Unpressurized EPDM Storage Questions

[SteveJ]

For those of you using an unpressurized EPDM lined storage tank with submerged heat exchangers:

1. Has anyone mounted the heat exchangers from the bottom (STSS style) and then floated the top EPDM liner? Placed the liner at the top of the water level rather than the top of the tank?

2. For supporting the heat exchangers, wrapped concrete blocks has been suggested (https://www.hearth.com/econtent/index.php/forums/viewthread/20638/) as has CPVC footing and frames (http://woodnotoil.googlepages.com/constructionlog). Who is using what and with what success and lessons learned?

I based my design on http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Tank.htm and am trying to seal the top and to mount the Amtrol HX for best stratification and serviceability and least damage to the EPDM.

Any comments or suggestions would be greatly appreciated.

Thanks,
Steve

 

[WoodNotOil]

I think there are two keys to the lid: 1- To have a vent pipe to release air and heat pressure. (I plan to use a CPVC pipe with a ball on top, I think Eric Johnson came up with that one) 2. Have the lip of the inside liner and the top liner touching one another and then use wood and screws to clamp it together. (With a vent pipe there should be no air or pressure trying to relieve itself between the liners.

I really liked the CPVC option for supporting any copper inside the tank. I got the idea from one of the threads here, but can't remember which one. CPVC is inexpensive and has the 180* temp rating.

You were quick to spot my latest log, I only posted it last night. Good to know people are utilizing the information I put up and it is not a waste of time.

 

[Dave T]

Steve,you mention concrete blocks,If you mean cinder blocks (which break down on roofs over time) you will have to just about dip them in that dry lock coating for basement walls..I don't suggest you use cinder block in your tank at all..Concrete block is a different story that would hold up well..A couple things I like about the design you plan to use,only 4 corners will save you a lot of time installing the EPDM,large pig ears shows no cuts in the EPDM (seamless),on the pic it looks like they left a lot of membrane up and over the edge Don't cut yourself short on the top untill the tank is full of water..EPDM does not float,leaving the lid (baggy) to touch the water is going to work against you in the effort of sealing the tank..Hope this helps
DAVE

 

[SteveJ]

Dave,

Thanks for the heads up on non-floating EPDM. I think the guy who told me that was supporting the sides and letting the middle bow down to the water level.

Has anyone used tried trex for around the top retention of the EPDM? Like shown here - http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Changes2007.htm

Alternative to hole in the EPDM with hose clamp.

Thanks,
Steve