Ventilation Solution for Bedrooms in my house

Joined
14 Oct 2013
Messages
4
Reaction score
0
Location
London
Country
United Kingdom
Hi,

I have a problem in that both the bedrooms in my 2 bedroom Victorian house have poor/no ventilation when the windows are closed.

Closing the windows at night in the front bedroom which faces onto a road is essential for a good nights sleep because of noise outside : cars, people, aircraft.

The room at the back facing onto the garden suffers less from outside noise, but its window is located very close to two boiler outlet plumes from our house and the neighbors, so it's usually best to keep it closed at all times.

Both the rooms are located on the upper floor of the house, they make up the entire upper floor. We are desperate for a quiet nights sleep with good quality air.

I have thought about it a lot and come up with various ideas for solutions, all of which I am very unsure about because I am not in the know about these kinds of things :


Solution A

Both the rooms used to have fireplaces which have since been blocked up. No ventilation grills were put in the walls to ventilate the chimneys as various sources have recommended to me. I could create these ventilation grilles/holes to try and create air circulation in the room. I am guessing air would be sucked out through the grills creating a vacuum into which fresher air from downstairs would fill via openings around the bedroom doors.

However :

i.) Would this work ?

ii.) What if air came down the chimneys into the rooms? Couldn't this bring soot, poisonous gases from other nearby chimneys, and other bad stuff with it ?

iii.) With the doors closed in the bedrooms, wouldn't this prevent air from being able to get into the rooms ? It's nice having the doors closed to prevent noise coming in from the rest of the house.

iiii.) We want to install a gas fire with new flue in the lounge underneath the front bedroom, which shares the same chimney as the front bedroom,
wouldn't this interfere with this plan for vent grill in the same chimney upstairs ?


Solution B

Fit acoustic ventilation grills into the upper part of the exterior walls of both the bedrooms. Again, concerned about the effectiveness of this option in terms of ventilation and noise reduction. Also, concerned it would look odd on the outside, especially at the front and not even sure this is OK with the council / no other house on the street seems to have one at the front.


Solution C

Some other much much better solution that I haven't even thought of yet !


Any advice hugely appreciated,

Thankyou.
 
Sponsored Links
Joined
4 Nov 2010
Messages
5,912
Reaction score
603
Location
Cumbria
Country
United Kingdom
Solution C

Some other much much better solution that I haven't even thought of yet !
Might be worth looking into heat recovery ventilation systems - gives forced air changes, but recovers the heat from the extracted air. I believe the "typical" install takes warm damp air from kitchen and bathroom (the rooms usually suffering from/producing the most damp and supplies air to some central place like the landing.

In your situation, it might make sense to supply the fresh (but warmed) air into the bedrooms.

I do know what your problem is. I'm lucky enough to live in a quiet area looking out over fields. On the occasions I venture into the city, I often find it a toss up between getting no sleep because it's stiflingly hot and stuffy or getting no sleep because of the racket coming in the open window (or both !).
 
Joined
14 Oct 2013
Messages
4
Reaction score
0
Location
London
Country
United Kingdom
Hi,

Thanks for this suggestion. I am currently having a very tough time sleeping with noise outside/cars waking me up ; the bedroom window has to be open slightly or i cant breathe. So I am determined to sort out the problem.

It's an old house with thin/fragile bedroom ceilings so wouldn't any noise generated in the loft by this electrical equipment likely to be in hearing range? Also, the system sounds like it could be expensive to run. And I probably wouldn't want to bother with extracting air from downstairs / the kitchen & bathroom as they are some distance from the loft and I already have dedicated ventilation for those areas which is effective.

So perhaps just a passive system of an air inlet grill at the front of the house connected to two pipes in the loft leading to grilles in the ceilings of the two bedrooms might be a solution or at least a starting point, any thoughts about this? If this is viable, how would sound reduction from outside be achieved? As a rough idea, would coiling of the pipes reduce any possible noise? Would the pipes be very susceptible to dirt/mould? Which way would air be likely to flow, up and out of the house or the other way around? Could I configure it so air only flows one way ?

