Dometic Mini Heki very stiff in operation.

[paul_richardson]

Hi,

Just before Covid (yes that long ago) I bought a new Dometic Mini Heki Rooflight to fit on my camper, it was to replace a much smaller rooflight.

I have only just got around to fitting it but unfortunately it's not closing properly, it's very hard to close, and doesn't seem to be latched in place by the little plastic bits on the side. I'll try and take a phot tomorrow to show what I mean.

Has anyone else experienced a similar issue?

Regards,

Paul

[Derek Uzzell]

This link includes information on Dometic rooflights

https://www.dometic.com/en-gb/outdoor/uk/products/climate/ventilation-solutions/motorhome-and-caravan-rooflights

There are two Mini Heki versions - the "Style" type (example here)

and the "S" type (example here)

 

My Rapido 640F had a "Style" Mini Heki, but I don't recall any real difficulty in opening or closing it. I've no practical experience of the "S" version, that looks more complicated. 

I think you'll need to say which version you have - "Style" or "S" - (if you provide a photo, that should make it plain) and go into more detail about the closing issue.

[paul_richardson]

Hi Derek,

Thanks for your reply, Mine is the "Style" and I was going to take a photo today, but it's been wet virtually all day.

Thanks to you I don't need to as I have borrowed your style photo and drawn a circle on the area which I suspect to be the cause of the trouble.

There is a little piece of hinged plastic with a groove in it that the handle slides up, and what looks like a latch at the top, I think it's supposed to pull the Dome down the last few centimetres but it doesn't.

The rooflight was bought brand new but has been stored (in it's box) in my garage for a few years.

Any ideas would be appreciated, I wondered if it might just need lubrication, but I've no idea what I should use on plastic parts.

[Brian Kirby]

We have a similar, possibly identical, rooflight on our van.  The only aspect of opening/closing that I have found awkward is the need to pull down on the transverse bar to unlatch/latch the mechanism.  I haven't access to the van at the moment, so can't elaborate further.  However, I should have it back tomorrow, so could have a look then if you're still having difficulty.

Just one question.  When you say it is "hard" to close, do you mean that the mechanism itself is obstructive and resists closure, that it is physically difficult to manipulate the mechanism, or that you cannot quite understand what you are supposed to do positively close it?  Sorry to split hairs, but I'm having a little difficulty understanding what it is that is is at the root of the problem.

Regarding lubrication, all I have done is to spray a little Thetford seal lubricant (silicone) onto paper towel, and then wipe the sliding parts with that.  I've found that remarkably beneficial, and also on the sliding blackout/flyscreen blind tracks, which seem to become sticky after a while.

[witzend]

If there's a rubber seal around between the frame an dome is it fitted correctly when mine came it was with the grove down I had to reverse it to get the dome to clip down comfortably. I use silicon spray grease for lubricating plastic like Brian suggests 

[Derek Uzzell]

Pauk

These links include guidance on installing/operating a Mini-Heki "Style" roof-light

https://manuals.plus/dometic/mini-heki-style-roof-light-manual#axzz7y1EoeJID

https://www.manualslib.com/manual/1687662/Dometic-Mini-Heki-Style.html

and these images are extracts

 

What you have circled on the photo in your last posting is referred to by Dometic as a 'slider'. There is a slider on each side of the roof-light and (as it says in Secetion 8.1 above) these are used to lock the U-shaped tubular metal operating bar ("bracket" in Dometic-speak) in place when the roof-light is in the half-way open position. (Presumably this locking feature is there for people who wish to drive a motorhome/caravan with the roof-light part-open, or to minimise the chance of damage occurring if the roof-light is open in windy weather.)

My Rapido 640F's Mini-Heki roof-light was over the rear bed and I very seldom opened it. When I explored how the sliders were used, I remember finding them reasonably easy to move to their locked position, but a real b*ggar to unlock them. If the sliders on your roof-light do not move fairly easily, I suggest you spray them with a silicone or PTFE product (I use WD-40 Dry PTFE Lubricant).

I did find with my Mini-Heki that, when the roof-light had been closed (with the bar having been lifted over the top of the release-button) the bar was not as 'tight' against the release-button as I liked, meaning that the roof-light was not as firmly closed as I wanted it to be. To improve matters I cut a lengthways slot in an appropriate length of suitable diameter/thickness white plastic tube, warmed up the tube, pushed the tube over the bar where it met the release-button and glued the tube in that position. The tube increased the diameter of the bar where it contacted the release-button by a few millimetres and the resultant extra pressure pulled down the roof-light more firmly.

[Keithl]

Paul,

Did you try opening and closing the vent before installing it? If so was it stiff or free? Is it possible that that the outer frame has distorted slightly during installation?

Keith.

[Derek Uzzell]

This is an image of one of the 'sliders'.

 

When the roof-light is to be put into its half-way open position, the bar is moved (from left to right on the image) in the lower groove, then lifted upwards into the curved groove that leads to the base of the slider. The slider is slid upwards, the bar is moved to the end of the curved groove (red arrowed) and the slider is slid downwards behind the bar's rear, locking the bar in place. To disengage the bar, lift the slider and pull the bar along the curved groove (right to left on image) until the bar drops into the lower groove. 

[paul_richardson]

Thanks for all of your advice, it's much appreciated.

I've borrowed your image again Derek and put another circle on it.

 

My problem is just behind the slider right on the edge of your image.

