Geekzone: technology news, blogs, forums
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.

3 posts

Wannabe Geek

# 251543 30-Jun-2019 11:46
Send private message quote this post

Hi everyone new to this site but at our wits end Hopefully someone can shed some light on our problem.


We have an old 1950's timber floor weatherboard house which has been totally renovated with all new weatherboards, double glazed windows insulation in walls, half of the ceiling (no space to get to the rest of the area). There is no insulation underfloor as no room to get access but we have the thickest underlay and good quality carpet. Our heating is  gas fire and heater which are  both flued to the outside. We have a shower dome over our shower. No doors are ever closed except for bathroom when in use there is only the 2 of us living in the house. 


Approx 1 year ago late June 2018  we had a home ventilation system put in by a provider we have used in other houses. (won't mention the company name at this stage)


The system comprises of 2 ceiling vents one in open plan lounge kitchen dining  and one in the hallway. remembering no doors are ever closed so there is no need to have any ceiling vents in any of the rooms which has always worked with no problems in our last 2 houses.


There have been problems from the beginning in all the bedrooms off the hallaway with wet windows/ frames so the hallway vent was opened up even more to get more airflow. 


We paid 1/2 of the amount owing but held onto the balance to see how this winter went with the condensation. After have a great summer to dry out any dampness in the house


This still hasn't helped the worst room is our bedroom (the hallway ceiling vent sits right outside the door to this room) the window frames are basically dripping with condensation, the glass is clear of condensation except for 5 inches from the bottom.


The other rooms off the hallway still have a couple of inches of condensation on the windows at the bottom and on the frame .


No problems with the house drying out as over the last summer the house was drenched in sun and the hottest room which attracts the peak sun is our bedroom..


We just don't know where to go from here, the installers seem to be fobing us off and not returning my calls.


So any ideas much appreciated.







Create new topic
2262 posts

Uber Geek
+1 received by user: 470

Lifetime subscriber

  # 2267281 30-Jun-2019 12:16
Send private message quote this post

And the location is??

3885 posts

Uber Geek
+1 received by user: 1757


  # 2267286 30-Jun-2019 12:26
quote this post

Are the window frames Aluminium? And if so, guessing that they are not thermally broken? If that is the case, then the frames will get cold enough that you are still going to get condensation.

Guessing that the ventilation system is just a cheap positive pressure system, rather than a heat exchanger based balanced system. Often the humidity of the outside air at night time gets to 100% or close to it. So bringing in outside air is often worse than useless. As you are making the house colder, but without removing any moisture.

Are you keeping those rooms heated? Or are you trying to keep them dry without using any heating? If no heating, then switch off the ventilation system and put dehumidifiers in those rooms instead.


547 posts

Ultimate Geek
+1 received by user: 41

  # 2267296 30-Jun-2019 12:54
Send private message quote this post

Do you also have curtains or blinds? , we have to leave sunblinds half way up when curtains shut so the air can get to the windows to dry condensation. The provider even suggested leaving curtains open at night

3 posts

Wannabe Geek

  # 2267312 30-Jun-2019 13:49
Send private message quote this post

We have venetian blinds which are shut at night. This has never been a problem before

3 posts

Wannabe Geek

  # 2267313 30-Jun-2019 13:52
Send private message quote this post

The window frames are aluminium and only a year old so no broken thermal.


The system is not a heat exchanger but a Eco Home ventilation system, in our other houses we have never installed heat exchanger systems only ventilation systems and never had a problem. 

22259 posts

Uber Geek
+1 received by user: 4784


  # 2267320 30-Jun-2019 14:34
Send private message quote this post

What is the relative humidity inside the house?


8654 posts

Uber Geek
+1 received by user: 2977

Lifetime subscriber

  # 2267335 30-Jun-2019 15:24
One person supports this post
Send private message quote this post

dont compare houses, they are likely different enough to make any comparisons irrelivant.




how fast is the fan on the ventillation system running at night?


why did you choose not to put vents into the other rooms?


what other heating do you use? even a small amout of heating make a big difference in the amount of moisture you get.




we have a 1950's weather board house with single glazing and a DVS system, and we only get a light misting of condensation on the windows every morning, not enough to even pool water at the bottom. but we have 350w heaters in the vent lines to the bedrooms. with the heaters off there is significantly more condensation on the windows, and with the system off entirely, a lot more. it works great in our house. i have tweeked the fan to run 50% higher than normal to ensure more airflow.


14885 posts

Uber Geek
+1 received by user: 2794


  # 2267454 30-Jun-2019 19:42
Send private message quote this post

What ventilation / extraction does your bathroom and kitchen have? Where in the country are you?


What's the humidity and temperature of your home at say 3pm, 7pm, before bed, and first thing when you get up? What's the temperature and humidity in the bathroom, kitchen, and lounge at say 7pm?


