Plumbing, can't desolder

[TBark]

Hot water tank isn't putting out as much hot as it used to, its 17-18 yrs old now.
First thing I wanna check is the inlet tube, maybe it's cracked or has holes.
Guy who installed the tank way back didn't give me any unions, just soldered joints. So I gotta part a joint now to thread the inlet tube out.
I shut main water off, opened all upstairs hot and cold taps to drain back & drained the tank.
Hitting one joint with propane torch and it just won't budge.
1/4" tap for humidifier is close to this joint, I pulled off the tap and I do see steam or vapour while I'm torching, so it's not totally dry.
So should I just wait a while till the tank has dried out ?
That's the only reason I can think of as to why it won't pop.
I even had a second torch going at the same time, maybe more heat in some way ?

TBark

[M@G]

I agree with your assumption, still water in the connection. The water will absorb the heat quickly and you'll never get it hot enough to melt the solder.


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[Dean2]

Open downstairs taps., open drain on tank. Likely need a new tank anyhow so a hacksaw or pipe cutter may not be much of an issue to detach the joints. Just make sure you cut on the proper side of the joint.

[dodgeboy1979]

use a pipe cutter to cut the pipe, solder in a union then you are set for any future repairs.

[fishtank]

Originally Posted by dodgeboy1979

use a pipe cutter to cut the pipe, solder in a union then you are set for any future repairs.

this and install a flex line on the inlet .. easy future changes

[buckmaster]

Originally Posted by TBark

Hot water tank isn't putting out as much hot as it used to, its 17-18 yrs old now.
First thing I wanna check is the inlet tube, maybe it's cracked or has holes.
Guy who installed the tank way back didn't give me any unions, just soldered joints. So I gotta part a joint now to thread the inlet tube out.
I shut main water off, opened all upstairs hot and cold taps to drain back & drained the tank.
Hitting one joint with propane torch and it just won't budge.
1/4" tap for humidifier is close to this joint, I pulled off the tap and I do see steam or vapour while I'm torching, so it's not totally dry.
So should I just wait a while till the tank has dried out ?
That's the only reason I can think of as to why it won't pop.
I even had a second torch going at the same time, maybe more heat in some way ?

TBark

The drip tube is probably toast! Cut the pipe if its copper and install a good ball valve. The joints will not come apart if there are still traces of water in the pipe. A new drip tube is about $12;00 and a ballvalve is about the same. If there is a shut-off valve then a coupling will do the trick. The shut-off is usually on the cold water pipe.

[CaberTosser]

On a tank that old you've hit the point of diminishing returns. Change it. There will be enough hard water scale in the bottom that it's reducing heat transfer (efficiency). New tanks are both more efficient and generally have better recovery rates.

Barring that, as already noted you should cut it and put in some couplings or dielectric unions (either the short type or the ones with a length of ribbed flexible copper. No plumber attempts to de-solder a joint in a closed system, it's always cut open first to ensure its fully drained.

[TBark]

Got it,
It needed to drain down and dry completely before solder joint parted.
And I twisted off the dip pipe, corroded at the fitting held it while I unscrewed it, and it fell into the tank trying to pull it out. ugh.
So I couldn't tell what the condition was. Replaced the pipe.
So new dip pipe, union and gate valve on the inlet now too.
Doing a weak chem clean /soak on the water side now, 12 litres of vinegar, will flush it after 3-4 hrs.
I also wire brushed the internal stack pipe with a long pipe cleaner, vacuumed all out the bottom too.
That's about all I can do, $40 in maint, ifs it's no better, new tank in the near future.
Thanks for the tips folks.

TBark

[roger]

While your putting in a new tank. Put a full port brass ball valve in the bottom to replace the plastic one. And a drain or hose to the floor drain blowdown the vessel occasionally.

[Big Grey Wolf]

T Bark, just helped son replace his water heater last week after 10 years. It depends how hard your water and did you drain sediment. I was very surprised warranties were 6/9 and 12 years. So if you do not buy high end heater will need to throw away within 10 years. You need to be very careful to polish copper ends and lots of flux/paste and sodder, definitely no water to get good joints. Most contractors will put in low end 6 year heater.

[CaberTosser]

Originally Posted by Big Grey Wolf

T Bark, just helped son replace his water heater last week after 10 years. It depends how hard your water and did you drain sediment. I was very surprised warranties were 6/9 and 12 years. So if you do not buy high end heater will need to throw away within 10 years. You need to be very careful to polish copper ends and lots of flux/paste and sodder, definitely no water to get good joints. Most contractors will put in low end 6 year heater.

And you get this information from where? The main difference between entry level priced tanks and more expensive ones is an additional sacrificial anode, the tank enamelling process is pretty much the same otherwise. Myself & most other plumbers I see are putting in tanks with 8 year warranties, the longer warrantied tanks are generally just more expensive with little in the way of actual construction differences. Flushing hard water scale accumulation from your tank can help it maintain efficiency as the scale inhibits thermal transfer, but it doesn't do much for adding life span. I was at an AO members business just yesterday and it had an 18.5 year old water heater that was still going, which originally would have had about a 6 year warranty IIRC (warranties have improved for water heaters over the years).