Home PIV units - Anyone got one?

[mole]

Hi

So another update:

 

Tues 6th. Both dry

Wed 7th. Both dry

Thurs 8th. Both dry

Fri 9th. Both dry.

Sat 10th. Both dry.

Sun 11th. 1" light condensation on bottom of both.

Mon 12th. 1" light condensation on bottom of both.

Tues 13th. Both dry.

Wed 14th. Both dry.

Thurs 15th. Both dry.

Fri 16th. Both dry.

 

Plus as an added bonus a superb not too scale professionally drawn plan of where the windows are:

 

 

 

I probably won't do any more updates until the weather get colder, wetter and more dismal.

[mole]

Hi all

 

So just a quick update on the Nuaire Drimaster Eco Hall.

 

Just before Xmas I changed the airflow setting from 3 (30 litres per second) to 4 (40 litres per second) as due to some cold days/nights the condensation reappeared.

 

Since the change however the condensation has been held at bay with just a very light misting of about 3cm so this is good.

 

Hallway under piv still a bit cold but elsewhere it is fine.

 

Cannot tell if related or not but son has completely stopped coughing from asthma and the humidity in his room has dropped from 70% to a almost constant 50%-55%.

[Danp]

I didn't even know such a thing excised! Thanks for this. We have really bad condensation which is just about kept under control if the bedroom windows are all put on the latch every morning and locked again at night. Annoyingly, none of our windows have a draft vent. Looks like this is what I need. How is the condensation in the loft? This is an other area I find it. Partly because I have had the full think insulation fitted and then boarded most of the loft (on loft legs) and use it for storage. This means we get condensation in the loft and the corners of the 3 bedrooms do have some black mildew stains on the outside corners which I have to bleach every couple of months to keep at bay.

[mole]

Our loft of condensation free - however it has a lot of air flow through it - 4 tile air things and then where the roof meets the top of the wall there are vents all around (sure these things have proper roofy names) in fact when the wind blows you can feel the draughts in the loft.

 

If you have ventilation gaps etc in the loft the piv should eventually help with condensation due it drawing air through.

 

Tomorrow to increase my loft insulation from 100mm to 300mm and board a walkway down the middle on loft legs.

 

I know it seems like madness to basically blow in cold air from the outside into your home but we have not noticed any temp difference in the bedrooms - only directly under the piv/on the landing - and a bit down the walls as I had to place mine on the hallway not above the stairwell.

Edited January 22, 2019 by mole

[bald_pig]

This might be a silly question, but what is the difference between this and a dehumidifier, other than the location of the air intake?

[Andrew_C]

This might be a silly question, but what is the difference between this and a dehumidifier, other than the location of the air intake?

100% different.

 

A dehumidifier works like a fridge to cause the moisture in the air to condense on a cold surface. A PIV pulls (relatively) warm, dry air in from your loft, displacing moist air from within your home. It is more in the line of a forced extract fan, but they then pull fully cold air in through whatever gaps.

[bald_pig]

100% different.

 

A dehumidifier works like a fridge to cause the moisture in the air to condense on a cold surface. A PIV pulls (relatively) warm, dry air in from your loft, displacing moist air from within your home. It is more in the line of a forced extract fan, but they then pull fully cold air in through whatever gaps.

 

So the PIV doesn't actually remove moisture from the air? Fair enough. I'll have to look up the pro's and cons of each.

[Meldrew]

I've found my PIV more effective than a dehumidifier. Whereas I found the dehumidifier needs the room to be relatively warm in order to be able to condense the water out by chilling it, the PIV doesn't need this. Also, where a portable dehumidifier might be useful for a room, a modest sized PIV would work for a whole house. I believe cheaper to run too, but probably more expensive in initial outlay.

 

Meldrew

[Wolverine77]

Our loft of condensation free - however it has a lot of air flow through it - 4 tile air things and then where the roof meets the top of the wall there are vents all around (sure these things have proper roofy names) in fact when the wind blows you can feel the draughts in the loft.

