Coffee pot physics query

[danny la rouge]

I use a Bialetti stovetop pot. Into it I put the grinds from beans ground in a DeLonghi electric burr grinder. Recently I replaced the pot's rubber gasket, as you have to periodically.

However, recently the pot has been leaking as it boils and producing one and a half demi tasse cups instead of two. This is insupportable. What is going wrong, and how do I rectify it?

 

[mauvais]

Leaking from where? The valve or the base/cup interface?

 

[danny la rouge]

Leaking from where? The valve or the base/cup interface?

The valve.

 

[mauvais]

The valve is a safety relief valve designed to open at a given pressure, so you have either increased pressure in the chamber by limiting the ability for steam to move upwards, or the valve is dysfunctional in some way.

The pressure problem could be caused by a blocked filter - the metal disc - or by putting too much/too fine/too packed a coffee in it that the steam can't get through. This is why they say don't tamp it.

 

[danny la rouge]

The valve is a safety relief valve designed to open at a given pressure, so you have either increased pressure in the chamber by limiting the ability for steam to move upwards, or the valve is dysfunctional in some way.

The pressure problem could be caused by a blocked filter - the metal disc - or by putting too much/too fine/too packed a coffee in it that the steam can't get through. This is why they say don't tamp it.

Hmm. I’ll try some things to test which of those it is.

 

[Riklet]

Yeah I'd clean out the metal filter really thoroughly and if that doesnt work, replace it.

You should also try just using boiling water and running it through a few times (ie without coffee). Try not filling the water level up so much initially. There might be a gentle cleaning solution you could use too to degunk the inside... maybe a dash of white vinegar.

Is the water hard in your area?

 

[danny la rouge]

Is the water hard in your area?

No. Very soft. It comes from Loch Katrine.

The main variable is the new grinder. It grinds slightly too much coffee. I have it on its lowest setting, but still produces a surplus and I suspect I’m putting too much coffee in the pot because I hate waste.

 

[Sue]

Ah, could be that the coffee's too fine?

 

[danny la rouge]

Ah, could be that the coffee's too fine?

No, it’s just right. I’m pretty convinced it’s an amount thing.

 

[killer b]

The main variable is the new grinder. It grinds slightly too much coffee. I have it on its lowest setting, but still produces a surplus and I suspect I’m putting too much coffee in the pot because I hate waste.

I have a similar issue with my grinder, and put the surplus in a tin for use when I've run out of beans but haven't been to the shop to pick up more.

 

[danny la rouge]

I have a similar issue with my grinder, and put the surplus in a tin for use when I've run out of beans but haven't been to the shop to pick up more.

That’s a good plan.

 

[Riklet]

Clean thoroughly inside. Run it through twice with water and once with water and vinegar and then report back. Doubt its the coffee, although if you properly overfill it and tap it down hard then it could affect the pressure yeah.

 

[killer b]

(I have had issues with the holes in the metal filter getting blocked too though, so would definitely look at that too)

 

[kalidarkone]

I have a similar issue with my grinder, and put the surplus in a tin for use when I've run out of beans but haven't been to the shop to pick up more.

That's exactly what I do

 

[Sue]

No, it’s just right. I’m pretty convinced it’s an amount thing.

I mean too fine so it blocks the holes.

 

[danny la rouge]

I mean too fine so it blocks the holes.

Aye. It’s courser than the preground espresso grind.

 

[teuchter]

These things are known to circumvent laws of physics. In my household one person occasionally manages to make a pot where the water fails to come through, similar to what danny la rouge describes. This never happens when I make it. This is confined to one stovetop pot in particular. There is no discernable difference in method; this has been checked by close observation. The only explanations are supernatural ones.

 

[Orang Utan]

I use a Bialetti stovetop pot. Into it I put the grinds from beans ground in a DeLonghi electric burr grinder. Recently I replaced the pot's rubber gasket, as you have to periodically.

However, recently the pot has been leaking as it boils and producing one and a half demi tasse cups instead of two. This is insupportable. What is going wrong, and how do I rectify it?

 

[existentialist]

View attachment 263999

Post reported for offensiveness.

 

[danny la rouge]

View attachment 263999

Out of order. Please delete.

 

[Orang Utan]

Out of order. Please delete.

It’s the best wake up juice out there

 

[danny la rouge]

It’s the best wake up juice out there

I’ll fight you if you say that again.

 

[Cid]

I wouldn’t dismiss the grind as a potential factor. Overheating might be an issue as I guess that would increase pressure in the chamber, spike it. That would also potentially cause some form of channeling (forcing the water through gaps in the coffee rather than extracting evenly). Start with boiling water, low heat, remove from heat as it starts to bubble is iirc the right approach. I just use an aeropress but they’re better suited to single cups.

 

[dessiato]

These things are known to circumvent laws of physics. In my household one person occasionally manages to make a pot where the water fails to come through, similar to what danny la rouge describes. This never happens when I make it. This is confined to one stovetop pot in particular. There is no discernable difference in method; this has been checked by close observation. The only explanations are supernatural ones.

We have that with our printer.

When I try to turn it on it can take a lot of attempts until it does, or it doesn't at all.

When I need it I get my wife to turn it on. It always starts first time for her.

 

[existentialist]

We have that with our printer.

When I try to turn it on it can take a lot of attempts until it does, or it doesn't at all.

When I need it I get my wife to turn it on. It always starts first time for her.

It's the other way for me. People tear their hair out trying to fix things, call me in, and it works first time. It has got to the point where I'll say "look, I'll just stand here while you do it, and we'll see what happens". It would seem that my mere presence is often enough to get computer equipment (particularly) behaving itself. Of course - and much as I prefer not to disagree with the estimable teuchter - there is nothing metaphysical about it.

 

[Cid]

We have that with our printer.

When I try to turn it on it can take a lot of attempts until it does, or it doesn't at all.

When I need it I get my wife to turn it on. It always starts first time for her.

Do you by any chance impatiently stab at the on button?

 

[TopCat]

You replaced the gasket thus stopping pressure leaks at that seal thus increasing the pressure through the valve.

 

[dessiato]

Do you by any chance impatiently stab at the on button?

By the tenth time of trying, yes. At first I'm always very careful to just press. I am sure it does it to wind me up.

 

[8ball]

I was expecting physics - not “help me ungum my appliance”!

 

[danny la rouge]

I was expecting physics - not “help me ungum my appliance”!

It’s both!