h2c servicing

This page is dedicated to servicing the H2C unit.

Can the system be serviced?
Well, yes, but with some special parts and a lot of patience. It all depends on what is wrong, and what revision you have.

First, let's break down "servicing" into two portions: re-filling the system "for service", and replacing parts.

Re-filling the system
Here it is boys and girls, ta da! The answer to how to refill the H2C units... Buy an R134a 16mm "high-side" quick disconnect fitting, hopefully with some type of hose fitting. I found these pretty cheap:

http://www.t-motorsports.com/car-ac-r134a-system-port-quick-connector-adapter-hvac/

They have 1/4" SAE fittings on them. I wrapped some plumbers tape around the SAE fittings and clamped a 3/8" I.D. hose onto it, and BAM - my refill station is now operational.

I pretty knew this would work because I've been in the car service arena for a long time, and done my far share of A/C work. I thought the service port looked like one of the R134a quick disconnect adapters, and I was right!

Now, as for refilling, I am still working on that procedure. I was finally able to refill an Rev 01 over the weekend after a lot of trail and error. What's important in these small sealed systems is to remove ever last air bubble. And I'll tell you what, that is NOT easy... I'll post more details as I run across them. I'll try to source a vacuum pump during my next rebuild of these, as drawing a vacuum should really help refilling these systems quite easily.

Replacing Parts
Replace parts all depends on what revision you have.

Rev A00 was made by Delphi and uses 3/8" I.D. hosing and tubing. This makes it extremely easy to dissassemble and replace parts, such as the CPU waterblock and pump.  A member or two here has even installed the Corsair H80 CPU/Pump and used the OEM A00 radiator and waterchiller with TEC plates.  That, my friends, is the ultimate upgrade!

While you are lucky to have an A00 to upgrade, these are the ones that fail very quickly though. I'm guessing this is due to the dissimilar metals in the Rev A00 units - aluminum radiator and TEC waterchiller block, and copper CPU block. This causes a conflict in pH levels in the water, and creates "scale" or white particles that clog up the inline filter, pump, and other parts. The Rev A00 I have that I tried to flush out, I removed the inline clogged filter and the pump is at full speed - it still only dribbles a little amount. I suspect the radiator is clogged, but I am planning a full overhaul anyways.

Another advantage the Rev A00 has is it uses 3/8" I.D. tubing. I know I said this before, but really this makes it quite easy to purchase high-grade aftermarket watercooling components to replace parts.  I'd recommend a copper-core radiator, good copper waterblock, a decent Laing pump, and a 10% anti-freeze mixture with all new tubing (get rid of all hardlines, go for clear 3/8" I.D. tubing so it makes it easy to bleed the system when you can see the air bubbles!).

Rev A01 and Reb 02 are more difficult due to their hose connections though. There are a few ways of tackling the hose issues. I personally would create a double-flare at the end of the steel tube, which effective creates a Barb fitting. Now, you can slip over standard 3/8" I.D. rubber tubing and clamp it down. Another option is to tap the end of the steel tube, and screw on a barb fitting.  More difficult in tight spaces.  Either way, you need to be handy with these type of tools or you'll be left with a humpty dumpty situation.

The Rev 01/02 units have 1/4" I.D. tubing. IMO, this doesn't cool as much as less water is flowing to the block.  CoolIT Systems is known to make "just good enough" cooling solutions using their own cpu waterblock designs, and the H2C units they made for Dell is not exception.  It cools just "good enough", but nothing to praise home about as they are reusing Dell's original intension of using the same TEC waterchiller.

The advantages that the Rev 01 and 02 units have though is 1 thing: they are all of the same metal. This means there is very little chance of scale forming. A simple refill can usually put the Rev 01/02 units back into service quickly.

I have an A02 unit here that Alex graciously donated to see what I can "do with it" to extend upon. It will be my last project to attempt. Mainly because of the 1/4" restriction of the TEC waterblock. If I can figure out a way to get 3/8" inlet/outlets onto that TEC waterchiller from the Rev 01/02 units have, then it's a walk in the park (by upgrading the rest).

What about re-pressurizing the system?
After messing with the Rev A00 and 01 over the weekend, there isn't much to do about re-pressurizing unless you have a vacuum pump handy to draw the liquid in and to cap it off. Just refill it and check it once a year or so.

What is the special adapter that looks like a pressure cap?
That's a simple 16mm R134a A/C connector from autos to refill the A/C system. Yes, they are rated for up to 650 PSI - this system does not have 650 PSI. More like 2 PSI.

See the above about servicing using that port for refilling.

Can I replace the pump?
Of course you can! The pump I see in the R00 version here is of the old Laing DDC design (aka DD Laing, aka Swiftech MCP355). It's a solid powerful pump, that is rebuildable actually. There seems to be some type of diaphragm in the R00 revision of the H2C unit. I wouldn't worry much about it, and would just scrap it if you can and mount a new Laing on the metal bracket.

Just remember. The OEM pump is a PWM pump (4-pin). Most aftermarket pumps are 2/3-pin pumps, meaning you'd have to power it by other means. I for one love the self-monitoring and self-control of the master control board, so I'd recommend sticking with a PWM pump.

