SA indoor noob needs help choosing COBs

[Randomblame]

3 ways - a watercooled set up beats the air !!!
your graph shows only 1 reason why a low Tj can rise efficacy of led light. (~10%)

- the 2nd reason is much more evident and important.

Light-Heat-Cogeneration

is a simple addition of light & heat efficiencies.
While your light efficacy = your energy efficacy
My energy efficacy is light + heat !!
I`m able to rewin 60% of the electr. input as stored, hot service water to use it in my household.
That means i.e. a 1000W coolmac system with a daily consume of 15KWh can produce 9KWh of stored heat power = (~250L of hot service water)
This is only ~80% of the total produced heat - and the radiated heat by the LES is still ~20%. (and hard to rewin), but also desired to heat your grow room.

You can be shure that all heat measuring with hot water are ways more exact than a measuring of radiant flux in an integrating sphere.

If your chip is 25-30% light efficient @ Tc 90°C - it will rise to 27,5-33% @ 15°C.
With an aircooled led i can not reach this region without an expensive amount of heatsinks and driving dozens of fans, while my watercooled chips has no heat resistance at all
- and Tc = ~Tj = watertemp. (15-35°C)

and this is the third way, that rise efficiency of a watercooled lamp build.

you have to spent much more additional electricity for active cooling (10-20 fans // 25-50w)
- i spent 2,4w with a tiny waterpump able to cool down the whole 1000w much lower, better smarter.

what do you want, if you go out to buy a car ???

Yes - it must be a good one --- ...and they are all watercooled

No no, Porsches are still aircooled, at least the good ones, lol.
What do you think about watercooled low driven F-strips? Almost half of the heat is radiated frontwise so does it make sense?
I have plans in the drawer for a passive water-cooled system, whose waste heat will be used down in the area of the roots by long radiators. It's for a greenhouse in the garden of my mom.

These are the passive radiators I have in mind. 8-10 of this "tubes" should be enough for 300-400w(120-140€).
I'm not interested to keep the temps below 25°C instead I want watertemps around 50-55°C. It needs probably a few hours but could be done with a reservoir with the right size, or what do you think? Maybe even without reservoir?

 

[Randomblame]

Agreed and the number of cobs that i want to buy from you are in excess of that minimum order amount.

So i will be stuck with internationals

These are 16inch/40cm strips with 96 LM561c or b+, max. is ~48w/9000lm per strip and you can get them for 7,50$ ea. Ask for some samples or look for another offer if you need less than 50.
If you ask them they write a lower price on the invoice (below $20) and you get the "corrected" invoice only online, that way you can save alot on customs fees.

https://m.alibaba.com/product/60730934376/Quantum-boards-96-LED-Samsung-lm561C.html?spm=a2706.8288997.0.0.75021fd79UMjhO

 

[ANC]

instead I want watertemps around 50-55°C

I would say that is roughly what my 100W strips are running at without any fancy cooling.

 

[Randomblame]

I would say that is roughly what my 100W strips are running at without any fancy cooling.

Yepp, low driven seems to make no sense. I should instead use some COB's to realize that project, its a more effective heat generator. Assuming the Tj is ~10°C higher as the watertemps I would need COB temps around 65°C which is more easily to reach with fewer COB's. 1,4A/50w or 1,75A/65w should be enough and frame from squared alu-tubes.

I've been thinking that for a long time, but never built it. Maybe I just hang her a few strips in, without floor heating. She could easily bring the heat down to her plants with a fan.

 

[ANC]

Bridgelux COBs have a very good conductive base. They really don't skimp on this. When I was running the CXMs hard, their CPU coolers were maybe 45C... During veg, they felt the same as ambient temps almost.

 

[mahiluana]

What do you think about watercooled low driven F-strips?

should be no problem - you could also drive them a bit harder and they will stay close above @ 5°C + to your desired watertemp.

my watercooled led lamps work like a radiator yet - and i can bring heat back as much as i produce and with an electr. boiler as much as i need and i can pay,
and i`m not shure if extra radiators to the roots is necessary and worth the installation.
But in a special room for seedlings und cuttings it can makes sense, if floor insulating is not sufficient in winter.

For a 300-400W watercooled led lamp system - i use a 80L electric boiler with integr. heatexchanger (brandnew with anti corrosion magnesium anode/200$) and reach 50-55°C @ the end of the day - but then will loose heat during the night because we take showers or the water flow keeps the grow room close to day time temps.

To maintain a steady heating with 8-10 radiators @ 55°C you don`t need an extra water reservoir, if your radiators have enough volume itself --- but the ones you showed seem to have very small total volume.

A radiator with 40-50L should give you enough storing capacity and a quick heating up.

To have a good insulated, sealed case for your pots helps to create a steady warm temp.-
as it do if you install a bigger well insulated water tank.
And with an open loop you could produce warm, wet air............ your plants like that !!!

....in my country some energy providers started to offer e-cloud accounts for renewable electricity... that makes it possible to use 100% of your self produced energy and so calculate
a pv or wind system that covers your needs of electricity and heat.

