Replacement Heater for (some?) Nova Darkroom print processor

[MToma]

Hello all,

As my old Nova processor's (I think it's a Quad) heater were faulty (bought them as such), I decided to replace them.

It's quite easy to take them out, as they're basically just "pushed in" some rubber grommets - start with a flathead screw driver to pry them out, then twist and pull in small increments, and they'll come out relatively easy.

My old heaters had a diameter of approx. 2.33 - 2.35cm, length around 24cm, and were 150W each. As my 12x16" Nova had more length available and I noticed that Nova is selling 200W replacements, I decided to get some longer/more powerful ones (around 32cm long, and 200W each).

I got supremely lucky, and the Diversa Thermo Plus 200W ones that I bought are approx. 2.35-2.37cm in width, just fractions of a milimeter thicker. With a bit of greasing and/or slight enlargement of the holes, I think they will fit in just perfectly.
https://www.diversa.info.pl/en/products/heaters/thermoplus/

To the best of my knowledge, all the heaters in the Thermo Plus range should have the same diameter, only the length differs (and that's specified on their website). They seem to be available through Amazon.de, and many Eastern European shops (they're a Polish brand, from what I see).

Here's hoping they hold out well in time.

P.S. Sorry for the slightly spammy post, but I had issues in finding proper replacements and/or HOW to take the old ones out. I said I'd give back some information to this wonderful forum, which helped me a lot (I'm a loooong time lurker).

 

[MToma]

Update: with a bit of lubricant smeared on the rubber grommets, they went right in. After a lengthy calibration, a target of 20-22C inside each chemical jacket seems to work properly (I went for a bit above 20C, as in the summer, it's closer to that in my darkroom... and the Nova can't cool down the chems).

Caveat - they're quite sensitive, and try not to push them in too far. I tried to pull one back a bit with a metal vise, and I "ripped" off a bit of the ending glass, because of this. In case they'll need to be re-replaced, it won't be very funny... It'll likely involve drilling a hole in the opposite direction of the entryway and pushing them carefully with some stick. It's likely that sliiiightly enlarging the entry holes would've been a better choice.

 

[Kino]

Thank you, MToma for this information.

This will be handy in case my heaters should decide to fail on my Nova Slot Processor.

 

[MToma]

My pleasure.

Another addenda: it's possible that a 150W heater might be better suited, as it MIGHT have less thermal inertia after stopping. As their temperature regulation is not really precise, the temperature swings are a bit more than initially thought. After more careful measuring, I'm getting 19-23C in the developer slot (the >22C temperatures stick around for about 1/2 an hour after a heating cycles, then 3 good hours of 19-22C before the next cycle)... Which is absolutely decent, but I'm a stickler.

 

[AgX]

One might have a look at the similar german heaters from Eheim too. The 100W versions have a tube diameter of +/- 24mm.
Stated reciprocity: +/- 0.5K , Range:18-34°C

 

[MToma]

One might have a look at the similar german heaters from Eheim too. The 100W versions have a tube diameter of +/- 24mm.
Stated acuracy: +/- 0.5K , Range:18-34°C

I also had a look at the Eheims, as they looked better quality, but couldn't find anything lower than 28cm in diameter. Which model do you have?

 

[AgX]

I had at hand the model 3604, the predecessor to the curent Thermocontrol 3614 model. But the only difference seems to be the design of the temperature dial. Tube diameter seems identical for all 18 models. Also for the Thermocontrol E range. All take same holder.

The various models are confusing... But to my understanding the major difference is just the manner of temperature setting:

-) old Thermocontrol models
if necessary adjust the setting until the heater is at equilibrium at intended (metered) temperature ; the scale setting may then be off a bit fom metered value

-) new Thermocontrol models
if necessary adjust the setting until the heater is at equilibrium at intended (metered) temperature ; the scale setting may then be corrected to coincide with metered vaue (or the other way round; in any case, the pointer is adjustable.)

-) Thermocontrol E model
temperature will always be as set on scale

 

[lantau]

When I fitted the new Nova heaters the manual did state to grease them. They were a pretty tight fit. The regulator does get feedback on the temperature and as it rises will reduce power until it only maintains the temperature at the set level.

 

[MToma]

When I fitted the new Nova heaters the manual did state to grease them. They were a pretty tight fit. The regulator does get feedback on the temperature and as it rises will reduce power until it only maintains the temperature at the set level.

The original ones, you mean, right? I'd surmise those have better temp control.