Thanks, very excited about solving this.
 
Joined
4 Nov 2010
Messages
5,912
Reaction score
603
Location
Cumbria
Country
United Kingdom
It's an old house with thin/fragile bedroom ceilings so wouldn't any noise generated in the loft by this electrical equipment likely to be in hearing range?
Yes, so it's important to a) pick a quiet system, and b) don't dit it on the joists. If it's well designed, it'll use a quiet and well balanced fan, so vibration should be minimal but with care you can avoid conducting any vibration into the ceiling.

Also, the system sounds like it could be expensive to run.
Shouldn't be. All you are running is a small, low power fan. The key is that the heat exchanger captures the heat that would otherwise be thrown away with just a ventilation system.

So perhaps just a passive system of an air inlet grill at the front of the house connected to two pipes in the loft leading to grilles in the ceilings of the two bedrooms might be a solution or at least a starting point, any thoughts about this? If this is viable, how would sound reduction from outside be achieved? As a rough idea, would coiling of the pipes reduce any possible noise? Would the pipes be very susceptible to dirt/mould? Which way would air be likely to flow, up and out of the house or the other way around? Could I configure it so air only flows one way ?
Very tricky.
Firstly, any airflow will be ill defined. You may get a flow one way, the other way, or none at all. Eg, wind wind on the front of the house, air pressure will push air in the way you want. With wind the other way, it'll suck air out of the grill and reverse the airflow. In still air, you get no air flow.

For sound reduction, a length of flexible hose will help (noise energy can easily pass out (or in) though it's flexible walls), but you may need an attenuator* which will further restrict air flow. Plus, all the air flow you have will be letting cold air on and warm air out.

* Attenuators may be something the air passes through (eg an open cell foam) which will restrict airflow, or a "straight through" design (inner perforated cylinder, outer solid cylinder, and acoustic wadding in between to absorb noise).
 
Joined
14 Oct 2013
Messages
4
Reaction score
0
Location
London
Country
United Kingdom
Hi,

So could I have a powered system without drawing in air from downstairs / the kitchen bathroom? How much would this kind of system cost ? Does the proposed position of the air inlet sound good? There is a chimney, so perhaps air could be outlet though that somehow? I had in mind the outlet grilles being positioned in the bedroom ceilings, does that sound realistic ?

Thankyou for your help.
 
Joined
4 Nov 2010
Messages
5,912
Reaction score
603
Location
Cumbria
Country
United Kingdom
BTW - I'm not an expert in ventilation either …

Yes, you can have a powered system without all the heat recovery stuff. The downside is that a) the air you blow in will be cold when it's cold outside, and b) the air that goes out to make room for it will take heat with it. That's what the heat recovery units are designed to do - recover that expensive heat and cut down on the heating costs compared to "plain ventilation".

In principal you want a grill somewhere that can get outside air without drawing in rain etc, some ducting, an inline fan (look at the noise specs and choose a quiet one), and some terminals. Potentially you might want a variable speed controller for the fan as well so you can experiment with different airflows and/or adjust it according to conditions. Also, you may want to consider a filter if the outside air can get dusty/dirty.

There are ventilation units (basically a fan and filter) designed to take the intake air from the loft. The argument is that the loft is generally a little warmer than outside - though that's much less the case these days with proper insulation. This would save you a hole in the building, but you would want a filter as lofts tend to be quite dusty - and in particular tend to have glass fibre particles floating around any time you disturb it. Lofts tend to be quite leaky (and in fact usually need to be to avoid condensation and the resulting timber rot), so this shouldn't be an impediment to taking air from the loft instead of from outside.


Don't under-estimate the discomfort from a cold draught ! You need to pick your terminals carefully - selecting ones that will direct the airflow along the ceiling (see Coandă effect), where it can mix with the warm air, and then sink down. You really don't want one that either dumps a column of air down onto whatever is underneath (or just onto the floor to make your feet cold), and you don't want one that allows a draught onto the room occupants.

