PIV loft mounted units

[Spectric]

Hi

I also live in a bungalow and there is no reason why a bungalow should suffer condensation any more or less than any other build type. Having spent many years in engineering you learn some important rules and one of those is that to solve any problem you need to get to the root cause and not look at ways of overcoming it, that is like sticking plasters over plasters. You have condensation for a reason, there is a cause and you need to find out why. Some good producers of water vapour are, drying washing inside without ventilation, poor extraction in the bathrooms and kitchen. You say it does not suffer from damp but it may be worth having a survey done because that is another good source and is not always obvious. Do all windows suffer the same level of condensation, you may have blown units in some windows so they are colder on the inside. Has this been a long term issue or more recent, could it be like many you are staying in for long periods and not going out.

 

[artie]

to solve any problem you need to get to the root cause

I bought this old house a couple of years ago, built, they say in 1935. There was no sign of damp anywhere even though it had been unoccupied for a while.
The roof space insulation was about an inch thick, open fires in three rooms, draughty sash windows to front single glazed elsewhere, a couple had been replaced with double glazed units.
I closed up 2 fireplaces, replaced the sash and other windows with double glazing, new back door and put about 300mm insulation in the roof space.
That's when the wet windows started.

 

[RogerS]

I bought this old house a couple of years ago, built, they say in 1935. There was no sign of damp anywhere even though it had been unoccupied for a while.
The roof space insulation was about an inch thick, open fires in three rooms, draughty sash windows to front single glazed elsewhere, a couple had been replaced with double glazed units.
I closed up 2 fireplaces, replaced the sash and other windows with double glazing, new back door and put about 300mm insulation in the roof space.
That's when the wet windows started.

There's your answer. You sealed the house up.

Which reminds me. I've got one of these up in the loft. Just not got round to connecting it all up.

 

[owen]

Soveriegn chemicals sell one of these, my boss has had them fitted at about ten or so different properties of his and they have worked in every single one.

https://www.sovchem.co.uk/shop/condensation-mould-control/piv-units-ancillaries/auto-concure-20-20/

 

[Rorschach]

I should be clear, I am not saying PIV units don't work as intended, they most certainly do. However they are basically the same as opening a window and putting a fan in front of it while you run your heating, would a sensible person do that?
Honestly I am surprised in this green revolution we are going through that they haven't been banned, at least the non-heat recovery type.

 

[CaptainBarnacles]

We live in an old stone-built house which we moved into about 2 years ago. The first winter we were here we had such extreme levels of damp and condensation (leading to lots of mould) that I decided to do something about it. I fitted a MVHR system and can honestly say that it's THE BEST money I have ever spent. I dropped lucky on a deal on ebay for a "virtually new" Triton unit and proceeded to plan out the system. I did a lot of homework (buildhub is a brilliant resource) before I started but essentially there was nothing difficult about the installation.

The difference goes way beyond chalk and cheese. Within 3 days it felt like a different house. All our windows are 1970/80's single or double glazed, all units have lost their seal but where they were streaming with condensation before they were bone dry now. Fresh produce in the pantry that was going mouldy in a couple of days now lasts for weeks. And the biggest and best improvement, my wife's asthma has improved massively.

Many people said that it was pointless to fit an MVHR to such a badly sealed (leaky) house, I disagree entirely. I know that it doesn't work at it's optimum performance and that installing it in a Passiv Haus would be great but for me it has solved the problem that I needed solving, it doesn't cost a fortune to run, it looks after itself (apart from cleaning the filters now and again), it automatically boosts itself when it detects high humidity (eg when using the shower or boiling veg in the kitchen), it can be boosted manually via a push button in the kitchen and bathrooms to remove odours, and although it loses about 10% of the heat in the exchanger, the net result "feels" like a warmer house because the air is being moved around the house more effectively so we don't have hot/cold/damp/dry spots anymore, everywhere feels about the same.

I looked into PIV and was almost sold on it, I'm so glad I went the MVHR route. I know the outlay is more but I installed our system (three bedroom, two storey 1800's cottage) for about £1200 and I'll say it again, it is the best money I ever spent. It repays itself in terms of not having to constantly clean mould from walls, window frames, leather sofas, food lasts longer, family are healthier and the house is just a much more pleasant place to be. The only downside that I have encountered is the slight humming noise that comes through the vents but I soon got used to it and at some point I might fit an acoustic attenuator.

