Dual boiler vs Heat Exchanger

Cuir Beluga · March 2015

Question time again ;D.

Can someone please explain the difference and the pros/cons of Heat Exchange and Dual Boilers?

TIA (again), Sue

.

Moon · March 2015

I have neither of those functions on my machine .. but others will fill you in. Double boiler allows you to pour espresso and steam milk at the same time. With a budget of around $2000 .. I'd give this one some serious consideration You can pour the shot, steam the milk simultaneously .. and it is an HX heat exchanger machine. HX machines are all the buzz and widely recommended for the enthusiast. http://www.jetblackespresso.com.au/shop/p/diadema-junior-plus-lever/ Bean Roasters/Cosmorex are forum Sponsors only their new website isn't up yet by the looks. Brett bought his Diadema from Cosmorex. *Jet-black used to be a Sponsor of this forum .. but isn't anymore Just putting it out there :angel:

Cuir Beluga · March 2015

on 1426681040:

I have neither of those functions on my machine .. but others will fill you in. Double boiler allows you to pour espresso and steam milk at the same time. With a budget of around $2000 .. I'd give this one some serious consideration You can pour the shot, steam the milk simultaneously .. and it is an HX heat exchanger machine. HX machines are all the buzz and widely recommended for the enthusiast. http://www.jetblackespresso.com.au/shop/p/diadema-junior-plus-lever/ Bean Roasters/Cosmorex are forum Sponsors only their new website isn't up yet by the looks. Brett bought his Diadema from Cosmorex. *Jet-black used to be a Sponsor of this forum .. but isn't anymore Just putting it out there :angel:

Thanks Moon, as far as I know you can steam and pour with both an HX and a DB but after that I am not sure if there are any differences, eg. Is one likely to last longer than the other? Does one have parts that are more under pressure than the others? So on and so on. I was looking at a single boiler set up such as the ISomac Zaffiro but as the coffee drinkers in the house are all milky drop drinkers, it is probably pointless. I don't mind waiting for steam but not 2 minutes like I had read. Perhaps this is wrong? I have been communicating with Cosmorex and JetBlack do have some nice machines, I have been drooling over them ^-^.

Koffee_Kosmo · March 2015

on 1426674347:

Question time again ;D. Can someone please explain the difference and the pros/cons of Heat Exchange and Dual Boilers? TIA (again), Sue .

The core operation differences between a Dual Boiler and a Heat Exchanger (HX) machine is Two Boilers one to brew one to steam over a HX - One boiler for steaming and that boiler heating fresh tank brew water by seperate heat exchange unit inside that boiler Both work well at brewing coffee A dual boiler machine is said to be more temperature stable however with a HX machine it is recommended to do a quick flush of the hot water as the water in the HX coils may heat up over the recommended heat temperature On the other hand A dual boiler machine will have old water heated and reheated in its cycles with small injections of fresh water when a coffee is made And a HX machine uses fresh tank water for brewing The construction of the heat exchanger unit is normaly a coil of copper pipe fitted inside the boiler, when the boiler heats up for steam duties it also heats up the water inside the coil of the HX pipe to be used for brewing duty KK

Cuir Beluga · March 2015

Thank you KK, you have cleared up a couple of things for me

. Is there a general preference for one over the other or am I over thinking things ::)?

Koffee_Kosmo · March 2015

on 1426721799:

Thank you KK, you have cleared up a couple of things for me . Is there a general preference for one over the other or am I over thinking things ::)?

You could be overthinking things ? If I knew what you were thinking I may be able to answer For home use I would get a HX machine However don't overlook the importance of a high quality grinder The best machine in the world would strugle when it's fed a bad grind KK

Cuir Beluga · March 2015

on 1426722580:

You could be overthinking things ? If I knew what you were thinking I may be able to answer For home use I would get a HX machine However don't overlook the importance of a high quality grinder The best machine in the world would strugle when it's fed a bad grind KK

I'm not sure what I am thinking myself, I just want to do what I can to insure I am not regretting my purchase 6 weeks later :angel:. Grinder wise I have a Smart Grinder Pro at the moment.

