A question for all you out there with MVHR.

What are the best and most useful controls?

I am thinking that I should have humidity sensors that auto switch the unit to boost in every bathroom so that they switch to boost when having a shower etc and possibly another humidstat in the kitchen. Also a central boost switch downstairs maybe linked in with the kitchen one.

Also summer bypass - good idea?

I can understand individual sensors if you have multiple heat exchangers, or if you zone your house, but otherwise , why split the sensors out? Get a unit that detects humidity and adjust flow accordingly, that way you avoid wiring & sensor duplication.

We have a CO2 sensor as well, which allows the unit to run at low speed most of the time. It turns it up if the house is full of people, or when the gas stove is used (lots of CO2 from this). I think they should just come with both these sensors fitted.

Summer bypass - depends if you will use it, or switch off the unit & open windows at night. We had a break in pre mvhr, so I suspect we will keep it on to avoid leaving windows ajar.

As well as the security aspect of keeping windows closed in summer, hay fever sufferers might also want to do this and let the MVHR filters catch the pollen. In that case, summer bypass could contribute to cooling, though probably not enough on the really hot nights (wonder if they'll be any of those this year...)

Nigel

Thanks guys, this is valuable real world opinion, keep it coming - I suspect it will help a lot of folks specifying their MVHR.

an02ew,
if my calcs are correct, the 2 ducts @63mm dia will have a flow rate of 2.3m/s at 53m3/h. That's not an excessive speed, but you don't mention if that is the 'normal' flow or 'boost' flow. If it's 'normal', then I'd start to be a little concerned about noise at the intake shrouds during boost. Not so much of an issue when you are cooking and have the recirculating extractor fan running, but when it boosts due to bathroom humidity, then the kitchen could be a bit noisy.

Just consider that your 2 off 63mm ducts wil still only have half the area of a single 125mm duct, so velocity will be double - hence higher noise. Also, something to think about is that you may review the flow rate you run the MVHR at (once you'r living with it), as I find that the BRegs values (taken from the volumetric calc) are much greater than it need be to maintain a fresh environment. So you might possibly end up backing off the fan speeds for normal flow, but keep a good boost flow.

I considered the HRV 10Q plus (Titon unit I'm thinking of) for a recent project, and only discounted it because of the duct intake positions on the unit - otherwise I might well have gone for it.

Not sure I actually answered your question

thanks all