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Indirect-fired water heater v tankless coil in boiler

I'm seeking advice on which system to install inside my house utilizing oil fired system
1) Purepro Trio boiler w/ Amtrol indirect hot water heater
2) Weil-McLain using tankless coil.

Time to replace the old boiler, house has 4 bedrooms, 2 zones, using forced hot water via baseboard heating. I can see advantages to both systems, just trying to get advice.

Re: Indirect-fired water heater v tankless coil in boiler

The indirect hot water heater is recommended over anything else that's out there.

The tankless coil is an outmoded device that is still sold with some hot water boilers---it's simply 10' or so of copper tubing coiled inside the boiler & produces a gallon or so of hot water---this is clearly inadequate for all but a family of one person in the household, and even there it won't allow for dishwashing or clothes washing, or even a bath.

While the cost of the typical 40-gal. indirect is between $700-$1500, it's a one-time cost & you'll never run out of hot water; and they are highly insulated, and very efficient.

These indirects typically last for decades without any maintenance or breakdown; they're essentially a heat exchanger that uses the boiler water for heat & have no combustion chamber of their own to cause problems or burn fuel.

Amtrol Boilermates are o.k., but they have only a copper coil running down the middle of the tank; the STAINLESS STEEL tank models by Triangle Tube Phase 3, HTP Superstor, Weil-Mclain **** Plus, or TFI Everhot have a tank within a tank & are thus more efficient in their use of fuel---they run $300 or so more than the Amtrol, but are preferred; on the other hand, I've had good luck with Amtrols.

There are sites that calculate the size tank you will need (usually 40 gal.) based on family size & peak hot water usage (usually during morning rush hour); also comparative sites on preferred equipment.


Re: Indirect-fired water heater v tankless coil in boiler

Appreciate the advice. I was leaning the way of indirect but figured I would ask. Thanks again

Re: Indirect-fired water heater v tankless coil in boiler

It's a little late but I'm looking to replace my oil fired boiler. The comment from NashuaTech about the capacity of the coil doesn't fit my experience. Have had a coil for 27 years and have never had a problem with having enough hot water. It supplied a family of four and a wife who couldn't tolerate seeing clothes in the hamper.

Re: Indirect-fired water heater v tankless coil in boiler

I strongly agree with Nashua Tech on the poor performance of the tankless coil and the superior performance of the indirect HWH, and disagree with the above poster vantyle.

My experience goes back 40 years as a homeowner who has always had oil-fired hydronic boilers with both tankless coils and the indirect HWH, and also as an installer of the Amtrol indirect, as well as most of the other indirects mentioned by Nashua Tech.

We were constantly running out of HW when we had the tankless coil at the most inopportune times, such as every morning rush hour when myself, my wife & my daughter had to fight to be the first one in the bathroom to use the shower because the shower water was ICE COLD for the 2nd & 3rd family members who also had to take a shower at that rush-hour time.

Nashua Tech has listed 2 websites that clearly illustrate the gallon amounts typical families use, and the tankless coil doesn't come close to meeting these needs.

In addition, the previous poster doesn't mention, or is not aware, that once the one gallon of HW is used up by the tankless coil, the boiler has to immediately fire up to heat the entire 10 to 15 gallons of cold water in the boiler, just to heat up the 1 gallon of now cold water in the tankless coil---and this goes on again and again endlessly, burning up an excessive amount of fuel in this very inefficient way (the MOST INEFFICIENT by innumerable numbers of hydronic expert installers & homeowners) of producing a tiny supply of hot tap water, better known as domestic hot water (DHW).

Even when the typical small family makes elaborate plans to arrange the judicious use of the one gallon or so DHW from the tankless coil to avoid a cold shower, or dishes or clothes washed in cold water, the boiler is CONSTANTLY coming on to heat the paltry amount of dhw in the tankless coil---this is the reason why the tankless coil is regarded in the heating industry as being one of the most inefficient ways of obtaining DHW.

In my own family's experience we went from 1200 gallons of oil usage per year to 600 gallons simply by installing an Amtrol indirect---the savings in fuel usage has paid for the indirect HWH many times over, and we NEVER run out of HW.

This is especially critical in the era in which we find ourselves where those who have to rely on #2 fuel oil, because nat. gas is not available in their area, are faced with steadily increasing fuel oil costs that is most parts of the country are well over $3/gallon, and there's no sign that oil will go down in the foreseeable future; most likely, it will keep going up.

Re: Indirect-fired water heater v tankless coil in boiler

I agree that there is inefficiency with a coil and it keeps turning on the boiler to heat the domestic water, even when just brushing your teeth for a minute. This goes on all summer.

But I disagree with running out of hot water when using a coil. I take very long steamy showers (my psychiatrist) and the hot water never runs out, even after having done laundry and dishwasher. I can feel a slight temperature change as the hot water decreases but then within a minute becomes boiling, so I know the boiler is keeping the domestic water flow hot. I have a Weil-McLain boiler/burner with the original coil inside for 14 years (cleaned twice when the hot water decreased).

Another new post by me is asking opinions about my replacing the coil due to the efficiency and oil fuel cost.

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