Water cooled COBs

loftygoals said:

My eventual idea is underfloor heating. Not feasible in my current house it'll be in the back of my mind in the future for sure.

Imagine a wet underfloor heating system where some of your rooms are heated with waste heat from your grow lights. Energy efficiency goes from 50% to 100%.

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Millsie said:

Could you please take closer photos of the water cooling rig, I'd like to see how you fixed the COBs to the water blocks and possibly even a link to the type of water block you're using

Cant wait to see what you do under it

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loftygoals said:

Thought I'd share my water cooled COB build here.

I've built 8 light bars with cheapo chinese COBs. The idea being to initially build them cheaply and then swap chips to something more efficient after a couple of grows. As this is a bit of an experiment I didn't want to spend thousands and thousands on expensive COBs from the outset (I knew there was a chance this would fail miserably as nobody else has jumped on water cooling yet).

Anyway I made a steel frame from 4cm flat steel sections. The frame is 100cm long and 25cm wide. I epoxied the water blocks onto a steel frame and then made "clamps" out of flat steel sections and 4mm bolts (epoxy alone was slightly dubious). The water blocks aren't going anywhere when clamped! I then used thermal glue to mount the COBs onto the water blocks. The glue can be separated with a razor blade easily which would make upgrading straightforward.

View attachment 3686113

I've used Meanwell HLG-600H-36A drivers because I have no interest in dimming the lights. They're just over 96% efficient at full power. Each COB is running at 0.835A (16.7A total for 20 COBs).

I've used 8mm ID (14mm OD) hose on the 10mm barbs with 12mm hose clips.

Here's the hoses mounted and wiring done:

View attachment 3686114

View attachment 3686115

I've alternated cheap warm and cool COBs. If I were doing this again I'd pick one and stick to it because the power draw of different chips is unpredictable when running off a HLG-600H in parallel. Certainly when I upgrade the COBs later this year I'll be going for 1 uniform type.

Anyway here's the money shot of the lights in action (excuse the lonely auto):

View attachment 3686119

I made an earlier version of these with voltage controlled drivers and current limiting resistors. That's the 8 COB bar you can see at the top. I learnt a lot from building those which I used to make better lights with version 2 (these 20 COB lights).

The water gets pumped around the system with an Eheim 1250 water pump. All the water flows through the water blocks and then into a car radiator mounted on a timber frame where it's cooled:

View attachment 3686110

I have a 16 inch 1800cfm car radiator fan running off a 12V PSU.

The main advantage of this setup is temps inside the tent are dramatically lower than when running air cooled lights as I'm not relying on the air in the tent to remove the heat any more. When running an 8x4 tent at full blast at 2100W (2x600W and 2x450W lights) the tent stays at 25C under lights and 20C in the shade (room where the tents are located is at 19C). If I run only the 2x600W lights so 1200W total, the temp stays at 22C in the tent under lights. COB surface temp is around 45-55C (measured with FLIR camera).

I could make some improvements but this will do for now Promised myself there'd be no more tinkering with lights for 2 grows and have put my tools away!

Edit: I should probably mention cost. £167 for the Meanwell HLG-600H, £60 for water blocks, £10 for hoses, £5 for hose clips, £20 for wiring and terminal blocks, £44 for COBs, £10 for steel, sections, £10 for bolts (inc eye bolts for hanging). £326 approx for each light bar.

£15 for car radiator, £15 for radiator fan, £12 for PSU, £65 for water pump. £107 total for radiator and pump.

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ttystikk said:

Have you bought yourself a proper chiller yet? Cuz if ya haven't, you're nowhere near effectively utilizing the technology. It's not enough to merely shed excess heat from the system, but to actively drive the operating temperature of the chip down to the coolest possible. My chips run in the mid 50s. This gives me between 5-10% more PAR/W than those fan cooled at ambient tempetature plus, let alone those run passively and allowed to get hot.

