Installation of Navitron collector – roof detail.

[rhannington]

My 20 tube 58mm collector installation last 'summer'

One of the first things I did was to fix a piece of softwood to the frame with holes spaced the same distance as the manifold bolt holes.This made the frame easy to lift onto the roof in one piece and held the frame in the correct  position for the straps to be fitted.

Once straps were in place I fixed the bottom of the frame with the special bolts/screws I bought from eco-nomical.co.uk. These consist of a carriage bolt type head and thread at the top half and a wood screw thread and point at the bottom half.
The bottom of the frame was supported on a piece of timber so it could be held above and to one side of the positions for drilling through the concrete tiles.
Taking care to measure for the center of the batten I used a masonry drill very slowly with plenty of water to lubricate it. Tough and brittle stuff , a lot of patience is required!

The special screws were screwed into the tile battens using a spanner on the square head. The holes were stuffed with  plenty of silicone compound prior to the screws going in, then more around the screw and tile once the screw was in.
I made aluminium ‘tiles’, the lower one having a hole drilled to fit over the screw, more silicone, then a plastic washer (supplied with the screw),  stainless steel washer and nut tightened onto the ‘tile’, then brought the frame down so the top of the slot rested against the screw shaft. Finally, the flat washer, shakeproof washer and nuts were fitted to secure the frame.
Incidentally, I chose to use screws at the bottom of the frame rather than straps for two reasons.:
1.   I have very limited access to this part of the roof from the inside, and the position the frame needed to be mounted in meant the bottom was very close to the eaves.
2.    I was not happy that straps would secure the frame without some lift in high winds(which are plentiful here near the coast).
However, I was concerned about holes in the roof and leaks, hence the copious amount of silicone and the care in fitting ‘tile’ and sealing washer. 9 months on there does not appear to have been any rain penetration, despite a great deal of rain and wind over that period.

The manifold was bolted to the frame and the hole drilled through the tile to take the 15mm copper pipe. Silicone was squirted into the hole, then the end of the pipe plugged with putty so it did not take in any silicone on its way down. The copper plate was drilled beforehand on the workbench.
The sealing ‘boot’ is actually a transport rubber from a washing machine, which is a very tight fit on the pipe, and the underside is smeared with silicone before pushing down onto the copper. I had tested this rubber in a pan of boiling water for about 10 minutes and it did not soften or change in any visible way.
I used a 22-15mm elbow. 
 
On the ‘hot ‘ side I used  a 22mm tee for the vent pipe, the end of which is reachable from the Velux window for bleeding.
The sensor cable was taken through the tiles making use of the gap between tiles to thread it through.

 
       
If anyone would like further information on my installation feel free to ask. I wrote this up to help anyone with a roof installation, but I can also give details and pictures of my internal layout too if desired.

Richard

[rhannington]

All tubes and reflectors in.
I found that the weight of the (58mm) tubes causes quite a bit of sag in the middle of the frame, so I used a computer CPU heatsink to support the bottom bar.
The reflectors are fiddly to fit but after a bit of practice I got quite quick, positioning them at the bottom of the frame by feeding them edgeways between tubes so they rested on the tiles, then using the plastic clips to ‘hook’ them back up into position at the back of each tube, finally turning the clip steadily through 90 degrees to tighten.
Note: Only partial lagging shown in pic. Armaflex used throughout.

[wdh]

Richard, thanks for posting those.

Perhaps you'd have another go at the first lot of photo's -- they are a bit small!

And (unless you REALLY trust Virgin's spam-stopper) you probably don't want to be leaving that email address displayed like that... 

[rhannington]

Thanks wdh, I have removed the email address.  I will resize the pics in the next couple of days, I had trouble keeping within the site's space limits.

Richard

[solar_cambridge]

Thanks wdh, I have removed the email address.  I will resize the pics in the next couple of days, I had trouble keeping within the site's space limits.

Richard

Does the manifold and the bottom bracket have to be located at the end of each of vertical support? If it could be say 1/5th from each end then that would probably stop the middle section from sagging? I can't really see from the pics if that would be possible?

[itsnewtome]

How do you reach the air vent? Can you reach it from the velux?
I don't really understand the need for one. Presumably it is a pressured system which shouldn't entrain air should it?

[rhannington]

"Does the manifold and the bottom bracket have to be located at the end of each of vertical support? If it could be say 1/5th from each end then that would probably stop the middle section from sagging? "

Hi solar_cambridge
To answer the above questions, yes, the frame vertical layout dictates the positions of manifold and bottom bar at each end, with 'tabs' stamped out at right angles from the verticals that take bolts/nuts at each end.
I can't see how putting them 1/5th in would help anyway, as it is the bottom bar itself that flexes under the weight of the tubes. Hence my CPU heatsink as block between tile and bar to hold it up.  It may be that 58mm tubes are more of problem than 47mm in this respect as they are heavier of course.

Richard

[rhannington]

How do you reach the air vent? Can you reach it from the velux?
I don't really understand the need for one. Presumably it is a pressured system which shouldn't entrain air should it?

itsnewtome
Yes, I reach the air vent from the velux.
An air vent is necessary for bleeding air out of the circuit initially during filling. Once all air is released the screw cap on the end of the vent is tightened to seal the system, and the system then pressurised . I keep mine at around 1.25 bar. 

Richard

[solar_cambridge]

"Does the manifold and the bottom bracket have to be located at the end of each of vertical support? If it could be say 1/5th from each end then that would probably stop the middle section from sagging? "

Hi solar_cambridge
To answer the above questions, yes, the frame vertical layout dictates the positions of manifold and bottom bar at each end, with 'tabs' stamped out at right angles from the verticals that take bolts/nuts at each end.
I can't see how putting them 1/5th in would help anyway

I would have thought putting the verticals nearer the middle would cause less bending since the moment would be less as the there is less downward force.  Also more importantly I'd like to choose where I put the verticals and the bottom bracket since its ok for flat tiles but if you have roman or other types of tile you only have a very small valley on each tile run the support strip from.

Do you think its possible in some way to move them inwards? Does the manifold have tappings to take the bolts?

[Billy]

Looking at mine now and yes it does.  I guess there are captive nuts rather than the casing being threaded as it is thin sheet.  It would be possible to move the mounts, fiddly but possible with a little bit of minor fabrication.

 

[Amy]

When i installed a 30/47 system on a flat roof, i made up a main frame from Dexion to bolt the Navitron frame onto.

The navitron paper thin stainless angle and channel was just too flimsy and had no torsional stability

[Billy]

Can you get stainless Dexion I wonder, shudder to think of the price.  Always used to be able to find the ordinary stuff somewhere.  Most handy for bodging sumut together as Frot would say, or indeed for the purpose of making a rigid frame for the tubes.  In my case I am too close to the saline stuff and it melts.

 

[Amy]

The only place you might find SS Dexion or pre drilled angle is in catering places but because of all the holes and slots it wouldnt be hygenic, so very much doubt it.

looks like good old galvanised, cos galvanised is best, ........and she said, Ernie, i'll be happy if it comes up to my chest.

That tickled old Ernie, and he drove the fastest milk float in the west.   

[Billy]

Was that the old galv wire crates?

[solar_cambridge]

looks like good old galvanised, cos galvanised is best, ........and she said, Ernie, i'll be happy if it comes up to my chest.

Box section extruded aluminium would be cheaper, lighter and corrosion resistant.  Thanks for the comments re: mountings. I am quoting for two navitron collectors on a pitch roof so lets hope I get it and can experiment with this.