New Velux triple glazed, frame condensation

[Sparrowhawk]

We had two new Velux UPVC windows fitted in November 2022 and went with the 62 glazing as top of the range. Codes: GGU PK10 0062 with BDX PK10 2000

 

When -1C/-2C outside we've had condensation on parts of the frame, and I thought they had slight air leaks at the top. So I got the installer back who said "nothing to do with me" and raised with Velux Technical support.

 

Velux technical support have said that  "Condensation is an environmental issue, there is too much moisture within the room. You have used BDX collars so we know the window has been insulated properly."

 

Photos from today

The room was at 61% RH at 10.2C this morning. -1C outside according to the Met office, feeling like -6C.

 

In the top 4 corners, we get corner condensation on the frame. This is where I thought/think there were air leaks, assuming that was cooling them down:

 

At the bottom on both sides of both windows, for 8 inches up from the corner we get condensation:

 

The glazing gets some condensation round the edges of the entire window, but I was expecting that (triple glazing isn't a miracle, right)

 

So...

Is this normal/expected?

 

If it was too much moisture within the room as Velux say I'd expect condensation around more of the frame, not specific areas.

 

As a comparator we had a third Velux replaced at the same time in a different room in the same aspect. It's a cheaper GGU PK10 0068 with EW PK10 6000 and has no condensation issues (but is in a room we don't sleep in). RH in that room this morning was 54% at 11.1C.

[MikeGrahamT21]

Mine are the 66 variety, and painted rather than PU.

 

Its currently -4C outside, room is 15.8C and 51% RH and i've nothing on mine, just ice on the outside.

 

Your window seals haven't been adjusted right, you see where its kind of folding back on itself on the right, you need to pull the top seal to the left to get this out.

 

 

 

The strip of condensation on the straight bit is odd tho, must be something different there for it to collect in that specific place, and it'll likely be installation.

[Redbeard]

Yes, that's not right. The fact that you have condensation on some of the frame and not on the rest suggests a local shortcoming. As far as the condensation on the glazing goes I don't know the glazing spec but my triple-glazed (3G) windows (some 4/18/4/18/4/soft-coat Low E/Argon and some same spec but 16mm and 20mm spacers respectively) have *never* had any internal condensation*. What's the make-up of the Velux 3G unit?

 

* Loads (frozen) on the outside!!

[ProDave]

We have the very cheapest wooden 2G velux windows.  No condensation on the frames at all not even in the en-suite after a shower and at our colder outside temperatures.

 

We do get some condensation around the edge of the glass, so I regret not choosing 3G glass, but on the other hand this thread suggests I would still get condensation there?

[Conor]

We would get the same if the trickle vent is left open. Cold air falls in and causes condesation at the top of the frame. If it's closed, nothing, except a bit after a got shower.

 

But a 10c ambient temperature hints at some serious heat loss / air infiltration.

[Sparrowhawk]

10 hours ago, MikeGrahamT21 said:

Your window seals haven't been adjusted right, you see where its kind of folding back on itself on the right, you need to pull the top seal to the left to get this out.

 

I thought so! Velux said (direct quote) "The seals look fine" when I raised this.

 

[Sparrowhawk]

10 hours ago, Redbeard said:

Yes, that's not right. The fact that you have condensation on some of the frame and not on the rest suggests a local shortcoming. As far as the condensation on the glazing goes I don't know the glazing spec but my triple-glazed (3G) windows (some 4/18/4/18/4/soft-coat Low E/Argon and some same spec but 16mm and 20mm spacers respectively) have *never* had any internal condensation*. What's the make-up of the Velux 3G unit?

I've been unable to track down the makeup, their brochure says:

Thermal transmittance window Uw 0.92 - 1.0
Thermal transmittance glazing Ug 0.5
Energy transmittance g 0.47

 

The other Velux we had replaced in the Study has had ice on it all day long.

