Tankless Water Heaters, Who makes best?

Dan C._3

Is there a consensus opinion among hydronic pros about who makes the best (reliable) tankless unit? I have more and more customers asking about these due to increasing fuel prices. We don't sell them, but we installed one that a customer had purchased. It is a Bosch. I'm not overly impressed by it, but that's just my opinion. Thanks for any feedback you can give.

Dan, Service Tech.

Alan(CaliforniaRadiant)Forbes

Tankless

Takagi, Rinnai and Noriz are my favorites in that order. Of those three, which one I use depends on where it can be installed on the job and GPM requirements.

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Scott Gregg

My $.02

I prefer Noritz as my choice from the big 3 of tankless.

Noritz and Rennai together hold right at 70% of the worldwide market share of these products and there is a very good reason...they work great! In the US it probably more like 80%.

I have found Noritz to have a broader line in the US and better support. I think you get a little more for your money. However the Rennai is a very good product as well.

They must be installed correctly of course which is why I do not favor Takagi. They will sell to anyone with a credit card with very little consideration on if the product will be installed properly. I think this is short sighted of them. Any bad tankless job is a black eye on an industry that is still new to the US.

The "home center" products do not impress me at all. They obviously are way behind the technology curve and have a lot less capacity. One look inside the cabinets of each will show you a lot.

Try one of these (Noritz/Rennai) and you will be impressed.

Plumdog_2

Bradford-White or Rinnai

> Is there a consensus opinion among hydronic pros

> about who makes the best (reliable) tankless

> unit? I have more and more customers asking about

> these due to increasing fuel prices. We don't

> sell them, but we installed one that a customer

> had purchased. It is a Bosch. I'm not overly

> impressed by it, but that's just my opinion.

> Thanks for any feedback you can give.

>

> Dan,

> Service Tech.

Plumdog_2

Bradford-White or Rinnai

They are both made by Rinnai and are technically ahead of the others. The vent system is tops and the optional control panels are great. Some of the others don't provide direct-vent option, and the shortcomings are not divulged to the buyer until too late.

Dirk Wright

gas or fuel oil?

If you have fuel oil and not gas, then Toyotomi is good. I have one and it's been reliable and powerful. Plenty of hot water and a very advanced burner.

Ron Schroeder_3

Tankless vs indirect

Are you sure that a tankless (on demand if I understand you correctly) water heater is the best way to go? Perhaps, if you do not have a condensing boiler to drive an indirect tank, you might consider one of the condensing water heaters?

On demand heaters place sever restrictions on the amount of water that can be delivered in terms of a rapid dump as in a roman or soaker tub. They also typically require a lot of power (read energy) to make them work. A single faucet opening has te same effect at the gas meter as do may faucets opening. Just a thought...

Scott Gregg

Easy...

Go easy on the "Severe" talk there Fred. Most new home piping can only support 8-10GPM anyway and most tub spouts only put out about 3-4GPM. Even an 8GPM soaker tub filler normally is only going to get about 6GPM (total) after all the pressure losses are figured in from the system.

Being related to many hundreds of installs of these machines in last few years I can honestly say we have 0 complaints at high flow rates.

I went through this on a house with the Delta Rep. He said the same thing. I said "show me". He opened a tub filler on a soaker tub on full hot and then turned on hot only in two lavatory faucets and hot only in the shower. The flow rate indeed slowed down. He said "See?" I said "Yep...now try it with just the cold water." Guess what?...same result.

The moral of the story is to measure, test, feild trial and listen to your customers. No complaints is the best test you can ever get.

Ron Schroeder_3

Sorry to appear to overstate the case, Scott

My experience with "instantaneous" direct fired domestic hot water producers is lilited to one installation at the townsend Park Field House in chilliwack, BC, Canada. The original engineered specification was for a 185MBTU boiler and a 450L verticel (their spec). The Local representative for bosch convinced the client (the city) to purchase instant hot water heaters instead. For the same load as the indirect tank was connected to, both as far as input and water output goes, eleven Bosch heaters were installed: one heater is for the utility room sink. The other ten heaters supply the showers. Five heaters make the first temperature lift from city supply. The second set of five heaters lift the water from the first five to 130F. The configuration was specified by the Bosch rep in our area, Astravan Distributors.

Please explain to me how the present 1.1 million BTUH plant is cost effective as compared to one 185,000 Btu boiler and one 450L (120USG) indirect fired tank.

Oh, by the way, they had to install the 185MBH boiler to provide winter frost protection to the building also.

Plumdog_2

single faucet vs multiples

same effect at the gas meter? Not at all, because the unit measures the flow in volume and ramps up or down the burner rate to achieve the set output temp regardless. This only works within the lowest flow required to trigger burner and the point at which heat exchanger/burner can no longer maintain, obviously. Sizing is important, but gas usage varies with load.