When choosing your fan, it needs to be suitable for pushing air down a long length of ducting. This generally means selecting a centrifugal or mixed flow fan. The majority of small and cheap fans are axial - these don't generally have good pressure capability and so can offer poor air flow volumes down long ducts.
Rigid, smooth walled ducting give the best airflow - but it tends to duct noise as well. Flexible duct has significantly higher resistance to airflow, especially if not pulled tight to make it's walls smooth, but it doesn't tend to duct noise as much and is easier to route.
 
Sponsored Links
Joined
14 Oct 2013
Messages
4
Reaction score
0
Location
London
Country
United Kingdom
After a lot of thought, something like what you describe above sounds like what I need.

I have some more questions though:


1. The loft is very dusty so I think I would have to draw the air in directly from outside, somewhere. The only feasible place for this would be to the side wall of the house. This would be over the top of a thin alley/strip of land between my house and the neighbours house. It is quite muddy and damp in that alley, and the neighbours boiler plume (which would be about 8 metres away) tends to flow down there, so I am worried that the air being drawn in might be holding a lot of moisture/bad air, is this something I should worry about?

2. In order to have horizontal facing outlet vents as described in the post above, and to avoid having to make holes in the ceilings, I thought feeding the inlet ducts from the loft to the bedrooms upstairs and lounge downstairs through the old chimneys might be a good option. Would this be difficult?

3. Would the ducting require regular cleaning? I can imagine they might do, so if they were embedded inside the chimneys I guess that would them very difficult to clean?

4. The position I had in mind for the fresh/warm air outlets would be quite close to the bedroom doors; wouldn't this mean most of the fresh air would get sucked out of the doors instead of circulating in the rooms?

5. To get an idea of the performance, for example, if the inside of my house had a temperature of 23 degrees Celsius near the air extraction vent, and the temperature outside was 0 degrees Celsius, what kind of air temperature could I expect from the fresh/warm air outlet vents ?

6. Bearing all this in mind, can you suggest a suitable unit I could buy from the internet ?
 
Joined
4 Nov 2010
Messages
5,912
Reaction score
603
Location
Cumbria
Country
United Kingdom
1. The loft is very dusty
Most of the commercial units have filters - mostly because all air has a certain amount of dust/dirt in it and they need to avoid clogging the narrow passages in the heat exchanger. All lofts are "dusty" - I think that's more because they don't get cleaned than because they are naturally exposed to lots of new dust.
I think I would have to draw the air in directly from outside, somewhere. The only feasible place for this would be to the side wall of the house. This would be over the top of a thin alley/strip of land between my house and the neighbours house. It is quite muddy and damp in that alley, and the neighbours boiler plume (which would be about 8 metres away) tends to flow down there, so I am worried that the air being drawn in might be holding a lot of moisture/bad air, is this something I should worry about?
The boiler is something I'd be considering, but I don't know how big an issue it really is. I don't think being muddy at ground level isn't really an issue though.
2. In order to have horizontal facing outlet vents as described in the post above, and to avoid having to make holes in the ceilings, I thought feeding the inlet ducts from the loft to the bedrooms upstairs and lounge downstairs through the old chimneys might be a good option. Would this be difficult?
Wouldn't have thought so.
3. Would the ducting require regular cleaning? I can imagine they might do, so if they were embedded inside the chimneys I guess that would them very difficult to clean?
From my limited experience with aircon in the office is that the filters will need cleaning, but not the ductwork.
4. The position I had in mind for the fresh/warm air outlets would be quite close to the bedroom doors; wouldn't this mean most of the fresh air would get sucked out of the doors instead of circulating in the rooms?
I think there tends to be considerable airflow around most rooms - the radiators cause quite a lot of convective currents for example. If it's a concern, fit a direction diffuser and direct the airflow along the ceiling into the middle of the room.
5. To get an idea of the performance, for example, if the inside of my house had a temperature of 23 degrees Celsius near the air extraction vent, and the temperature outside was 0 degrees Celsius, what kind of air temperature could I expect from the fresh/warm air outlet vents ?
It depends on the airflows - especially whether they are balanced or not. If the inlet airflow rate is higher than the extract, then you maximise heat recovery, but the supply air temperature will be cooler than the extract. Assuming the flows are balanced, then it depends on efficiency, as a very rough approximation (which ignores any latent heat from condensing water from the extract air), then just look at the claimed efficiency. Delta-T on the supply will be roughly delta-T on the extract * efficiency. So at 70%, and with your stated temperatures, I'd expect around 16˚ supply (23 * 0.7); or at 90% I'd expect around 21˚. 16˚ is cool enough to feel as a cold draught, but not nearly as bad as a 0˚ from an slightly open window !
6. Bearing all this in mind, can you suggest a suitable unit I could buy from the internet ?
No thoughts on that. Having looked, the units seem to be either very small or very expensive - hence why I'm looking at making one.
 
