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Posted by on January 20, 2007, 8:33 pm
That Noritz unit must have a whopper of a firing rate? What is the
Btuh input? There was no doubt once we got past the tiny output Euro
models, with good reliability and a big enough gas line, these
instaneous water heaters would be the way to go. 13.2 gallon per
minute at what incoming water temperature. We run about 45F or less
here in winter and 50F in summer.
wrote:
>You have a very good point. BUT in alot of cases for us, we have installed
>TWH's for unlimited hot water usage. Took out (2) 50 gal atmospheric HWT's
>(in a LARGE house) and installed (1) Noritz N-132M (13.2 gal per minute) The
>Dr wanted the biggest. He had 5 baths (3 whirlpool tubs) 5 children and the
>story goes on. Installed with the option flush kit and remote controller.
>Ended up with all hot water taps opened with 132° at all taps. Dr happy and
>paid the bill (cash). We have been once to flush appliance...routine
>maintenance. He has said his gas bill is down and the consumption is also
>down. Maybe a few of the kids moved out :o)
>
>>
>> Finally some good advice re tankless wtr htrs. The reason they have a
>> problem with mineral clogging is because of how they work. They
>> regulate the flow and pressure to ensure that the water comes out at
>> 120 F for example. When you heat water and change the pressure,
>> minerals tend to drop out. Ground/water source heat pumps can also
>> have that problem.
>>
>> Tankless water heaters require very high firing rates, at least in the
>> north where the entering water temperature is 50 F or lower, to give
>> us the amount/volume of hot water most people are used to. In many
>> cases, around 200,000 Btuh or more is required to do that. In many
>> existing homes the gas piping will not accommodate this along with a
>> gas furnace and other appliances without a piping up-grade, adding
>> further to their already high cost.
>>
>> The standby losses through the tank walls for a conventional or power
>> vented gas water heaters is about 6-7%. Most of that loss is inside
>> the building envelope and in many areas reduces the normal heating
>> load of the furnace. During the AC season it can add to the AC load,
>> a minor problem in the north and a non-issue in most homes with
>> basement installations.
>>
>> It is also difficult to find a service contractor who knows how to fix
>> the ductless units, especially since there are so many brands out
>> there. I also imagine parts availability can be a problem in many
>> areas. Part prices may also be very high.
>>
>> Most people that try the tankless water heaters are not happy with the
>> flow rate they get. We have often had to remove many of them and
>> replace them with a regular PV model.
>>
>> Where I live, the average family spends about $350 a year for gas hot
>> water heating. Conventional gas water heaters can be installed for
>> somewhere between $600 and $700. A tankless water heater might save
>> $150 a year in this example. At that rate, the payback period will be
>> quite long, not even counting the annual acid flush and other repairs
>> that WILL be necessary over its life. Very little goes wrong with a
>> conventional water heater - we ought to know as we rent out well over
>> a million of the things.
>>
>> Having said that, one day in the not to distant future, I will think
>> we will see them become the norm in new construction, especially as
>> the short comings get addressed.
>>
>>
>> On Fri, 22 Dec 2006 20:56:41 GMT, "Bob_Loblaw"
>>
>>>
>>>
>>>> Tankless gas is less efficient at heating the water. If the usage is
>>>> infrequent then the savings from not having to keep the water hot
>>>> outweighs that. In a normal household that is not usually the case.
>>>> There is the added advantage of never running out of hot water though.
>>>
>>>When water is heated, the minerals drop out of it.
>>>Tankless heaters get a build-up of minerals much like a persons veins do
>>>with hardening of the arteries.
>>>They should be flushed out with a vinegar solution every year(the tank,
>>>not
>>>your veins.Veins should be flushed with copious amounts of Stella Artois).
>>>This is just one more reason to stay away from them.
>>>If you place your hand on the side of a conventional type of tank ,you
>>>will
>>>notice that there is very little heat transfer due to the high insulation
>>>value of most tanks.
>>>Turn off your water heater and you'll still have hot water 8 hours later.
>>>Tankless heaters are popular in Europe mostly due to space constraints.
>>>They are not a good idea unless you need the extra room.
>
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