Air quality with mvhr

[lizzie]

anyone know what you would expect indoor air quality levels for pm2.5 & pm10 to be when mvhr in use with highest level filters......

the same as outside

better than outside

worse than outside

 

thank you for any input

[Jeremy Harris]

Depends on the intake filter and how well sealed to the MVHR it is (we've seen some examples here where filters aren't that well sealed in some cases).  A G4 filter will filter down to about 10µ, an F7 filter will filter down to about 1µ.  So an F7 filter should remove all PM10s and a lot of PM2.5s (the numbers in the PM designation is the particle size in µ).

[lizzie]

@JSHarris thank you!  I dont think my mvhr is as effective as it should be so I bought a meter.  I have F7 filter in both sides.

 

My indoor air quality is the same if not worse than outside.  I am sitting at my desk and getting readings of 23 for PM2.5 and 38 for pm10 in this room.  Outside is reading 25 for pm2.5 and 35 for pm10. I wonder if its the drain smells  that may be from the gurgling trap they are always more evident in this small room.

[Jeremy Harris]

You shouldn't be getting an particulate measurements (PMs) from drain smells, but you will get them from any dust particles in the air, so shed skin flakes, microscopic fibre fragments shed from clothes and soft furnishings, etc.

 

Just counting the particulate concentration doesn't tell you much, unless you also have an idea as to what those particulates are.  So, as an example, measuring particulates outside, near a road, means you'll have a pretty high likelihood of measuring vehicle-related PMs, which can be confirmed if you also measure something like NOx concentrations as well.  Measuring particulate concentration in open countryside will most likely be measuring dust and pollen, plus things like spores.  Measuring particulate concentration in a house where the intake filter is a well-fitted F7  (no point in having an F7 on the exhaust - change it for a G4, as all the F7 is doing is costing you more in additional resistance and electricity consumption through the MVHR, and reducing the MVHR efficiency) should mean that the particulate concentration will be mainly harmless stuff like skin flakes.  We each shed around 30,000 to 40,000 skin cells per hour, and most of then end up in the air.  A skin cell is around 25 to 40µ so will definitely register as a PM10!

[lizzie]

@JSHarris thank you............... so I need to change the exhaust filter back to the bigger one, I didnt realise I should have different on each.

 

I measured outside, on the drive, no vehicle fumes or plants out there its a hard surface desert LOL.

 

TBH I was expecting a meter that measured more than these 2 items but I think I bought the wrong one, got dizzy from looking at so many.  I just feel the air quality in this house is not great and the intermittent smells are not helping. Its almost better with mvhr off some and windows open on tilt.  Maybe the filter thing is why I am not getting great air quality.  Will order G4 filters tomorrow.

[Jeremy Harris]

The exhaust filter won't change the indoor air quality, but will make the MVHR run more efficiently, as there will be less flow resistance on the exhaust side,

 

Measuring air quality is pretty complex, and hard to do properly.  A simple particulate counter, that measures particulates in two dimensional bins (say, PM10 and PM2.5) doesn't really tell you much on it's own.  You can be pretty certain that a well-fitted F7 intake filter will keep out most particulate allergens and harmful stuff from vehicle exhausts, combustion devices etc, but there are loads of harmless particulate sources inside the home, from all those tens of thousands of skin cells being shed all the time, through fragments of fibres from clothing and furnishings, to dust mites and particulates created when cooking food.

 

The harmful small particulates tend to come from combustion, so vehicle exhaust, burning coal, wood and oil, etc.  There are also gases emitted from combustion sources that are harmful, like nitrogen oxides etc, which you cannot filter out. 

 

Finally, any new house will take time for all the volatiles used in its construction to evaporate out of the structure.  There are loads of these, from adhesives used in lots of materials, through to the paint used in the house, and they can take several months to evaporate away.  The MVHR will help a great deal, by guaranteeing regular air changes, so the concentration of volatiles should drop steadily over the months, but it can be a slow process before the majority of the volatiles have evaporated off, plus there will always be new volatiles coming in, on everything from packaging to printed media.

[NSS]

Hi @lizzie, I've not done any measurements here but totally agree re changing exhaust filter to G4 and, as @JSHarris says, it takes a while for a new home to 'settle'. We've been in ours for 10 months now and the benefit to Mrs NSS has been remarkable. For 18 months before we moved in she nebulised twice daily. In the last 8 months she's used it twice, in total!

[lizzie]

I was hoping to feel the same sort of benefits but for various reasons I have not as yet and I am 4 :months in. The very hot summer has meant windows open (overheating issues) and the trap drying out and drains smell that I get is unpleasant.   I just dont think my mvhr is working properly all the time, I think I need the installer back its more than house settling I feel. I am so pleased for your wife.  She is a beacon of hope for the future. Thnak you.. @NSS

[TottenhamFC]

Hi all @lizzie @NSS @JSHarris-

sorry to jump into this feed but I hope you guys might be able to help me out. My mvhr unit is getting really noisy and some colleagues suggested that I should try and change the filters for it. I’ve looked online and they’re all about £50 or more and really difficult to get hold of. Any idea of where I can get them but for a reasonable price, either online or in store? 