My best guess is high humidity possibly combined with lower temperatures, but with that information we can help work it out.

1810 posts

Uber Geek
+1 received by user: 129

  # 2267811 1-Jul-2019 15:33
One person supports this post
Send private message quote this post

I would be guessing but i'd say you have non-thermally broken aluminium windows (not that thermally broken ones are the golden ticket) and the ground under the house is bare earth (rising damp from the ground is surprisingly common). 


If you're talking about a positive pressure ventilation system then you do need to keep an eye on your humidities inside and out. There's not much point dragging all the air from the ceiling/outside into the house if it's relative humidity is higher again. 


It sounds like an unfortunate combination of things causing the ventilation system to underperform. 


Have you tried it for a few days without the ventilation system working at all? If it's better when off then you can rightly be disappointed. If it's worse when off, then there's an argument that the system does work, even if not to your expectations. 



243 posts

Master Geek
+1 received by user: 41

  # 2268030 1-Jul-2019 21:50
Send private message quote this post

No access to underfloor means you could have rising damp. A huge difference was noticed in my 60’s house when we put polythene on the ground under the house.

990 posts

Ultimate Geek
+1 received by user: 46

  # 2269690 4-Jul-2019 08:51
Send private message quote this post

If you have bare soil and an enclosed underfloor cavity, that may be evaporating huge quatities of humidity under the house. Wet soil without grass or a vapour barrier over it continuously smokes water.



Passive ventilation in some houses has been known to make them damper after the ceiling cavity air was drawn out up the walls from the underfloor area.



Solid aluminium frames are going to heavily condensate in winter if relative humidity is high. They're designed with condensation channels or else the water pools and rots the wood. You're not going to see much condensation on the inside of double glazing unless there is a severe humidity problem.



Winter outdoors air is often at or near 100% relative humidity in most of the country. Only significant heating above the outdoors temperature reduces that to an acceptable 60%. I'm picking relative humidity is above 75% indoors. Relative humidity indoors may have been high in the past but between air leaking old wooden windows and low room temperatures it may not have shown up in condensation.



A passive ventilation system isn't going to be a substitute for an externally vented rangehood. Thermal curtains over the windows should help keep the warmth in and reduce relative humidity.



You could buy one of those personal weatherstation units that tells you what the temperature and humidity is inside and outside.

755 posts

Ultimate Geek
+1 received by user: 144

  # 2269842 4-Jul-2019 12:51
Send private message quote this post



The other rooms off the hallway still have a couple of inches of condensation on the windows at the bottom and on the frame .



Because it doesn't work. It's a joke, seal your house up then stick in the power eating DVS crap and expect miracles.


Of course they won't admit it to you.


We had one. Useless piece of junk, we didn't install it though.




And have had an older house that wasn't sealed up like a plastic bag, no condensation issues at all....



8654 posts

Uber Geek
+1 received by user: 2977

Lifetime subscriber

  # 2270131 4-Jul-2019 19:55
One person supports this post
Send private message quote this post

@shasin are you going to reply to any of the questions or ....

Create new topic

Twitter and LinkedIn »

Follow us to receive Twitter updates when new discussions are posted in our forums:

Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:

Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:

News »

Dunedin selects Telensa to deliver smart street lighting for 15,000 LEDs
Posted 18-Jul-2019 10:21

Sprint announces a connected wallet card with built-in IoT support
Posted 18-Jul-2019 08:36

Educational tool developed at Otago makes international launch
Posted 17-Jul-2019 21:57

Symantec introduces cloud access security solution
Posted 17-Jul-2019 21:48

New Zealand government unveils new digital service to make business easier
Posted 16-Jul-2019 17:35

Scientists unveil image of quantum entanglement
Posted 13-Jul-2019 06:00

Hackers to be challenged at University of Waikato
Posted 12-Jul-2019 21:34

OPPO Reno Z now available in New Zealand
Posted 12-Jul-2019 21:28

Sony introduces WF-1000XM3 wireless headphones with noise cancellation
Posted 8-Jul-2019 16:56

Xero announces new smarter tools, push into the North American market
Posted 19-Jun-2019 17:20

New report by Unisys shows New Zealanders want action by social platform companies and police to monitor social media sites
Posted 19-Jun-2019 17:09

ASB adds Google Pay option to contactless payments
Posted 19-Jun-2019 17:05

New Zealand PC Market declines on the back of high channel inventory, IDC reports
Posted 18-Jun-2019 17:35

Air New Zealand uses drones to inspect aircraft
Posted 17-Jun-2019 15:39

TCL Electronics launches its first-ever 8K TV
Posted 17-Jun-2019 15:18

Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.

Support Geekzone »

Our community of supporters help make Geekzone possible. Click the button below to join them.

Support Geezone on PressPatron

Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.