indirect fired h/w heater v. tankless v. standalone

Tom S.

Being a new homeowner with an old system that seems pretty convoluted to me (oil burner converted to gas, tankless h/w, forced h/w zone running of a heat exchanger from the boiler), I am potentially looking to replace it all with a more modern and efficient system.

What I don't really know is which is the best kind of h/w to get: tankless, standalone tank or indirect fired? I don't really know what the difference would be between tankless and indirect, since both of them I would think would keep the boiler running all year.

Any thoughts? On any/all of the options above.

Thanks much,

Tom

Jay_14

DHW tanks

Tankless coils require that you keep a hot boiler 24/7/365. An indirect tank only fires the boiler when the tank has cooled off and the result is the boiler can stay off for long periods of time. A direct fired hot water tank essentially has a chimney in the middle of it, again resulting in a huge amount of wasted energy.

I would recommend the indirect tank. Unfortunately this also the most expensive route.

In my opinion, tankless coils should be banned.

Just my $0.02.

Jay

Ken_8

First we need to know...

if your main system is steam or not.

The way you state the base system suggests it is not already water - by virtue of you mentioning a forced hot water zone via a HX.

Indirect water heaters are THE way to go. The efficiency of the boiler becomes the efficiency of the water heater. The warranty on most is "lifetime," and no flue is needed. Further impacting the comparisons is the huge added expense of the newly adopted "flame arrester" burner on simple gas-fired water heaters.

A few digital pics may help.

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Tom S.

Appreciate the opinions, seems like indirect is definitely a winner.

FYI, the main system is steam. The forced h/w zone only services one room and uses a hx (of sorts) off the boiler to heat the water for that zone. I'd post some pics of (what seems to me to be) the mish-mash of pipes etc. around the boiler, but I'm off for Thanksgiving. Perhaps on Sunday.

Thanks again,

Tom

Firedragon_4

You have no right to say

that tanklesses should be banned, FACT!

I tried 3 indirects, they all failed due to OEM defects. I've used a free-standing tankless for 9 years now, it's outlasted them all (TFI-Everhot EA).

Further, cold-start operation is horrible for oil, even worse for gas and all it saves is less than 2-1/2% on my fuel bill. Since going to warm-start my boiler runs better and looks 150% better after 4-5 years of operation and soot is not money in the bank, FACT!

One other thing, in an independent study done by the State of New York it was found that for overall performance a tankless was more efficient than a free-standing heater and AS efficient as an indirect.

Please know your facts before you comment, just my $1.50 because I do put my money where my mouth is. ;-)

Murph'_5

Check your **** george

.

Firedragon_4

Not true and not fair on your part!

Sticks and stones............................

Firedragon_4

And just for the record

a tankless is also the only form of DHW heater that cannot increase or produce the Legionella bacteria!

Ken_8

Hey George,

Your failure to differentiate an internal from an external coil is a mjor faux pa in your post.

Internal tankless coils are the least desirable of all options. Scalding being the # 1 issue. Failure from scaling and the short life of mixing valves being the other.

FACT!

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Ken_8

And George,

He also states it's gas - not oil.

Yet another faux pa.

Your over your limit lad (;-o)

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Firedragon_4

I'll agree with part of that Ken,

I truly believe ALL water heaters should have anti-scald devices. Most of the scald cases in this country happen with free-standing heaters. What most people do is their business, but my scalding workload goes up every day.

Commercial installs are the worse since maintenance is zilch in many cases on the mixers and anti-scalds and they are a PITA, but a lawsuit is much worse. Besides, I thought the idea was to have work and make money, just 1/2 serious there!

As to tanklesses, I hate the internal, front-mounted round since the surface area exposed to water is horrible, bad, bad idea, on that we agree. But, an external is the nuts and also can work well as a by-pass or part of a Primary-Secondary pumping system and be awesome.

If I have to use an internal due to price constraints a horizontal in the rear section is the only way to go, JMO. When you compare the free surface area exposed to the water in the boiler to the round, there's just no comparison.

Didn't want to offend Jay or commit a faux-paix, just wanted to put my opinion on the line too!

Firedragon_4

Sorry Ken,

when it comes to hot water, a Btu, is a Btu, is a Btu and it looks like I'm in plenty of it now :-)

Dave Yates (PAH)

but the real question

points out a glaring problem in our industry - there are no uniform standards whereby water heating devices are judged for their performances. As a result, homeowners (and contractors too) are left to ponder ads promoting one type vs. another. Lots of hype being put forth by manufacturers that does not hold up to close scrutiny when crunching GPM flow rates and required temperature rise.

Until the day arrives where each appliance is put through the same paces, this argument will never be settled.

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Dale

Thanks for the thoughtful comment Dave

I have been part of the hot water heater effeciency argument for 25 years or so now and I totally agree that there needs to be national variable independent research on this topic. I find that most of the decisions are on a case by case basis. Here's what I have found for MY area. The first question is how many people in the house and let's look at your current fuel bills. Alot of people now live in one or 2 person households. If the widows gas and electric bill is TOTAL $95 a month every month with a gas furnace and and electric water heater what is the payback of the even the most effecient gas water heater she could buy? Since water is very hard here I have seen NO connected hot water coils in boilers, alot of disconnected old ones though. What are the elect rates, any time of use offered. A heat pump 80 gallon elect water heater on time of use elect rate provides plenty of hot water and costs less to run a month than the most effecient gas AND the basement dehumidifier at a dollar a day can be turned off. I personally think the future is products designed to do one thing well, not hvac swiss army knives. The direct vent tagakai(sp?)type instantaneous heaters with variable input burners and NO storage losses seem to be the most reasonable long term choice. But, as you say without good research we just argue and stay fixated on our local experiences.

Ron Schroeder_2

Hi Tom,

My first choice is an inside out indirect like the Ergomax. Close second choice is a conventional indirect. In some cases, point-of-use instantanious is the best choice.

Ron

Constantin

If you're going to replace it all...

... seriously consider going with a condensing gas boiler like the Munchkin, Trinity, Ultra, Vitodens, etc. and a indirect water tank.

The indirect not only will heat your water a whole lot quicker than most stand-alone heaters can, the condensing gas boiler basically ensures that the indirect will do so at the highest efficiency that is currently attainable.

The only potential downside is that if the condensing gas boiler cannot be side vented (for aesthetic or safety reasons) that you'll have the additional expense of having to reline the chimney. However, any efficient boiler will practically necessitate this, even the non-condensing ones.

Tankless coils are, indeed, energy-hogs. Controlling their output temperature is another bugbear, allegedly.

I would get several quotes and figure out what equipment the various installers are good at installing and maintaining. Also, get the house insulated and weatherized before installing the new heating equipment. There is no sense in getting a very efficient heating system just to create a microclimate outside your house.

Ron Schroeder_2

Hi Firedragon,

I think some of the responses is about confusion between "tankless" in the boiler hot water heaters and "tankless" instantanious stand alone hot water heaters.

Ron

Bill_39

Try find a pro

Bruce M.

Why didn;t you include an On-Demand Heater?

IMHO an on-demand hot water heater is the way to go. Plenty of hot water at lower cost.