Koffee_Kosmo · March 2015

I recommend a Bezzera for its build quality and finish - they finish a machine better than most on the market - I myself own a Bezzera Sorry for this answer - Get a better grinder I would argue that a grinder is as important as the machine KK

Cuir Beluga · March 2015

I have looked at the Bezzeras but think they are a bit more than I want to pay. I probably will be getting a better grinder at some stage, not yet though :thumb:.

Koffee_Kosmo · March 2015

Think of your purchase like a car Base model is XYZ $$ mid model is a little more XZY $$ top of the range is a little more XZY$$ again A Bezzera is a top end model at a mid model price and that represents good value for money when compared to others

Cuir Beluga · March 2015

I definitely know what you are saying KK but I have already upped the budget 5 times and probably can't push it much beyond what I have ;D.

Lacehim · March 2015

Fact is budget. I would love a Porsche 911 sitting in my garage, but I have a Hyundai.

A HX is a good machine. Avoid the single boilers. If you just won lotto or have some cash to splash, buy a dual boiler. KK is right that you will see an improvement in upgrading your grinder, so I would keep the budget in check, buy a decent HX (you will not be disappointed), and save up for a grinder upgrade. I don't know if KK has use the BSG you have, but IMO they are a great entry level grinder, and they will cope with a new machine just fine. When you upgrade the grinder you'll know how to use your machine and the transition will be smooth.

Dry_bean. · March 2015

I have a different opinion re dual and single boiler machines Lacehim. I have a single boiler Bezzera HX, does everything I need in the brewing and steam dept, in fact more than enough steam. Re twin boilers, means two boilers along with additional electronics to maintain or fail, I'm a big believer in the KISS principle.

samuellaw178 · March 2015

Maybe it's just picking at the terminology, machines like Rancilio Silvia are true single boiler machines. HX is more like single and more boiler(the actual boiler and the heat exchanger for heating water). Dual boiler has two boilers, there you have it. :P With Heat Exchange(HX machine), you usually need to flush a bit more water than the dual boiler to achieve target brew temperature. Generally that's the main difference. Both can be excellent, but has slightly different workflow to get there. For dual boiler you're basically paying a lot more for getting similar result that can be achieved by HX, but it's slightly easier to get there with less water flushing. So if you have the spare cash, I'd go for dual boiler. Otherwise, I'll be happy with a HX too. Not much can go wrong as long as you go for a reputable HX, rather than some maybe China-made HX that has no supports. That's unlikely tho. :laugh:

Dry_bean. · March 2015

Chris from Talk Coffee had this to say re HX V dual boiler machines on another forum back in 2006, pretty well sums up my thoughts as well. My Bezzera Domus Galatea is a HX machine and is not at all prone to over heating.

"Yes and no, in my opinion Monti...A well made HX is also temp stable. My machine is capable of knocking out as many shots as I want without temp variation. The routine, whether hx or dual boiler is to flush until the water looks good and then go for it- doesnt matter which style of machine you use. What many CSers can forget is that the dual boiler machines- Minore II for example- are chock a block full of components and technology whereas the HX machines are simple- you lift the hood and its like looking under the bonnet of an old car...there is not much in there- therefore not much can go wrong. I have little doubt that ownership of a dual boiler machine will be more expensive in the long term because they are so full of boiler, water lines and electronics- which are not that crazy about heat.... Both types of machine are capable of superb coffee with a modicum of training...just as they are capable of garbage."

Brett H · March 2015

I've had all styles from thermoblock, single boiler then HX to double boiler! They're all capable of good coffee. The further you go down the list the less you fiddle to get great coffee and the most out of the beans! The PID in the double boiler allows you to vary the brew water temperatures to ensure you get the very best or worst out of your beans!

Cuir Beluga · March 2015

Thanks guys, I have had a quick read but motherly duties are calling. I'll be back ^-^. Thanks

.