 

If you have ventilation gaps etc in the loft the piv should eventually help with condensation due it drawing air through.

 

Tomorrow to increase my loft insulation from 100mm to 300mm and board a walkway down the middle on loft legs.

 

I know it seems like madness to basically blow in cold air from the outside into your home but we have not noticed any temp difference in the bedrooms - only directly under the piv/on the landing - and a bit down the walls as I had to place mine on the hallway not above the stairwell.

 

Hi Mole

 

how are you finding the PIV unit now?

 

was it worth the investment?

 

I have installed one last week and it seems to slowly be bringing RH down, can this take time?

 

mine is one setting 6 as I have a 2600 sq ft + bungalow and this setting was recommended by Nuarie.

 

any advice would be really appreciated.

 

thanks

[mole]

Replied via PM - had it turned off all summer, turned back on 2 weeks ago, level 3...for now....

[creztor]

Curious about the humidity where these piv units are being used. My understanding is that air in the loft where these units are being used is lower than that found around the rest of the house. By blowing this loft air in which has a lower level of humidity this then slowly forces out the air in the house hence lowering humidity levels. Is this right? If so then is it common for houses that use piv units to have high humidity levels in the house, much higher than air in the loft?

 

An example of this is I just checked the humidity levels online for London. It's apparently 83% with a min of 1 and max of 8. So, I assume these houses with condensation and mould problems have humidity levels much higher than what it is outside? I ask because I live in Tasmania, Australia. Our winters seem to be like some places in the UK. Outside humidity is usually very high, not uncommon for 90 or higher and the days are just damp, wet and cold. However, house humidity levels inside would be lower or at worst the same as outside. Is this not the case for people who use piv units?

Edited December 3, 2019 by creztor

[Andrew_C]

Damp, wet and cold - yep, that sums up a typical English winter. I don't have stats here, but I can fine in/out figures for work once this cold let's me get back!

 

Currently 52% indoors at home, but a nice bright sunny day.

 

You are right in your description of the theory. I put mine in instead of an extract above an internal clothesline. I also fitted an extract above the shower on a photocell switch.

 

We only get a little condensation on windows.

[creztor]

Thanks, Andrew_C. What I'm a bit confused about is if in winter when RH is say often above 90 outside and houses are getting condensation and mould, this must mean the average RH inside the house is extremely high, like 90 to almost 100. As these piv units are meant to be left on 24/7, then it would mean RH inside the house is always this high, otherwise why would you replace low RH air inside your house with air from the loft which has a higher level of RH? I guess that what's confuses me. We get some condensation in winter here but I've never tracked RH in the loft or house. I'm doing that this winter.

[jinnantonnixx]

Thanks, Andrew_C. What I'm a bit confused about is if in winter when RH is say often above 90 outside and houses are getting condensation and mould, this must mean the average RH inside the house is extremely high, like 90 to almost 100. As these piv units are meant to be left on 24/7, then it would mean RH inside the house is always this high, otherwise why would you replace low RH air inside your house with air from the loft which has a higher level of RH? I guess that what's confuses me. We get some condensation in winter here but I've never tracked RH in the loft or house. I'm doing that this winter.

 

I *think* (and I might be totally wrong), that the RH is inextricably linked with the air temperature. The key word here is 'relative' in 'relative humidly'. It's defined as the air's ability to absorb moisture. The colder air (at the same RH as the warmer air) has a lower RH as it warms up when it enters the house, thus lowering the house's RH. I think that's the principle, but happy to be corrected.

 

I fitted one a couple of years ago and I'm reasonably convinced that it's helping with dampness in the house.

Edited December 4, 2019 by jinnantonnixx

[Dos_Box]

Thanks, Andrew_C. What I'm a bit confused about is if in winter when RH is say often above 90 outside and houses are getting condensation and mould, this must mean the average RH inside the house is extremely high, like 90 to almost 100. As these piv units are meant to be left on 24/7, then it would mean RH inside the house is always this high, otherwise why would you replace low RH air inside your house with air from the loft which has a higher level of RH? I guess that what's confuses me. We get some condensation in winter here but I've never tracked RH in the loft or house. I'm doing that this winter.

