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  #61  
Old 2nd July 2020, 09:57 PM
EdmundH EdmundH is offline
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Quote:
Originally Posted by Mike O'Pray View Post
Pete, your pics make your Nova set-up pretty clear but unless you are only meant to fill up to the level of the hole which means only half a water jacket full then I'd have thought that the plugs have to be completely watertight to work and that's where leaks are possible

Perhaps the plugs are watertight and that is what Alex was referring to when he mentioned having to change them for new ones at intervals

Given that water-jacket draining by syphon is relatively easy and Bob's method is even simpler, I am not sure that the holes half way up were an improvement.

Mike

I bought new level plugs for mine, and they were definitely not watertight. I don’t bother with them.


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  #62  
Old 3rd July 2020, 09:22 AM
John King John King is offline
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Default level plugs

I forgot to mention my early processors, the level holes always leaked so I disposed of the bungs and after filling to the correct level I gently lifted the back of the processor 1/2" or so to let the water level drop at the hole level then after wiping the area dry, taped over the holes with black Gaffa tape. That is waterproof, but if you have to change the water bath the tape is easily removed.
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  #63  
Old 3rd July 2020, 04:38 PM
High Sierra High Sierra is offline
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Quote:
Originally Posted by Mike O'Pray View Post
Pete, your pics make your Nova set-up pretty clear but unless you are only meant to fill up to the level of the hole which means only half a water jacket full then ......

Mike
I clearly didn't make it clear in my earlier post, you are only meant to fill to the level of the holes.
Pete
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  #64  
Old 3rd July 2020, 07:08 PM
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B&W Neil B&W Neil is offline
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Originally Posted by High Sierra View Post
I clearly didn't make it clear in my earlier post, you are only meant to fill to the level of the holes.
Pete

I do agree - when I was using Novas for both colour and colour reversal my understanding was to fill up the jacket to the holes in the back of the tank, until water came out, and then put the plugs back in.

Always worked for me :-)

Neil.
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  #65  
Old 3rd July 2020, 09:48 PM
Mike O'Pray Mike O'Pray is offline
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It certainly suggests that filling the water jackets more than half full in the case of Novas that only have holes on top is unnecessary. I had always assumed that you were meant to get the water level close to the top but this, I admit, was always an assumption on my part as I have never seen any instructions on how high to fill the water jackets. They may well have said to only half or 2/3rds fill the jackets. I got my Nova secondhand and there were no instructions with it

It would make moving the Nova easier and possibly safer with that much less weight

Mike
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  #66  
Old 4th July 2020, 06:44 AM
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Bill Bill is offline
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Quote:
Originally Posted by Mike O'Pray View Post
It certainly suggests that filling the water jackets more than half full in the case of Novas that only have holes on top is unnecessary. I had always assumed that you were meant to get the water level close to the top but this, I admit, was always an assumption on my part as I have never seen any instructions on how high to fill the water jackets. They may well have said to only half or 2/3rds fill the jackets. I got my Nova secondhand and there were no instructions with it

It would make moving the Nova easier and possibly safer with that much less weight

Mike
Mike - As the water bath is there only to warm the pods holding the chemicals it is not necessary to have the pods fully immersed just enough to cover the heaters and say be half way up the pod. I was given my Nova Trimate and it had no bungs so I did not know there should be any. I just fill until the water dribbles out of the holes.

Somewhere I have a pdf of the instructions that I was given by another member. I will send them to you when I find them.

Bill
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  #67  
Old 4th July 2020, 07:20 AM
John King John King is offline
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Default Water levels

My argument against having low(ish) water levels is, although the chemical tanks will warm up eventually it will be slower and as the convection current generated inside the chemical slots gets higher the temperature is bound to drop. So while the temp at the bottom and about half way up will be (hopefully) 35C at the upper levels it could be as much as 2 degrees cooler.

I have shown this to be correct when I was calibrating my current 16x12 3 bath processor where I inserted a long mercury thermometer (Yes I still have one and no it's not for sale!), This reached within 3" of the bottom of the chemical slot which was where I took the initial reading from. It was showing 34.5c

I then lifted it up to sit 4" down from the top and the temp and left it for 10 mins and the temp was now down to 32c..... and this was with full water heater cores.

I have also checked other points about the Nova where temp is concerned and that is when using a 3 bath with the centre slot having the stop bath. When the temp off the developer and blix are around the 34/35c range the centre slot can be as high as 40c because it has an insulated jacket on both sides.

As mentioned before the upper levels of the dev and blix slots can be lower closer to the top than down below, I have used an expanded polystyrene sheet, cut down to fit tightly in the upper half on the outside between the centre and upper black strips and this has reduced the temp differential almost to nil. I had to re calibrate the heater and was able to reduce the dial down by around 3C. Nor does the heater have to come on so often

So with whatever version of a Nova you have the water level guide is designed to be used as such and for the tanks not to be only partially filled. This of course is with my 16x12 tank with a 10x8 or a 20x16 it will be different again. A user will not have to change the water jacket often, say every 24 months- if that. In all the years I have being using them I have never encountered a problem of draining the heating cores so long as the chemical slots are drained 1st. The weight the tank itself with of full heating cores but no chemicals weigh something in the region of 10 kilos, say a stone and a half thereabouts which not an unmanageable weight.

While the Nova system is not perfect, I have found you need to adapt and 'tweak' it slightly to make it more constantly accurate. It is a good and reliable way of making colour prints and far superior to the Jobo drum system..

Last edited by John King; 4th July 2020 at 07:34 AM.
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  #68  
Old 4th July 2020, 11:37 AM
Mike O'Pray Mike O'Pray is offline
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Interesting point John. What you have discovered does not appear intuitive to a user such as I and I suspect many others.

In b&w developing this range of temps probably doesn't matter but may be more critical in RA4 although even here the 2 mins at room temp for open tray RA4 processing suggests that time isn't that critical as long as the bottom end of the range still exceeds say 70C

I tried Nova slot processing once with RA4 at about 25/26C while ignorant of your effect and it seemed OK but I reverted back to b&w after one session. I had left the RA4 dev in the tank for probably a couple of weeks with no activity and when I came to change the chems back to b&w the tar build up was quite substantial

Matters were not helped by having only one Nova.

I'll have to check my temps out of curiosity as mine is only a 8x10 Nova so may be less effected

Just out of curiosity I can quite envisage how the polystyrene fits. Is it just a block of it glued to the outside of the Nova against the water jackets. How thick is it and how wide and high?

Thanks

Mike
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  #69  
Old 4th July 2020, 11:54 AM
Tony Marlow Tony Marlow is offline
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I did read in Novas instructions that you should not try and move or lift the tank unless all the liquid had been drained or else you may damge the tank and crack the joints.

Tony
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  #70  
Old 4th July 2020, 01:26 PM
John King John King is offline
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Default Tar Build up

Yes you do get a lot of tar left especially in the developer slot and less in the stop bath, but that is the nature of the beast.

I am not consistent with maintenance but last year when I was away over in Europe I drained the chemical slots storing the dev and blix in 2 L lemonade bottles with the air excluded. (It didn't work!) The slots were then filled up with quite a strong bleach diluted to about 33% the lids replaced and double covered with cling film.

On return the slots while quite not 'as new' were clean and all I needed to do was flush the slot out with the taps removed. The NOVA cleaner is possibly quite dangerous and I'm surprised they are still allowed to sell it. The fumes are pungent and if anyone had breathing problems it won't do them any good at all.
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