Discussion in 'HVAC' started by Danvilletim, Jun 16, 2018.
Thanks, I will mention that to our ac tech.
A lot of techs clean chillers with muriatic acid and it's hell on the metal. Dometics new chillers use Titanium for the heat exchanger loop to help against this.
Always use the proper additive in the coolant water, never straight water. Dometic makes one that works well, they won't warranty chillers if there's none in the loop.
I hear good things from engineers aboard with the newer titanium condenser coils and less fouling. I don't know what the cost difference is manufacturing wise between the two (copper vs titanium ) Even Barnacle Buster mixed hot will take a mil or two of copper along with the growth every time you de-scale much less muriatic acid mixed 50/50 with H-2/0 . Better for a weaker mix or a pre mix and longer flush ,circulate times to save the coils.
My Cat mechanic just told me to use Rydlyme Marine to flush boat raw water systems.
I have used the Trac descaling products before. It's much better to pull all of the coolers off of the motors (and gear) and have them professionally cleaned at a shop. The descaling products won't remove some things like zincs stuck in passages. Also it's very good to get an eye on the inside of all of the coolers and pressure test them.
Yeah, I agree but for descaling AC and coolers between scheduled maintenance if it does no harm to the metal. Titanium sounds like the right metal to use on marine raw water equipment, our Cat HE's are plate titanium type coolers. Basically impervious to marine environment. Still would probably need to use the right solution to clean the systems.
Titanium may sound like a good material but is not the best at transferring heat. Please note the many plates it takes for those Cat heat ex-changers to do the job. Copper plates would take half the area.
IMO, it's usually sediment entrapment that are the Achilles heels of these Cat units. Lower flow rates (to transfer the heat) will not flow/blow thru the sediment and the collected/settled sediment will not dissolve with acids.
Dockside water will not blow out these sediments either.
When the temps start coming up, somebody will be breaking down your fancy multi plates to get the mud out.
I would not want copper pipe for any raw water system. Especially when you do not know what solution has been used for flushing. I just experienced this on two chillers with cupronickel piping which contains copper and has perforated due to using corrosive solutions to flush. I found a gallon of barnacle buster and bromine tablets onboard which was probably used to clean the system. Many boat owners probably are not aware what solution is being used by others when flushing AC systems. Not something you can visually see when surveying for purchase unless leaking to the exterior which is not the case when you have a pipe in a pipe condenser. As for the fancy Cat titanium plate HE's, they are known for longevity and like any raw water cooler needs to be serviced at some point. Was in sheet metal business for 30 years and did some work with titanium, very durable material and would pick it over copper and stainless as raw water system material in a marine environment. The only downside is cost and probably the only reason you don't see it used much in recreational boats.
My A/C guy uses Calgon Nickel-Safe Ice machine cleaner. Phosphoric and Citric acid, I believe. Does a great job.
I never said Titanium was a bad material nor would not hold up.
It takes a lot of it and the raw water flow is lower vs copper alloy H/Es. Silt settles in them when used in multi plate H/Es.
Copper-Nickel is the usual standard. It does work very well.
It does get abused by people repeatedly poring acids into those devices. I have always been against this practice either for H/Es or Condenser pipes.
On the chilled side, the water going thru the ship from cabin to cabin, Water with some Glycol is all that is needed.
Just enough to protect the different metals in the loop, keep the water from turning black, maybe a longer life in the hose sections and the pump seals from deteriorating to quick.
Capt Raph, I would agree that copper may be more efficient at transferring heat but my point is it is titanium is much more durable and corrosion resistant. Having work with titanium in the shop and in the field it is noticeable tougher than copper. Over the years have replace fuel coolers, heat exchangers, and gear coolers own boats we have owned and not due to us not maintaining them, they failed and may not have been maintained properly before our ownership, we do not buy new boats. As far as the Cat HE's, the maintenance schedule only requires inspection and not pulling to be cleaned at a specific hour or calendar period, much different than the schedule for copper alloy coolers. Being perturbed over our recent failure of two chillers in our current boat it is apparent to me that there are much better materials that could be used, especially with the use of highly corrosive products to clean a raw water system. My fault for not inquiring and if we buy a different boat in the future this will be added to the list of maintenance info to be verified by the owner. Just never thought of requiring that information. Of course we are new to chillers and they are different from the standard AC system used in most boats. Practical to use in larger boats and at a very high cost when amortized over the age of the units. Granted had they been cleaned properly, might be going strong for a long time. I mentioned in a earlier post that the first chillers lasted 9 years and these lasted 7 years. That is the track record I have to go on. Not good.
Checked glycol in Aqua Air chilled water loop was very low. Aqua Air requires 20% minimum glycol in system for warranty to be valid. So much for just running water. Told tech to make sure we had minimum 30% glycol for warranty.
We used to build marine gas inboards. we spec'd min 20-30% in FL waters. More to help the equipment than freezing.
Water to water moves more heat, not the chemical.
No explanation why Aqua Air requires 20% glycol for warranty to be valid....like you said it might help the equipment someway. Techs are having a problem putting glycol in the system...drained out a few gallons and only was able to replace one gallon. I read there are valves on the air handlers that could be used to drain and refill. Seems you would need to know how much fluid is in the system to get the glycol ratio right? I'm thinking drain the system and refill with pre-mix. Any suggestions?
I wonder if the old test strips are still available for Glycol %?
Heck, there used to be a test strip for everything.
Usually the valves on AH are to isolate them from the system to remove them. Often there is a purge line but it s too thin to use as a filler
Chiller loop are usually under pressure so you can’t just open a valve and top it off.
Our cruisair system is plumbed to the fresh water system and is refilled by opening a valve and bring pressure back to 20/25 psi. No idea how you d add glycol to the system
On my boat the Flagship system uses a small tank located above the highest AH. That easy to fill with anything needed and it pressurize the system by gravity.
Ours setup is the same except not sure about tank at high point, will have to check ph unit in flybridge for a tank. Our circulating pump has a valve on suction side to drain or add fluid but likely would not fill without a bleed valve open. Thanks for that info, will pass on to tech. Main tech went on vacation Saturday for a week, not sure assistant knows system and i'm not there to monitor. Thinking we need to drain system and refill with fresh pre-mix glycol. We can use circulating pump to fill and open top bleed valve. There is an auto air bleed valve on the unit in the er which should bleed off air coming back to pump. Will be at boat tomorrow.
You need to use a pump capable of maintaining a lot of pressure, like a freshwater pump. Open the bleed screw on the highest unit, usually flybridge. Pump in straight glycol, a few gallons, shut bleed screw then run the circulating pump a few minutes and test, if too concentrated, add water with the fill valve and drain some out of the flybridge unit, and keep adding a little water from the water fill valve until you get the correct concentration.
The only time that I ever had freeze up controls go south on me was on two Aqua Air chiller systems using their infamous
Remco Temp sensing bulbs that J.D. Nall / Aqua Air continues to use in their chiller plate inlet /outlet wells even though they have gobs of data about catastrophic failures resulting from Chiller boxes bursting due to expanding ice so by all means add as much glycol as possible to reduce your freeze up temps by a few points. JD Nall /Aqua Air were the Bees Knees 40 yrs. ago in the marine air conditioning industry and were used by Feadship & numerous quality builders at the time but they've been passed by technology wise and more importantly, the quality of components used in the units build. Unfortunately, Dometic & local private builders have easily surpassed Aqua Air in build quality and components used and then of course there's the Gold standard of H&H