vivienz Posted March 20, 2018 Posted March 20, 2018 I'm proposing that our downstairs loo will have a fixed window to stop people opening it and messing up the MVHR. I've been looking at the duofresh cistern from Geberit - has anyone installed/used one of these? Do they work?
le-cerveau Posted March 20, 2018 Posted March 20, 2018 All 6 of my toilets are Duofresh, however they are hooked up to the MVHR not the Duofresh system, get the duofresh frame and install, take off the pipe up the side and connect to the MVHR exhaust. details in my blog.
vivienz Posted March 20, 2018 Author Posted March 20, 2018 Aha! That's where I spotted It, thanks le-cerveau. have you found them to be effective?
Onoff Posted March 20, 2018 Posted March 20, 2018 I'm making my own version by hacking a standard Geberit. Details in my bog... 2
Onoff Posted April 25, 2018 Posted April 25, 2018 Only hijacking @vivienz's thread as it's recent on the subject. So I'm DIY'ing my own version of this. The Geberit system I have being too old to have it incorporated. So far I've CT1'd an elbow into the top of the cistern: Then taken a 32mm pipe in solvent weld up into the loft: In terms of a fan unit I've found this in the stash of "that'll come in handy one day" parts and a suitable 24vdc power supply is no problem. It'll probably be triggered by some short range proximity sensor + timer when you sit on / stand next to the loo. Spec for the fan is: DC Fans Tubeaxial, 60x25mm 24VDC, 27.1CFM, Ball I'm thinking to either fit this in an adaptable box or square section ducting. Is the 27.1CFM adequate for the application do we think? Cheers 1
PeterW Posted April 25, 2018 Posted April 25, 2018 It’s a bit much tbh and you may “feel it” and definitely hear it as that looks like a server fan ..!
le-cerveau Posted April 25, 2018 Posted April 25, 2018 16 minutes ago, Onoff said: Is the 27.1CFM adequate for the application do we think? Way over the top 10-15% of that would be fine. 1
Onoff Posted April 25, 2018 Posted April 25, 2018 22 minutes ago, le-cerveau said: Way over the top 10-15% of that would be fine. You haven't been in a karzi after me have you?
PeterW Posted April 25, 2018 Posted April 25, 2018 With that fan running you won’t be able to leave the seat ..!!
Onoff Posted April 25, 2018 Posted April 25, 2018 27 minutes ago, PeterW said: It’s a bit much tbh and you may “feel it” and definitely hear it as that looks like a server fan ..! It was out of a dead variable speed drive from memory. I'm sure I have some around half this size...
le-cerveau Posted April 25, 2018 Posted April 25, 2018 27.1 CFM = 46m3/h = 12.7 l/s, more than twice the required WC extract rate for Building Regs!! In my design I planned on just over 6l/s for the WC room plus just under 6l/s split between two cisterns. I ended up with 3 - 3.5 l/s per pair of cisterns and that is fine, no complaints of lingering smells. This gives 11.8 - 13.7% of your potential flow, however you will need to take in account pressure losses! I measures the cistern flow pipe before the toilet seat was mounted, wouldn't know how to do it now that are fitted!
Onoff Posted April 25, 2018 Posted April 25, 2018 (edited) @le-cerveau, how about 7.77 CFM? About 25% of the first one. Thinking though that my diy set up will be lossy around the flush plate? Or...I fit the bigger one and a little pwm speed drive. If I can smell it, I turn it up! Something like this: https://www.esr.co.uk/products/frame_motor-control.htm Edited April 25, 2018 by Onoff
le-cerveau Posted April 25, 2018 Posted April 25, 2018 37 minutes ago, Onoff said: @le-cerveau, how about 7.77 CFM? That is probably a more realistic value, The losses are more likely to be restrictions due to pipework etc.
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