Which Tankless? Bosh, Rinnai, Takagi or?

[Scott Townsend]

We are looking for Tankless Hot water heaters. I have 2 Uses. One in my home and one for a Granny unit we are building.

For the Main Home, I was going to install it at the Far end of the house closest to the 2 Full Bathrooms and leave the Existing 40 Gallon LP Tank to service the Kitchen and Laundry.

The Granny will be for the entire unit. It will have 1.5 baths, Kitchen Sink, Dishwasher and Laundry.

So I'm thinking a 4 Gallon unit would work fine for both applications.

Most of my local home improvement center carry the Bosh Auqastar line of tankless hot water heaters, our LP Supplier recommends the Rinnai and I've had Friends tell me the Takagi is the way to go.

There seems to be a big price jump with the ones they sell at the home improvement centers vs. the Rinnai and the Takagi. Makes me think that the ones at the home improvement centers are just ones to get you by...

Any one have an opinion on any of the Tankess options out there?

Thanks, Scott

[Mark Schofield]

[m Ransley]

Takagi makes Bosches larger 188000 btu unit, The small 117000 btu Bosch is what I have, a pilotless piezo ignition powered by 2 d cells, My D cells last 2 years so far. It heats 33f incomming for a 110f shower not being set on high so it works well. Water flow Gpm, and Temp rise per Gpm, are how you rate all of them. so if you are in a cold area measure incomming water temp now, but for me near Chicago with a warm winter it is not accurate now since my incomming is 40 but can in a cold -20f winter be 33f, so adjust your temp to calculate a lower temp. Why not heat the whole house water with it, I figured my savings at 25 a month from removing an electric tank, my payback is substantial, apx 4 years. A Rinnai or Takagi, or Bosch-Takagi-same thing, output in the

180000-190000 btu range, enough heat for full house Gpm and Temp rise in cold incomming water areas. The better units have remote thermostats, and the Rinnai and better Takagi may heat To a Temp. My bosch 120 heat to Temp Rise and gets hotter as incomming gets warmer, so I turn down the temp as summer comes, the better units may maintain a set point. The cheap Bosch 120 is 83% efficient, The Takagi TH1 is 93% efficient. The best gas sears tank has an energy factor in the 60s, Tankless go into the 90s, there is your proof tanks are Crap for energy efficiency and another reason to prove to junk your tank you plan to keep.

One thing you must know first is Gas supply, a 190000 btu unit takes alot of gas, my little 117000btu unit needs 3/4 Ng line over 10ft, a

190000 btu unit at a long run will need a big big pipe. You must use a Manometer with competing loads on to calculate flow and account for supply pressure variances, or you will never get 100% output. If cost is not an issue get the Takagi TH1, Rinnai is also good, reasearch all the specs. tankless are the way to go.

[Bob]

How does your incoming water get down to 33 deg. F? Is it public water, with the pipes running through frozen ground? Do you have a freezing problem in the winter?

[GreenGA]

I'm considering one for our second floor as the remodel continues/restarts. The one thing I learned about these units is sizing for the demands required of it.

I had to determine/measure the coldest temperature coming into the house during the winter, determine the hotest temperature I needed at the faucet and the flow rate at that termperature. This allowed me to size the unit for it's purpose. I tell ya, I needed a unit much bigger than I had originally planned when I started looking into these things.

I do not know if this helps at all, but it is certainly something to think about during your planning stage.

As for manufacturer...

The Takagi adn Rinnai units "seem" to come out on top in most of the reviews I found on the net; and I spent weeks researching these things.

Oh yes, one more thing...

Venting! The gas-fired units seem to put out more BTU's psf of unit size and the vents need to be of higher grade materials, etc., etc.., etc... This requires plannnig for the vents and routing.

HTH

[m Ransley]

My 33f incomming at -10 or lower comes from dirt eroding off the hill the main was buried in over many decades, I know I lost 1 ft in 20 years It may also be the contractor likely did not go as deep as he says he did. It is city water and under street mains branches have frozen here requiring a welder to melt them with electricity .

[Scott Townsend]

Thank you all for your replies.

I think what I need is something that will do 70 Degree Temp Rise @ 4 gallons/minute. So that leaves me with Bosh 250SX Takagi T-K2 Rinnai 2520FFU

So if Takagi makes the high end Bosh, which one? The 250SX is only 175,000 BTU, Is that the one you are referring to? Which Takagi would be its Cousin?

Thanks, Scott Takagi makes Bosches larger 188000 btu unit, The small 117000 btu Bosch

[m Ransley]

Are you sure 4 gpm at your main incomming, mine varies on time of day and season.

70 f rise , did you test water temp at-near the heater and the loss it experiances at its use point, you should measure shower head output temp, I loose apx 5-10f.

What is your temp incomming lowest, in a cold year, test now but lower it 10f easily.

Cross comparing can only be done possibly on a specification since rebadging, recasing, or a single line for Bosch is likely.

It is better to upsize than make an expensive mistake. Although I do fine with 117000 btu and 4 gpm and 33f incomming not even set to high, my shower output might be 1-2 gpm. Be sure your gas can handle the extra load, im sure your furnace is not near 180000+ btu. Load must be measured with all apliances on.

Look for a unit that maintains output temp and has a remote thermostat, my unit does not maintain output temp, it maintains temp rise, so in winter I must turn it up manualy. But I am happy with the savings I get.

