How do I properly bury the condendate return

FME

I am have one pipe steam system and I am replacing my wet return, currently black pipe laid on top of the concrete slab.



I want to take opportunity to bury the return in the slab (makes basement renovation projects easier).  I know this can be problematic as the concrete can corrode pipe from the outside while the water corrode from the inside.



How do I install the pipe in the trench properly to protect it from corrosion?



Can I simply wrap it in insulation, lay in the trench and poor concrete over it?  Also thinking of simply packing trench with sand, sealing top of trench with concrete or plastic membrane since I will then be laying padding and carpet on top.  All thoughts appreciated



Thanks

Rod

Burying the Wet Return

Hi-  You need to protect the pipe from the surrounding elements (soil, cement etc) as in a lot of older houses they dumped the coal ash (clinkers) on the dirt basement floor and then at a later time cemented over them and this makes the soil very acidic which isn't good for copper pipe.  I used 20 mil - 2" x 100 ft. "pipe wrap" which is like a super sized black PVC electrical tape. Like electrical tape,it's self sticking. Any plumbing supply should have it.   Be sure to wrap the pipe to several inches above the finished cement level and then back fill the trench with clean sand so the pipe is surrounded by the sand.



   Since the buried pipe forms a loop that can trap dirt and crud you should install fitting so that you are able to flush out the buried return occasionally. I've attached a diagram below.just  to give you an idea of the basic  flushing setup. You can move the "flushing outlet"  to the boiler end of the wet return and place the shut of valve on the pipe connecting the equalizer. That way the setup will flush the whole wet return.



If you don't want to go to the trouble of burying it, another alternative is to run the Wet Return along the wall and box it in to hide it.

- Rod

FME

Thanks - How about a pipe resevoir

Rod,



Thanks for the advice.  I will make sure we use the PVC wrap and put in the cleanout fittings.  Note, pipe will be laid withing not below slab (i.e no soil contact).  Does this change advice about sand?  Also, does it make sense to oversize the buried pipe to act as a settlement resevoir (Increase to 2inch)? 



Thanks,

Fred

Steamhead

If you have to bury it

I'd surround the pipe with pea gravel, so if any water gets into that area it can drain away. Also cover and insulate it to keep heat in. The gravel will also let the pipe move a bit as it expands and contracts, which will help keep soldered joints from breaking under expansion stress.



But running it along the wall is a much better way to go, as Rod suggests.



No need to increase the pipe size.

Rod

Burying the Wet Return

Hi- As I've always buried the piping in a trench, I'm afraid I can't give you much info on burying it in the cement. Copper piping has been used a lot in cement for radiant heating so it should work okay. You might want to post your question on the Main Wall and /or the radiant forum as the radiant people probably have more experience with this.  The concerns would be expansion of the copper  (approx 2 inches per 100 ft ) and that any additives to the cement were acidic. (like fly ash)

   I wouldn't make part of the wet return pipe larger for a "reservoir" as I don't think it would serve much purpose and you are adding cost and more joints. Having it all the same size will also blow out any sediment easier.  Pipe Size-  according to Dan's LAOSH,  Page 90, you can get away with  a 1 inch wet return if your total EDR is less than 700 sq. ft.  Be sure to use full port ball valves so you don't have any restrictions.''



Edit:  I see Steamhead posted while I was putting together an answer for you. What he mentioned about the pea gravel and expansion is why I buried mine in sand though in the future if I bury a line it will be in pea gravel per his suggestion. He is a very experienced steam pro so you should put a lot of regard to his suggestions, I sure do.

- Rod

RDSTEAM

i believe Rod is referring to...

flyash. thats basically what eats away at the copper. If you bury your copper in crushed limestone it should outlive you and your home