I helped my Dad put a system in his bungalow and it was so much easier to install than my system because he had easy access to all rooms from the loft. We had it up and running in just over a day and he's equally delighted with the results.

Hope that helps.

 

[Rorschach]

@CaptainBarnacles Your situation is one where the system you have described is probably the best option available to you. The simple fact for you is that nothing you can do will produce house that is warm, dry and fairly cheap to make that happen. The house was never designed for that, it was built in a time when people accepted that a house was cold in the winter and used a dry heat source to warm what little areas they could. Attempting to seal it up and then add a central heating system is what causes the problems you experienced, the more you fight it, the worse it gets.
A powerful dehumidifier might have produced a similar result but the construction of your property would work against it.

Contrast that against a house built in the 20th century which was designed with some winter warmth in mind and your solution is counter productive as a more "modern" style of building can be renovated to allow a simple dehumidifier to solve the winter problems.

 

[transatlantic]

Hi

I also live in a bungalow and there is no reason why a bungalow should suffer condensation any more or less than any other build type. Having spent many years in engineering you learn some important rules and one of those is that to solve any problem you need to get to the root cause and not look at ways of overcoming it, that is like sticking plasters over plasters. You have condensation for a reason, there is a cause and you need to find out why. Some good producers of water vapour are, drying washing inside without ventilation, poor extraction in the bathrooms and kitchen. You say it does not suffer from damp but it may be worth having a survey done because that is another good source and is not always obvious. Do all windows suffer the same level of condensation, you may have blown units in some windows so they are colder on the inside. Has this been a long term issue or more recent, could it be like many you are staying in for long periods and not going out.

I live alone, and have one bath a day. The bathroom has an extractor. The kitchen has an extractor (although I don't cook much to be honest). Clothes are not dried indoors. All windows appear to suffer the same level. And yes, it has been a long term issue, so not related to me being at home all the time due to recent events.

 

[Jonm]

I live in a big old house that is predominantly single glazed and we had a few humidity problems. I fitted a PIV and we have had good results. Ours has a heater but I've never used it. Been running it for 3-4 years andonly switch it off in the Summer when it is drawing hot air from the roof space which I don't want. I know there are a few people who don't believe in them (including Peter Ward who I have a lot of time for) but it definately improved things for me. I also need to improve extraction from my bathroom and had been looking at the fan that artie points out. My biggest issue is venting to the outside as my house roof doesn't lend itself to venting out of the soffits (I don't have any). Not sure venting into the roof space is a good idea. Fitting a heat recovery system would be nice but retrofitting to an existing building would be a challenge in a lot of cases.
I would go the dehumidifier route as well if I were you as the reduction in humidity makes the house feel warmer irrespective of the actual temperature, prevents mould etc.

I would definately advise you not to vent in to the roof space. In cold weather the moist warm air will cool and condense in the roof space, potential there for rotting timber. I have seen sodden wet timber above a bathroom from air leakage through a hole next to the soil stack vent pipe.

You can get Air vents which fit in the tiling, some are obvious and some discrete, I attach a photo of mine with vents circled.

The other problem is condensation in the vent pipe where the pipe passes through the attic. You can get insulated Flexible pipe which should prevent this problem and this is what is fitted to my house without any problems so far. The other solution is to lay rigid pipes to a fall with a low point and a condensation trap with drain to the outside (bit like an overflow pipe from a tank in the roof) as per this link
https://www.vent-axia.com/range/condensation-trapHope this helps.

 

[artie]

I did an experiment last night.
I placed a RH meter in the sitting room, reading was 61%
After lighting the fire and letting it warm up I closed the bottom vent, which brings air from outside and slightly opened the front vent which takes air from the room.
Obviously it made no difference to how the fire burned, but interestingly within an hour RH had fallen to 55%.
Could I take from that, that it doesn't take a lot of air flow to make a difference?

 

[Rorschach]

No it's more complicated than that. Certainly part of the drop is that you were drawing potentially drier air from outside, but also in that time the room would have warmed and the key in an RH number is "Relative" Humidity, the humidity is dependent on temperature as well.

 

[artie]

Begs another question then, is it better to dehumidify hot or cold air?
Hope the op doesn't mind as this may be relevant to him.

