Condensation on Water Heater Cold Nipple

[alfuzzy]

Hey folks...looking for some insight from all you experts with my situation.

Last week I replaced my natural gas water heater. Everything is working fine (no leaks) & water is heating fine...but I do have a strange problem.

Almost immediately when the gas burner kicks on...the cold water nipple & the copper threaded adapter on the cold nipple start to have water condensation on them...and I hear a "sizzle" sound every 3 seconds or so (only while the gas burner is running).

My best theory is the cold water pipe is "cold"...and the heat coming from the vent hood at the top of the water heater is causing water condensation to form on the cold water nipple. This water condensation eventually forms droplets that then come in contact with the center of the water heater (where the hot burner gases are venting out of the vent hood & flue).

This doesn't seem quite right to me (that water condensation forms on the cold water heater nipple & then sizzles when it comes in contact with the hot surfaces from the exhaust gases at the top of the water heater).

Here are a couple photos of the old & new water heater. The vent hood in each photo is basically the same exact diameter...but the hot/cold nipples are much closer to the vent hood on the new water heater (compared to the old water heater).

With the old water heater...the distance from the outer edge of the vent hood to the outer edge of each hot/cold nipple is 2". With the new water heater...this distance is only 0.5"(much closer).

Old Water Heater:



New Water Heater:



I'm guessing since the nipples are so much closer to the vent hood on the new water heater...they are being affected much more by the heat of the vent hood...causing water condensation to form.

As mentioned. There are no leaks. All threaded connections & soldered copper joints are 100% leak proof...and are 100% dry when the gas burner is NOT running. But as soon as the gas burner turns on...water condensation forms on the cold water nipple & makes a sizzling sound every 3 seconds or so when the condensation touches any hot surfaces.

What do you guys think is the issue? And/or...could this be normal & nothing to worry about?

Thanks

p.s. I also noticed that the "Flue Baffle" can be rotated. The install instructions didn't say anything if the flue baffle should be oriented in a specific way. Should the flue baffle be oriented in any special way?

 

[Twowaxhack]

Sounds normal to me.

 

[Jeff Handy]

Burning natural gas creates water vapor.
You might have a poor draft up the vent pipe.
So flue gases, containing water vapor, are collecting long enough to condense on the cold pipe.

 

[Jeff Handy]

Aren’t there two slots that the baffle rests in?

So the position would seem to be dictated by the slots, not random placement.

 

[Twowaxhack]

Aren’t there two slots that the baffle rests in?

So the position would seem to be dictated by the slots, not random placement.

Exactly

 

[Jeff Handy]

Your old cold nipple was corroded, so this probably is not a new issue.

The new heater has closer nipples, so it is just more obvious now.

 

[Twowaxhack]

Water heaters can and do rust from the outside in. Not always but it happens.

Very Cold incoming water or running the tank out of hot water on a regular basis.

 

[havasu]

Another reason why I like braided lines the last 18". You will never know if it is just a loose connection with the soldered lines attached like that.

 

[alfuzzy]

Burning natural gas creates water vapor.
You might have a poor draft up the vent pipe.
So flue gases, containing water vapor, are collecting long enough to condense on the cold pipe.

Hello Jeff...thanks for the help.

What you said about burning natural gas creating water vapor...and maybe not having good draft up the vent pipe makes a lot of sense.

My home is 105 years old...and has a very low ceiling in the basement (where the water heater is located). Basement ceiling is less than 6 feet & water heater height is around 63"...thus not much of the chimney is a exposed for the vent pipe to connect to the chimney. In fact...the 4" hole in the chimney for the old/new water heater vent pipe is only at 67" (at the center of the hole in the chimney).

I also read in many areas the code for the vertical height of the flue pipe (where it connects to the vent hood)...is supposed to be a minimum of 12". My water heater setup has two 90° elbows that connect directly to the water heater vent hood...then these elbows connect to a positively sloped section of horizontal vent pipe that goes into the chimney.

Inspector has passed this setup as acceptable (old & new water heater). I also have a CO (carbon monoxide) detector installed fairly close to the water heater...and it has never gone off. Hot water gas furnace is also located in the same small room...and no CO issues.

But I agree & it makes a lot of sense. The draft on the water heater vent/flue pipe is probably not ideal...and water vapor from the hot combustion gases is probably what's causing the condensation on the cold water heater nipple...then the condensation is making the "sizzling" sound where it hits the hot metal from the flue gases.

