VMC or fan?

[Corona]

@billybutcher

In practice I wonder if our VMC contributed to the problem of damp when left running over the past 18 months or so - because Brittany is, well, often a bit damp and the VMC just draws damp outside air into the building.

I’ve taken to leaving a small dehumidifier funning on constrant drainage - the power consumption is about the same

Yes if the outside air is wetter than inside it would be a bad idea to introduce that into the building. I cant quite believe a powered dehumidifier is about the same as a VMC but resonably low cost either way. Unfortunately dumb machines cannot control environments very well, its why I am involved in building management systems these days.

[Roboman]

Hello, I thought I’d throw in my three-penneth as there doesn’t seem much detail in this thread. I’ve been thinking of replacing my VMC as it’s been running 24/7 since before we bought our house 16 years back… I think it deserves a rest

The cost of running a VMC is minimal. Here’s a link to a UK site that does a cost comparison … if you are as adverse to clicking links as I am, then go to the site through your own search engine …

Energy Saving Lighting Electricity Cost Calculator

I’ve used this one as the cost unit happens to reflect what I pay to ENGIE, but in GBP instead of EUROs, ie 0.24/kWatt

The power of a VMC depends on the model, so off the Brico depot to browse for more information … I see power consumption between 20Watts and 60Watts … this is standard running versus boost when the bathroom is damp and/or heat recovery with double flux.

Let’s average this to 30Watts … this is an hourly measure, like a light-bulb. So the annual power consumption is calculated in the same way: 30 x 24 x 365 = 263,000 Watts per year.
Cost depends on your provider, but at 0.24Euros per kiloWatt … 0.24 x 262 = 63Euro per YEAR.
The rest depends on your preferences:
VMC vs Bathroom fan is like an aircon split system vs wall (banger) installation … both can be equally efficient, it is the noise that is relocated.

Cost of VMC and ventilator/ cost of installation … again, personal preference, what is important to you… cost/benefit???

The VMC is designed to run 24/7/365 to circulate air and keep your house damp free … we have an old vigneron house, upgraded with double-glazing etc, which was our holiday home until retirement in 2015. We have never seen or smelled any damp during all that time; we lock up and go with complete confidence.

If you install a VMC please ensure it has it’s own contact breaker.

I hope this helps and wish you good luck with whatever choice you make.