[Sparrowhawk]

10 hours ago, ProDave said:

We have the very cheapest wooden 2G velux windows.  No condensation on the frames at all not even in the en-suite after a shower and at our colder outside temperatures.

The wooden frames we replaced never had condensation either. Though being 20 years old and never revarnished the frame had split and the previous owner had removed the seal between sash and frame so they could still be opened...

[Sparrowhawk]

10 hours ago, Conor said:

We would get the same if the trickle vent is left open. Cold air falls in and causes condesation at the top of the frame. If it's closed, nothing, except a bit after a got shower.

 

Re trickle vent that's a really good point. I knew I'd seen this kind of condensation before on a frame, and that reminded me it was when I left a trickle vent open (on other windows in a previous house).

 

10 hours ago, Conor said:

But a 10c ambient temperature hints at some serious heat loss / air infiltration.

 

Welcome to my story

 

Last night the windows were shut in the bedroom & en-suite, but I married a woman who likes a cold bedroom, so (until today) the heating's been off in there. And the ceiling mounted extractor fan in the en-suite lets a draught in.

 

Mind, by morning the rest of the house was 9-11 degrees so yes there's serious heat loss / air infiltration going on.

[Radian]

13 hours ago, Sparrowhawk said:

If it was too much moisture within the room as Velux say I'd expect condensation around more of the frame, not specific areas.

 

There seems to be a very sharp cut-off in condensation part way up the left hand side of the frame. This side seems to butt up directly with an internal wall. I'm wondering what the build-up of this is and if there's a substantial cold bridge here. I forget, do you have an IR camera or thermometer?

[Nickfromwales]

12 hours ago, Sparrowhawk said:

And the ceiling mounted extractor fan in the en-suite lets a draught in.

I fitted an Icon fan in mine a few months back, and it's brilliant. It has an iris which opens a few seconds after switch on, and closes relatively tightly after it powers down. Has stopped 95% or more unwanted ventilation heat losses from the bathroom which now stays notably warmer since installation. Best money I've spent in a while. It's not the quietest fan in the world, but none of these are.

 

I bought a second one as I plan on taking a multi-tool to ( both of ) these to remove the local fans, and then having just the remaining shroud and iris in the ceiling. I will then have an inline fan remotely mounted in the ceiling void above for quiet / silent operation. If it goes well, I will install both in the same bathroom so I end up with 2x iris ( original one plus experimental one, if it comes around after the anesthetic ) teed together for better distribution / improved 'coverage' for absolute removal of damp / moisture residual from using my kick-ass rainfall shower in a not huge bathroom. 

 

There are square ones on the market with linear 'slats' but they're utter shart and do not close tightly, so don't confuse those cheap-o units with the Icon, as they're incomparable.

 

Get that one changed out and you'll be super happy with the results. May stop a lot of unwanted cold air influx and lower the issue with the window.

[Sparrowhawk]

10 hours ago, Radian said:

There seems to be a very sharp cut-off in condensation part way up the left hand side of the frame. This side seems to butt up directly with an internal wall. I'm wondering what the build-up of this is and if there's a substantial cold bridge here. I forget, do you have an IR camera or thermometer?

I need (okay want) to get an IR camera but I do have an IR thermometer.

 

After wiping the condensation off the bottom part of the frame on both windows, that part measures 7.5C. The rest of the frame up the side of both windows measures 9.5C-10.1C (close to room temperature).

 

These sides are butting up with the roof construction which is 50mm PIR between rafters. My guess for the bottom section is the installer hacked back the PIR too enthusiastically and didn't foam up to the window. Could be the same at the top, but the Velux foam collar should've dealt with this I'd have thought.

Edited January 18, 2023 by Sparrowhawk
Clarification

[Sparrowhawk]

6 minutes ago, Nickfromwales said:

I fitted an Icon fan in mine a few months back, and it's brilliant. It has an iris which opens a few seconds after switch on, and closes relatively tightly after it powers down. Has stopped 95% or more unwanted ventilation heat losses from the bathroom which now stays notably warmer since installation. Best money I've spent in a while. It's not the quietest fan in the world, but none of these are.

