MVHR and bathrooms

houseyhouse

Considering putting demister mirrors in my bathrooms during renovation but not sure if it’s worth doing when we’re getting MVHR. Will the mirrors even fog up much after showers with these types of ventilation systems?

Calahonda52

4 considerations

Mirror surface temp

room air temp

location of extract vs source of water vapour.

will you use boost when showering?

I always try put it over the shower and use a small drop down in the ceiling around the shower to retain the moisture vapour somewhat to give the extract time to deal with it

samcr440!

Hi OP

I have MVHR in my house. We use the boost when showering. The vent for my shower is over the shower itself. I don't take long or a very hot shower and the mirror will be clear after me. The wife on the other hand…. We have the mirrors with demister and we use them after the long and hot showers

We often shower with the bathroom door open and then the mirror only slightly mists and subsequently clears very quickly. However if I have the bathroom door closed it will steam up and then takes about 5mins to clear. The MVHR unit has a built in humidistat but it rarely triggers when showering. I sometimes put on a boost when showering but since i have to go through my phone app to trigger it so I rarely bother. Nothing but the mirror and the shower screen mists up and there is no condensation on any of the walls.
So if its important to you to be able to look in the mirror after a shower then its probably not a bad idea to add heated mirrors. Alternatively if you are adding more home automation you could add a localized humidistat in the bathroom and get that to trigger the MVHR boost.

Dr.Tom

https://www.boards.ie/discussion/comment/122632578#Comment_122632578

Can you elaborate on the "small drop down in the ceiling" comment please?

houseyhouse

Thanks everyone. I think we’ll have a humidistat and a boost function in the bathrooms but it seems like it might be worth doing in the family bathrooms anyway. Long showers and looking in the mirror seem to be favourite pastimes for my teenagers ;)

What about towel rads? We’ll do them upstairs but the downstairs bathroom will have underfloor heating. Is it worth adding an electric towel rad?

Bass Reeves

https://www.boards.ie/discussion/comment/122632692#Comment_122632692

Kinky devil showering with the door open

https://www.boards.ie/discussion/comment/122632859#Comment_122632859

A demister mirror will only encourage them to have longer showers and spend longer looking at the mirror

Calahonda52

https://www.boards.ie/discussion/comment/122632768#Comment_122632768

extreme case I have seen is a fully enclosed shower to trap the water vapour

Others have retro fitted a fan over the window and run a boxed out duct to the shower and put the drop-down full width of shower

mjp

We have mvhr but the boost is controlled centrally downstairs and none on bathroom. Couldn't do without the demister on mirror and can be a pain the odd time forget to turn on the light with it before shower. I'd def get it as don't have to be turning on boost on mvhr then.