Indirect Water Heater

Brad White

Naturally it all depends on your usage.

To me, the biggest inefficiency with an immersion coil is the cost to keep that boiler hot and ready so you can rinse out a glass in the sink. A little flow and she fires to limit or will soon.

(If you are starting from a position of having an indirect or even a separately fired DHW heater, you can imagine what a step backwards that would be to go to an immersion coil, especially in summer time.)

An indirect (or even a non-coiled "coil booster" such as by HTP and others) allows you to "charge" the tank from which you will draw. This allows longer, more efficient firing periods and some time to rest between.

An indirect will perform similarly but of course will heat the water with boiler water brought to it.

I see little technical difference in performance between the two. With an immersion coil you can run a small bronze "charging" circulator versus a slightly larger heating circulator is about it, coupled with the potential mineral build-up and leak potential of the immersion coil.

My "ideal" set-up would be an indirect coupled to a boiler for winter use with a "summer-only" tankless heater and piping allowing back-storage into the indirect, This I would do especially if I have a high-mass cast iron heating boiler.

Maybe that is another topic, but my point is to ask yourself how much you use it (gallons per day of HW) starting in summer as a baseline and carry that across the year.

You may find that if your DHW loads are large, a separate heater may work better for you than imposing that interruption on what might otherwise be a lean, fast responding heating-only boiler. Too often a nice, small, properly sized ModCon is tasked with DWH production and possibly over-sized in the process.

My $0.02

Brad

Flats

Indirect Water Heater

I was looking to see if someone could tell me what the cost savings would be between an instantanous water heater (Coil in a boiler) and an indirect (Superstor type).

What would the savings be per year on an oil system?

Big Ed

Savings

Would be hard to determine .

If you use the same boiler and water temperture setting I see no savings. Maybe a minute loss due to the minute heat loss of the storge tank... But the quality of the hot water supply is night and day...

Now using the same boiler system and using a indirect you now can lower the boiler temperture and could also further drop the stand by temperture if it has the proper controls..This would save on boiler heat loss.The savings would depend on the boiler size and model..

Another savings can be had with a indirect over a coil is that you can (most of the time)use a smaller boiler with a storage tank. Hot water is a big load on the system..

Using a coil the boiler has to be big enough and standing by hot enough all the time to deliver hot water...With a storage tank it can build up the load of needed hot water on off periods , more slowly .
But a storage tank is by far the way to go for a good hot shower.Coils ....how can I say it ?.....suck! Too hot in the sink to ,not enough for a tub..Not enough for a good shower in the winter months...Me I always had a storage tank

Al Letellier_9

indirect savings

As said in the other posts, it depends on a lot of variables. But here is an example. My home has a Weil boiler with a coil. I discontinued the coil, added a 40 gallon indirect and a Tekmar reset control ( 260 ). Only my wife and I in the house, temp set at 69* with no setback, and we went from 825 gallons/year to 425....not bad. The reset control added a lot of savings and should be added to any boiler/indirect, in my opinion. Well worth the investment.

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