Relocating the Boiler

robsimpson

You can also easily use a water-water heat exchanger to isolate the distribution system from the boiler loop. That will allow you to use any boiler you'd like without fear of destroying the boiler prematurely. I've had great success with Flat Plate Heatexchangers.

Rich_49

Laurelie said:

The main reasoning for the Prestige vs the Challenger is the Prestige's better stainless steel fire tube heat exchanger. As I've posted before, I am working with inaccessible non-barrier pex tubing installed by a former owner. Meaning 1) I can't rip it out and start over and 2) I need as much non-ferrous material as possible.

I've read that Challenger's HX isn't as good as the Prestige with non-barrier tubing.

I am willing to pay for a more compact stainless steel unit like the Vitodens 100, but again, that HX isn't as good as the fire tube. I want less maintenance.

(As an aside, sometimes I think about moving on to the Versa Flame, but again, with ferrous materials for the radiant heat, I don't trust it.)

Finally, after living with a tankless DHW for so many years, and getting a max of 3gpm, I'd like to move on to an indirect tank. I want more water pressure and more flow. And of course, the max efficiency.

If I relocated everything I gain a closet--which is a big deal in a city--and I gain room to have a nice panel and indirect tank. Not to mention the ability to access everything without disturbing tenants.

Why rule out the Versa Flame so fast ? Out of all the makes and models throughout this thread the Versa is probably your safest bet . Any air coming back from the system would rise to the top of the tank and be eliminated . HX is CuproNickel and Stainless , tank is stainless . Any nasty garbage from the system hits a plate at the bottom and falls to same . Can be removed by flushing . You can use your Delta T circ .

Versa Hydro is an option also . Use a quality magnetic dirt sep like Fernox TF1 and 2 purge / flush arrangements at the FPHX , flush once a year with a good solution and be done .

SWEI

robsimpson said:

I love mod-con boilers, but unless they are truly modulating they aren't that efficient. If you need 140 degree water or higher to get enough heat to the staple up zones, I'd rethink everything.

Even a system that need 160°F water on a design day will condense during a large majority of the heating season.

A non-modulating boiler will still need an ODR-controlled mixing valve to properly handle the floor zone. By the time you add the cost of that, along with the additional pipe, fittings, and labor it needs, the price of a mod/con starts to look good.