Condensing Boiler Serving Only Indirect

Hardeep

I serviced a newer modulating condensing boiler connected to an 80 gallon indirect tank. Boiler was a 100,000 BTU and modulates down to 20,000 BTU.

The system serves only one purpose : To provide a high volume of domestic hot water for a busy restaurant. There is no space heating connected to this boiler, that was taken care of by a seperate large forced air gas furnace.

Will this boiler ever condense in this application, as with such a small volume "in the loop", wed never see condensing temperatures?

Even at the lowest level of modulation, my return temperatures were 160F with the supply target of 180F. Upon ramp up, the delta T shortened further to 170F in the return to 180F in the supply.

Do we care about condensing in indirect domestic hot water modes in general?

Just wondering if I am overthinking this or if their is any long term consequences with this type of set up.

Thanks!

LRCCBJ

It's basically impossible to obtain condensing temperatures in the application you described. You are always providing high temp water at high flow rates.

There are no long term consequences other than a slight decrease in efficiency due to the inability to condense.

Of course, if it wasn't a commercial application, you could use a SWT of 150 and keep the flow rate down so the RWT is 120. This would take forever to heat the indirect however.

PC7060

Maybe venting out the side of building was simpler than running b vent through roof.

hot_rod

what temperature is the tank operating at? If the dishwasher has a booster heater, maybe it can supply 120?
HeatFlo high output tanks are rated down to 120 boiler temperature. At 240 SWT, it could condense the boiler

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