Bad Advice

Unknown

This guy built the house 6 years ago,,,,



After an outdoor wood-boiler(which he got tired of <em>stoking</em>),,, he was <em>talked into</em> the "on-demand"(propane-hog),,,,,,,,<span style="text-decoration:underline;">  finally</span> he came to me.



I did a H/L,,,, but he`ll have to <em>fiddle-around </em>to find his curve for this <span style="text-decoration:underline;">un-designed</span> radiant system.



BTW- Mark,, I gave him your article on<span style="text-decoration:underline;"> </span><em>bubble-foil </em>!  

Unknown

Well OK,,,,,,

Usually no-one posts pictures of installs,,,,, then I do and get the "brush-off",,,, I guess ME & HR own this site!



How the heck are you more interested in bunnies???

Tim Potter

OnDemand vs mod/con

So why is the OD so much more of a propane hog than the Mod/Con ?



Thanks for posting



Tim

EricAune

Why? Continuous cycle of flow restriction

For starters, a typical tankless unit will restric flow to achieve set point temps based on delta "t".  This flow restriction is counter-intuitive in that return water returns @ even lower temps. due to the flow problem.  The pump has its hands tied due to the flow restriction of the tankless, besides, most of the guys installing these things are not even sizing the pumps for the system to start with.



The TT  pictured has outdoor reset with real world modulation, the tankless will modulate but not until return water temps start to climb.....which depending on the emitters in the system, could be a really long time.



Another discussion altogether would be the ever decreasing efficiency of these units as the heat exchangers become scaled/gummed through time as they are known to do in most radiant systems. 



I'm sure I could come up with more....getting too long.

Mark Eatherton

Sorry dude...

I don't comment on every post, and I nor HR owns the place, Dan H does.



Good for you for bailing the consumer out.



Their gas bill should drop at least 30%, if not more, and thier comfort levels should increase.



ME

Unknown

Thanks Mark,,,,,,,

just "spoutin-off" as per usual for me. . ;-)



I apologize old friend!