Takagi as \"boiler\"

JIMBO_2

Has anybody successfully used a Takagi (T-K2) as a "boiler" for radiant or hydronic heating? I'm completely re-fitting a new system for a small, summer house and they've suggested a neat-sounding system, offered by A.I.M (Anderson). But I'd rather make a fool of myself here on the Wall than after installing a questionable heating system. Know what I mean? So please let me hear your ideas and/or complaints. Of course cost is a factor, but so is reliability and effectiveness. After calling them, explaining my situation, they assured me i'd be a GREAT system. On the real side, what else could they tell me? So I'm asking you guys. Thanks, Jimbo

Jim Eastman

Takagi as hydronic heat source

I did a small baseboard job with a TK-Jr replacing a NetaHeat unit. We had lots of problems with the pressure switch locking the unit out. After many attempts to correct the nuisance problem, a Takagi tech rep told me to take the pressure switch out of the system by flipping the dip switch to the position for an outdoor installation. We haven't had any problems since. I requested an official authorization letter from Takagi, but never received it. We will not put another Takagi heater in for this purpose until we get the proper documentation from Takagi.

Jim Eastman
Precision Plumbing
Boulder, CO

Dan Peel

Instant water heaters wishing they were boilers

This Rinnai unit is backup to solar on an off grid project. The Rinnai is tied directly to the domestic water of an 80 gallon dual coil indirect. The lower indirect coil receives the solar inputs, the upper coil steals heat from the DHW for distribution to radiant and also includes a counterflow circuit which captures heat from a flue collection HX mounted in a high mass stove/oven unit. Do the math a couple of times, these little instant units require high temperature differentials and significant flow to rev up and deliver even close to their rated capacity. Enjoy.....Dan

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Weezbo

i have installed flash heaters....

however only for the intended purpose though it occured to me that indeed there might be some way to get them to function as a heat source for space conditioning..At this time i havent and wouldnt consider using one ..although there is heat comming outta them you might find a boiler at or near or less than the cost of it that would preform both functions with out issues.

J Persons

I've looked at Tagaki and Rinnai as possible radiant heat sources and discovered each time that as the return water temperature increases, that the high capacity instantaneous heaters can no longer use their full output capacity without overheating or getting dangerously close to the high temperature limits. Realize these systems were designed to operate with a 70 degree temperature rise with entering water starting at +/- 50 degrees and leaving at 120 degrees. If you take one and start feeding it 100 degree return temperature from a radiant panel and want the supply to be 120, these units need to operate in a Primary / Secondary piping arrangement and will be chugging out fluid at a temperature of ? 160 degrees and be running at less than full fire capacity. So do not expect to be able to get full rated capacity from them when you are at design load conditions. An insight to this whole conversation.....I'm using Munchkin boilers and am much happier with their operation and controls than with the non-condensing wall hung units.

Paul Rohrs

Have you considered

using it as an injection station? Cut out the primary loop, and only have it feed a secondary loop.

Let me know what you think?

bill clinton_3

Takagi

I've not yet used a Takagi for radiant, but I'd shy away from it. My assessment is that this is only one more of a long line of flash heaters miscast as boilers. There was the Paloma from Japan, the Celtic from France, the Myson from England, the Fais from Italy. All very similar. All promoted here for a while. All long gone and welcome to be so. Pause to think long and hard.

Bill

Alan(CaliforniaRadiant)Forbes

Takagi & Rinnai

We have used them both for radiant with varying success. I don't like to use them as the dedicated heat source. They work best when used for DHW with a heat exchanger for radiant.

This is one we did in 2001. It's a Takagi Mobius (the big one) that does domestic, about 1,000 [] of radiant in the basement and has a solar pre-heater.

The only problem we had was the filter screen on the Takagi filled up with rubber debris; don't know where it came from.

We also did a job with a Rinnai water heater that served panel radiators and radiant; no domestic. I didn't like it because you have to use a high head circulator to overcome the pressure drop of the HX; expensive to run.





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Jack_23

GPM X Delta T X500 = BTU

I represent Rinnai. I have hundreds on heat, many more on dhw. They are approved for space heat...BUT! Whichever on demand unit you choose to use the above formula applies. The but means, make sure your numbers are right and pay close attention to your circ selection. Pressure drop is quite high compared to a regular boiler. I prefer them on low temp systems. Radiant/hydroair are best. Small baseboard is ok but for no more than 50-60kbtu. On a Rinnai you won't get any more than 5 gpm with any sane circ. 20F delta t and plug in the numbers. the most I've seen anyone get out of one was a hydroair/radiant combo with the rad. using the hydroair return water to supply the slab. big delta T equals bigger output. In that case 120kbtu. On baseboard, the max output of the unit is 180F. I tell everyone to run them at 160-170F (why run at the max). Do the homework, go slow, build confidence with them and limit your exposure until they have proven to you that they can do it and you are comfortable. For DHW they are the balls. Commercial waterheating has been great. Have done a bunch of laundromats, comm laundries, restaurants etc. Happy heating!

lchmb

done one so far

This system was done for a 34x36 garage. It houses a very nice Ferrari racer and is a sealed system. Do to location it is also antifreezed. No problem's to date. The temp's are set at 120 and return temp has not been an issue...

hr

Why?

Is the decision price driven? There are so many small wall hung boilers, and condensors, built for this exact application. Save yourself some hassles!

Also check for code issues in your area. They may not fly without a listing stating they are acceptable for stand alone, closed loop heating applications.

hot rod

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S Ebels

From what I understand

These units (takagi at least) are used extensively for heating over in Japan where they are built. What do they know about piping these things that we don't? Probably nothing when it comes right down to it. Like anything else new, compact and high efficiency there is a learning curve. Look at all the guys who had installation related problems with Munchkin for example.

Hot Rod brings up a very valid point that needs to be researched in your home jurisdiction. That is, are they even approved for use as a heating appliance? Here in good old stuck in the mud, backward, overunionized, political backscratching Michigan, they are not. Pete Caruso has been beating his head against the wall down in Lansing trying to get Monitor Products approved and he's having a heck of a time trying to do that. We all know the level of quality that product comes with. What could realistically be the issue? $$$$.$$ in the right pocket?

Mark Eatherton1

Read and follow the instructions...

and follow the manufacturers installation manual.

Who reads that crap??

Whattya need to read aboout. There's a gozinta and a gozouta and you put a pumpy thingamajig between 'em and you got your self a heetin' system. It gets hot, you get heat.

What more could you ask for?

Misapplication and misrepresentation are the two big foul players in this scenario. When it doesn't work, people are not satisfied and bad feelings result. I know where there are 150 misapplied appliances right now that the building owner is trying to unload on the design engineers E&O policy. I estimate 1,25 million to fix it...

Let me tell you about my gas bill :-) (he sez like a proud grandfather would talk about his fishing partner grandson)

Last year I was getting my summer DHW from an 80% efficient tankless (ELM AquaStar). Endless source of 100 degree F rise water (@1.25 GPM)...

This summer I'm getting it from my Well Hung 50K Munchie with the "Posidon" DHW "system", and my bill is 21% less than it was last year. If the ELM was rated at 80% efficient, does that make the Munchie 101% efficient? (80% plus 21% savings = 101% :-))

Month to month loading exposure (2 adults, 3 dogs) was identical. I think I actially cheated and turned the heat on in the latter parts of May...

I could see my breath outside at sunset tonight. I can't remember EVER being able to see my breath at the end of June.

Climes, they are a changin':-)

ME

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