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Question DetailsAsked on 3/29/2017

I have an old locked down R 22 5 ton heat pump that I have to replace. I can't replace the evaporator at this time

I've never flushed all the way through a fan coil before. How can I flush through the lines and the evaporator coil at the same time. All I want to buy is a heat pump and TXV. I can't get the fan coil out at this time. All I have is a RX 11 flush kit. Thanks

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2 Answers


You said a "locked down" heat pump and can't get fan coil (condenser coil) out - if you are rebuilding it, I am unclear on why you do not have full access to the cabinet to do that - and for that matter, if "locked down" how are you going to get at the TXV and heat pump to replace them ?

Sounds like you do not have all you need by a long shot - even assuming the manufacturer does not specifically recommend against using that sort of a product, which at least several do. And that the product is compatible with your specific type of refrigerant, because the different types have different chemical bases.

To flush in-place you need several things - if the unit is charged a refrigerant extraction pump and tank to first evacuate the existing gas. Then an adapter fitting for the tubing to the RX 11 connection, probably at the TXV, to allow you to inject the solvent - and don't forget to disconnect the line at the intake side of the compressor so you don't put the solvent and any flushed-through debris or sludge into the compressor (which the solvent should definitely not go into anyway). Actually, I have very little confidence in this sort of solvent process, especially with a gas rather than a liquid, using just a pound or two (as recommended by manufacturer for your size system) because it is just a small amount making one pass through the system and not under substantial pressure - to truly flush out pretty much any system of tubing or hoses requires a substantial amount of fluid passing through it under pressure.

Then after you inject it into the system, you need a nitrogen tank with regulator and fittings to blow it on through and blow out any solids or sludge or residual solvent-softened contaminants (or oil-free air compressor to first blow out the system after the solvent has been used, then nitrogen to purge the air and any residual moisture). And a charging kit (gage set and fittings, evacuation/charging pump if applicable, scale or charging cylinder, etc) and replacement refrigerant canister of gas to recharge the system. And of course operating data on the installed system (may be on manufacturer's plate, maybe not) for what the amount of replacement gas should be, and what the high and low side pressures should be at any given ambient temperature (the operating curves chart or table). Andprobably about a half dozen or more tools I did not mention, thermometer, etc, etc.

I am assuming this is the gaseous RX-11 you are talking about, not a liquid - which should mean it can be flushed through all right regardless of configuration, but also means it will likely have very little effectiveness againt sludge or burnt-on deposits. But - with liquid solvents you have to be sure the system configuration is such that it will all be blown out by the nitrogen - because if the condensor or evaporator coil or TXV assembly/manifold has low spots where the liquid or sludge can settle (meaning the exit tubing connection is not at the lowest point, especially on coils) then you have to dismount the coils to clean them - generally the best approach anyway because it allows tilting to ensure all liquid is drained, and provides full access for excternal cleaning as well.

Oh - and of course the filter/dryer cartridge has to be changed afterward and the housing cleaned out after flushing.

I did not address the legality of doing this uyourself - even though you can buy replacement refrigerant it is illegal for you to remove or install it.

I also did not address WHY you want to flush it - my feeling - if normally operated, nitrogen gas should flush it well enough before recharging. If it got scorched bad enough to sludge or soot up the lines, they should be pressure flushed with a lineset recirulating flushing kit - pumps liquid solvent around in the lineset to clean it if it cannotreasonalby be replaced, as it should be if badly smoked. And in that case the coils should be taken out and tanked to clean them properly before putting in a new heat pump, othewise you are counting on the dryer/filter to prevent any gunk/ junk from migrating to the new heat pump and trashing it.

Answered 3 years ago by LCD



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Answered 3 years ago by Member Services

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