Mechanical Ventilation (MVHR) and Opening Windows

B

Buddyboy

Registered User
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799
Hi all,
my conundrum is that I am installing new windows and MVHR. I don't think the windows need to be openable, as the MVHR will take care of the ventilation.

However, (suprise, suprise ) my wife does not agree, and thinks that we should be able to open the windows to let in air. To be honest I don't think she has the same faith that I do in MVHR and airtight houses.

So, has anyone got mechanical ventilation, and what sort of windows do they have ?

By the way, it's a bunglow, so all rooms will be ventilated.
 
My understanding is that you should not have to open the windows as the heat exchanger will regulate the temp also.

By the way.. what type of system did you go for & why pick that one (asking as I am looking into it at the moment- but there are a lot of diff brands on the market)
ninsaga
 
All habitable rooms will (probably) require fire escape windows.
(The probably has to do with circumstances where a Fire Engineer approves an alternate system which has the equivalent function of providing escape routes in event of fire)
 
I was waiting for someone to bring up the fire escape issue. Some of the issues that sprung to mind, and I don't know the answers are

The existing windows only have small openings at the top, and therefore do not allow escape in the event of a fire. There are no large opening windows in the whole house.

So, can they be replaced like for like, or do any new windows in an existing house need to have large openings.

And where does the fire engineer come into it. Are replacement windows in existing houses inspected by a fire engineer?

Would a hammer, e.g. "In case of fire break window" beside the window suffice?
 

I am going for the ERV 300 from MTD solutions.
[broken link removed]

I came across them at the self-build and they impressed me with their approach.
I have talked to them since and again, I was impressed with them. The system seems to be fairly advanced, and a lot of the controls are automatic. e.g. it senses when there is an increase in moisture, e.g. a shower (or large party on), and increases the throughput accordingly. It also claims 97% effeciency in heat recovery.

Estimated installation coast is €5k + VAT.
 
I'm also probably going to go with the same unit. A guy called and went through all the installation etc and I liked what he had to say. Having said that I'd like to hear about the experiences of others who installed this unit.

Re the windows, my architect was concerned at the thought of us not opening the windows. Also I'm wondering what you'd do during those glorious summer days when you'd love to have a cool breeze through the house i.e. through open windows.
Just my thoughts
F.
 

The system itself has a summer bypass, where it ventilates but doesn't go through the heat exchanger. This should provide cool air. I also am contemplating having a selectable inlet. Taking air from the west side in the winter, where it is slightly warmer and having a pre-heater solar air heater (same as a solar water heater, except it is air in the frame rather than water pipes), and taking the air from the north (shaded) side in the summer.

So this gives a regulated amount of cool air, which is the same during windy days and windless days.

The jury's still out by the way (I haven't convinced her yet ) We will probably compromise (in other words, she will get her way), and have openings in the windows, which she will then never want opened as it will be too draughty
 
Buddyboy said:
We will probably compromise (in other words, she will get her way), and have openings in the windows, which she will then never want opened as it will be too draughty
Click to expand...

Except when
* the electricity is off
* the unit is malfunctioning
* you are trying to sell the house, and non-opening windows puts someone off

No harm having them. You don't have to use them.
 
Don't know much about the mech vent systems, but I do know that in a house any habitable room requires a window that can be used for means of escape. If the house was built after the 1997 Building Regulations came into force, then each window requires an unobstructed opening of 850mm high and 500mm wide and easliy openable from inside.
I would be very very cautious about blocking up your windows or providing the non-openable type.
 
Mugsgame,
you have a point. Five of the current windows are double glazed and have openings. We may be keeping these windows, depending on the cost of replacing them. Heavier curtains would probably be a cheaper option.

Tufty1,
the house was built prior to 1997. By replacing the windows, do you now have to comply with this, or can you replace like with like?
 
You can replace like for like in that case. But ask yourself, why is there now a regulation specifying the size of window openings? For the very good reason, to allow people to escape in the event of a fire. If you don't have openable windows, you ain't getting out!
Personally, I would'nt touch a house that had non-openable windows, which would not allow me or my family to get out in the event of a fire and I would question anyones motives who believes this is acceptable.
By the way, I am in the fire industry and have many times seen the outcome of people not being able to get out a window in the event of a fire.
 
tufty1 said:
By the way, I am in the fire industry and have many times seen the outcome of people not being able to get out a window in the event of a fire.
Click to expand...

You have a very good point there.

And in thinking about it, that is another reason for replacing the existing double glazed windows (which are all in the bedrooms). I can replace them with ones that allow egres. As these are also in the guest bedrooms, the possibilitys of not replacing them don't bear thinking about. And it more than justifies the expense.

All the other rooms will have external doors, so non-opening windows are fine.
 
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