[Scott Townsend]

this is New Construction, at least for the Granny. So its hard to take Temp Measurements now. (-; We live off well water. Though when the Granny unit is all said and done, it will be pumped out of a semi buried 2500 gallon Tank.

For the Granny, its going to have at most the Dishwasher and the Shower going at once, so that would top out the 4gpm, and if the water was 33f, a

70f rise at 4gpm would be enough even if it dropped a few between the tankless and the shower. That is worst case. Most of the time it will be just one application at a time in the Granny, so at 2gpm for the shower most units are 120f+ temp rise. The LP under the house is 3/4" and the main feed is not in yet. They know we are going tankless, so they did things accordingly.

The one I really need to think about is the main house.

I'm kind of stuck between a rock and a hard place. I have 2 location where I need hot water. The back end of the house, 70'+ away from the Existing tank heater, and the Kitchen, 20' from the tank heater in the opposite direction.

it Currently takes 2 minutes for the water to get to the back end of the house for showers. So I'm thinking of cutting off the Hot at the Kitchen split and just putting in a 4gpm @ 70f temp rise at the back end of the house. So the 2 full baths get the Instant Hot.

Then some day when I redo the front end of the house, replace the Tank with another tankless to take care of that end of the house.

I've thought of getting just one bigger unit for the entire place and doing recirc. I don't mind the 2 minute wait, its the water in the Septic Tank/Leach field I worry about.

Better to have one big unit or two medium sized units? Cost Aside... hey I could put in a By Bad valve so if one unit failed I'd have failover in a pinch?

[Wayne Whitney]

You might also consider the Noritz units, e.g. the Noritz N-069M-DV. For an indoor install, I highly recommend direct vent.

Cheers, Wayne

[m Ransley]

A recirc system just wastes money, for greatest savings on your bill replace tank now with one big unit , later do the bath, but your idea will work, be sure to get pilotless ignition.

[3D Peruna]

An institutional client I work with uses the Takagi. Less maintenance (virtually none) and that means a lot to them. The units just work with few parts that can wear out/break. They won't touch the "Home Depot" stuff because of reliability issues.

[m Ransley]

Bosch sold at box stores are the same sold anywhere, you can get a 400 basic unit or order a better 1000 unit. the best Bosch -Takagi are near

1000. Rinnai I believe needs a factory certified installer for any warranty to be in effect, Worth checking out before you purchase a Rinnai.

[Scott Townsend]

The Takagi says the same thing in their Manual too about having it professionally installed.

Front page of the T-K2 Manual: WARNING This product must be installed and serviced by a licensed plumber, a licensed gas fitter, or a professional service technician and/or in accordance with all local code. Improper installation and/or operation, or installation by an unqualified person, will void the warranty.

Rinnai has it there too: Installation and service must be performed by a qualified installer, service agency or the gas supplier.

Whats a DIYer to do?

Scott Bosch sold at box stores are the same sold anywhere, you can get a 400

[m Ransley]

Takagi-Bosch does not require a certified installer , Rinnai certifies them, this is my understanding. They all say a Pro must install it, but I think Rinnai wants their name to check on their database. Look into it, I installed my Bosch and got warranty service. But venting and sizing and measuring gas flow is not an average amature job, you should get help, or you may never get 100% output.

[Bob G.]

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from an dealer...sign it and IF everything goes as it usually does you will have no problems until 4 days after the warrenty period expires anyway......

Bob G.

[yellowbirddog]

[udarrell]

Inconsistent water temperatures would be a pain in the neck, or hands. If supplying a shower, forget it! - udarrell - Darrell

[Wayne Whitney]

That article is bogus. In doing the cost comparison, the author assumes that the tankless gas water heater always uses gas at its peak rate, which is false. A tankless gas water heater has a modulating gas valve, and it will only use enough gas to provide the required temperature rise. It is incontrovertible that all other things being the same, a tankless heater without any standby losses will use less energy than a tank heater with standby losses.

The author also complains that tankless water heaters provide a constant temperature rise, so that the hot water is hotter in the summer when the incoming cold water is hotter. While I believe some older models do this, most current models will modulate the gas usage to provide a constant output temperature as the input temperature changes.

In other words, the article's two chief complaints are invalid.

Cheers, Wayne

[m Ransley]

I read the link, so the idiots utility bill went up with his family, so what, that is not a verification of anything but overuse. What is verificartion is the Energy Factor and Efficency Rating, verified and published. Sears best tank the PowerMiser, has an energy factor of .63 Sears lineup goes from .58-.63 Energy Factor with an efficency of only in the 80% range. Tankless start with an Energy Factor of .81 an go to

90+ with efficiencies from 82%-94% for the Takagi Th1. That guy is a total idiot if he can`t figure out ratings and math.

My unit lowered my utilities from 25-30 for a electric Newer Rheem foam insulated, with added blanket, to 6$ Ng in the summer, and that includes dryer and all cooking. So my payback is apx 4 years. Sure tell the kids you have an endless supply of HW and watch what happens. As to Eveness of temp, Rinnai-Takagi have units that keeps outflow monitored. My Bosch 117000 btu unit does not, but never varies more than 3 degrees- hardly an issue. Bottom line they work, just don`t tell you kids the HW is endless, or your gas bill will be endless.