The reason why is temperature droop. The colder you get the chip, the more efficiently it runs. Interestingly, it also draws more forward voltage, thereby running harder without losing efficiency. Is this a double win, aka free lunch? I don't know, I invite others to investigate further.

In any case, water cooled chips certainly don't deteriorate as fast, and the environment isn't directly heated by the lighting system. And yes, lenses are mandatory, but desirable.

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loftygoals said:

I've thought about a chiller in the circuit but I'm very limited for space. I have nowhere to put a chiller with enough cooling capacity to handle my lights. Then there's the additional ambient heat to consider. If I weren't in a loft it might be an option... Maybe in the future!

I've seen your chiller setup. Looks ideal

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loftygoals said:

Yeah, the system is filled with RO water and I've added an antimicrobial additive.

Also made sure the radiator is aluminium to match the water blocks. Mixing copper with aluminium would have been a disaster.

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Airwalker16 said:

Also, where did you pick up those NIFTY 4x4 rubber mats?!

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Flowki said:

This is so good but damn, water and electrics that close is beyond the nerves of many I'm sure.

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ttystikk said:

The drivers people use are generally rated at IP67, which means it runs fine while dunked in the water.

Click to expand...

loftygoals said:

Thought I'd share my water cooled COB build here.

I've built 8 light bars with cheapo chinese COBs. The idea being to initially build them cheaply and then swap chips to something more efficient after a couple of grows. As this is a bit of an experiment I didn't want to spend thousands and thousands on expensive COBs from the outset (I knew there was a chance this would fail miserably as nobody else has jumped on water cooling yet).

Anyway I made a steel frame from 4cm flat steel sections. The frame is 100cm long and 25cm wide. I epoxied the water blocks onto a steel frame and then made "clamps" out of flat steel sections and 4mm bolts (epoxy alone was slightly dubious). The water blocks aren't going anywhere when clamped! I then used thermal glue to mount the COBs onto the water blocks. The glue can be separated with a razor blade easily which would make upgrading straightforward.

View attachment 3686113

I've used Meanwell HLG-600H-36A drivers because I have no interest in dimming the lights. They're just over 96% efficient at full power. Each COB is running at 0.835A (16.7A total for 20 COBs).

I've used 8mm ID (14mm OD) hose on the 10mm barbs with 12mm hose clips.

Here's the hoses mounted and wiring done:

View attachment 3686114

View attachment 3686115

I've alternated cheap warm and cool COBs. If I were doing this again I'd pick one and stick to it because the power draw of different chips is unpredictable when running off a HLG-600H in parallel. Certainly when I upgrade the COBs later this year I'll be going for 1 uniform type.

Anyway here's the money shot of the lights in action (excuse the lonely auto):

View attachment 3686119

I made an earlier version of these with voltage controlled drivers and current limiting resistors. That's the 8 COB bar you can see at the top. I learnt a lot from building those which I used to make better lights with version 2 (these 20 COB lights).

The water gets pumped around the system with an Eheim 1250 water pump. All the water flows through the water blocks and then into a car radiator mounted on a timber frame where it's cooled:

View attachment 3686110

I have a 16 inch 1800cfm car radiator fan running off a 12V PSU.

The main advantage of this setup is temps inside the tent are dramatically lower than when running air cooled lights as I'm not relying on the air in the tent to remove the heat any more. When running an 8x4 tent at full blast at 2100W (2x600W and 2x450W lights) the tent stays at 25C under lights and 20C in the shade (room where the tents are located is at 19C). If I run only the 2x600W lights so 1200W total, the temp stays at 22C in the tent under lights. COB surface temp is around 45-55C (measured with FLIR camera).

I could make some improvements but this will do for now Promised myself there'd be no more tinkering with lights for 2 grows and have put my tools away!

Edit: I should probably mention cost. £167 for the Meanwell HLG-600H, £60 for water blocks, £10 for hoses, £5 for hose clips, £20 for wiring and terminal blocks, £44 for COBs, £10 for steel, sections, £10 for bolts (inc eye bolts for hanging). £326 approx for each light bar.