I also documented the 5-pin fan connectors, and 6-pin pump connector Dell uses. They are just plain ol' PWM 4-wire controlled in special connectors. I guess to keep people like you and me from knowing how to re-wire it (didn't work, I have traced them out and already rewired my new PWM fans to use the Dell 5-pin outputs of the MCB). :)

(insert wiring diagram, or link to dedicated page)

The hoses are leaking, what do I do?
There's a lot you can do. In the Rev A00 units, leaking is going to be common with the simple connections that was using. I highly recommend removing all metal and rubbing hosting and install all new 100% clear 3/8" I.D. tubing in place, and yes, again, remove all metal tubing. Get rid of the stainless steel.  And use regular screw-type hose clamps you can get from the auto parts store.

As mentioned above, the Rev 01/02 units will be much more difficult to service the unit but you can and will need to be familiar with a few tools.

Rule #1 when dealing with leaking hoses, get rid of them! Do not try to compensate, do not try to cut and reshape, etc. A leaking hose, especially the rubber-type in revision R00, has been heat formed and will always leak. Just get some new 3/8" tubing of your favorite color and reclamp them. I recommend clear though, so it will help with bleeding the system.

But again, read above about servicing the newer R01 and R02 units.

What is the coolant mixture?
Dell originally used 70% distilled water, and 30% Water Wetter in revision R00, so they say. When I took apart the Rev A00 unit I have here, it had anti-freeze in it - not waterwetter. Maybe the previous person before me attempted to refill it, I don't know.

Water Wetter has anti-corrosive properties which allowed the not-supposed-to-do mixture of metals that the H2C system has. You can read for days about all sorts of combinations. My advice is 10% anti-freeze, 90% distilled water and a drop (a single drop) of iodine to kill the germs. Just be careful around pets, as all of this is toxic for them and the environment (I wouldn't pour it down a household drain either). Personally, I construct my custom w/c systems to have 100% of the same metals, so I do not get corrosion (e.g. all copper/brass). That allows me to use just distilled water, with a couple of drops of iodine to prevent algae. But that is not possible here with the A00 H2C units, so you will have to use some else.

The Rev A01/02 units though are of the same metals, so pure distilled water with a drop of iodine will be fine. But add in some anti-freeze just in case - the A01 and A02 units I have here had anti-freeze in them already, go figure.

Can I replace the CPU waterblock?
This gets into the difficult area because from what I can see, these waterblocks are all custom made specifically for this kit. More difficult to deal with is the metal bracket and stand that supports the pump, hoses, VRM fan, and upper cover as well as clamping down the waterblock.

To replace the waterblock will mean to be prepared to make a custom metal bracket to re-mount the pump and fan as well as the upper cover, or to relocate them. That is, if you want want to keep the clean look of the original H2C 1-piece design. Else, feel free to break it apart and place it wherever you like.

As for performance, after my initial (still preliminary) testing, the A00 CPU waterblock sucks. Yes, it "will" work on an LGA1366 chip, but it does not cover the entire chip. And, it is the worse performing out of all of the revisions. The Rev A01/02 cpu waterblock, which look to be the same between revisions A01 and A02 so far (haven't tore them apart yet), don't perform very well. As a matter of fact, they perform worse than any CPU waterblock I have ever owned in the past 10 years! I say this because of my initial testing, their are wide 35 to 40C differences of idle and full load temps. I even remounted the stock HS&Fan just to see, and yes even they are the same. Here, we have CoolIT Systems' custom CPU waterblock being "just good enough to get the job done", but nothing special.

So yes, I would highly recommend replacing the CPU waterblock and figure out some custom way to mount the bracket of all of the stuff above it.

What is this 2nd radiator-looking thing? Is it not the radiator?
You are exactly correct, because it is NOT a radiator! This is where the "cool" factor (phun intended) comes into play with Dell's H2C unique "hybrid" design.

The H2C unit is a two-stage cooling unit (aka Hybrid). It not only uses water-cooling, but also TEC (Thermal Electric Cooling) to lower the temps of the water electronically. This is done by using four TEC plates of 40W @ 16V each (as I measured recently, on all 3 revisions), with 2 placed on the top and two placed on the bottom of a copper waterblock. They are wired in series, per pair, creating two circuits. This effectively removes 32W of heat, at 12V, per pair for a total cooling capacity of about 65Ws at 12V with both circuits powered up.

I am still diagnosing the master control board's use of the TECs, so I will post more here later about when they turn on, off, and at what temps that thermistor on the waterchiller block turns the system off (I'm guessing ambient). Also looking into disassembling the MCB's binary as well, to see if I can pull out the scalar values/tables.

This, in and of itself, is very cool (again, phun intended!). This is what we call a Water Chiller, and I had no idea that Dell did this in the H2Cs - or I would have been all over this earlier!

