It's that time of year again... help with temp issues in my cold cold kitchen?

Jack Blackmore

So winter is finally starting to settle in again and I'm back to fighting against the bracing chill for my morning coffee!

My kitchen skirts somewhere between 12 - 15 in the morning and there's not much we can do about it at the moment (high ceilings, large windows, poorly insulated and electric central heating) so at this time of year I find myself battling against the cold to fight back the sourness from my espresso.

Reiss has posted the follow chart a while ago showing PSTAT vs ambient temperature which I've been following.

15 59 1.5
17 63 1.4
20 68 1.3
24 75 1.2
27 81 1.1

I've cranked my PSTAT up to 1.5 and I'm getting a slight hiss from the pressure relief valve as the heater clicks off. It's made a noticeable difference but there's still an unpleasant amount of sourness in the shot so I was wondering what else I can do to increase the brew temperature without stressing the boiler even further.

I've got the machine on a time for an hour before I wake up with the portafilter lightly in the grouphead so everything's up to temperature by the time I come to use it except the beans maybe?

I'm using 15.5g in the tapered basket that came with the machine as it ends up being much more consistent than my VST basket and with a light tampe it's level is maybe 0.5cm below the ridge. I'm fortunate to own an R120 so the grind is super consistent and I'm getting roughly 30g in 28s from when I release the lever.

The pour is nice and even although it does seem to blonde a little early (which I think could be a function of the temperature). If it would be helpful I'll try and post a video of the extraction tomorrow but I don't think (maybe naively) that it's the issue. I've also got a BWT bestmax filter installed so the water shouldn't be the issue.

Would dosing less or grinding coarser help to increase the brew temp at all? Could anyone point me in the direction or any steps I can take? I'm hesitant to turn the pressure up higher as I think the relief valve may have a little scale or dirt in it as if I turn the nipple it goes off at around 1.2 bar whereas I've managed to find a position where it only hissing slightly at 1.5. Also I've found at 1.5 bar if I'm steaming a lot of milk a small film of dark metallicy grease is pushed onto the ball toggle of the steam handle which I think is a result of the pressure and temperature.

Sorry for the long post just wanted to answer as many questions I may have been asked as possible!

Frans Goddijn

The 1.5 bar is about the max and I'd suggest to lower it to 1.45 so as to avoid the hissing of the valve that opens when the limit is reached.

You could wrap a wool shawl over and around the machine, while still allowing air to flow in from the bottom and out through the back. You could also cut the toes off a thick wool sock and slide it snug around the brew group.

Grinder, grind and dose seem perfect!

Jack Blackmore

I was thinking about insulating the grouphead but I'm sure I read in some random post that if can interfere with the thermosyphon. This morning I was trying to picture how it could interfere but it should be fine as regardless of the insulation on the grouphead.

The hot water will be coming out of the top of the boiler, cooling (however slowly) as it hits the grouphead and then returning into the bottom of the boiler?

Insulation would be a perfect option as the room warms up over the day, albeit not much, so it would give me a variable control I'll let you know how I get on!

Reiss Gunson

hi jack

at the risk of sounding churlish an LR would definitely solve the problem, but i am assuming that is an unacceptable solution

so i would suggest you try replacing the safety valve for new design that we released just a couple of months ago; i cant guarantee it but my expectation is that for a relatively small outlay the valve should hold 1.5 bar and not begin to open

also be sure to leave the portafilter attached to the group when the machine is idle, so it is kept warm

an open port flush of the group on the L1(2012-2016) will also elevate the group temperature significantly for a time, although you will need to experiment by flushing into a measured container or similar to determine the correct volume to flush to elevate the temperature to the level you require for your bean & taste preferences

and my final suggestion is to head for darker roasts that will extract more readily at lower brew temperatures

kind regards

reiss

Gregory Green

Surely if the group temperature is too cool due to ambient temperature being low, a small sleeve of insulation on the group will solve the problem.

I’d bring the pressure back down to about 1.4 and then experiment with insulation. I’d probably start with the top section of a sock over the top of the group.

As long as the group temperature stays in the low 80’s the thermosiphon is going to behave the same as it would normally.

