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joe viola
tankless hot water heater

Does anyone know where I can get the ratings of the tankless hot water heaters. I'm trying to see which is the best for my application and the cost. It would be a gas tankless hot water heater I'm looking to install.
I've seen the Bosch which looks and sounds good but I need to do some comparision shopping.

Re: tankless hot water heater

You can check out the manufacturers web site and find the ratings, look in the install or spec. manual pdf's. Bosch has some nice units, but the cheaper ones are standing pilots and not as energy efficient. I looked into the rinnai, rheem, bosch, takagi,noritz, and they all seem about the same to me, keep in mind that these units have to be flushed if they have build up in the heat exchanger, also I have heard the controls are quite sensitive and need periodic maintenance, any gas savings may be offset by the cost of service. Good Luck!

Re: tankless hot water heater

There are many disadvantages to tank less heaters other then what has already been mentioned. The newer dish and clothes washers don't have a high enough flow rate to fire the heaters. If your replacing a tank type heater the gas line and the flue pipe will have to be upgraded as they are to small for a the tank less. All this adds to the install cost. The pay back in gas savings may never be happen. Even if you save 50% of your fuel cost it would take 10 years to get a return on your investment. That is not taking into account the repairs the unit will need.


Re: tankless hot water heater

Here is some interesting reading from another forum I am a member of. The sad part is this is not uncommon.


Hi guys. When I moved into my house a couple of years ago, I was delighted to discover that it came with TWO Navien CR-210A units. They are hooked up master/slave, supplying both hydronic heat and hot water to the tap with circulation.

While I like the units in principle, the day to day reality has been disappointing. Here's a list of some of the problems I've had:

1) Both units had ignition problems (error 3). We replaced the circuit boards.
2) One unit had an intermittent problem with the flow adjustment valve. We replaced the entire unit.
3) I've had two flow adjustment valves that failed (error 34), requiring new valves.
4) Both units have been through a handful of flow sensors (error 36). They seem to last 3-6 months.
5) One unit gets intermittent air flow faults (error 10).

With the recirculation system, the units short cycle constantly. Each new ignition causes a nasty belch of exhaust as the units clear themselves. My elderly neighbor complained about the fumes. The gas company showed up and red tagged the units. Testing revealed that the units are venting "as designed" and we simply turned them back on after a chat with the neighbor.

I've finally had enough. I'm not a plumber and I'm tired of dealing with this mess, not to mention the expense of constant repairs.

So, what should I use to replace my broken heaters? I need hydronic heat, hot water, and (ideally) a new circulation system. It has to fit into the existing (smallish) utility room. I've got PVC venting at the moment. I know very little about plumbing, so please use small words and be specific.

Re: tankless hot water heater


If tankless water heaters were dependable, affordable, efficient and reliable as they were intended to be, don't you think that every house would have them by now?

The traditional tank water heater, with all its flaws is not going away anytime soon. Today's tank water heater is almost the same as the original water heater that Edwin Rudd put together in 1889. OK, maybe the burner, gas valve and T&P valve are different, but this fact tells you something.

If you still insist on a tankless, Bosch is as good (or bad) as any of them.

Re: tankless hot water heater

I'm looking at the AO Smith Vertex HE water heater. One model is direct vent, 100kBTU and 96% efficient. The other uses a single pipe, is 75kBTU and 90% efficient.... and costs $500 less.

My current heater vents through the chimney without a liner, so I might as well go to a direct vent and use PVC, rather than spend $1000 on a new liner.

The Vertex units can be used with a circulator pump for hydronic heating systems. I'm actually tempted to put a couple radiators back into service for some zone heat in 1 room and a radiator that's mounted to the garage ceiling. Plus I might even switch to an airhandler and hydronic coil on my upstairs system that only needs 30k BTU"s of heating based on my load calculations.

I'm assuming however, that's I'm need a indirect tank since the boilers are cast iron.

Re: tankless hot water heater

I just replaced an electric HWH and a gas HWH. After researching on demands, the best value was to stay with the traditional heaters. My 2 person family uses natural gas for cooking, dryer, heat (for our fairly short heating season) and the HWH. In the summer months we don't hit the minimum gas charge even though we pretty much stopped using the microwave to make coffee. The energy savings were there, but the monthly out of pocket costs would have been pretty much the same for us considering our few dollars saved in the winter wouldn't have amounted to much. COmpared to an additional $500 for the on demand, it would have taken 20 years to break even.

Just my 2 cents

Re: tankless hot water heater

The new tankless units are a nice option if you have a new install or addition, but if you have to replace a tank type water heater all your connections are already there, if you want to switch to a direct vent tank type. All I have to do is add an outlet and cut a 2" hole in the sidng to run the vent. The tankless would have cost me at least 3 times as much, and that did not include running the 3/4" gas line from the meter 20 feet to the new location of the tankless. If you plan on staying in your home forever then the option is yours! If your tank goes bad you just throw it away, its kind of hard to throw a tankless away after you shell out over $2,000 installed cost, thats why most people keep fixing them until the can no longer be repaired. Good Luck!

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