When I am closing the rooflight all goes well until the last little bit, when you push the bar over the big button at the back.

By looking at the outside I can see that the Dome is not sitting on the frame correctly on the drivers side at the back, so the little hooked piece of plastic (that is just peeping into view at the edge of your picture) is not catching on the dome.

It's only a tiny bit out, but enough to stop it working.

I thought about releasing the tightness of the screws in that corner, but I've used Dekaseal 8936 for the first time and I'm not sure what will happen if I release the pressure.

I really don't want a leak.

Regards,

Paul 

[paul_richardson]

20 hours ago, Keithl said:

Paul,

Did you try opening and closing the vent before installing it? If so was it stiff or free? Is it possible that that the outer frame has distorted slightly during installation?

Keith.

Hi Keith,

It was stiff to operate before I fitted it, but I put that down to it not being mounted in place, so making it was tricky to open and close when it won't hold still.

Paul

[paul_richardson]

21 hours ago, Brian Kirby said:

Just one question.  When you say it is "hard" to close, do you mean that the mechanism itself is obstructive and resists closure, that it is physically difficult to manipulate the mechanism, or that you cannot quite understand what you are supposed to do positively close it?  Sorry to split hairs, but I'm having a little difficulty understanding what it is that is is at the root of the problem.

Regarding lubrication, all I have done is to spray a little Thetford seal lubricant (silicone) onto paper towel, and then wipe the sliding parts with that.  I've found that remarkably beneficial, and also on the sliding blackout/flyscreen blind tracks, which seem to become sticky after a while.

Hi Bian,

I wasn't able to explain very well what was going on, but having looked at what happens from outside while my wife tried to close it, I can see what's happening, I have explained as best I can now using Derek's latest picture (above).

Regards,

Paul

[paul_richardson]

21 hours ago, Derek Uzzell said:

Paul

 

 

 

Hi Derek,

Many thanks for all the info, I'm quietly confident that I am doing it right, It's just not hooking on the catch (4) on the drivers side.

Paul

[Brian Kirby]

2 hours ago, paul_richardson said:

Hi Bian,

I wasn't able to explain very well what was going on, but having looked at what happens from outside while my wife tried to close it, I can see what's happening, I have explained as best I can now using Derek's latest picture (above).

Regards,

Paul

FWIW you're welcome.  🙂  Having seen the above updates it is now clear that the rooflight in our van, while similar, does not have the same raising/locking mechanism as yours.  Sorry.

[paul_richardson]

Today's experiment was with me on the roof and my wife inside.

I was pushing and pulling the dome in different directions to see what happened.

It turns out that if I move the dome to the drivers side of the van, the catch on that side works (the passenger side always works) and the rooflight locks perfectly.

The catches I am referring to are marked (4) on the sketch posted above by Derek.

I've left it closed in the hope that maybe it will get used to being in that position 🙂

I don't understand how the square frame going into my square hole (I double checked it) can end up slightly out of line.

[Keithl]

The roof of a panel van normally has some curvature to it (to add strength) so it may be that the frame is twisted ever so slightly. Could you try loosening the mounting screw or is rigidly fixed to the roof?

[paul_richardson]

17 hours ago, Keithl said:

The roof of a panel van normally has some curvature to it (to add strength) so it may be that the frame is twisted ever so slightly. Could you try loosening the mounting screw or is rigidly fixed to the roof?

I think you might be right  but It's fixed pretty tight, maybe I overtightened the screws.

I've been considering Taking it off and starting again, but I'm not sure how easy the Dekaseal 8936 will be to get off. 

[onecal]

The aperture you fit the unit into needs to have a a little free play all around so as there is no pressure on the frame itself 

This will causing binding on the sliders Just as Keith has suggested if your roof has exceptional curvature you may have twisted the frame on over tightening  

Start again with caution and refit may be a good move 

Regards

[paul_richardson]

1 hour ago, onecal said:

The aperture you fit the unit into needs to have a a little free play all around so as there is no pressure on the frame itself 

This will causing binding on the sliders Just as Keith has suggested if your roof has exceptional curvature you may have twisted the frame on over tightening  

Start again with caution and refit may be a good move 

Regards

Is it difficult to remove Dekaseal 8936?

[onecal]

Hi 

Its flexible and should not be too difficult to remove 

Time and patience and caution 

 Ensure the skylight fits in and out freely without binding. When you are happy with that replace with your mastic 

On re fitting,  the new mastic  should take up for any slight curvature in the roof 

Making sure you do not tighten down the fixings too tight 

Regards

[paul_richardson]

Hi Guys,

I chickened out from a full removal and install and opted for an attempt at adjustment.

I went round inside and slightly slackened off all of the fixing screws, I could hear slight "creaking" noises and could see that the drivers side was moving upwards. I continued with another round of slackening concentrating on the drivers side and it moved upwards again. These were only tiny movements, but they were in the right direction.

I went up the ladder and checked that the Dekaseal was still filling the gap and it was. I then popped back inside and to my delight it closed PROPERLY.

I went back around the screws to make sure they were not physically loose, tightened the passenger a little and I have left it like that for the time being. I'll check next time it rains (probably in about 5 minutes 🙂) and make sure it doesn't let water in.

As people have said, it definitely looks liked I panicked and tighten the screws way too tight when I installed it.

Paul 

[onecal]

Hi Paul

That's good news 

It should not (hopefully) let in water as its flexible, unless you really overtightened it 

Regards