Posted Sun Apr 20, 2014, 12:53pm Subject: Volume of heated water in HX to brew
I'm working on an espresso machine which needs a new HX setup inside the boiler. The previous design used a small tank inside the main boiler, and had a total volume close to 200mL. This design had the disadvantage creating a gas volume inside the heat exchanger, as the inlet tube was not at the top of the small tank, and it's also impossible to drain without disassembly.
Does anyone know the volume of water heated in a HX setup running to the group for a smaller single group espresso machine? I suppose 200mL could work, but it seems a little much.
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 7,734 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Vene. A1, La Cimbali M32 Grinder: Azkoyen Capriccio, Major Vac Pot: 40s era Silex Drip: Msl. Com. brewers Roaster: gave it a try, decided no
Posted Mon Apr 21, 2014, 6:39am Subject: Re: Volume of heated water in HX to brew
The volume of the HX will be different for each machine, the service it was intended to be used for etc.
I don't understand the issue you are having with the manufacturers design. The HX WILL fill completely, it may take a few volume exchanges to happen but it will happen. As to draining it, again I am not sure why you would want to???
When you venture out on your own for design, you then become the designer, you set the parameters, you do the calculations, you determine the service duty.
In real life, my name is Wayne P. Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!
Feed the newbs, starve the trolls and above all enjoy what you drink!
Posted Mon Apr 21, 2014, 2:27pm Subject: Re: Volume of heated water in HX to brew
With the HX espresso machine I bought, the seller said the boiler was emptied, but the inner hx chamber was most likely not emptied. When it arrived, the bottom of the hx was blown out and sitting in the boiler. Since it did have to ship over the mountains, it most likely froze the remaining water in the HX. The current design fills from near the top of the HX chamber, and has a dip tube that pulls from near the bottom of the chamber. I personally prefer the design where the inlet is in the bottom & outlet is on the top of the HX. The old HX needs to come out and I'll probably be playing with a TIG welder this coming weekend :-)
skydragondave Senior Member Joined: 18 Feb 2013 Posts: 167 Location: Ontario, Canada Expertise: Professional
Espresso: Commercial Only Grinder: Commercial Only Roaster: Has Garanti HG5
Posted Mon Apr 21, 2014, 4:25pm Subject: Re: Volume of heated water in HX to brew
You should be seeking restitution from the buyer for this shipping mistake. He damaged the machine by not preparing it properly for shipping. But if you are determined to repair this yourself, understand that you are working with a pressure vessel, the repair you make is going to come in contact with potable water, and that water under pressure can release with explosive force so you need to be extremely careful here and be sure that your weld joints are solid. Most HX tubes are affixed with NSF rated silver solder and are brazed in place. This is because silver solder can be worked at a lower temperature than the copper's melting point, and has less chance of cracking due to stress risers. Directly welded copper joints are not unheard of, but are usually done under very controlled automated conditions. Do this repair at your own risk. Good luck
Posted Tue May 20, 2014, 2:27pm Subject: Re: Volume of heated water in HX to brew
I figured no real harm done as long as I could do the repair.
I've been travelling for work, but here's an update. I cut out the heat exchanger and welded it back together. After welding everything together, it's all holding pressure with no leaks. Sadly, I had to use SS flux core with the MIG (no TIG until autumn), so it's not pretty but works great. Until I run some numbers and figure out what is the ideal volume for my HX (time to break out the thermodynamics books), it'll be easier to keep the internal volume the same. Eventually, I'd like to add a hot water tap and redo the boiler for my volumes of consumption.
Symbols: = New Posts since your last visit = No New Posts since last visit = Newest post
Forum Rules: No profanity, illegal acts or personal attacks will be tolerated in these discussion boards. No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum. No SEO style postings will be tolerated. SEO related posts will result in immediate ban from CoffeeGeek. No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum. Who Can Read The Forum? Anyone can read posts in these discussion boards. Who Can Post New Topics? Any registered CoffeeGeek member can post new topics. Who Can Post Replies? Any registered CoffeeGeek member can post replies. Can Photos be posted? Anyone can post photos in their new topics or replies. Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts. Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.