 

I need to stop being a parsimonious ***e and get one of these to try.

 

6 minutes ago, Nickfromwales said:

I bought a second one as I plan on taking a multi-tool to ( both of ) these to remove the local fans, and then having just the remaining shroud and iris in the ceiling. I will then have an inline fan remotely mounted in the ceiling void above for quiet / silent operation. If it goes well, I will install both in the same bathroom so I end up with 2x iris ( original one plus experimental one, if it comes around after the anesthetic ) teed together for better distribution / improved 'coverage' for absolute removal of damp / moisture residual from using my kick-ass rainfall shower in a not huge bathroom.

For that kind of money have you considered a good quality backdraught shutter instead? The Naber THERMOBOX is the only one I've seen and thought "that's well engineered" about (I asked for other recommendations at https://forum.buildhub.org.uk/topic/30851-back-draught-shutter-recommendations/) but with an inline fan it'd be worth an experiment to see what it would do?

 

[Nickfromwales]

Just now, Sparrowhawk said:

For that kind of money have you considered a good quality backdraught shutter instead?

Not while I've got a hole in my you-know-what......🤢🤮

 

They are horrible things, block open with lint / dust etc, and flap back and forth on windy days sounding like you've got bobby-knockers in your bathroom. They also do not stop warm air being 'pulsed' out of the room every time there's positive air being blown into the house.

 

"That kind of money" will save you £££ in heating costs. Just ask if you can pay a pound a week  

 

Stop quibbling, get yourself down to TLC / other, and go make the magic happen.  Don't forget the timer module is a separate item so you'll need that too ( when you go and buy one.... )

[Mr Punter]

6 minutes ago, Nickfromwales said:

Don't forget the timer module is a separate item so you'll need that too ( when you go and buy one.... )

 

If it is in an en-suite or WC the delayed start timer is really good.  It gives you about a minute before it kicks in.

[Nickfromwales]

Cheers, not noticed / considered that tbh. Another good idea to add to the arsenal  

Give yourself the rest of the day off,  with full pay.

[Sparrowhawk]

Velux have responded. Oh dear.

 

My message to them, photos removed as same as above

Quote

Hi,

Thanks for your reply. With regards to how I established air leakage, it was with a wet finger and an assumption due to the location of the condensation. I spoke with other Velux owners who say they only get condensation at the top of the frame if they leave the trickle vents open, so air flow seemed most likely.

I disagree with the condensation being an environmental nature, as the photos taken today and included below show it is localised to parts of the frame.
 

The room was at 61% RH at 10.2C this morning. -1C outside according to the Met office, feeling like -6C.

 

In the top 4 corners, we get corner condensation on the frame. This is where I thought/think there were air leaks, assuming that was cooling down the PU:

[Photo]

 

At the bottom on both sides of both windows, for approx 8 inches up from the corner we get condensation. Above this, no condensation until the top corners.

[Photo]

I do not think that patches of condensation on the frames of your premium windows is expected.

 

A photo of the 0062 3G glazing with condensation round the edges

[Photo]

 

By contrast the other Velux that was replaced in the Study (same roof, same aspect) was covered in ice externally this morning and had no condensation on the PU frame, and just 1cm x 1cm of condensation in the corners of the window glass. RH in that room was 54% at 11.1C. As I write this email at 1.30pm the heating is on full blast and it's still got ice on it.

 

I do not have a thermal camera here at present to take measurements. Can you provide the emissivity of the glazing and PU frame for accurate calibration?

 

Kind regards,
Peter

 

And their response:

Quote

Good Morning, 

Thank you for contacting VELUX.

 

Condensation is an environmental issue. 

 

The problem is that you now have a window that is performing the best that it can and is keeping all heat within the room. This is proven with the fact you said the heating was on full blast and there is still ice externally. 

