condensation resulting in mould growth in rental property

marmitemayhem

Answering slightly for Richard as when I installed my PIV I asked the same question as my PIV outlet is <2m from the shower extractor fan, and this is an "always open" vent (e.g. when fan isn't running the vent is till open)


Their response was: "The unit will work perfectly without worring about vents etc"


and they are right I have also installed vents into previously closed up fireplaces - and my house is not airtight by any stretch.


(My fan isn't on all the time, just when the shower is on (also runs shower light, and +30m once shower light off - its the 550m3/h one - which as ducting isn't full size it is probably nearer 2-300m3/h actual.)


The answers you will get from PIV users make it sound very salesy and TV info-mercial-esque as (in our case) it does unbelievably just work.

pd001

marmitemayhem wrote: »

Answering slightly for Richard as when I installed my PIV I asked the same question as my PIV outlet is <2m from the shower extractor fan, and this is an "always open" vent (e.g. when fan isn't running the vent is till open)


Their response was: "The unit will work perfectly without worring about vents etc"


and they are right I have also installed vents into previously closed up fireplaces - and my house is not airtight by any stretch.


(My fan isn't on all the time, just when the shower is on (also runs shower light, and +30m once shower light off - its the 550m3/h one - which as ducting isn't full size it is probably nearer 2-300m3/h actual.)


The answers you will get from PIV users make it sound very salesy and TV info-mercial-esque as (in our case) it does unbelievably just work.

Thanks for you input, it is appreciated.

So, the fan in your bathroom runs on for 30 mins after the light is turned off.
Does that not meant that the bathroom get very cold in winter?
As well as all the stale air in the bathroom it must pull out a hell of a lot of heat from the upstairs of the house?

Do you have the PIV unit that includes the heat or the normal non heat one?
I assume that you had a condensation/mould/damp issue of some description which prompted you to install PIV?

I can see how a PIV unit works.
By that I mean that pulling, or in the case of PIV pumping, fresh air into a house is a good thing.

However, I struggle to see how it ventilates the whole house and doesn't just push stale air out through the point of least resistance, ie maybe a vent in the bathroom, or indeed maybe an open window somewhere else in a house?.

I am not saying PIV doesn't work. After all there are many many reviews that say it does work. I am still open minded about it.

richardc1983

Pd001 you are partially correct in what you are saying. You seem to be gaining a good understanding of how these systems work. To answer your question fully the drimaster has an airflow rate between 10 & 70 litres a second. This is set at install via a speed switch set between 1&6. The Cyfan has an air flow rate between 6&60ls configurable via the dials mounted on the unit itself.

So in my example our drimaster is set on speed 3 which provides air flow between 30&42ls depending on loft temperature. If loft is warmer than 15c it speeds up to boost airflow and bring warmer air into the house, great in spring or autumn. The Cyfan is set to a maximum boost (when light switch or humidity sensor activates) of 25ls so basically even if all that air was being sucked out of the house this is still less airflow than the drimaster is putting into the house so that excess air goes to other areas of the house. We only have the bathroom fan set to stay on boost after the light is turned off for about 5 minutes and that seems enough. Background trickle is set to 6ls which is a very small amount of air when you see what the drimaster puts out.

Air will take the path of least resistance so we also leave a trickle vent open at the furthest end downstairs away from the drimaster vent on the landing in our case that is our kitchen. But again you don't even really need that as the air will find ways out down the back of kitchen cupboards - no house is airtight in the way we class airtight in scientific terms. It is best to have all windows closed and encourage air to take the path you want it to take... Such as opening the trickle vent the furthest away.

Ours is only a small bathroom but we only have the fan set to 25ls (it can go as high as 60ls) as this is enough to stop the steam building up and because of the fresh air provided by the drimaster this clears and most of the mist on the mirror within 2 minutes of opening the bathroom door. Any higher and you do find the bAthroom can get quite cool as a towel rail in a bathroom isn't very efficient at heating the room up.

Hope this helps... I can send you the documentation on the drimaster and Cyfan if that helps?

richardc1983

We also have the drimaster heat version. This is set on a timer to temper the incoming air via the 500w heater to 12c this is only for our comfort. We have the timer to switch the heater on at 6-8am and 6-8pm as this is the times when upstairs is occupied for getting ready and showering so it means the landing vent isn't cooling the landing too much. The heater in no way affects the operation of the drimaster unit at all. It doesn't improve performance or make it worse it is purely a comfort thing for us. It's a very small heater some people think it will blow warm air like a fan heater but it that is not it's purpose and it is not capable of making the air hot.

richardc1983

A good comparison is a hospital operating theatre. They pressurise the theatre with a lot of highly filtered clean air this exits the theatre over the top of the doors via the flaps that you may have seen opening and closing depending on whether the theatre doors open or close. This ensures fresh air is circulated and dirty contaminated air does not get in. Drimaster works the same but doesn't folter to the same standard and doesn't produce as high a flow rates.

It's good as well I haven't been poorly this winter but one of my house mates has and I rest assured that his bugs and germs are constantly diluted down and fresh air is constant.

You can only educate people so far though. My house mates do a lot of cooking and they boil veg on the hob in pans without the lids on. Last night my kitchen windows were literally covered top to bottom in condensation due to this. If they used Lids things would cook quicker and less steam would be produced. But you just can't tell people. Our cooker hood only recirculated and I have no extract in the kitchen but its not needed as the drimaster cleared the windows within a few hours.

cazs

I have not been through the whole thread so some of this may be repetitive but..