I never heard the "sizzling" sound of this condensation previously with the old water heater (maybe because the nipples on the old water heater were farther away from the vent hood...and not nearly as much condensation was building up.

Thanks!

 

[alfuzzy]

Sounds normal to me.

Thanks Twowaxhack for the help. It does sound like this may be normal from what you guys are saying. Maybe if my water heater flue pipe had better draft...this wouldn't be happening.

 

[alfuzzy]

Another reason why I like braided lines the last 18". You will never know if it is just a loose connection with the soldered lines attached like that.

When I first connected things up (soldered & threaded copper connections)...I assumed there was a bad connection (either not tight enough threaded connection...or bad solder connection). But I felt everything...and everything was bone-dry.

I still unsoldered the cold side...and undid the threaded connections. Then I tightened up the factory cold side nipple...used both pipe dope & teflon tape on the threaded copper adapter that goes on the factory nipple...and did all fresh solder connections on the copper pipes. Of course I was seriously ticked off after doing this a 2nd time (unnecessarily)...since the condensation was still forming...and the "sizzling" sound was still happening (only when the burner is on).

Yes I would have liked to have been able to use braided lines for the last 18"...but the ceiling is so low in my basement...that not even a 12" braided line could be used (without needing to relocate the shut-off valves).

Thanks

 

[havasu]

That was a logical course of action. I would have done the same thing.

 

[Twowaxhack]

Those copper adapters are tightened too tight. One might split one day.

 

[alfuzzy]

Those copper adapters are tightened too tight. One might split one day.

I hear ya...hopefully not. When I did things the 2nd time around...I wanted to be sure everything was real tight...so I didn't need to do it a 3rd time. Unfortunately it sounds like I didn't need to do things the 2nd time. Lol

Do you really think they might split in the future? Copper is pretty soft/flexible compared to other metals...and if they didn't split at the time I was tightening them...I would think they would be fine in the future.

I've got about 40 years of auto repair experience. Usually if something is going to break/split...it does it at the time of the tightening/torquing.

Thanks

 

[Twowaxhack]

I hear ya...hopefully not. When I did things the 2nd time around...I wanted to be sure everything was real tight...so I didn't need to do it a 3rd time. Unfortunately it sounds like I didn't need to do things the 2nd time. Lol

Do you really think they might split in the future? Copper is pretty soft/flexible compared to other metals...and if they didn't split at the time I was tightening them...I would think they would be fine in the future.

I've got about 40 years of auto repair experience. Usually if something is going to break/split...it does it at the time of the tightening/torquing.

Thanks

It can split at anytime. Probably won’t because the nipple you screwed those adapters over are soft. They’re super thin with plastic lining.

If it were a sch40 nipple I’d be more concerned.

 

[alfuzzy]

It can split at anytime. Probably won’t because the nipple you screwed those adapters over are soft. They’re super thin with plastic lining.

If it were a sch40 nipple I’d be more concerned.

Good deal...I hope they won't split. I used a 14" pipe wrench to tighten them. I'm not super big guy...so I don't think I torqued them too much...but I'm sure they're pretty snug. The first time I used only pipe dope. The 2nd time I used pipe dope & teflon tape. Adding the teflon tape seemed to make it easier & smoother to get the right copper fitting tighter. I only did the left nipple once (pipe dope only).

If it wasn't such a pain in the butt to desolder & re-solder things...I would probably redo the right copper fitting. I'm sure for an expert like you it would be no big deal. I'm not so experienced at soldering. I can do a good functional soldered joint...but it's usually pretty butt-ugly! Lol

 

[Jeff Handy]

Your soldering looks better than most.

 

[Jeff Handy]

I think the poor draft should probably improve as the flue pipe heats up.
So that condensation issue might only occur at the very start of a heating cycle.
Or maybe not.
You might need to put a dehumidifier in your basement.

 

[Mitchell-DIY-Guy]

Where are you located? What’s the relative humidity and temperature in your basement? Many basements have very humid air. Many flowing cold water pipes will sweat. 105 year old basement? I bet it’s pretty humid down there…and that’s a major contributor to the condensation.

 

[alfuzzy]

Your soldering looks better than most.

You're too kind!