Takagi Water Heaters

Wild Bill

Good Day,
Do any of you have experience with Takagi flash water heaters, a customer is asking for one and I don't know if I should try to steer them away or not.

Thanks,
Bill

jackchips_2

Bill,

I installed a Takagi Aquastar 240 in series with my 50 gallon water heater over a year ago and it has performed flawlessly. We have not run out of hot water since.

It is also piped through a heat exchanger this time of year and helps keep my pool (with a solar cover) at 87 degrees.

Jack

Bill Barrett

Takagi

I have 3 in no problems.

S Ebels

Lot's of 'em

Be careful with sizing and flow rates, match the unit capabilities to the job and you'll heat your H2O for 1/2 of a standard gas water heater.

Dave Yates (PAH)

1/2?

Where did you get the information that using the Takagi cuts hot water costs by 50%?

This link was in an earlier post regarding on-demand water heaters & pretty much takes a 180 degree opposite position regarding operating costs.

http://www.askthebuilder.com/451_Tankless_Water_Heaters_-_Some_Surprising_Facts.shtml

When FVIR hits the direct vent (power venter) water heaters, the price disparity will be nill. Top that off with new high efficiency on-demand water heaters rapidly emerging that vent with plastic and offer a very wide modulation of input & we're going to see the dynamics of our market change dramatically over the next decade.

Once cost is no longer a big factor, the only negative to overcome will be that long wait for hot water.

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S Ebels

Dave

Takagi has a unit coming out yet this year, I'm told, that is condensing, 95%+ at normal (120*) water temps, PVC vent and of course it includes a modulating burner. The thing has more safety's and limits than the boilers we install. As far as the 50% goes, look at the energy guide $$$ on a Takagi compared to any gas water heater. Of course this is all DOE testing in a controlled lab environment. I don't know the methods they use to test such totaly different appliances but the $$$.$$ of difference on the sticker must mean something don't you think?

Dave Yates (PAH)

90+ modulating models

are on the way from virtually all of the manufacturers. If you compare one of them to a standard model water heater, you can't help but save money. But let's compare apples to apples (or as close as we can get).

An indirect coupled to a condensing boiler vs the Takagi (or pick a brand).

Any one of the newer ultra-high efficiency water heaters (Bradford claims extremely high efficiencies with their E-Force) vs the Takagi.

Modulation is the key to unlock the door as far as efficiency and prevention of short cycling is concerned (IMHO).

Each system has advantages and disadvantages.

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Jack_21

GAMA figures

Don't know about the Takagi but go to www.Rinnai.us. At the home page go to Technical References. You will have to register. When that is approved you can access the GAMA numbers (as well as all other tech info) for Best/worst gas/elec etc.

S Ebels

Interesting article

I for one would NOT like to step into a 115-120* shower. I like to get out with all my skin intact thankyouverymuch!!

A simple fact that Bob the Builder overlooked, or at least failed to mention is that, a Btu is a Btu is a Btu no matter if it's applied with a 30K burner or a 200K burner. Equating the size of the burner with efficiency shows his ignorance of this type of equipment. He should stick to driving nails and sawing boards.

He also is silent on the point that a tankless uses no energy maintaining 40-80 gallons of water at usable temps. A tankless has no such energy loss. A typical Takagi has a low enough exhaust temp that you can lay your hand on the vent pipe right above the heater and not be burned. Not so on a standard natural draft water heater. Power vents of course dilute the temp down drastically allowing the use of PVC.

These are just my observations out here in the sticks. I'm not trying to start a war.

Dave Yates (PAH)

Glad

we agree! I too was stunned by his assertion regarding bathing temps and his statement regarding the human threshold for pain (which is 106 F).

I thought you might find his comments regarding costs a bit off the mark(G). I think he was thinking the control was strictly a bang-bang operation? If it were, he'd have a point (to a much more limited degree). You're right, of course, that imparted Btu's don't give a hoot how they get into the water.

I see two things here with respect to these systems: tank storage offers the ability to give consumers "instant" hot water via recirc; on-demand eliminates standby heat losses (for the most part - you'll still have parisitic losses, albeit small ones, upon shut-down)

Drawbacks: stand-by heat losses in storage tank types; long wait for hot water in on-demand types.

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Scott Denny

Glad

Dave
As far as "long wait for hot water in on-demand types", some of these units have built-in aquastats that allow them to accept recirc pumps and not fire all the time. The only requirement is that the pump be rated at least 1/12 hp.
I also read the article by Bob the Builder. Though I question his statistical analysis, I would like to see someone like Consumer Reports do a comprehensive cost study of tankless, modulating and conventional units.
Scott

Dave Yates (PAH)

info

Scott,

If you can direct me to the infor regarding recirc, I'd appreciate the help. Why 1/12th as a threshold?


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S Ebels

Pump size

Most tankless units require a flow of at least 3/4 gpm to initially fire the burner. I think they recommend that size circ to ensure that requirement is met with most normally encountered piping layouts.

Scott Denny

pump size

Dave
Go to http://www.takagi-usa.com/web2003/applications/tk2/TK2orTK1SwRecirculating T-K2Recir.pdf. It shows a typical piping scheme w/circulator. In the fine print you'll find the mention of 1/12 hp on the pump. I believe that pump velocity fires and an internal aquastat controls the on off cycling of the boiler. From personal experience I know that a 1/24 ph pump will not fire one of these boilers. I generally prefer to learn things the hard way. Also check http://www.noritzamerica.com/n132.html and go to the installation manual (page 59) for specific flow rate information on from another manufacturer.
Scott

Dave Yates (PAH)

curious

Given that a recirc line doesn't represent much of a load, how do you keep the unit from short cycling itself to death?

Our salesman dropped off Takagi literature & a CD. I see their statements regarding 50% in one and "it saves more than 45% on utility costs" in yet another. The wording tends to represent this as being in every case, which leads consumers to believe they'll see the same results. They then state this unit is running at a "max 82.3%" thermal efficiency, which leads me to believe it doesn't under the full range of input/operation. That's mighty close to the thermal efficiencies claimed by standard water heaters, so where's the more than 45% savings? The standby heat losses from standard water heaters aren't anywhere near that figure!

As the guy who has to answer to my customers, I'd have to point that out and forewarn them they won't likely see the same results.

Toss in the parasitic energy costs these on-demand water heaters have due to the electronics and combustion blowers (which a standard water heater does not) and I'd be suspecting they're in a dead-even spot. Toss a 1/12th HP bronze or SS circ in place of a 1/40th HP circ & that get's a bit more interesting.

In spite of all that, I still like the little buggers! I'd like to see the literature be more realistic though.

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