Also, I have children and obviously want to make sure they’re in a clean environment at home. If I don’t change the filters regularly, is the air in my home getting worse? Bad enough to have an impact on their health? 

Thanks for listening 

Edited September 3, 2018 by TottenhamFC

[Temp]

21 hours ago, lizzie said:

I was hoping to feel the same sort of benefits but for various reasons I have not as yet and I am 4 :months in. The very hot summer has meant windows open (overheating issues) and the trap drying out and drains smell that I get is unpleasant.   I just dont think my mvhr is working properly all the time, I think I need the installer back its more than house settling I feel. I am so pleased for your wife.  She is a beacon of hope for the future. Thnak you.. @NSS

 

Traps should only dry out if not used for say two weeks. Check you don't have a design problem with the water being syphoned out. The cure might be to add a AAV.

[Temp]

6 hours ago, TottenhamFC said:

Hi all @lizzie @NSS @JSHarris-

sorry to jump into this feed but I hope you guys might be able to help me out. My mvhr unit is getting really noisy and some colleagues suggested that I should try and change the filters for it. I’ve looked online and they’re all about £50 or more and really difficult to get hold of. Any idea of where I can get them but for a reasonable price, either online or in store? 

Also, I have children and obviously want to make sure they’re in a clean environment at home. If I don’t change the filters regularly, is the air in my home getting worse? Bad enough to have an impact on their health? 

Thanks for listening 

 

What sort of filters are they? Our system is quite crude and the filters are very coarse. Only designed to stop bugs getting in but they can be washed out with a hose.

[NSS]

7 hours ago, TottenhamFC said:

Hi all @lizzie @NSS @JSHarris-

sorry to jump into this feed but I hope you guys might be able to help me out. My mvhr unit is getting really noisy and some colleagues suggested that I should try and change the filters for it. I’ve looked online and they’re all about £50 or more and really difficult to get hold of. Any idea of where I can get them but for a reasonable price, either online or in store? 

Also, I have children and obviously want to make sure they’re in a clean environment at home. If I don’t change the filters regularly, is the air in my home getting worse? Bad enough to have an impact on their health? 

Thanks for listening 

Can't really comment ref the noise and whether changing the filters will address that, but I guess it's possible if the filters are particularly clogged and the fan is struggling as a consequence. As for cost, you don't mention which MVHR you have but you might want to look at www.topswtwfilters.nl/en I've not used them myself but believe others on here have.

As for health implications, if the house was designed to have MVHR then it's not only poor air quality that could result if it's not running as designed. How much that could affect your kids is hard to say but, for example, if they suffer with asthma or the like then it could be detrimental. 

[Jeremy Harris]

7 hours ago, TottenhamFC said:

Hi all @lizzie @NSS @JSHarris-

sorry to jump into this feed but I hope you guys might be able to help me out. My mvhr unit is getting really noisy and some colleagues suggested that I should try and change the filters for it. I’ve looked online and they’re all about £50 or more and really difficult to get hold of. Any idea of where I can get them but for a reasonable price, either online or in store? 

Also, I have children and obviously want to make sure they’re in a clean environment at home. If I don’t change the filters regularly, is the air in my home getting worse? Bad enough to have an impact on their health? 

Thanks for listening 

 

There are a couple of different companies that can make and supply filters for just about any MVHR at a lot lower price than the original manufacturers ones, but as @Temp says, you need to know what size and type the filters are.

 

Generally MVHR filters need to either be changed (if they are non-washable) or cleaned/washed at least every 6 months.  I've found that our intake filter gets badly fouled after 6 months and wouldn't want to leave it any longer before changing it.

 

I've had custom replacement filters made for our Genvex MVHR by this company  http://www.jasun-envirocare.com/for a great deal less than the cost of the real Genvex ones, and they look identical except for the label, but our unit has non-washable paper filters, so I don't have the option of being able to clean them, only try and vacuum them if they aren't too bad or replace them.

[P1234]

Hi All,

 

Does anyone happen to know if it is ok to change service the MVHR once a year rather than every six months. I am not in the flat most of the time. The MVHR button is always on. I do not cook or do anything dusty. I hoover weekly when I am around. The air flow from the ceiling vent seems the same as it has always been when it was last serviced in January and the serviceman confirmed everything was fine.

 

I live in London. My flat is not on a main road. There are hardly any cars on my road. I am on the 3rd floor so quite high up above ground level. I do not open windows wide the whole day. Only halfway for around an hour daily if I am around.

 

The flat was built 2-3 years ago.

 

Just that all the dust bugs and things coming out of the ceiling holes and ladders really stress me out. So trying to minimise this event.

 

Just wondering how often people in a similar environment to mine have their MVHR serviced.

 

Any help much appreciated.

 

Thank you.

