Comet stove in dire need of repairs

@pete sav the NRV should work like on the old svea external NRV.

Spring + pip like on normal NRVs…

Nicola

 

Ok found finally some photos:

 

Thanks Nicola but the problem with the one on the comet is you cannot get to the bottom side of the pip to replace any rubber that maybe on the brass pip
i can find no evidence of any either and it needs to seal so pressure does not escape back up the pump tube#
cheers pete

 

Could you share a photo with a view of the inside of NRV location?



Probably pip and spring are gone… maybe removed by previous owner.

 

The pictures are there on my last post the nrv seems to be inside the tank and soldered inside. So its not really serviceable. I intend to remove it all tomorrow so i can take better pictures Nicola
Thanks for the intrest pete

 

Hi Pete,
Some photos I'll post here might save you some time. I've just taken these of a dismantled small Comet tank which I just happened to have lying around here. The positioning of some of these components on the tanks differs from your larger size tank, but the components themselves are the same. I hope they'll explain how the NRV works and how it is serviceable from the outside.


The fuel pick-up for pipe to the burner:


The external access point to the NRV with plug removed:


Now here is the crucial NRV body (with screw-in outer plug) which, as you show in your photos, gets soldered around the inner edge of the outer flange onto the outside of the tank, and into the feed pipe from the pump at the narrow end:

On mine there are air outlet holes in the NRV body on both sides, not just on the one side visible in the photo.

Now looking into the NRV body from the outside there are 2 points at which changes in the internal diameter create shelves:




The first 'shelf' is the point to which the plug reaches when it is fully screwed down:


The seal of the plug screwed down on to this shelf is what prevents fuel leakage to the outside. The smaller diameter section below the plug seal is where the NRV pip, carrier and spring need to be pushed into. The shallow point on the bottom of the plug both helps the seal against leakage and helps keep the NRV spring centred. The NRV pip itself locates and seals onto a tiny final internal shelf/flange which lies below those prominent vent holes, which lead out of the NRV body into the tank itself, and immediately before the very bottom of the NRV body (just before it fixes into the link pipe from the pump).

If this all makes sense you'll see that, unless it is necessary for some other reason, there is no necessity to unsolder any of that pipe/NRV assembly from the tank. That assembly itself looks to be sound. All that is required for the NRV to function is to source a brass pip carrier, cork pip and a suitable length of spring, insert them into the NRV carrier body from the outside of the tank and then seal everything in by screwing down the brass plug.

 

Good Morning @pete sav, very impressed with the progress so far, i am sure this restoration is going to be a success looking forward now to the next stage well done there

 

Thankyou for the help so far especially Nicola and igh371 for taking the time with uploading pictures of the nrv setup.
Now on this stove the spring is long gone maybe lost by a previous owner but the little bush that holds the cork pip would not come out.
The hole where it falls out of the tank was burred over not much but enough to stop me removing it.
After seeing how it works i got a needle file in there and opened the hole and it drops out now job sorted thanks lads.
Just a new pip and suitable spring and it should work fine.
Intend to progress with tank repairs now.
Thanks again pete

 

@pete sav
I know when we discussed your Comet project at Ashover we wondered whether the end caps were silver soldered on. Evidently not Pete, so your proposition to use silver solder internally for the cracks, then soft solder the end cap back on is a go-er.

Access for cleaning and soldering is a lot tighter than on the Blanchard tank, so maybe applying the silver solder externally is the only practicable way to do it? You’d avoid all that pipework too.

John

 

Yes John the ends were soft soldered on so that was good so today after sorting the NRV out with a stuck pip i set to and removed all the bits i could to make access to the internals easier.


i then cleaned all the bits up and removed as much old solder off the parts and tank as i could get off.

here they are all cleaned up ready for putting back together i give the tank a quick dip in safety pickle to remove all the oily dirt



got it setup to solder the cracks but was difficult to get the right angle with the torch inside the tube but done well enough i think



well thats as far as i got today not a perfect tank but much improved from how it was.
By the way John that clicking when the knob was turned on the stove it is a spring action for the missing pricker pin more of that later

cheers pete

 

Everything looks very promising! Cheers!

Nicola

 

Great stuff! Watching with interest.

 

@pete sav
I might have known, you didn’t mess about Pete, whipping out the pipework. Makes sense, the soft-solder in the joints would have dribbled out with the heat of silver soldering no doubt.

Yeah, the clicking pricker. I think I read something about that in Bo’s (‘Optipri’s) post.

Cheers,

John

 

Right been doing this stove and have managed to re solder all the tank up and it appears to have no leaks and i have run it for maybe 90mins in 30min tests, the tank does get warm with the 111t burner on. The pump shaft does get a drip of parrafin out of it after pumping it up but i am not 100% happy with the NRV yet but its working and holds pressure in the tank.
I had to silver solder the tank lid up as it would not hold air due to a big crack its ok but i need to tidy it up yet make it look better.



The repairs to the tank are not invisible but they dont show daylight thro them most important its not leaking and holding pressure



Last and finally a picture of it running with a 111t burner fixed on to the tank intend to run it for a good while and clear it of any solder and water contaminantion
Now of course there is the burner to look at but i suspect it wont be as bad as this tank


Cheers Pete

 

Great result!

Can’t wait to see it finished.

 

Outstanding work Pete.

 

Excellent!

Good luck with the burner.


Cheers

Tony

 

Well i am still plugging away with this old stove and to be honest its hard going. i am not sure that nrv is working right as the tank holds pressure but i cannot get loads in it will run the 111t for a good while but i feel its lacking pressure some what, so today i had a mess with the burner for a change
some pics of the burner as it came.

Now the pricker is very clever its spring loaded and jumps thro the jet when you turn the knob at the front of the stove



The pricker wire is in a hole\slot in the main pricker operator wire



right so now the repaired burner on the comet tank



ok but not great

so now on a optimus tank with a slightly out of control preheat !!!!!



much better flame now with not many pumps so maybe its back to the drawing board with the comet tank

lovely flame on that burner

cheers pete

 

What a wonderful flame that is! Keep at it, you'll get there!

 

@pete sav.
Absolutely brilliant work Pete, i am looking forward to seeing the end result well done there