Good Lesson Learned Plumbing for Potable Water

[SmokeEater]

SmokeEater tell us that the black iron is only on your boiler water side not the same DHW that you are drinking from?

The black iron is on both sides! The two are completely separate, but I did plumb the DWH with black iron. I just received a shipment of copper fittings and pipe to re-plumb that DHW loop.

 

[SmokeEater]

Black iron pipe and fittings are perfectly fine for a closed hydronic heating system, most boilers are made out of mild steel anyway, what difference if the pipe is as well, although I have to admit copper makes for a much nicer looking job. Black iron cannot be used in systems with oxygenated water, this includes domestic water systems as above.

Morgan, I now wish that i had learned what you've just given me earlier. I just didn't see anywhere in the forum that I couldn't or shouldn't use black iron on DHW. Now I know, but a little late.

 

[SmokeEater]

The heat exchanger would be the component used to seperate the domestic hot water (open loop) from the boiler and hydronic water (closed loop). Heat exchangers require two circulators to operate effectively. The stainless grundfoss would be used for pumping the domestic water through the heat exchanger. I hope you have at least two expansion tanks. One expansion tank for potable water on the dhw side and another expansion tank for the boiler and radiant side.

Here are a few pics and in them you'll see 4 expansion tanks. One each for each boiler, one for the heating loop (down low) and one on the DWH tank. Also note in the pics I have a stainless Grundfos on the DHW and a Taco on the heating loop. The forum did give me some very good data on how to plumb these loops.

 

[maple1]

I think I have figured out your setup - your boilers heat the indirect tank via built in tank coil, then the typical DWH heated tank water has a loop to a heat exchanger that exhanges heat to your distribution loops. And you've got black iron between the indirect tank DHW hookups & the exchanger. Don't think I've seen a setup like that before, but if it's working (aside from the iron in your DHW), it's working.

It's hindsight now, but could you have maybe instead used a dual coil indirect tank & eliminated some of that? Lower coil for boilers, higher coil for house loops? Tank water for DHW?

 

[SmokeEater]

I think I have figured out your setup - your boilers heat the indirect tank via built in tank coil, then the typical DWH heated tank water has a loop to a heat exchanger that exhanges heat to your distribution loops. And you've got black iron between the indirect tank DHW hookups & the exchanger. Don't think I've seen a setup like that before, but if it's working (aside from the iron in your DHW), it's working.

It's hindsight now, but could you have maybe instead used a dual coil indirect tank & eliminated some of that? Lower coil for boilers, higher coil for house loops? Tank water for DHW?

Yes, you have it figured. I could have used the two coil IWH, but chose the Smart because of its large boiler, inlet, and double outlet connections. It is also warranted for life (whatever that is). I can actually run both boilers simultaneously if I need to. I have 3300 sq feet of house to heat and 872 sq. feet of garage with radiant in the concrete. When running the two together, the Smart can absorb all of the 240,000 btu/hr input. I didn't find any other tank out there that could handle that load.

 

[woodsmaster]

Black iron pipe and fittings are perfectly fine for a closed hydronic heating system, most boilers are made out of mild steel anyway, what difference if the pipe is as well, although I have to admit copper makes for a much nicer looking job. Black iron cannot be used in systems with oxygenated water, this includes domestic water systems as above.

Once you insulate the pipes it's pretty hard to see the copper.