Does the mister water filter work for calcium on the A/C coil?

[@throttlebottle5906]

that's why it says "Calcium Inhibitor" and not "filter", one would be closer to an lie, as understood by many. lol ** those are something like polyphosphate, which does more or less coat the calcium so it doesn't adhere and buildup on surfaces. likely neutralizes the ph balance somewhat.

[@MrChipBryant]

Thank you Sir, I'd really like to meet you someday.

[@grayfurnaceman]

Welcome GFM

[@averyalexander2303]

Great point about possibly dropping the head pressure too low at night or on cool days. Of course there are multiple ways to prevent that, but if the goal of buying the misters is to save money, the customer probably won't want to spend the money on fan controllers, pressure switches, solenoid valves, etc. As a general rule of thumb, what would be the minimum condensing temperature we would want to see for a typical modern system with a TXV?

[@grayfurnaceman]

First, We have a parts bill that exceeds any possible savings. I would like to see about 100F. GFM

[@averyalexander2303]

​@@grayfurnaceman Exactly my point. Even if there's no damage to the coil, by the time you get a proper mister setup with actual filtration and a solenoid valve controlled by a pressure switch or some other way to control the misters and pay for the water, the payback period would likely be longer than the unit's remaining lifespan. Thanks, 100 degrees seems about right. Now that I think about it, I suppose someone could figure out approximately the ideal head pressure for their system by slowly dropping it until the delta T starts to decrease. I'd think the efficiency should be pretty good right at the point where the delta T is at its lowest or just barely starting to increase.

[@TofuInc]

@@averyalexander2303 With a TXV you can lower it to just above the point where flash gas starts forming at the TXV. The ideal head pressure doesn't really exist since is changes based on operating conditions. You can add more and more controls to chase that ideal pressure, which is what manufactures are doing.

[@averyalexander2303]

@@TofuInc Great points. Wouldn't using a receiver in the liquid line possibly allow for slightly lower head pressure by helping to ensure that only liquid reaches the TXV? My understanding was the main reason a receiver is pretty much always used on vehicle AC systems with a TXV is because the head pressure can't be effectively controlled since the ambient temp and condenser airflow is so variable.

[@TofuInc]

@@averyalexander2303 In a modern condenser the bottom 1/4 of a condenser is basically used as a receiver. Adding a receiver would allow for more of the condenser to be used, more heat rejection would result in a lower heat pressure. In that case you could run quite a low subcool and still not starve the TXV. It's quite invasive solution though and you are adding quite a bit of refrigerant to the system. A simple way to address low ambient is just with a fan cycle switch. connected to the mister. A better way to address the situation is to instead of using misters use a higher RPM condenser fan motor. Most come with a 825 RPM motor and 1075 RPM are readily available. Then add a ICM fan speed control. This is what I have done with my unit. Added a high HP 1075 RPM motor and changed the stamped, square blade fan for a swept blade fan off a commercial packaged unit. This resulted in much more airflow without increasing amp draw and actually resulting in a quieter unit. It also lowers my head pressure in mid summer. I'm using a ICM326HN to reduce the fan speed at low ambient. It has quite a bit of advantages such as not starting the fan immediately allowing the head pressure to build quite quickly. I can actually see the sight glass clear in under 30 seconds where before it would take several minutes.

[@GannDolph]

if a mister is configured to ensure 100% evaporation before reaching the coil, say in a hot/dry southwest climate, does calcium still accumulate or does it blow straight through as dry white 'dust'?

[@throttlebottle5906]

so, build a swamp cooler for your ac condenser? lol, yes that would work even better, but rather impractical on a wrap around coil. an old flat "slab" coil unit with fan/s it would be good on. but as mentioned, head pressure needs to be maintained in low ambient conditions, so you'd need to add a fortune in bypass dampers, fan cycle/head pressure controllers and more or at manually turn off and bypass the cooler. yes there's other ways, but not practical and complex custom built designs.

[@grayfurnaceman]

At one point, I built a wood frame about 8 inches away from the coil and mounted the misters on it. Did not seem to make a difference. However the humidity was about 15%. GFM

[@TofuInc]

Scale inhibitors dissolve a chemical into the water that bind to the calcium and dissolved solids in the water supply. It usually not the beads themselves but a coating on the beads. Even after the cartridge is used up the beads will remain. The chemical used depends on the manufacture and reputable ones will use a food grade additive. DI Resin cartridges work to remove the calcium. The work via a similar process as a water softener, just without the sodium exchange. The result is pure water with a neutral ph of 7. The "RO water is corrosive" is a bit of a myth. It stems from when RO is put though a pipe that has previously had high TDS water transported through it. The RO water will dissolve any mineral deposits. RO water may dissolve some copper but the amount is small and would be practically immeasurable being sprayed on a condenser coil. The lower the TDS of water the less conductivity. Electrolysis requires conductivity to take place. Therefore RO water would not increase electrolysis, it would actually decrease it. But to the point of the video I think there are better way to go about lowering head pressure than misting systems.