 

This is because they are designed to keep the pressure (slightly) higher in the house preventing water from condensing. It also forces air and moisture out though tiny gaps in window frames etc.

I think the whole point is that your house has to be able to be sealed quite well to get best effects. In the UK they were fitted to a lot of older houses who were not very airtight but succeptable to damp.

[Danp]

Took my time, but had ours fitted last week. Noticed a difference with condensation on windows within 24 hours.

 

72 hours later, all gone!

[Koldov]

What make/model did you get (did you get a heated version)?

 

How big is your house?

 

How did you wire it up?

 

Where is the placement of the vent in the house?

[Danp]

What make/model did you get (did you get a heated version)?

https://www.permagard.co.uk/nuaire-drimaster-eco-lc - no heat

 

How big is your house?

Average 3 bed with downstairs extension. Late 40s but since had double glazing, cavity wall and loft insulation fitted

 

How did you wire it up?

Had a sparky do it. He took a feed off the hall ceiling light

 

Where is the placement of the vent in the house?

Upstairs landing.

 

In the dead of night, we can just hear the pump, but otherwise you would not know it was on. It's currently running at speed 3 of 5.

[Andrew_C]

What make/model did you get (did you get a heated version)?

How big is your house?

How did you wire it up?

Where is the placement of the vent in the house?

No heat - Nuaire Drimaster

Exten

ded 4 bed - not all that big - now down to two of us most of the time.

I used the redundant supply that used to feed the immersion. Also feeds bathroom extract. Needs altering as the cats have taken to jumping into the bath in the middle of the night, triggering the extract via PIR sensor.

Above the staircase (and the drying washing).

 

 

[DeGrimmy]

I've been watching this thread for some years now, and it's really interesting - It looks like the sort of thing we'd need in our eternally damp and humid 1st floor flat. We've got a couple of dehumidifiers and we're constantly emptying them. Trouble is, we don't have any ventilation without keeping the windows open. I think we'd first need to install an extractor fan in the bathroom before anything else to see if that makes a difference, but a PIV unit might do the job. I'll keep it in mind if the extractor fan isn't enough!

[Koldov]

Looking at the heated version, because our house is cold already and I'm apparently a 'scrooge' with the heating... don't really want to start blasting cold loft air in as well.

 

But is it really worth another £200...?

 

Not sure I can justify that, but these days turning the heating up would soon cost the equivalent!

[Danp]

Looking at the heated version, because our house is cold already and I'm apparently a 'scrooge' with the heating... don't really want to start blasting cold loft air in as well.

 

But is it really worth another £200...?

 

Not sure I can justify that, but these days turning the heating up would soon cost the equivalent!

 

I didnt look at the running costs of the heated version, but surely that's got to be considered. It should be less than running the central heater for the whole house though

[Andrew_C]

It isn't going to heat the whole house... I'd guess it is only necessary if the outlet is going to blow cool air on you - say above a bed?

[stevewill6]

I have the heated version(had a very good discount) i have never used it. Running costs are too high to run the heater all day every day.

[KK20]

We have had one for years. They are awesome. Dont bother with the heater element, its not worth it.

 

Keep the doors closed in the house, it works better in our house with the doors closed. Our house is a 5 bedroom old house, ventilation is not great, we have a pair of dehumidifiers in the house, one in the utilty room where we dry washing and one in the corner of the kitchen/dining room. One central staircase with pair of landings, the nuaire vent is at the top of the stair ceiling, you can notice a temperature difference going onto the landing but since the doors are closed it doesnt affect us. Ours cuts out if the air that is drawn in is too cold - we notice the condensation build up when this happens. It also cuts out if the air is too warm - we also notice the temperature in the stairs increase when this happens!

 

We used to have a problem with black stuff appearing behind book cases that were in the corner of the larger rooms - no more since. I was skeptical about the overpressure thingy but no more.

Edited March 31, 2023 by KK20