Author Topic: Using Thermoblock as preheater  (Read 30732 times)

Offline reox

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Using Thermoblock as preheater
« on: December 17, 2017, 02:36:51 PM »
I own some thermoblock of some old coffeemachines and I thought about putting one of them in front of the boiler to pre-heat the water. Thus the temperature drop during a shot should be reduced.
Here is already some trials but it seems nobody succeded with the Classic?
Instead of letting the thermoblock running all the time, I would only run it when the pump is running.

Has anyone done some thing before?

Offline jerryseabridge

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Re: Using Thermoblock as preheater
« Reply #1 on: December 24, 2017, 11:00:25 AM »
....a belated response... I did something similar by adding a "pre-heat" boiler to my Gaggia "New" Baby (same boiler as in Classic but in a different case and using silicone tubing) - if you search around this forum you'll find more details. Some thoughts on adding a Thermoblock (TB):

1. There's very little spare room inside the Classic, esp if you've already put a PID/SSR in it - TBs are relatively bulky so I doubt they would fit, at least not the ones I've seen.
2. You would need a new OPV so that the flow is pump to OPV to TB to main boiler - you could do this using the plastic OPV that's fitted on all Babys, Pures/Colours and the 2015 "Classic" (stainless steel boiler version) as it screws directly on to the pump - it's officially a non-adjustable OPV but (again there are threads on here about this) by nibbling the internal spring down it the working max pressure can be lowered. These plastic OPVs are not as robust as the standard Classic ones but - IMHO - work just fine.
3. What piping to use - the TBs I've seen need the high temp silicone tubing unless you do some very clever metal pipe work - I've had a lot of experience of this tubing and find it is prone to springing the occasional leak - I keep some spare and once every few years I found I've needed to replace the odd piece of old piping. You'd also need to invest in Oetiker clips (do not be tempted to use Jubilee clips!) and the tool to fit them.
4. One way to go might be to attach a box to the back of the Classic to house a TB, then run the piping from the pump into the new box into the TB then back into the main unit. Again I've done this "adding a box" approach with the Baby models on a few occasions - I dont notice the box on the back and have found having the extra space makes life a lot easier.
5. Think about max current required - the Classic already draws around 10A IIRC - adding a TB may increase total current and might trip your fuses. I doubt it will as you'd only be using it once the main boiler was up to temp so it wouldnt require that much power.

Would it be worth it? Speaking from my own "pre-heat" boiler experience, then I believe my pre-heat approach delivers a consistent intra-brew temp AND means I can make multiple espressos of the same quality in a succession with no wait time between them.

On the other hand if you goal is purely intra-shot stability then I doubt it's worth the effort (though it might be fun if you're that way inclined!) - instead I'd study the various threads here and elsewhere regarding pre-extraction steam blips and blipping during the extraction.




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