 

It is almost completely air tight but at the small points where it is not the moisture within the room will be causing condensation to form. This is worsened if the ventilation bar is left open as it can cause the internal sections of the window to feel cold. 

 

Naturally there will be more moisture in a bedroom in comparison to a study because of the amount of moisture caused while sleeping. 

 

You need to ensure the ventilation bar is closed and instead the windows are regularly fully opened throughout the day and this will reduce the condensation. 

 

It is not a product fault, it is the window performing well and it is noticeably different because the windows it has replaced would be no where near as thermally efficient. 

Please do not hesitate to contact us for further assistance.

 

Kind Regards,

 

Edited January 19, 2023 by Sparrowhawk

[Redbeard]

"It is almost completely air tight but at the small points where it is not...."

 

Errrr.......

 

Good luck with the 'negotiations'. Of course they may not entertain comparison with others' products but what your pics show is not typical.

[NickK]

Move into a study for few days and see if what they say it’s true. I’m not sure it is.

[MJNewton]

Regarding the variable emissivity of the different surfaces, just put a small piece of black insulation tape on the surfaces to be measured and that’ll correspond well to the default calibration of the IR thermometer.

[Radian]

On 18/01/2023 at 08:25, Nickfromwales said:

I bought a second one as I plan on taking a multi-tool to ( both of ) these to remove the local fans, and then having just the remaining shroud and iris in the ceiling. I will then have an inline fan remotely mounted in the ceiling void above for quiet / silent operation.

 

What about using these?

 

[Radian]

On 18/01/2023 at 08:29, Sparrowhawk said:

These sides are butting up with the roof construction which is 50mm PIR between rafters. My guess for the bottom section is the installer hacked back the PIR too enthusiastically and didn't foam up to the window. Could be the same at the top, but the Velux foam collar should've dealt with this I'd have thought.

Could do with a photo showing the velux in context with the reveal and roof but the rafters must be in the region of 175mm? With only 50mm PIR between rafters (none underneath the plasterboard crossing the rafters?) some of the reveal would seem to be flanked by almost direct contact with outside air (assuming ventilated rafters).

[Nickfromwales]

13 hours ago, Radian said:

 

What about using these?

 

I just removed a cheap experimental one that I bought off eBay, an all metal ( stainless steel ) one, but it got stuck closed. Binned it. 
Moving electromechanical parts in an inaccessible place equals failure.

The icon fans need a monthly dust out, but perform flawlessly. Just the noise is kissing me off ( going back from a silent in-line fan. ) so improvements are to follow. 

[Radian]

5 minutes ago, Nickfromwales said:

I just removed a cheap experimental one that I bought off eBay, an all metal ( stainless steel ) one, but it got stuck closed. Binned it. 
Moving electromechanical parts in an inaccessible place equals failure.

That's worth knowing. I wish there was an Icon that sat on the outside wall so no part of the internal ducting had cold outdoor air inside it. When you look at the thermal image in my post about the shutter you can se the entire length of the duct is a cold bridge into the utility room ceiling. Being outside would mean less fan noise, and on the ground floor would still be accessible for cleaning.

[Roger440]

On 19/01/2023 at 10:09, Sparrowhawk said:

Velux have responded. Oh dear.

 

My message to them, photos removed as same as above

 

And their response:

 

 

Hmmm.

 

Ive talked before about air leaks past the seals. Is the actually happening? If so, hopefully that can be adjusted out.

 

Sounds like there trickle vent cuts straight through the fancy UPVC sections, allowing cold air to circulate within the frame itself. Thats properly crap, though according to some here, pretty normal.

 

Is this a cavity or solid walled house? The pics suggest that the lower part of the wall is probably quite cold.

 

61% at 10 degress isnt a great place to be. Why so cold? If you were at 20deg, the RH would drop away and i doubt you would have a problem. So to some extent they are right.