Insulation on inlet / outlet pipes?

[Matthew Hardy]

This question may have a really obvious answer so apologies if I am just thick. I am replaced my 15-year old American Water Heater that was well past its time. I live in Southern California and had a number of items to bring the install up to current code (i.e. added a thermal expansion tank, sediment trap to gas line, etc.). Code in my city is the 2016 California Plumbing Code.

As background, I have a 74-gallon AO Smith on a platform in my garage (along side two furnaces). I have a an older Grundfos recirculation pump with a dedicated return. I installed a thermal expansion tank on the cold water inlet after the shut off valve.

One requirement that I am not sure I fully understand is insulation of the pipes. I believe I am supposed to insulate the first five feet of pipe from the water heater (both cold and hot) as well as all hot water pipes 3/4" or larger, all pipes on the recirculation line, all pipes between water heater and kitchen, etc.

I am assuming that I am only responsible for insulating the new pipes from the install (i.e. not required to rip all of my drywall to expose and install all interior pipes), but want to make sure I understand what I need to do.

• I do not have 5 feet of exposed pipe to and from the water heater before it goes into the wall so do I just insulate both lines to the wall? Also - does the five feet include the flexible connectors (i.e. do I insulate the flexible connectors also)?
• I assume I also need to insulate the pipes that tee off and go to the thermal expansion tank?
• The dedicated line for the recirculation pump is under the platform and not exposed so I assume I just insulate from where it surfaces from the platfrom to the outlet where it reenters the water heater?
• Is the insulation the same as I would use for something like the AC lines and does it just need to be as thick as the pipes?

Thanks in advance for any help.

 

[Dana]

Interpretation of the code is usually up to the local inspector, and on retrofits there is usually a fair amount of leniency where demolition of finished walls would be required to both implement and inspect the solution.

Yes, the tee to the tank has to be insulated, but I don't think the tank itself has to be insulated under either Title 24 or the CPC. Both are in play here, and they differ on the specifics on pipe insulation. Whichever is most stringent is what's actually required, but local inspectors have some latitude (or take some liberties?).

A short-sheet primer discussion on it is in this one-pager.

 

[Sponsor]

 

[GTOwagon]

With that foam insulation, in that spot, you will save at least theee cents a year in energy and the amount of carbon that gets into the atmosphere will be compensated for against the production of the foam in seventy seven years.

 

[Matthew Hardy]

Thanks. I went ahead and added the insulation back to the wall. I am not sure I totally understand having to insulate the cold inlet as the only heat that would be lost (e.g. when the water expands and pushes back to the expansion tank / cold water inlet) or why this is really necessary as the water heater is in a garage and we live in an area that rarely gets below 60 degrees, but oh well.

 

[Dana]

Both water and metal piping are fairly thermally conductive. Insulating the incoming water line reduces the standby loss of the tank incurred by that thermal conductivity.

Almost every line that makes it into the CA Title 24 undergoes somewhat rigorous lifecycle financial analysis and actual in-situ measurement. Perhaps GTOwagon's financial & carbon accounting has been subjected to the same level scrutiny(?). CA Title 24 has had major errors that have gotten corrected in subsequent versions (there's a new revision released every 3 years), but the pipe insulation bits have been pretty stable for several versions now.

 

[GTOwagon]

I have a 75 gallon heater that uses maybe $10-15 worth or propane a month. That would be eight to ten gallons per month. As I mentioned before, in Saratoga County I am now at 520 gallons of propane for heating and hot water in my forty eight hundred sf home due to my attention to sealing and insulation. SINCE SEPTEMBER ONE. Most of my pipes are insulated, for sure. But not my cold coming in.You can chase all the shadows you want you save three cents. If you can't cover every portion of the pipes without reconstruction of the premises, then you can't. This poster cannot. These codes are written by people at desks with computers who don't operate in the real world. Furthermore the incoming cold water pipes should dissipate the heat somewhat rather than contributing to expansion in the cold water line. Again, these modelers need to account for more thermal expansion and that causes peopleto add bigger expansion tanks, driving costs. I maintain that practically, the cold water in the the cold water line shouldn't need to hold heat. There simply isn't enough energy to be saved there. On the hot water lines, it is more practical and worthwhile, obviously.

 

[GTOwagon]

And all of the hot water lines in my house are insulated which is way beyond code. I get more out of insulating that rather than trying to keep heat in the cold water line that gets flushed down the drain when a cold water spigot is opened!

 

[Jadnashua]

It sort of depends on where the WH sits. Heat loss can be helpful during the heating season! NOt great when you're running the a/c, though. It's more than just the heating losses, it can contribute to your cooling load as well.