[Jeremy Harris]

The main issue is the incoming fresh air filter, not the extract filter.  This has potentially dirty air flowing through it all the time, whether the flat is in use or not, as long as the MVHR is turned on.  I find that 6 months is the absolute maximum limit for our filter changes - this is what a six month old fresh air intake filter looks like compared to a new one, and we live in a very rural area, with pretty clean air:

 

[TottenhamFC]

Hi All

thanks for coming back to me. My machine is A Vent Axia Lo Carbon Sentinel Kinetic V MVHR system. I think the system is about 4 years old. 

 

Those images show exactly what I’m faced with. Hoovering them is almost impossible! I’m living in a more built up area and I’m really keen to get into the habit of changing them regularly once I can buy a bulk of them. 

 

Some of you are suggesting getting them manufactured. Do you not need them to be “official” filters relating to your brand. Eg. Vent axia for me? 

 

Also, I’ve seen on some blogs there are different types. Eg. G3 and G4 and some sort of pollen filter. Do you think it makes that much difference?! 

 

I have put a few calls today in to developers of new housing estates to see if they have suggestions on where I could source some. 

 

 

13 hours ago, NSS said:

Can't really comment ref the noise and whether changing the filters will address that, but I guess it's possible if the filters are particularly clogged and the fan is struggling as a consequence. As for cost, you don't mention which MVHR you have but you might want to look at www.topswtwfilters.nl/en I've not used them myself but believe others on here have.

As for health implications, if the house was designed to have MVHR then it's not only poor air quality that could result if it's not running as designed. How much that could affect your kids is hard to say but, for example, if they suffer with asthma or the like then it could be detrimental. 

 

[TottenhamFC]

@P1234

 

my manual says to service the mvhr system every 12 months but I think this seems unreasonable albeit living in London may mean this is needed more often. 

 

I feel that if you if you can change and replace your mvhr filters (or hrv - not sure what the difference is between the two definitions) more regularly you could probably get away without servicing it for years ! 

[Declan52]

I have more or less the same unit, mines the b+ model. It takes about 1 min to swap over the filters. Each 12 months I take out the central core of the heat exchanger and put it in a bath and run hot water through it. Let it sit out side and dry of. Or use a hair dryer if you can't do that. It's never that bad but I live in the countryside. 5 mins takes it out but just be careful with the screws as they are a pain in the arse to line up when you put it back together.

When you have the core out you can use antibacterial wipe and clean the inside.

All in it's a 45min job.

[Jeremy Harris]

There are several different filter grades and which you choose depends on where you live, whether you suffer from any allergies and how concerned you are about particulate pollution.  A G4 filter only filters to about 10µ and generally the most harmful particulates in urban areas (mainly from combustion processes, like vehicle engines) are less than 2.5µ, what are often called PM2.5s.  To filter most of these out needs an F7 filter, which filters down to about 1µ.

 

After market filters are generally just a good as the manufacturers own brand ones, and may even be better made in some cases.  I've been using after market ones for the past couple of years with no problems at all.

 

In my view, checking the intake filter every 12 months is too long a time interval.  Our MVHR would almost certainly have virtually stopped working if I left the intake filter that long; it's bad enough after 6 months.

[TottenhamFC]

Really helpful @JSHarris and @Declan52

 

I wrote on another blog on this site yday and just seen that someone has really helpfully suggested buying the replacement vent axia air filters from filterworld or https://filtermate.co.uk/

 

Theh both look like the stock our ones for a much more reasonable price! 

 

@Declan52 good to hear you have a similar machine. have you used filtermate or filterworld? Would you recommend them? The reviews look good but it would be good to know where you get yours from. 

 

Everyone makes seevicing the units sound simple. I will be trying this myself moving forward! 

 

Thanks 

[Declan52]

I get mine from here. I ordered 10 pairs near 4 years ago as they where on a deal at the time. 

https://www.fairair.eu/en/hrv-filters/vent-axia/

[TottenhamFC]

Ordering in bulk is the way forward. Thanks all for your help. 

 

@Declan52 out of interest do you use G3 or G4? 

 

Im going to try filtermate I think because they offer free delivery. I’ll let you know how I get on. 

[HerbJ]

For anyone with  a PAUL MVHR, Paul Scotland offer very competitive prices for single sets of filters  at the moment - see https://www.paulheatrecovery.co.uk/shop/  

 

[Declan52]

1 hour ago, TottenhamFC said:

Ordering in bulk is the way forward. Thanks all for your help. 

 

@Declan52 out of interest do you use G3 or G4? 

 

Im going to try filtermate I think because they offer free delivery. I’ll let you know how I get on. 

Mine are G4.

[P1234]

On 04/09/2018 at 12:00, JSHarris said:

The main issue is the incoming fresh air filter, not the extract filter.  This has potentially dirty air flowing through it all the time, whether the flat is in use or not, as long as the MVHR is turned on.  I find that 6 months is the absolute maximum limit for our filter changes - this is what a six month old fresh air intake filter looks like compared to a new one, and we live in a very rural area, with pretty clean air:

 

Thank you. And wow that is dirty. I live in a block of flats. Was informed the ventilation system for all the flats are connected. I am hoping this means that all flats use the same incoming fresh air duct and filter which has been cleaned by the block management elsewhere in the building. And that the only filters in my flat are the extract filters.