It is not surprising that the condensation appears when the flat is being lived in. Much of it is down to breathing so wholly unavoidable. This if of course worseneed by the washing issue.

You mention a dehumidifier, I don't know which you have but there are several types. If it's not already, you might consider getting one that runs and turns itself on and off according to the humidity setting you tell it and also that has a laundry setting to dry laundry sat next to it on an airer. I decided to get one of these last Christmas and been using it for a year now and am very 'fond' of it. I too suffered from condensation on the windows when the temp dropped and also wanted not to tumble dry everything or leave things wet around the flat. If you're intereted it's the EcoAir ECO DD122 Desiccant Simple Dehumidifier - White from Amazon.

Finally could they open the vents when they leave for work perhaps and close them when they get home. If it's a high up flat like mine, then they could open the windows during the day and close them on their return. This would help a bit at least.

On a temporary note, Dettol does a good mould remover spray in a lime green bottle.

pd001

richardc1983 wrote: »

Pd001 you are partially correct in what you are saying. You seem to be gaining a good understanding of how these systems work. To answer your question fully the drimaster has an airflow rate between 10 & 70 litres a second. This is set at install via a speed switch set between 1&6. The Cyfan has an air flow rate between 6&60ls configurable via the dials mounted on the unit itself.

So in my example our drimaster is set on speed 3 which provides air flow between 30&42ls depending on loft temperature. If loft is warmer than 15c it speeds up to boost airflow and bring warmer air into the house, great in spring or autumn. The Cyfan is set to a maximum boost (when light switch or humidity sensor activates) of 25ls so basically even if all that air was being sucked out of the house this is still less airflow than the drimaster is putting into the house so that excess air goes to other areas of the house. We only have the bathroom fan set to stay on boost after the light is turned off for about 5 minutes and that seems enough. Background trickle is set to 6ls which is a very small amount of air when you see what the drimaster puts out.

Air will take the path of least resistance so we also leave a trickle vent open at the furthest end downstairs away from the drimaster vent on the landing in our case that is our kitchen. But again you don't even really need that as the air will find ways out down the back of kitchen cupboards - no house is airtight in the way we class airtight in scientific terms. It is best to have all windows closed and encourage air to take the path you want it to take... Such as opening the trickle vent the furthest away.

Ours is only a small bathroom but we only have the fan set to 25ls (it can go as high as 60ls) as this is enough to stop the steam building up and because of the fresh air provided by the drimaster this clears and most of the mist on the mirror within 2 minutes of opening the bathroom door. Any higher and you do find the bAthroom can get quite cool as a towel rail in a bathroom isn't very efficient at heating the room up.

Hope this helps... I can send you the documentation on the drimaster and Cyfan if that helps?

Got all of this and yes, i do understand what you are saying.

I have read all of the documentation that you probably have on the Nuaire website.

pd001

richardc1983 wrote: »

We also have the drimaster heat version. This is set on a timer to temper the incoming air via the 500w heater to 12c this is only for our comfort. We have the timer to switch the heater on at 6-8am and 6-8pm as this is the times when upstairs is occupied for getting ready and showering so it means the landing vent isn't cooling the landing too much. The heater in no way affects the operation of the drimaster unit at all. It doesn't improve performance or make it worse it is purely a comfort thing for us. It's a very small heater some people think it will blow warm air like a fan heater but it that is not it's purpose and it is not capable of making the air hot.

Hi again
I do appreciate that the Drimaster heat only has a 500W heater, and as such it doesn't act like a fan heater.
Even if it just takes the chill off the incoming air, i can see that the landing area, where the Drimaster is blowing in, would be slightly more comfortable than if purely cold air was being blown in from the loft.

pd001

cazs wrote: »

I have not been through the whole thread so some of this may be repetitive but..

It is not surprising that the condensation appears when the flat is being lived in. Much of it is down to breathing so wholly unavoidable. This if of course worseneed by the washing issue.

You mention a dehumidifier, I don't know which you have but there are several types. If it's not already, you might consider getting one that runs and turns itself on and off according to the humidity setting you tell it and also that has a laundry setting to dry laundry sat next to it on an airer. I decided to get one of these last Christmas and been using it for a year now and am very 'fond' of it. I too suffered from condensation on the windows when the temp dropped and also wanted not to tumble dry everything or leave things wet around the flat. If you're intereted it's the EcoAir ECO DD122 Desiccant Simple Dehumidifier - White from Amazon.

Finally could they open the vents when they leave for work perhaps and close them when they get home. If it's a high up flat like mine, then they could open the windows during the day and close them on their return. This would help a bit at least.

On a temporary note, Dettol does a good mould remover spray in a lime green bottle.

Thanks for your input to this thread.
The property is a circa 1900, two up and two down, mid terraced house.

Firstly, there is at least two people home during most days, one of which is a small child.
We agree that breathing causes water vapour, and we all have to breathe lol, but its the washing drying on the rads all over the house that we think is causing the condensation.
Don't forget the portable gas fire produces lots of water vapour as well, although that item should, by now, be a thing of the past..hopefully!!

My daughter will not be buying them another dehumidifier, because we don't think that they are using the one that they have already been provided with.

Hopefully the tenant is cleaning up using a suitable mould spray, but we really have no idea if this is the case or not?

richardc1983

Mines a 1930s 2 up 2 down but an end terrace