Moon · March 2015

I haven't either - so I'm totally going out on a wing here ::) As for getting a double boiler or whether to go with the single boiler with the HX - it would depend how many coffees at a time do you need to make in a session. If I was doing a fair amount of entertaining where visitors go coffee rather than say bottles of wine etc .. I'd go double boiler to handle the volume. If it is mainly for yourself or 2 or 3 friends over .. some preferring tea .. I'd go the single boiler with the HX .. only I'd go at least a 2 ltr boiler .. or even 3 ltr. Mine is a 3 ltr boiler which at first thought was way too big .. but I often only fill it up for one 40ml shot or perhaps 2 plus steam, which means it still has to boil a minimum of 1.2 ltr of water each time so as to not set off the low water indicator .. as you have to fill it up enough to cover the heating element plus more that is used + I am also aware of not being wasteful with electricity as well as not needlessly overworking the element to hopefully prolong its life. A double boiler needs more water and costs more to run. Even multimillionaires would be thinking of the extra $ cost of a twin boiler ::) When choosing a boiler size ... start with what you believe to be ample .. then go 1ltr larger. 8) One other consideration. Water gets stale if its been sitting in the boiler for longer than a couple of days. I can turn mine upside down to empty it. A drain plug so that you can easily empty it and refill with fresh (preferably filtered) water is essential imo. I've only had light weight machines that are easy to empty .. so make sure a heavy machine has a plug. I'm assuming they do .. or do they empty them via the hot water tap/arm? So .. basically - mainly personal use (HX) or regular entertaining (twin boiler)

Cuir Beluga · March 2015

on 1426738566:

Fact is budget. I would love a Porsche 911 sitting in my garage, but I have a Hyundai. A HX is a good machine. Avoid the single boilers. If you just won lotto or have some cash to splash, buy a dual boiler. KK is right that you will see an improvement in upgrading your grinder, so I would keep the budget in check, buy a decent HX (you will not be disappointed), and save up for a grinder upgrade. I don't know if KK has use the BSG you have, but IMO they are a great entry level grinder, and they will cope with a new machine just fine. When you upgrade the grinder you'll know how to use your machine and the transition will be smooth.

I am pretty sure I am heading for an HX. Usually the most I have to make at one time is two but that is pretty rare. Very occasionally I might have to make up to half a dozen but that would be a twice a year occurrence. A social butterfly I ain't ^-^. I will keep a better grinder in mind but if the BSG holds up ok with the new machine I won't be replacing it before it needs to be.

on 1426742368:

I have a different opinion re dual and single boiler machines Lacehim. I have a single boiler Bezzera HX, does everything I need in the brewing and steam dept, in fact more than enough steam. Re twin boilers, means two boilers along with additional electronics to maintain or fail, I'm a big believer in the KISS principle.

I am aiming to keep things simple for myself, believe me they need to be lol, that less that can go wrong, both operator wise and machine wise, the better >:D.

on 1426746387:

Maybe it's just picking at the terminology, machines like Rancilio Silvia are true single boiler machines. HX is more like single and more boiler(the actual boiler and the heat exchanger for heating water). Dual boiler has two boilers, there you have it. :P With Heat Exchange(HX machine), you usually need to flush a bit more water than the dual boiler to achieve target brew temperature. Generally that's the main difference. Both can be excellent, but has slightly different workflow to get there. For dual boiler you're basically paying a lot more for getting similar result that can be achieved by HX, but it's slightly easier to get there with less water flushing. So if you have the spare cash, I'd go for dual boiler. Otherwise, I'll be happy with a HX too. Not much can go wrong as long as you go for a reputable HX, rather than some maybe China-made HX that has no supports. That's unlikely tho. :laugh:

My son had his heart set on a Silvia, he likes the straight lines, the minimalistic and uncluttered look. I admit I did have more than a passing thought about going that route. I have my fingers crossed that not much can go wrong, that is why I am asking for advice from those who know ;D. The Chinese make HX machines? Well, who knew? Not me anyway :laugh:.

on 1426748699:

Chris from Talk Coffee had this to say re HX V dual boiler machines on another forum back in 2006, pretty well sums up my thoughts as well. My Bezzera Domus Galatea is a HX machine and is not at all prone to over heating. "Yes and no, in my opinion Monti...A well made HX is also temp stable. My machine is capable of knocking out as many shots as I want without temp variation. The routine, whether hx or dual boiler is to flush until the water looks good and then go for it- doesnt matter which style of machine you use. What many CSers can forget is that the dual boiler machines- Minore II for example- are chock a block full of components and technology whereas the HX machines are simple- you lift the hood and its like looking under the bonnet of an old car...there is not much in there- therefore not much can go wrong. I have little doubt that ownership of a dual boiler machine will be more expensive in the long term because they are so full of boiler, water lines and electronics- which are not that crazy about heat.... Both types of machine are capable of superb coffee with a modicum of training...just as they are capable of garbage."

The less components the better, in my opinion. Even hubby says the same thing and Electronic Engineering is his bread and butter ;D.

on 1426752890:

I've had all styles from thermoblock, single boiler then HX to double boiler! They're all capable of good coffee. The further you go down the list the less you fiddle to get great coffee and the most out of the beans! The PID in the double boiler allows you to vary the brew water temperatures to ensure you get the very best or worst out of your beans!

Getting the worst out of my beans. Now that is something to fear ^-^. Any thoughts on the PID Lelits? Yes, I am keeping all options open :P.

on 1426771018:

I haven't either - so I'm totally going out on a wing here ::) As for getting a double boiler or whether to go with the single boiler with the HX - it would depend how many coffees at a time do you need to make in a session. If I was doing a fair amount of entertaining where visitors go coffee rather than say bottles of wine etc .. I'd go double boiler to handle the volume. If it is mainly for yourself or 2 or 3 friends over .. some preferring tea .. I'd go the single boiler with the HX .. only I'd go at least a 2 ltr boiler .. or even 3 ltr. Mine is a 3 ltr boiler which at first thought was way too big .. but I often only fill it up for one 40ml shot or perhaps 2 plus steam, which means it still has to boil a minimum of 1.2 ltr of water each time so as to not set off the low water indicator .. as you have to fill it up enough to cover the heating element plus more that is used + I am also aware of not being wasteful with electricity as well as not needlessly overworking the element to hopefully prolong its life. A double boiler needs more water and costs more to run. Even multimillionaires would be thinking of the extra $ cost of a twin boiler ::) When choosing a boiler size ... start with what you believe to be ample .. then go 1ltr larger. 8) One other consideration. Water gets stale if its been sitting in the boiler for longer than a couple of days. I can turn mine upside down to empty it. A drain plug so that you can easily empty it and refill with fresh (preferably filtered) water is essential imo. I've only had light weight machines that are easy to empty .. so make sure a heavy machine has a plug. I'm assuming they do .. or do they empty them via the hot water tap/arm? So .. basically - mainly personal use (HX) or regular entertaining (twin boiler)

Size of boiler and electricity usage were a couple of things I had not considered. Thanks for giving me something else to ponder over

. Hopefully we have all bases now covered

. Thank you each and everyone of you for putting in the time to enlighten me and for giving me something more to think about. Sue XX

DrD · March 2015

I was at MICE on Sunday and spoke with one of the guys from the Dolo stand ... he was showing me their very impressive Orchestrale machines. Anywho, he mentioned that he thought domestic dual boiler units didn't really make sense; the boilers tend to be smaller than those found on a similar HX machine, which can lead to issues like reduced steaming capacity. I can't verify this claim, however I do know that my Giotto has more than enough steam to froth say a 600 mL jug of milk, but would probably struggle if you tried to repeat this in quick succession. It has a 1.9 L boiler. I have a Rancilio S24 that I use at work and it has a 3 L boiler ... it has heaps of steam and wouldn't need to recover between steaming a couple of jugs. This may not be so much of an issue if you're typically only making a couple of cups and not in a hurry :coffee2: Dan

Dry_bean. · March 2015

on 1426836164:

I was at MICE on Sunday and spoke with one of the guys from the Dolo stand ... he was showing me their very impressive Orchestrale machines. Anywho, he mentioned that he thought domestic dual boiler units didn't really make sense; the boilers tend to be smaller than those found on a similar HX machine, which can lead to issues like reduced steaming capacity. I can't verify this claim, however I do know that my Giotto has more than enough steam to froth say a 600 mL jug of milk, but would probably struggle if you tried to repeat this in quick succession. It has a 1.9 L boiler. I have a Rancilio S24 that I use at work and it has a 3 L boiler ... it has heaps of steam and wouldn't need to recover between steaming a couple of jugs. This may not be so much of an issue if you're typically only making a couple of cups and not in a hurry :coffee2: Dan

Evening Dan, Sounds like common sense to me. Nice to see you posting.

