[Greenbuilding] [BULK] Tankless HW and hard water

[Dr. C.F. Vasile]

The article you cite was written by a tank-type water heater manufacturer. I 
complained to the Publisher, who agreed they were duped. By the way, I don't 
own stock in any tankless water heating company.

----- Original Message ----- 
From: "Lawrence Lile" <LLile at projsolco.com>
To: "Greenbuilder list" <greenbuilding at listserv.repp.org>
Sent: Wednesday, September 06, 2006 1:56 PM
Subject: Re: [Greenbuilding] [BULK] Tankless HW and hard water


> Here is a test at a lab that showed an alarming decrease in efficiency
> in a head-to-head test of tankless and tank water heaters due to lime:
>
> http://64.233.161.104/search?q=cache:QVTCjQdsMUgJ:www.pmengineer.com/CDA
> /Archives/8cf9e86f7c298010VgnVCM100000f932a8c0____+lime+tankless+water+h
> eater&hl=en&gl=us&ct=clnk&cd=1
>
>
>
> " Testing showed that lime scale build-up is a major concern in hard
> water areas with tankless water heaters. Lime scale did not flush out of
> the heat exchanger from the water velocity through the coil, but
> accumulated in a very short period of time. Lime scale can also
> accumulate on the base of storage water heaters, but much more
> gradually, making storage water heaters more tolerant of hard water
> conditions. Adding a water softener on the water supply would prevent
> the quick accumulation of scale on the heat exchanger. Tankless #2
> started out with a higher efficiency rating, but dropped off for the
> two-week period of operation due to scale buildup in the heat exchanger.
> The efficiency rating could be up to two points higher using softened
> water. Tankless #1 was less sensitive to scale build-up, but still lost
> about 1.75% operating efficiency after a two-week period of hard water
> conditions. Both tankless water heaters have a procedure to remove the
> lime scale from the heat exchanger by flushing with vinegar using a
> circulator. This requires at least one hour of service time, adding to
> the life-cycle cost of the tankless water heaters in hard water areas.
> To maintain peak efficiency, the tankless models must have water
> conditions with less than 11 grains of hardness. The MI40T and M440T
> models did not show a noticeable drop in efficiency during the test
> program. "
>
>
>
>
>
> -----Original Message-----
> From: greenbuilding-bounces at listserv.repp.org
> [mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Keith
> Winston
> Sent: Wednesday, September 06, 2006 12:43 PM
> To: Greenbuilder list
> Subject: Re: [Greenbuilding] [BULK] Tankless HW and hard water
>
> It's not obvious to me why this would be so. Anyone care to share
> thoughts? Lime formation won't tend to happen below, I think, about
> 160F. But surely in a tankless there are hot spots that exceed that?
> Maybe that's the answer right there? Or perhaps it doesn't form well in
> a stainless steel environment...
>
> Keith
>
>
> Dr. C.F. Vasile wrote:
>> Yes. I've been heating my house and water with a 15 kW Tankless
>> electric heater since 1996. I live in Patchogue, NY where cold water
>> temperatures drop below 45F in January. We have very hard water and
>> have had no problem with calcification. In contrast, the tankless coil
>
>> in our obsolete oil burner used to "lime-up" in 6 months or so. When
>> it did, its 1.5 gallon per hour firing rate (oil) couldn't sustain a
>> low flow shower and its water-heating efficiency dropped below 25%.
>>
>> ----- Original Message -----
>> From: "Lawrence Lile" <LLile at projsolco.com>
>> To: "Greenbuilder list" <greenbuilding at listserv.repp.org>
>> Sent: Wednesday, September 06, 2006 10:45 AM
>> Subject: Re: [Greenbuilding] [BULK] Tankless HW and hard water
>>
>>
>
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