Indirect water heater used with a low water volume oil boiler.

bob eck

How do I go about calculating the energy savings (how many gallons of oil will be saved) when using a low mass oil boiler cold start and an indirect water heater vs using a steel oil boiler with a domestic coil and keeping this boiler at 180 deg all year long just for domestic hot water.

lchmb

The boiler you have was probably over sized for domestic HW. Size the new boiler based on actual heat loss and add an indirect. I'd consider a system 2000 with storage tank. I tell my customers they will save a fair amount of oil and have never had a complaint...

Robert O'Brien

NORA is revamping the FSA, which is based on Tom Butchers study referenced above. Should be ready in a matter of weeks. I can tell you based on anecdotal evidence, a typical tankless coil boiler using 900-1000 gals per year or thereabouts will use approximately 30% less with a triple pass, indirect, reset control. Larger consumers will see more, lower users less.
https://noraweb.org/fuel-savings-analysis/

Jason_13

I have been doing indirects sine about 1984 and never saw a tankless coil on an oil boiler use less oil than an IWH when comparing year round usage. We always tracked K factors and oil usage.

bob eck

Bob please let me know when this https://noraweb.org/fuel-savings-analysis/ is back up and running thanks

Robert O'Brien

Hatterasguy said:

Robert O'Brien said:

Larger consumers will see more, lower users less.

Is that on a percentage basis? If so............why would that be?

Yes, 1000 gallon houses routinely go to 700. 700 gallon houses rarely go to 490

Robert O'Brien

CH= Heating