Cuir Beluga · March 2015

on 1426836164:

I was at MICE on Sunday and spoke with one of the guys from the Dolo stand ... he was showing me their very impressive Orchestrale machines. Anywho, he mentioned that he thought domestic dual boiler units didn't really make sense; the boilers tend to be smaller than those found on a similar HX machine, which can lead to issues like reduced steaming capacity. I can't verify this claim, however I do know that my Giotto has more than enough steam to froth say a 600 mL jug of milk, but would probably struggle if you tried to repeat this in quick succession. It has a 1.9 L boiler. I have a Rancilio S24 that I use at work and it has a 3 L boiler ... it has heaps of steam and wouldn't need to recover between steaming a couple of jugs. This may not be so much of an issue if you're typically only making a couple of cups and not in a hurry :coffee2: Dan

Thanks for that DrD. I rarely make more than one drink at a time. As for time, well I have plenty of that, I am home all day ^-^.

Koffee_Kosmo · March 2015

Dry Beans Bezzera Galatea HX can steam 1 litre of milk KK

kbilleter · March 2015

on 1426771018:

I haven't either - so I'm totally going out on a wing here ::) As for getting a double boiler or whether to go with the single boiler with the HX - it would depend how many coffees at a time do you need to make in a session. If I was doing a fair amount of entertaining where visitors go coffee rather than say bottles of wine etc .. I'd go double boiler to handle the volume. If it is mainly for yourself or 2 or 3 friends over .. some preferring tea .. I'd go the single boiler with the HX .. only I'd go at least a 2 ltr boiler .. or even 3 ltr.

I think it might be the other way around for a small / medium machine. A double boiler means each boiler will be smaller. The main difference, as far as I can tell, is a double is easier to tune as the brew and steam temperatures aren't coupled. And some HX machines will require more flushing than a double boiler, which can lead to having to empty the tray more frequently if it's not plumbed.

Dry_bean. · March 2015

on 1426850400:

Dry Beans Bezzera Galatea HX can steam 1 litre of milk KK

Morning KK, 1 litre of milk! really, I had no idea, never had a need to steam that amount. :coffee2:

Cuir Beluga · March 2015

Can anyone chime in on "recovery" times between the pour and steam for machines like the Isomac Zaffiro and similar? Is it really 2 minutes like I have read or is it more along the lines of 30 seconds?

Brett H · March 2015

I don't think 2 minutes is out of the question given the size of the boiler and the temperatures to be elevated then returned. The Silvia was in that ball-park from memory. If you're a white coffee drinker go straight to a HX to save the desire to upgrade later. Buy well and buy once!

mwcalder · March 2015

To give you an Idea, I used my Bezzera Mitica on a coffee cart and pumped out 50 6oz coffees with ease within an hour and not worrying about recovery time or steaming time. (No cooling flushes as well) The Mitica is a HX and I'll never go for anything else!

Cuir Beluga · March 2015

Thanks guys, I am pretty well convinced an HX is the way to go. I just thought I may be able to save a few $$ and buy a bit earlier but I will be patient and wait a few extra weeks. Thanks again XX.

Dry_bean. · March 2015

on 1426922197:

To give you an Idea, I used my Bezzera Mitica on a coffee cart and pumped out 50 6oz coffees with ease within an hour and not worrying about recovery time or steaming time. (No cooling flushes as well) The Mitica is a HX and I'll never go for anything else!

The Mitica and Domus Galatea are pretty much the same machine with different cabinets. http://bezzeracoffeemachine.com.au/products/espresso-machines/domestic-coffee-machines.html

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