What is the room for improvement?
This is what I am now debating, since I now have all three of these (A00, A01 and A02). As you can see above, I am very excited about the water chiller that comes with this system and will be focusing around that component. First let's look at what we are restricted by:


 * Cannot control the TEC units of the water chiller (the master control board does this via firmware) so far. Though, I am currently hacking around the HEX values to see if I can find the scalar values, or to build my own TEC circuits. Stick around...
 * Cannot control the PWM water pump speeds as the master control board does this via firmware. Though, during inital testing with the latest version of the firmware in the MCB, I can see that the pump idles most of the time and increases in speeds with what seems to be the same as the front CPU fan, which is also controlled via the MCB. I'll do some recording to see their linear curves.
 * The waterchiller in the Rev A00 units uses 3/8" I.D. tubing, which allows for some very flexible and powerful upgrades. But the Rev A01 and 02 units use smaller 1/4" I.D. tubing on the waterchiller, making it restrictive. I'll tear one apart to see if it can be upgraded.

Notice I did not mention being restricted by the CPU waterblock or radiator? It's because the first thing I would do if I was to use one of these system is to throw out that waterblock. THe waterblock is the core of the system - it must perform well and beyond any expectations you have. Else, the entire upgrade will be for not.

The fact that you can replace the H2C unit with an Corsair H80 waterblock/pump combo, and immediately see a 10C drop in idle and load temps clearly shows the waterblock is crap in these H2C units. Get rid of it, and install a quality one.

That would be step 1 - replace the waterblock. If you are not prepared to go this extra mile, and figure out some way to remount the pump and top cover, then just refill your unit and carry on. The rest below only helps if you replace the waterblock with a higher performing one.

Next I'd actually replace the pump with another Laing DD. Even though they may be identical, put something in that you know how it performs. I would attempt to keep the PWM control of the pumps as well, so the master control board does its thing without my intervention. This also gives me the option of later controlling it via a different output of the Master COntrol Board (I've been hacking the MCB for some time now to gain full control over it).

Going the extra mile, I would look into upgrading to a thicker radiator. The Delphi radiator in the Rev 00 unit has 21 FPI, and the radiator in the Rev 01 and 02 versions have a 19 FPI radiator. These already are very thick FPI radiators, but they do make 30 FPI versions if you are really serious about removing every watt from the system. The Dell OEM fans can more than handle some huge 30 FPI radiator. The radiators are all 38mm in thickness. With some careful planning, you could squeeze in a 50mm thick radiator. But 60mm thick versions doesn't seem like it would clear the case when re-installing the unit. May have to make some modifications to that beautiful case if you go that large.

Now, if you want to get away from the MCB controlling your TEC and pump, and want to start to control these units yourself, this opens the door to a lot of modifications such as upgrading the TEC units to like the 80W plates, and wire them in series (that's ~32W across each plate, for a total of 130 Watts to be removed from the TEC, at full power, across all 4 devices wiring them similar to what Dell had). Adjust the TEC power supply to be based on the temp of the water, so it is very underpowered until you really need it. This will need a lot of caution though, as you can easily create condensation on the lines and short-out your parts.

There's so much more fun you can have with TEC, I can't even be giddy enough to go over them all. Feel free to look into www.overclockers.com for Extreme Cooling in the forums.

Following up, I'll be modding the units I have over the next few months to see what I can out of it.

Is it worth to even deal with?
Only if you like the nostalgia of using the OEM parts, with sacrificing a little performance. Personally, I'd sacrifice a few degrees to have this system running quiet.

The Corsair H80 units have been proven to be able to cool the new very hot X79 3930k 6-core CPUs, barely, but it can at high RPM fan speeds though they can't overclock too much. This Dell H2C has the potential of cooling even better than that Corsair unit, but you need to upgrade the CPU watercooling block first to have any chance at it.

It has to perform better than the H80! My goals is to outperform the CPU waterblocks from the H80 and H100 units, and having the TEC waterchiller and radiator remove as much heat, if not more, than the Corsair H100 unit. All while having the very-quiet operation of the original H2C design.

How is this thing controlled?
We'll close with the best part I like about this H2C unit. Dell did a lot of testing with water cooling systems, and found that the noise level of the fans is just too much to get the performance out of them being air-cooled. TEC systems have the inherit issue of being able to go below room ambient temp, which creates condensation to form on the tubing and drip onto components. That is bad.

So, Dell came up with this hybrid approach that uses ambient air to cool the heatsinks for the hotside of the TEC plates. The TEC plates are matched to be just enough to remove about 65W of heat from the water, under full load, and is controlled via the TEC unit. Just a perfect match to remove just enough heat from the system, without going overboard with having to worry about condensation. But it isn't enough for extreme overclocks, I will admit. That's why I'd be upgrading core components.

Of course you can go overboard and have sub-zero water-temps using a lot of TECs, with a lot of condensation. But that wasn't the point of this system. This system was designed to run extremely quiet. To learn more, look at the PDF I posted at the beginning of this document.

But it's the fact that the Master Control Board controls the TEC plates and pump speeds automatically is why I am going back to see what I can eek out of these units with some core upgrades.

I am still creating some test equipment and installing the parts for me to do more testing, so I plan to have more information in the coming months about this unit.