Joined
30 Jan 2012
Messages
18
Reaction score
0
Location
London
Country
United Kingdom
A few more questions :

1.) As I am very sensitive to noise when I am trying to sleep, an idea/quantification of how much noise I could expect from the outlet vents whilst the system is on is important. There is plenty of space in the loft for long ducting.

2.) If I had 4 internal vents, could i easily switch between which ones suck and blow?

3.) Is it common for these HRV systems to remove water vapour from the air taken in from outside ? If so, wouldn't this water need draining off to somehere? As the existing plumbing system is a long way from the loft, this could be tricky/expensive.

4.) If these HRV systems are so great in terms of saving energy, why don't I hear of more people installing them in the UK? Compared to things like loft insulation or solar energy, it isn't something I hear a lot about.

5.) Madcap idea ? ; I have been thinking about having a gas fire installed downstairs in the lounge, which might have a flue leading to top of one chimney. I imagine this flue could get very warm, so is there any way I could integrate the flue with the HRV ducting to boost the temperature ? E.g intertwining pipes.

6.) Probably another madcap idea but, since I am going to all this effort thought I may as well ask : boiler flue outlet is in very annoying position blasting out wet air over mine and neighbours windows/property/back door area; any chance i could integrate it into HRV system so the flue plume is sucked up with the rest of the waste air?
 
