducting?
I was thinking more along the lines of humidity sensors in each bathroom to start it up, not sure how constant running would be efficient and cost effective.

 

[norm]

Can you not get a 150mm inline fan and use solid ducting with a y-splitter to both ensuite/bathroom and have them trigger via a flow switch on the hot water pipe of either shower or bath.

That's how I have mine configured for bathroom alone and it means somebody entering briefly doesn't switch on the fan with the light (like most are normally configured) and it's quicker to react than a humidistat would be and from what I've read they can be temperamental.

 

[JRJ]

Can you not get a 150mm inline fan and use solid ducting with a y-splitter to both ensuite/bathroom and have them trigger via a flow switch on the hot water pipe of either shower or bath.

That's how I have mine configured for bathroom alone and it means somebody entering briefly doesn't switch on the fan with the light (like most are normally configured) and it's quicker to react than a humidistat would be and from what I've read they can be temperamental.

That's an interesting way of doing it which I like, which flow switch are you using?

Looking at the stats a 150mm Manrose inline fan extracts 500m3 where as the vent axia multi only does 440m3 at 3 times the price.

 

[norm]

I used this switch https://uk.rs-online.com/mobile/amp/p/flow-switches/0256562/ that's the one for 15mm pipework.

It's a simple affair fitting it, cut out a section of pipe, slide unit on and tighten compression fittings, I used a dab of LSX leak sealer around the olives for good measure.

Wiring up you take a feed from the live that's supplying the fan, connect the 'normally open' line on the switch back to the 'switched live' on the fan and away you go.

 

[pp111]

You can use a pipe thermostat to monitor the hot water pipe temperature. Turns the fan on when the pipe is hot. Has the advantage that it doesn't need a timer on the fan because it takes a little while for the pipe to cool down. Pipe thermostats hare usually adjustable so you can set the trigger temperature. Only works though if the shower is supplied from the hot water but saves you cutting the pipe if it can be used.

 

[JRJ]

Great thanks guys I'll take a look at those options, been sitting down today planning things and thinking if I go for a MEV unit I could potentially get the downstairs WC and utility room up to it as well so potentially 5 less holes to drill.
Then it got dangerous with heat exchangers and air filtration and crazy money

 

[checjb]

I used this switch https://uk.rs-online.com/mobile/amp/p/flow-switches/0256562/ that's the one for 15mm pipework.

It's a simple affair fitting it, cut out a section of pipe, slide unit on and tighten compression fittings, I used a dab of LSX leak sealer around the olives for good measure.

Wiring up you take a feed from the live that's supplying the fan, connect the 'normally open' line on the switch back to the 'switched live' on the fan and away you go.

Thanks for this info, norm. I currently have a humidity/timer fan but I really like the sound of this option. Given my shower only uses a cold water feed, this is better option than a heat sensor.
I had no idea either were an option though so it's good to learn.

I might have to experiment if it works with the sensor activating the fan and then the fan itself using it's own timer/humidistat to continue until the set point. No more fan running when someone goes to the loo at night.
Although, I'll need an override for when no-one uses the shower but the fan is needed for...odour management.

 

[JRJ]

Sat down and planned this a bit more I liked @norm idea but with 3 rooms and some half decent runs of ducting I was worried about the loss of extraction using 2 Tee's on one run, in the end I opted for a Greenwood CMEV.4eHT individual runs of ducting back to the fan and built in humidity sensor so no requirement to have anything wired in any bathroom.