Indirect hot water heater with gas steam boiler?

Montykitty

I am converting to gas heat and hot water from oil.  I am getting different opinions on whether it is advisable to have an indirect hot water heater with a steam boiler.  Some plumbers say that while it will work initially, within 2-5 years the heating coils will become clogged with rust and debris and will fail.  Others say no, that a filter can be placed and that the indirect system should work fine.  Does anyone have experience with this and can comment?

Wethead7

Steam & hot water

I would not use a coil installed in the side of the boiler(oil or gas). I would use a indirect with a non wet rotar pump. You may find lower first cost using a stand alone water heater. Tank type or tankless would be less costly , most likely than an indirect. The indirect should least costly to operate. The tankless installed in the boiler most likely lowest installed cost, but comes with the highest operating cost. The stand alone tank type next up on installed cost, then tankless stand alone. Indirect most likely top end of the installed cost.



Your installer should be able to help you with your choices. You may have other issues like space, flue, fuel source and others that could limit your options.

Jean-David Beyer

non wet rotor pump

I am curious why you recommend a non wet-rotor pump. My boiler and indirect hot water heater manufacturer recommended a  Taco 007 circulator for the smaller size boilers and indirect tanks, and 0010, 0011, 0012, 0013, and 0014 for larger boilers and indirect tanks. All these are wet-rotor type circulators. They basically want from 6.4 gph to 22 gph depending on the sizes.

Montykitty

Correction to question

Sorry, I wasn't clear.  The plumbers were saying that the coils within the indirect water heater become clogged - not anything in the boiler.

Mark Eatherton

The reason for non wet rotor pumps

The ferrous oxides from the cast iron system (essentially an open system) will lock a wet rotor pumped up tighter than a drum. There is not enough filtration available to get it out of the water.



ME

Jean-David Beyer

Thanks.

I infer your reply applied only to steam boilers. I know next to nothing about them.

jp_2

can't you

force a steam boiler only to make hot water in the summer?   seems this would be possible?   would save money if you can run the steamer at 170F during summer for making DHW.

Charlie from wmass

Yes jp

The boiler runs with an aquastat for the indirect when the system does not call for steam to heat. On some systems I wire the aquastat to turn on the boiler only when the indirect calls for heating fluid. This makes it a cold fire instead of keeping the steam boiler hot all day just incase the system needs to heat the indirect.