It works like that: we(2pers.) live in 80sqm 3 room flat in the middle of the city.
we need 80L of hot water/day //~ 30m³ /y
we need ~160L/day of extra heating energy in winter(6month). //~ 30m³ (in my region)

so together with the rest of electricity we need for other applications that is 5500-6000KWh/year

we have to mount only 36sqm of solar panels to cover all our needs with electricity.
Self installed this may cost 3-4000$ and then you can say goodby to oil, gas, trump and other fossiles for the next 30 years.

BTW did you know, that there are hybrid watercooled solar panels(1,6m²) avaiable ?
They produce 300Wp electr. + 921Wp heat and so even need less surface to produce the same.
15% more electricity production thanks to the low temps of the cells in midday summer sun. -
does this remember you to something we are knowing yet - and get more clear if we know that a led works like a (bad) pv - cell ?

 

[1212ham]

While your light efficacy = your energy efficacy
My energy efficacy is light + heat !!

In your previous post you referred to efficiency, now you are talking about efficacy.....

My energy efficacy is already light + heat!
I need heat in the house, air cooling transfers heat into the house so I am already 100% efficient. Water cooling can not exceed 100% efficiency.

 

[mahiluana]

been thinking that for a long time

put "watercooled" in the search above and receive hundreds of interesting posts with a dozen autors` examples of different ways to go.

 

[mahiluana]

so I am already 100%

...and how does your shower gets hot ?

 

[1212ham]

No no, Porsches are still aircooled, at least the good ones, lol.
What do you think about watercooled low driven F-strips? Almost half of the heat is radiated frontwise so does it make sense?
I have plans in the drawer for a passive water-cooled system, whose waste heat will be used down in the area of the roots by long radiators. It's for a greenhouse in the garden of my mom.

These are the passive radiators I have in mind. 8-10 of this "tubes" should be enough for 300-400w(120-140€).
I'm not interested to keep the temps below 25°C instead I want watertemps around 50-55°C. It needs probably a few hours but could be done with a reservoir with the right size, or what do you think? Maybe even without reservoir?

View attachment 4091189

Here is my light with water cooled Gen-2 strips and reservoir. I had to build a frame, so why not have water in it?
The frame is 1/2" (12mm) square tube. It is quite happy running water cooled or running passively without water.

At the moment, I use it move heat down to the bottom of the tent. Room temperature is around 16° and water is 30-32°. In summer it will be used to move heat out of the room.

 

[GrowLightResearch]

What do you think about watercooled low driven F-strips?

You wouldn't need that at all if you used single row strips.
I'm running some 4000K F-Series strips at 750 mA in an aluminum channel and the aluminum temp is like 29°C at 22°C ambient.

 

[mahiluana]

It is quite happy running water cooled

those electr. boilers are not really expensive and help to integrate the hot water into your household.

 

[ANC]

I just don't understand where does the cool water come from to cool the lamps?

 

[mahiluana]

where does the cool water come

where i live the incoming cold service water is 13°C in winter and 16°C in summer.
the cooling cycle in my lamp is only 2,4L heats up quickly and then let the heat drop into
the 80L heatexchanger.

 

[ANC]

my geyser is about 200litres, I still don't understand... I thought there would be some kind of loop. I mean the heat exchanger just sits in the water that is getting hotter as the day goes by.
Without any electricity, my water gets hot enough to burn you in summer...

 

[mahiluana]

Without any electricity, my water gets hot enough to burn you in summer...

i never used the boiler with electricity - but there is a magnesium anode inside and a 5 year warranty worth the money(190$).
in summer i grow with 350W --- in winter time up to 1200W
we now profit of electricity cloud accounts, that enables you to consume 100% of your self produced KWh by wind or pv. This is a revolution, that opens up better system planning and more profit for the production and use of green KWh.

 

[ANC]

I saw these small modular powerwalls that are an alternative to the Tesla walls, I need to find the link for you when I find the time.

 

[nevergoodenuf]

I am wondering if any of you have actually don't any par reading between watercooling and just a heat sink? I have built a couple and I am not convinced it is worth it. I took one of my monster heat sinks on a very cold day and took 2 par readings with the COB running @ 250 watts. The Tc while cold and light on was in the 20*c range. After an hour or so the Tc rises to 75*c. If water cooling is so effective, why did I only see a <10 Umol difference from chillin to hot.

 

[mahiluana]

to burn you in summer...

that`s insane - have a look to the waterflow of the system. The cooling tower works with vaporisation and is a cheap diy cooler, that don`t need additional energy if you connect it to the
air coming out.

 

[mahiluana]

why did I only see a <10 Umol difference

you should see what everybody see

water cooling is so effective

...because it is able to prepare hot water or heat a whole building - not only grow rooms can be watercooled. Light heat cogeneration is ~3 times as energy efficient as an aircooled led light -
if you use the heat energy to substitute fossiles.
My Tj is @ 20°C in the morning and 40°C in the evening.

good cooling and low Tj always give you more flux and longlife.
Tc 75°C means your Tj = ~100°C


If your led chip drives out e.g. 140lm/w @ Tj 100°C (after 1h)
mounted on an a watercooled heat sink would deliver ~168lm/w

If your monster heatsink is made out of aluminium it`s mass must be ~ 13-15kg ???
and your 250w led chip produce ~200W of heat power.
Things like this you can calculate here:

https://rechneronline.de/chemie-rechner/heat-capacity.php