Recommendation for loft PIV

[Burtones]

Hi,

I've had a little search on the forum but can't find anything on this. Basically, live in an old cottage and suffer from some damp and condensation through the winter (property has double glazing).

Going to try a positive input ventilation unit in the loft- does anyone have recommendations for a particular make/model?

At work we install nuaire and envirovent which looking online cost about £3-400 so wondering if there's a cheaper but as effective option.

 

[Baddegg]

Don’t know about positive input ventilation mate but I do know houses...see this a lot in older houses that have been insulated to high heaven and had double glazing put in, the house and materials used to build it were never meant to be airtight as per newer stuff, I’m in my second home from the 1850’s (moves 12 doors last time) my old house was,not by me, cavity insulated and stacked in the loft with insulation and the condensation was horrendous, the place we are in now I refused the free cavity wall and when the windows went in had trickle vents installed, the loft has dormers so although essentially built of insulation the air can still escape,basically it needs to breathe, we’ve had no problems at all with condensation in this property which considering the house is exactly the same age/build and location as the last speaks volumes I think,Do your windows have trickle vents as that would be my starting point, I have had more than one customer actually had their wall insulation removed due the walls running with water......Sorry if that’s not helpful but I look forward to learning about postive input ventilation ?

 

[dodger421]

Hi,

I've had a little search on the forum but can't find anything on this. Basically, live in an old cottage and suffer from some damp and condensation through the winter (property has double glazing).

Going to try a positive input ventilation unit in the loft- does anyone have recommendations for a particular make/model?

At work we install nuaire and envirovent which looking online cost about £3-400 so wondering if there's a cheaper but as effective option.

I had similar problems in the house I live in now and the landlord agreed to let me install a Nuaire Drimaster Eco. The research I did at the time led me to that as being the most effective unit.

It’s been in for about 18 months now and it has made a difference, but they are not miracle solutions on their own. We don’t have condensation and damp spots on the walls anymore, but we do still get condensation on windows if we don’t leave doors slightly ajar at night. I becomes a bit of a battle of ventilation vs pushing the heated air out vs fire safety at night.

In hindsight I’d recommend getting the heat version and swallowing the slightly higher running costs. Without it the air it’s pushing in is quite nippy in winter, especially noticeable as our unit is in the hall outside the bedroom door!

It’s important to get the flow rate right; too little and it’s not effective at all, too much and you’re just forcing the hot air out and spending more money heating the house. This is a large house so we’re running at 5 and it’s just about right.

A year ago I fitted Hive radiator valves so we could keep each room at a constant temperature (15.5 c) to also try and control damp and condensation so I can’t be certain the Drimaster can take all the credit for the success we’ve had but I do know it has given me less trouble than the Hive TRV’S (that’s a rant for another occasion; long story short they’re a great idea very poorly implemented).

The house was 70’s ish built and very poorly constructed throughout to be honest. There is cavity wall insulation and a thin layer of insulation in the loft/eaves spaces (not covering the eaves so allowing fresh air in for the PIV), but the gable walls in the loft are not insulated internally so the loft is just cold. The solemn space is large (the house is on a hill) and there is no subfloor insulation, but the ventilation bricks haven’t been blocked by the cavity wall so that’s a bonus. Double glazing has been installed, but no trickle vents.

Generally the place is just cold, a bugger to keep warm and suffered badly from damp and condensation. It’s better now but I can’t wait for the sale to complete on our next house!

 

[Mike Johnson]

The French Codes now require what they call VMC extraction, due to most new builds being hermitically sealed, but as said above it's no use extracting moist air if replacement air can not get in via trickle vents, in most Brico sheds that sell these there are heat exchange units that supposedly take the heat out of the moist air and return it to the room.

https://www.leroymerlin.fr/produits...oix-du-type-de-vmc":"VMC Double flux"}&page=1

 

[Burtones]

Thanks for the info. It's not as bad as walls running with water! To be honest, the condensation is mild but there are certain areas that develop damp on ground floor and upstairs.

1870's so solid wall with no internal or external wall insulation- and no trickle vents on windows- is that something that can be installed to existing windows? Don't know how much a full window replacement would cost (only 5 windows) but might be worth considering with the green homes grant now open.

 

[Mike Johnson]

Trickle vents can be retro fitted if the head of the window can be accessed by a Router (not normally an option), but a skilled carpenter could manually put them into a wooden window, it is recommended that trickle vents are installed at least 1.7M above floor level to prevent drafts.

 

[Mike Johnson]

Hi,

At work we install nuaire and envirovent which looking online cost about £3-400 so wondering if there's a cheaper but as effective option.

Surely if you work in the ventilation industry you should have access to a wealth of knowledge and can get a discount?

 

[Burtones]

Surely if you work in the ventilation industry you should have access to a wealth of knowledge and can get a discount?

I don't! I work in social housing and occasionally fit or replace the two brands I mentioned. The price is what I could find looking online- unfortunately we're not allowed to buy anything from work.

 

[Mike Johnson]

In that case independently ask one of the contractors to quote for the work, they should look favourably upon you, that can not be considered as buying anything from work.

 

[Baddegg]

Thanks for the info. It's not as bad as walls running with water! To be honest, the condensation is mild but there are certain areas that develop damp on ground floor and upstairs.

1870's so solid wall with no internal or external wall insulation- and no trickle vents on windows- is that something that can be installed to existing windows? Don't know how much a full window replacement would cost (only 5 windows) but might be worth considering with the green homes grant now open.

Trickle vents can be fitted retrospectively and are easy to do, that would be my first port of call to let condensation out over night mate

 

[freddo]

If you want piv and the property isn't too big look at the Nuaire flatmaster, a compact version of the drymaster.