£15 for car radiator, £15 for radiator fan, £12 for PSU, £65 for water pump. £107 total for radiator and pump.

Click to expand...

Airwalker16 said:

@loftygoals I cannot find online anywhere those black mats you have in this pic. Where'd you get em? I'd love to do this for my tent

Click to expand...

ttystikk said:

The drivers people use are generally rated at IP67, which means it runs fine while dunked in the water.

Click to expand...

Flowki said:

Even still, if something becomes faulty it surely increases the potential dangers.

Click to expand...

loftygoals said:

Thought I'd share my water cooled COB build here.

I've built 8 light bars with cheapo chinese COBs. The idea being to initially build them cheaply and then swap chips to something more efficient after a couple of grows. As this is a bit of an experiment I didn't want to spend thousands and thousands on expensive COBs from the outset (I knew there was a chance this would fail miserably as nobody else has jumped on water cooling yet).

Anyway I made a steel frame from 4cm flat steel sections. The frame is 100cm long and 25cm wide. I epoxied the water blocks onto a steel frame and then made "clamps" out of flat steel sections and 4mm bolts (epoxy alone was slightly dubious). The water blocks aren't going anywhere when clamped! I then used thermal glue to mount the COBs onto the water blocks. The glue can be separated with a razor blade easily which would make upgrading straightforward.

View attachment 3686113

I've used Meanwell HLG-600H-36A drivers because I have no interest in dimming the lights. They're just over 96% efficient at full power. Each COB is running at 0.835A (16.7A total for 20 COBs).

I've used 8mm ID (14mm OD) hose on the 10mm barbs with 12mm hose clips.

Here's the hoses mounted and wiring done:

View attachment 3686114

View attachment 3686115

I've alternated cheap warm and cool COBs. If I were doing this again I'd pick one and stick to it because the power draw of different chips is unpredictable when running off a HLG-600H in parallel. Certainly when I upgrade the COBs later this year I'll be going for 1 uniform type.

Anyway here's the money shot of the lights in action (excuse the lonely auto):

View attachment 3686119

I made an earlier version of these with voltage controlled drivers and current limiting resistors. That's the 8 COB bar you can see at the top. I learnt a lot from building those which I used to make better lights with version 2 (these 20 COB lights).

The water gets pumped around the system with an Eheim 1250 water pump. All the water flows through the water blocks and then into a car radiator mounted on a timber frame where it's cooled:

View attachment 3686110

I have a 16 inch 1800cfm car radiator fan running off a 12V PSU.

The main advantage of this setup is temps inside the tent are dramatically lower than when running air cooled lights as I'm not relying on the air in the tent to remove the heat any more. When running an 8x4 tent at full blast at 2100W (2x600W and 2x450W lights) the tent stays at 25C under lights and 20C in the shade (room where the tents are located is at 19C). If I run only the 2x600W lights so 1200W total, the temp stays at 22C in the tent under lights. COB surface temp is around 45-55C (measured with FLIR camera).

I could make some improvements but this will do for now Promised myself there'd be no more tinkering with lights for 2 grows and have put my tools away!

Edit: I should probably mention cost. £167 for the Meanwell HLG-600H, £60 for water blocks, £10 for hoses, £5 for hose clips, £20 for wiring and terminal blocks, £44 for COBs, £10 for steel, sections, £10 for bolts (inc eye bolts for hanging). £326 approx for each light bar.

£15 for car radiator, £15 for radiator fan, £12 for PSU, £65 for water pump. £107 total for radiator and pump.

Click to expand...

questiondj42 said:

Am reading correctly that you're going to be using actual water, and not coolant for this? CPU cooling uses a coolant that doesn't boil at 212*F. They're designed for heat transfer and are less prone to pressure fluctuations. Water makes vapor and pressure. It will boil inside those lines.

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