how do I solder the hot water coil?

I had a DOH! moment today. When I got my boiler I capped off one end of the domestic water coil and pressure tested it to make sure it didn't leak. Fast forward to today and I'm trying to solder a copper fitting to this thing and water keeps coming out of it. Hehe solder doesn't stick to water very well, no matter how much I want it to. There's no drain so when both ends are disconnected there is still water in the coil. What am I supposed to do now?

Hey e.alleg do you have a air comppressor if so put a piece of old hose on one end put the hose in a bucket put the air in the other end and blow it out no more water it will be dry to so you can solder have fun

Here is old plumbers trick if you are in a jam. You only need a few inches of dry tube for a good sweat. Get a piece of bread and jam it in the tube. when you are done, even if you can't fish the bread out, it will dissolve.

thanks, I'll try the bread trick today.

Bread works really well just make sure it is white bread. Also make sure the joint is really cleaned off and use mapp gas instead of propane.

I'd try really hard to get the water out. The bread trick may solve your immediate soldering problem but it's always caused me a future problem. Clogging up some small orifice, air bleed, inlet to temperature/pressure gauge, etc. I've yet to see a case where an air compressor, shop vacuum (suck or blow) or a leaf blower couldn't get the water out. It may make a mess but a leaf blower directed through a funnel into a pipe will blow out a lot of water in a hurry. Leave it run long enough and it will dry the inside of the pipe too. This eliminates steam when soldering which will sometime pressurize the pipe blowing the molten solder out preventing a reliable joint.

I often had to cap off a section of tubing. Problem is, the air inside the tube expands when heating and pops off the cap in which you are trying to sweat.

Use a female copper adapter and plug it with a brass or steel plug & pipe dope.

All set, no leaks! I had another problem I didn't realize until I started thinking about what I was doing. I was almost out of flux and I didn't really feel like going out to the store so I was using my finger to "scrape the bottom of the bowl" like getting the last bit of peanut-butter out for a late-nite sandwich. The oils in my finger must have contaminated the joints because they didn't look as nice as I'd like. The solder kind of lumped up around the fittings instead of flowing in. I redid the whole job with latex gloves and a fresh tub of flux and a new brush and it came out great.