 

[Rorschach]

Hot air is easier to dehumidify. The type of dehumidifier you own also matters, desiccant or compressor. I covered this in a previous post.

 

[Spectric]

I bought this old house a couple of years ago, built, they say in 1935. There was no sign of damp anywhere even though it had been unoccupied for a while.
The roof space insulation was about an inch thick, open fires in three rooms, draughty sash windows to front single glazed elsewhere, a couple had been replaced with double glazed units.
I closed up 2 fireplaces, replaced the sash and other windows with double glazing, new back door and put about 300mm insulation in the roof space.
That's when the wet windows started.

Hi

There is a guy near me who has an even older property cica 1875, stone built and in need of a little tlc. He had new windows throughout and new central heating but then had damp issues so went back to using the two woodburners and opened the vents again and no more damp.

 

[Ebbtide]

I'm looking into getting one of these to hopefully help reduce a lot of the cendensation I get in my bungalow. It doesn't suffer from damp, but in cold weather, I generally wake up to all my windows soaking wet at the bottom due to the condensation build up over night.

I appreciate that a site survey will need to be undertaken by the company I choose to fit it, but has anyone had one installed? did it solve the problem? any pros/cons?

I have a New Aire system in the loft of my bungalow. I put it in when we bought it 7 years ago because it suffered from condensation and also because I needed better quality air for health reasons. It cost about £300 pounds at the time and British made. I installed it myself a simple job all except the electric supply close by carried out by an electrician. It as not been turned off for seven years. the fan is only 12 volts. The price has increased a bit since I bought it. One of my better purchases and I would not be without it. I have changed the filters only once. I recommend this unit.

 

[jimmy_s]

Worth checking the bathroom fan as some of the fans installed are complete rubbish, prop fans and duct don't tend to work very well and maybe causing moisture build up. It may also be condensing on the windows if they are single glazed as the dew point of the inner face is more likely to be reached compared to double glazed units. Id check the fans etc first and then look at a dehumidifier. I would avoid a positive input vent unit - very energy wasteful, will resolve the issue but at the expense of fuel bill. If you still have an issue a small electric dehumidifier is prob best option. As mentioned above RH varies with temperature - increases as temp drops until dew point temp is reached - principal of how dehumidifier works if its a refrigeration type and why they work best with warm air. For dehum cool air or air with already lowish RH dessicant wheels are often used, we use dessicant mainly in specialist applications such as ice rinks/ curling rinks and pharma type situations. Also being used to stop forth road bridge suspension wires from rusting any further.

 

[RogerS]

We live in an old stone-built house which we moved into about 2 years ago. The first winter we were here we had such extreme levels of damp and condensation (leading to lots of mould) that I decided to do something about it. I fitted a MVHR system and can honestly say that it's THE BEST money I have ever spent. I dropped lucky on a deal on ebay for a "virtually new" Triton unit and proceeded to plan out the system. I did a lot of homework (buildhub is a brilliant resource) before I started but essentially there was nothing difficult about the installation.

The difference goes way beyond chalk and cheese. Within 3 days it felt like a different house. All our windows are 1970/80's single or double glazed, all units have lost their seal but where they were streaming with condensation before they were bone dry now. Fresh produce in the pantry that was going mouldy in a couple of days now lasts for weeks. And the biggest and best improvement, my wife's asthma has improved massively.

.....

Hope that helps.

Did you fit pipes in all your rooms ?

 

[CaptainBarnacles]

Did you fit pipes in all your rooms ?

Yes, I managed to run pipes to every room in the house. Extracts in the bathrooms, kitchen and laundry and vents to all other rooms.

I bought a £30 anemometer and made a contraption to measure flow at each vent. This made it easy to balance the vent vs extract of air and to provide the correct flow of air for the given room size. I run the system at about 5% positive pressure to try and counter any small drafts around doors etc.

 

[artie]

So, is the op any closer to a decision?

 

[transatlantic]

So, is the op any closer to a decision?

haha, .. not really. The comments in this thread seem pretty divided

I have tried a dehumidifer in the past (desiccant), but wasn't getting great results. It would collect maybe half a tank over night, but there were still droplets on the bottom of the window in the morning, so returned it. And it wasn't low power either, something like 360w. Which running over night or 24/7 adds up.

I think I'll try again, with a different brand.