Joined
4 Nov 2010
Messages
5,912
Reaction score
603
Location
Cumbria
Country
United Kingdom
1.) As I am very sensitive to noise when I am trying to sleep, an idea/quantification of how much noise I could expect from the outlet vents whilst the system is on is important. There is plenty of space in the loft for long ducting.
Dunno - no direct experience of them (yet). But as a generality, flexible ducting is quieter than rigid ducting - the flexible sidewalls allow noise to "escape" while rigid ducting channels it along the pipe. However, flexible ducting has a higher resistance to airflow.
2.) If I had 4 internal vents, could i easily switch between which ones suck and blow?
The simplest way to do it would be to physically swap the pipes round on the unit - but unless it's a few "lets try these arrangements and then leave it at the best" you'll find it a PITA to do. In principal you could use various diverters/dampers to do it, but IMO it wouldn't be worth the effort.
3.) Is it common for these HRV systems to remove water vapour from the air taken in from outside ? If so, wouldn't this water need draining off to somehere? As the existing plumbing system is a long way from the loft, this could be tricky/expensive.
No, they don't remove water from the intake air - but they do remove water from the extract air. Reason is: you use the warm extract air to heat the intake air - the intake air therefore gets warmer and thus relative humidity goes down, but the extract air gets cooler and relative humidity goes up. If the extract air is moist enough, it will cool to the dewpoint (for that amount of moisture) and water will condense out - the units have a drain for this, and you need to allow for it to go somewhere.
4.) If these HRV systems are so great in terms of saving energy, why don't I hear of more people installing them in the UK? Compared to things like loft insulation or solar energy, it isn't something I hear a lot about.
Because in this country we are backwards in many things, and certain trades are very much in the "we've always done it this way, be off with your new fangled magickery". If you want an example, just try mentioning "thermal store" over in the plumbing section :LOL:
5.) Madcap idea ? ; I have been thinking about having a gas fire installed downstairs in the lounge, which might have a flue leading to top of one chimney. I imagine this flue could get very warm, so is there any way I could integrate the flue with the HRV ducting to boost the temperature ? E.g intertwining pipes.
Well in theory you could construct a concentric pipe and do that, but there are practical issues to be aware of :
1) If you cool the flue enough, it will stop drawing air. The flue relies on the warmer air creating a natural updraught to take away the combustion products.
2) Also, if you cool the flue enough, you'll get condensation (which is acidic) - either eating into the fabric of the flue, or running down and causing havoc in or behind the fire.
3) If there are any leaks in the inner pipe, then you could draw combustion products into the ventilation intake - this is "not a good thing".
As an aside, this is effectively what is done in many (most ?) light aircraft. There is a shield places round part of the exhaust (usually the silencer as this is the largest part) so that ventilation intake air passes through a smallish gap between the exhaust and the shield and is thus heated. It has the very considerable issue that if the silencer develops a leak, you get exhaust fumes (containing, amongst other nasties, carbon monoxide) into the cabin - which again is "not a good thing" and people have died from it.
6.) Probably another madcap idea but, since I am going to all this effort thought I may as well ask : boiler flue outlet is in very annoying position blasting out wet air over mine and neighbours windows/property/back door area; any chance i could integrate it into HRV system so the flue plume is sucked up with the rest of the waste air?
Again, you have similar considerations. It's not something that's escaped me either, and I'm sure there must be some energy to be harvested - but it'll be difficult without interfering with having a boiler flue compliant with manufacturer specifications. I don't think I'd be wanting to draw the combustion products through the ventilation system - apart from the safety issues, they are a veritable cocktail of chemicals and slightly acidic.
 
Joined
4 Nov 2010
Messages
5,912
Reaction score
603
Location
Cumbria
Country
United Kingdom
6.) Probably another madcap idea but, since I am going to all this effort thought I may as well ask : boiler flue outlet is in very annoying position blasting out wet air over mine and neighbours windows/property/back door area; any chance i could integrate it into HRV system so the flue plume is sucked up with the rest of the waste air?
Again, you have similar considerations. It's not something that's escaped me either, and I'm sure there must be some energy to be harvested - but it'll be difficult without interfering with having a boiler flue compliant with manufacturer specifications. I don't think I'd be wanting to draw the combustion products through the ventilation system - apart from the safety issues, they are a veritable cocktail of chemicals and slightly acidic.
Thinking a bit more about this, one way might be to use a manufacturer's approved plume diversion kit, closely wrap the pipe with some copper pipe, and then well insulate the lot. Then use the slightly warm water to pre-heat the cold input to a thermal store.
In practice, the heat transfer area is going to be quite small - just the are of contact between the gasses and the inside of the pipe - so the results will be quite minimal and unlikely to be worth the effort.
To get decent heat transfer you'd need a good heat exchanger with a large surface area - but then you're back to it not being an approved flue for the boiler.

On the other hand, a Google search turns up some interesting results. Seems it's been though of, and Vaillant have a unit for this - no, I'd not heard of it either !. Bet it's not cheap :eek:
And some interesting information at http://www.superhomes.org.uk/resources/passive-flue-gas-heat-recovery-devices/ - including the detail "Costs start at around £1,200. Payback time depends on the type of boiler and usage level, and whether you fit it yourself or get in a plumber." which probably explains why I've not come across one. I bet if you ask most plumbers, you'll get that specially trained "sucking through teeth" that they stereotypically do and then a long list of reasons why you shouldn't fit one !


EDIT: The Vaillant one seems a bit cheaper than that, £736 from Plumb Nation.
 
Sponsored Links
Top