Scott Gregg

This is only my opininion but

"The Local representative for bosch convinced the client (the city) to purchase instant hot water heaters instead."

Right idea, Wrong Product. Plumdog has it. Tankless heaters modulate completely over their operating capacity but the Bosh unit lack anything close to the technology to pull off a job like that well. You have to use products that have systems that allow them to comunicate and using residential products on big comercial jobs is not the best idea most of the time.

A good system (Like Noritz) would be able to modulate properly without compounding minimum flow rates. Their multi-system controller can work with up to 24 of their big units. (much higher everything than the Bosch and built and rated for commercial use) A system like this has a minumum flow rate of .7GPM to fire and would fully modulate from 21,000BTU to just over 9,000,000BTU. If one unit develops a problem, It is by passed ans locked out and system continues to function.

Without seeing the job it is just a guess, but I'll bet a 4-unit N-132M Noritz multi-system could have easily done the ENTIRE project. 4 units each giving 13.2GPM, 380,000 BTU each fully modulating from 21,000 to 1,520,000 from .7GPM - 52.8GPM total capacity of over 31,000 GPH with built in automatic redundancy. (Pretty cool huh?)

What makes a good system like this a viable option is no storage or standby heat losses. The system is always off, until there is flow. If you have a recirc system (Like in most comercial jobs) you do use energy to maintain the DHW loop but you still do not have to keep hundreds of gallons of water hot 24/7 and you are only using the bare minimum nedded.

Putting a bank of bosch heaters together in a job like that makes about as much sense as going to HD an buying about two dozen $175 cheap residential tank heaters and trying to make them do the job. Commercial jobs are for commercial grade products.

One more thing...
"The Local representative for bosch convinced the client (the city) to purchase instant hot water heaters instead. For the same load as the indirect tank was connected to, both as far as input and water output goes, eleven Bosch heaters were installed:..."

It looks like he sized to same same capacity as what was there without consideration to actual need. How many times are jobs grossly oversized? The proper way to determin the capacity of this job would be to determin the highest "likely" flow rate and choose a system to meet that need.

Now after all that, if they had to install the boiler anyway for frost protection I'm lost. Noritz and Rennai/BW units have their own freeze protection systems. If they are trying to heat the building and make DHW, then IMHO switching to a tankless system at all with a boiler load like that seems a bit silly. Again from way down here in VA I don't get the thought process but there is always more than one way to skin the cat.

JackFre

on-demand info

www.rinnaisolutions.com
On this site you will find operational calculators/sizing/install/troubleshooting/parts, etc.
Spend a bit of time and this is a tremendous resource.

Paul Cooke

Water Heaters

1 Takagi installed....many callbacks....no like dis a heater no mo.

0 Noritz installed....therefore no can tell.

Many, many Rinnai installed. Replaced the heat exchanger on a 5 year old 2424 residential model yesterday. Fluke? Only time will tell. I thought I was doing brain surgery....it took 2 and a half hours....only had 2 little screws left over when I was done....not bad. Hooked it back up and it ran fine. Hopefully it will last more than 5 years. Rinnai won't pay for my 3 trips out to the job. Should the homeowner pay?

I have a 2532 commercial model in a restuarant kitchen...got to go out there for the 2nd time in the past year to flush out the heat exchanger...."lime condition". This one is less than 3 years old.

My advice....be ready for service. Gonna be lots of work out there for the trained technician to repair or replace the millions of these things going in every year.

Scott Gregg

????

If wonder if you know you have such bad water, why are you not fixing the real problem by installing water treatment? That same water is ruining everything it touches. Commercial equipment is much more expensive than tankless heaters and even a tank heater is not going to last long under such conditions.

Paul Cooke

Water Treatment

Scott D.

Are you recommending some sort of deliming filter before the cold water goes into the tankless?

Scott Gregg

Solving the problem

No, If you have water that is so bad that it is liming up the tankless in such a short time, it is also going to lime up everything else it touches. (Washing machines, Ice makers, faucets and other fixtures, etc.) That job needs a water softener. (At least)

A test should be done on the water. Most companies that can provide such equipment will test the water for free and then recomend the proper equipment.

By solving the water issue, you not only will save the life of the heater but you will make every piece of equipment that this water comes in contact with last a lot longer. The money spent on the softener will be saved on the longer life of other equipment and saved on service calls for repairs.

If you have water that is so bad, you are in there every few months de-liming a tankless, a tank water heater would probably last less than 5 years anyway before the bottom blew out. The tankless is selling your next job for you without forcing you to replace it.