Help and FAQs

Answers to some commonly asked questions
Why isn’t there any air coming out of the ceiling diffuser? My DVS is switched on at the control panel.

There could be several reasons for this. The most likely reason (assuming you have an Automatic, G3 or G4 model) is that the DVS has automatically switched off due to the roof space temperature exceeding pre-set cut-out levels. If this is the case, your DVS will automatically begin operating once the roof-space temperature falls. You should check again in the morning when the roof space is cooler and the DVS should have switched back on again.
If your DVS is still not working in the morning, hold a piece of paper up to the ceiling diffuser to see if it moves. If the fan is working, check the filter in the roof space as it may be clogged, preventing the DVS from delivering sufficient air through the ceiling outlets. If the filter is not clogged and the DVS is still not working, please call us on 0800 387 387

Back To Top

Why do I still get some misting or condensation in some rooms of the house?

Where a room does not have it’s own DVS ceiling vent, ensure doors to those rooms are left open during the day and at night. Open curtains and blinds fully during the day, and leave slightly open at night (if possible). Read Getting the best out of your DVSfor more trouble-shooting tips. If the problem persists, please call us on 0800 387 387.
I no longer have any condensation, but why does my house seem cooler during colder weather?
You may need to use a little more home heating during colder months to offset the cooler and drier air from the roof space needed to control condensation. See our Heating section for more information.

Back To Top

Why is there dust on the ceiling diffuser and on the ceiling near the diffuser?

This sometimes happens, usually as a result of dust already in the home being attracted by static electricity due to the drier air from the DVS brushing against the diffuser or ceiling surfaces, and by the flow of air within the region of the diffuser. Clean the surfaces with a clean dry cloth, brush, or use the brush attachment on the end of your vacuum cleaner.
If the problem persists check your air filter to ensure it hasn’t become clogged and check the ducting in your roof space for any damage. Occasionally tradespersons or other people working in your roof cavity can accidentally damage the ducting, allowing some dust from the roof cavity to enter your home, although this is not common.

Back To Top

Why is there a smell coming from the roof space through the ceiling diffusers?

Roof smells can occur temporarily when the DVS is first installed, or with a new roof. The problem should clear in time. However, if the problem persists, call us on 0800 387 387 and ask about ourActivated Charcoal Filters which can reduce smoke and odour smells to acceptable levels.

Back To Top

Why do we get the smell of smoke from wood or coal fires coming into the house from the roof space?

This can occur, particularly on still nights, when smoke from domestic fires sits around ground level and is drawn into your roof space. If the problem persists, call 0800 387 387 and ask about our Activated Charcoal Filters which can remove smoke and odour smells.

Back To Top

Why can I hear noises from the DVS fan during the day and night?

For older DVS systems (Pre 2005), it is possible that in the dead of night you may be able to hear a soft ‘hum’ from your DVS from certain rooms in your house, but it is unusual that you would hear it operating during the day. If the DVS is making ‘clunking’ or ‘clicking’ noises, or is very noisy, it may indicate that the centrifugal fan is damaged or worn and you should call us on 0800 387 387.

Back To Top

Why do I seem to be getting cooking smells and other odours coming back into the house?

Check whether any extract fans are vented into the roof cavity. If they are, please arrange for a local tradesperson to vent any extract fans outside the roof space. Or call us on 0800 387 387 – we may be able to do it for you, or recommend someone in your area who is experienced at doing this job.

Back To Top

For further information, consult the Operating Guide for your system. If you have any further questions or problems, please call us on 0800 387 387.

And remember…
If you are NOT satisfied, PLEASE LET US KNOW! We will respond and help as quickly as possible – your satisfaction means everything to us.

Either call us on 0800 DVS DVS (0800 387 387), or email us at

Sign up to the DVS e-newsletter

  • This field is for validation purposes and should be left unchanged.

Recognised by:

$0.000 items