Another water heater question.....

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Blue_Goose

Blue_Goose

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Guys...had HVAC guys replace vent pipes and the smell I was getting before has gone away.....

Now I've noticed something that maybe has happened all the time but maybe just seeing it now. When the water heater is firing the cold water line gets warm...and warms up decently..is this normal? My thought was that I am getting radiant heat from the flue and this is not a good thing....after everything cools down it seems to still stay warm right at the connection into the water heater...

But then I started to think (which is scary)that perhaps the pipe is heating up because I am heating the water in the tank and that pipe has to go through that 130 degree water so maybe that is where the heat is coming from? It seems to make sorta sense because when I was doing some tests and had WH up to 160 degrees that pipe got REAL warm....at about 130 it still gets warm but not like it did before


Anyone got some tidbits of wisdom? I just don't know if heating up and then cooling off with cold water going through it is such a good thing......will the copper pipe eventually let go if I let it keep cycling like this?


Thanks so much..you guys have been great



Goose
 
What you're seeing is normal. They make "heat saver" nipples to stop this, but I wonder if they would restrict flow.
 
Originally Posted By: zrxkawboy
What you're seeing is normal. They make "heat saver" nipples to stop this, but I wonder if they would restrict flow.


The ones I've seen look like 3" long 3/4" pipe nipples with a unidirectional valve arrangement inside that restricts flow to about that of a 1/2" pipe. Doesn't seem to affect flow much seeing how most new faucets/showers already have built-in restrictions to limit flow to that of a 1/4" pipe or less.
 
Thanks for the info...I didn't realize that hot water could be drawn out of the tank thru the cold water dip tube? So should not be concerned with copper pipe going from hot to cold? Won't weaken the soldered parts causing a leak?(by expanding ,contracting etc?) the pipe gets warm to the expansion tank about 14 inches away and beyond that as well.....I have a check valve on the water meter but that is in the garage..so I guess closed system? Shouldn't the warm water/pipes stop at expansion tank?
 
You have a tee at the expansion tank? As the water heats and expands in the hot water tank, hot water will flow back the inlet to the expansion tank. Your not going to have 2 branches of the tee hot and the third cold.

Those heat saver nipples are one more thing that can be more bother than they are worth. If you must save every last btu, just put some insulation on the outside of the pipes where it never can restrict the flow if it gets crudded up.

Don't worry about the thermal cycling. Pipping is made to take it.

I am very happy to hear you seemed to have the problem solved.
 
Maybe this will explain the T better......pipes warm all the way to expansion tank also all the way up past the shutoff valve...but not as warm up there as nearer the tank...

Ok at my Mom's house and and she had the dishwasher on..I heard the water heater fire up and went downstairs...when I touched the cold water pipe it was ice cold..then within a few minutes it started to warm up...not as warm as my pipes but I guess that could depend on her thermostat setting too no?


IMG_1743.jpg
 
Originally Posted By: labman
Copper is a great conductor of heat. Try feeling the pipes when no water has been drawn for a while.


That's my take. You have a highly conductive non insulated pipe submerged in HOT WATER. The cold water in the pipe will very quickly reach the same temp as the hot water in the tank if it's not refreshing the tank. It will have to internally convect that heat in the static water column and the pipe will conduct heat too.
 
Originally Posted By: andyd
What is that expansion tank about? I dont have one on my set up.


Something about if you have a closed water system (with a check valve) it prevents the water from backing back into the WH possibly rupturing it...thats what I think or was told why I needed it. Might be code in NH now and Sears had no problem whacking me 150 bucks extra to have it installed.

Thank you for the answers guys...makes sense
 
Maybe about 5 years ago many public water systems started installing check valves or back flow converters to keep one customer from contaiminiting others by water flowing back into the the water main. When water heats up in a tank, it expands and has to go somewhere, either back out the inlet or out the relief valve. So if you have a back flow preventer as I think are required now, you have to have an expansion tank. On a well, the pressure tank handles it just fine.

This caught some of us older guys on another site 5 years ago. There were a whole bunch of questions about relief valves leaking all the sudden. Some places were installing the black flow preventers and not telling the home owner they would have to have an expansion tank.
 
Originally Posted By: labman


I am very happy to hear you seemed to have the problem solved.


Spoke too soon
frown.gif
They re-ran the exhaust venting but added some Type B pipe at the end...this made it so the vertical rise off the heater shorter by maybe 2 inches...well that inches seems to make a difference as I think I am getting some spillage that I didn't have prior to them re doing the pipes...Man I am seriously bummed out...not to mention one heck of a headache after being in the basement with the water heater on...don't think it is CO as my detector didn't go off but whatever it is it is not good

Back to square one here...

Seriously should it be this difficult to get a water heater to run right???
 
It is amazing the old one worked fine until they messed with it. Do you have any before pictures to put it back just like it was?
 
Quote:
Man I am seriously bummed out...not to mention one heck of a headache after being in the basement with the water heater on...don't think it is CO as my detector didn't go off but whatever it is it is not good


Run an extension cord and place/hold the detector near the outlet when it's running. Mine will not read a transient emission unless it's above a certain concentration. On your body, however, the CO uptake is somewhat accumulative. It takes far longer to purge from your blood than it takes for it to be absorbed.
 
Originally Posted By: Gary Allan
Quote:
Man I am seriously bummed out...not to mention one heck of a headache after being in the basement with the water heater on...don't think it is CO as my detector didn't go off but whatever it is it is not good


Run an extension cord and place/hold the detector near the outlet when it's running. Mine will not read a transient emission unless it's above a certain concentration. On your body, however, the CO uptake is somewhat accumulative. It takes far longer to purge from your blood than it takes for it to be absorbed.




Oh oh...so these headaches aren't something that I should take lightly? In other words stay away for getting too close to the WH while it is running? I gotta admit I have had my face down low near the flue trying to detect spillage..I wonder if I have been pushing the envelope. What is the treatment for mild CO poisoning(if that what it is)


The CO detector is no more than 3 feet from the WH....nothing yet..in fact I have 2 of them there.....I can feel the heat coming out from under the draft hood in one section




labman...yes, the only reason for the re-run of pipe was because plumbers had stuck foil tape over all the joints and caused the a bad smell as the adhesive heated up.....nice huh? Just when I think I am getting ahead I get kicked below the belt again

I think I need a bit more vertical rise initially before the bend.....I think there is 6.5 inches before the first bottom bend there...I think the last piped maybe gave me 2 more inches of vertical rise of the first part of the pipe..doesn't seem like much but I guess that the vertical rise is the most important part in establishing a proper draft no? I may be wrong here but the draft hood is not perfectly centered either and the draft hood is hot to the touch..I don't remember it getting all that hot in last vent pipe setup
 
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