Greg

Matthew Hoffman

My boiler pressure is set to 1.15 bar. When I arrive in the kitchen at this time of the year, the ambient temperature is about 18C. As the temperature of my group is measured by a thermocouple and digital thermometer, I can see that the group is a degree or two (centigrade) below what I need it to be to produce brew water at the right temperature. All I need to do at this point is tap the steam pressure toggle to bring the boiler pressure up to maximum and then pull the lever until water begins to trickle from the shower screen. I hold the lever there until the pump engages to refill the boiler and then return the lever to its resting point. As group temperature goes up to 2 or 3 degrees above where I need it to be, I insert the portafilter I intend to use (to cool the group) and turn to preparing the puck. By the time I return to the machine to pull the shot, the temp is close to where it needs to be. ( I do monitor over my shoulder what is going on with the group temperature, in case I need to remove the portafilter before the temperature descends too far.)

This all sounds quite a rigamarole when I write it down, but it's actually very simple and natural to do. I find that the group temperature during the day, when the room is around 21/22 C, is stable. But if the machine is unused for hours, sometimes it gets to high, and I lower it with a room temperature portafilter (there is usually one warming in the group but as I have three of them – single spout, double spout and bottomless – there are always cooler ones handy).

Knowing and being able to control the group temperature also enables me to adjust for different types of beans and roasts as I change them from shot-to-shot or day-to-day. A single dosing grinder is also of help in this regard.

Matt

Jack Blackmore

Cheers for all the input guys! Dropping the boiler temp and a bit of insulation seem to be the first way to go so I'll experiment a bit over the weekend.

How / where did you attach the thermocouple to measure the brew head temperature and what sort of range are you trying to keep it in? I've got one sitting around and have half heartedly debated how to attach it for a while now? I was considering just using a bit of duct / electrical tape but was overly cautious about damaging the chroming.

Reiss an LR is out of reach for the time being but not something I'd discount in the long term! Out of curiosity how does it solve the issue? Do you have more control over the brew head temp?

If all this fails then I'll just switch to a darker roast over the winter period, would probably reflect the mood a bit better anyway

Frans Goddijn

I have also, in the past, monitored the group temp over a long period of time, with a temperature probe stuck against the outside chrome skin of the group, kept there by a piece of copper tape. I was aware that this way one measures the temperature of the tip of the probe, which is influenced in part by the skin of the group it is touching and also by the air flowing around it.

So in a cooler room, the probe shows a cooler temp but this only partly reflects the group temp and with a stable machine design like the Londinium and its heavy group I've noticed that some temperature swing of the environment doesn't disturb the espresso experience much.

Unless the machine is in a spot where the temp swings are very severe, in direct sun rays, or a window is opened allowing a steady draft past the group, the machine is much less sensitive to the changes than we humans are.

If we feel fairly comfortable, the machine is more than fine ;-)

Matthew Hoffman

I have it attached (horizontally) about 45 degrees from where the neck meets the cylinder and (vertically) about halfway up the neck. I fine that medium/light coffees are best if I pull the lever down for pre-infusion when the temp is a degree or two above or below 86.5 C. But you must measure for yourself: temperature readings taken at different points on the group vary quite a lot one from one spot to another.

Matt

Jack Blackmore

This makes sense, I've got no doubt at all the machine is purring along perfectly but might give the thermocouple a little go as it will hopefully give me something more solid to aim towards.

There are no massive drafts rushing past the machine it's just next to a big window cold window which saps the life out of everything in the winter

Jack Blackmore

So just thought I'd give a quick update. I've got the grouphead insulated with a small cloth held on with hair bands over a thermocouple held on with masking tape I've dropped the pstat down to 1.4 and it's back to working like a dream!

Depending on room temperature the thermocouple is reading between 82 - 85 in the morning and it's now super easy to regulate the temperature with a quick flush but I'm rarely needing to unless is particularly cold. Cheers for all the tips guys!

Reiss Gunson

hi jack
thank you for writing the last page of the story - this is what makes the forum of value to your fellow owners and builds a resource for you all to benefit from
kind regards
reiss.