Help with return water dip switch settings (Navien NCB 240e)

[Dobson]

I’ll keep this as short as possible. I’ve read the manual and scoured the internet and have yet to find a clear answer here.

I have a brand new Navien NCB 240e that so far has given me nothing but problems. However, I’m slowly finding out that my problems are from an incompetent installer and not the unit itself.

I’m finally getting this unit dialed in but I’m an effort to make this run as efficient as possible I turn to you… as of last week this unit was burning 9 gallons of propane a DAY. I found out that my installer left all settings as default, did not activate the outdoor reset, and had the unit running full tilt.

My installer has the return water dip switch set to off. Does flipping this switch to on help take advantage of the condensing return water or is this something else entirely different? Can anyone please explain to me how the return water works with this unit? I know it needs to be below 125 to condense since I’m running LP. However, I’m not sure if I need a special pump to utilize the return water dip switch. I’m sure this is a newbie question but I can’t find answers anywhere. Pics attached! Thanks in advance.

 

[Fitter30]

Return dip switch probably for a return water line for dhw. Boiler to be 95% efficient has to be 130° or less above 87%. What temp water in and out of boiler and through the loops? Take a pic of the piping at the expansion tank.

 

[Sponsor]

 

[Jac04]

That dip switch being OFF just means that you are running in Supply Water Temperature Control Mode. I've tried messing around using Return Water Temp Control on my Navien NCB-180E, but it never seemed to work well. IMO, I'd leave it in Supply mode and get your temperatures turned down.

What is your Supply Temperature set to now? Does the unit cycle on & off a lot?

9 gallons of propane a day is a LOT.

I have a 2100 sqft house just north of Hartford, CT. I keep the house at 70F during the day and 68F at night. 2 Teenagers that take 30 minute crazy hot showers every day. The worst consumption I've ever seen was 4 gal/day average over a 30 day period.