Winterising, cold shop, etc. (UK)

I’ve just started to really use my 80W laser for longer than cutting an odd thing or two, cooling by water bucket and fishtank pump. Chiller should be arriving today (here’s hoping). So questions popping out on how i’m going to laser during winter months.
I need to figure out the way of working in unheated but insulated shed. Weather in UK is not usually that cold, but i need to protect the investment i suppose.


  1. Cold start - whats the coldest ambient temp i can start in the morning ? Just checked the water in the tank and its 13C, laser hasn’t been run today.

  2. Preheating the room/machine. I’m planning on getting one of them cyllindrical oil burning space heaters to tide me over. We use one in another workshop, running one for 10 minutes makes me take the jacket off in a big’ish space (volume wise probably 10x+ of what my shed is.). Morning procedure.

  3. Chiller settings, off time running method. What would i need to set the chiller to for general work and should i keep chiller running during the nights ? What will chiller do if ambient is lower than set ?

  4. Coolant. Any good tips on coolant mixture ? Anti-bio and antifreeze. At the moment running just clean de-ionised water, dipping in occasional frozen bottle to lower temps…

I’m looking for any general tips on running an 80W/100W laser during colder than room temp seasons. What with spooktacular and xmas looming need to be able to do work.

You have several options. If you check out Russ’ videos, he has a pair of 50W bulbs under his tube, and a pair of 50W bulbs under his tank, all on thermostats. He’s about an hour N of London.

For me in the US, in the Kansas City area, I use a submersible fake rock bird bath heater in my coolant bucket with an internal thermostat, and an aux temp control relay system relay to power the pump and then the heater up in stages.

If the ambient temp drops to a set point, the submersible pump comes on, and it’s motor adds just a little heat to the water. Perfect for the evenings where it just floats near the freezing mark.

When the actual coolant temp drops near that mark, the DIY chiller is shut off and the heater is tripped by a second temp controlled relay to keep the water safely above freezing. It is partially powered by the first relay so they have to come on in sequence to power the heater. I use a mini fridge as a DIY chiller.

My first set up I relied on the internal thermostat of the birdbath heater for the coolant warming. Unfortunately they seem to think the birds over here have to have toasty toes. It wanted to keep the water around 55F.

My 80w tube comes from EFR and their spec for operating temperature is 10 - 40C and for ambient temp is 2 - 40C. Frankly, I think 2C is way too close to freezing!. I live in the UK too and I won’t be letting my system get below 8C this winter. I’m going to use a system similar to Dave01 with the water pump running on a timer and a very small aquarium heater in my water reservoir.

Modding your chiller to be able to heat, as well as cool, would be relatively easy, if you know what you’re doing.

Just plain de-ionised water should be fine if you have some frost protection. Keep the water in a reservoir with a close fitting lid, out of sunlight/daylight and you shouldn’t see any algal growth for a long time. But keep an eye on it.

My set up is a pair of temp controlled relays and a series of relays they talk to. In an ideal world, I would have had two DPDT temp controlled relays. In the real world it took those two SPDT temp controlled relays and three more SPDT relays to get things running properly.

One of the SPDT relays is an either / or relay. Normally it is not activated, and the pump is powered through it from the laser cutter.

Next comes the ambient temp relay. If the ambient temp drops below 40F it activates the pump through the first relay, and provides power to the second stage via another SPDT relay. The submersible pump puts out just enough heat to keep the coolant in the low 50F all by itself.

The second temp relay probe is in the coolant itself. If that drops below 35F, AND is energized by the ambient temp relay, it switches power from the mini fridge to the fake rock bird bath heater.

The theory is that during the summer I keep the fridge down cold enough that it might trip the coolant thermometer while I’m trying to keep my beverages and the laser cool while the ambient temp is no where near freezing. The two stage approach will only turn the mini fridge off and the heater on if both conditions are met. Ambient below 40F, and coolant below 35F.

I realize that the 32F / 35F is a bit close, but it is in an insulated area, it’s just not heated. The heat from the submersible pump is enough that on hot days I have to give the laser a break… and sit down and empty one or two of those beverages in the mini fridge. I’m a bit south of Kansas City, everything worked fine last winter, but it was a mild winter.

If we have some really cold nights, I may put a web cam on the temp displays and sit up and watch some old movies… just in case.