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Hot water woe

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Posted by humphill40 on December 25, 2008, 11:07 pm
 
Hi All,
Hopefully this long letter will help others, even if I get no good
answers.
My problem is how to get 3 showers a week in cloudy weather back in
the beautiful pucker brush where propane transport is a pain and a
coil in the wood stove not desired. Input water is 40 degrees, and I
now use an old propane water heater with the burner replaced by wood.
After much reading, it seems these are my options, (along with
problems).

*30 gallon propane water heater that I turn totally off between use,
(or at least put in pilot position). I can wait. Possible problem here
is that I am allways heating cold water as ambient in that room is
winter time 50 degrees an ground water is 40 degrees. The reliance
manual says condensation is an issue with cold water and might put
pilot light out. (noisy too). Anyone done this much with cold water?

*Tankless heater----The propane units with electrical ignition and
venting (that I'll call propane/electric) have two problems with off
grid.
     1) Freezing, since even tho the burner is inside cold air can
come
 down vent, worse case being losing heat exchanger. The watts required
to start, monitor and vent these is tolerable if you install your own
switch to turn off idle between uses, but it is unclear as to whether
you lose your programming when you do this. Whatever, the juice
required for 24/7 freeze protection is not acceptable.
     2) Require at least 30 psi and maybe more,( they won't say) to
work.

So we could pick a non electric model if we get one with a pilot
light. These are dissed because of the pilot loss but actually the
advantage is flame will keep HE from freezing all though to what
degree is unclear. So does anyone out there have any experience with
details on this? How cold was your room vs outside? And will the
regulator freeze if room is 45 and outside 20?, without their anti
freeze kit?. Draining every time is of course not too desireable, plus
is unclear weather one also needs to use compressed air to clear
horizontal pipes totally.

I would probably get the Paloma ph24 if i do this, plus the thing
works fully to 13 psi.

Two other issues with tankless are:
    *One plus to the propane/ electric type is that one can get direct
vent, sealed combustion models but if they are out for above reasons
then supposedly one has problem with the paloma ph24 in a small home
like mine, a 900 sq. ft 1970's single wide mobile. Especially with a
wood stove in another room. Supposedly you need 50 cubic feet per 1000
btu's which means for this 177k burner max you need 8500 cubic feet of
house with all the interior doors open!!!  hopefully this is B.S, but
does anyone have any examples to debunk this?

   *The last unknown is scale. What can you get away with? The
manufacturers suspiciously (Once again) won't say. If you have run
your heater for some time successfully my question would be for how
long and how hard is your water? Mine is 8 grains per gallon or 136 mg/
liter. Since all taps are cold water I can see no other indicators.
takagi supposedly told One blogger that even 1 grain required a water
softener, but off course it's not on there site or manual. Flushing
with acid once a year would be okay if the only issue was clogging,
but between flushes it is building up and trapping heat which burns
your HE up. I see that Neon John at rec.outdoors.rv mentioned
soldering leaky tubes in 2000 but in 2002 he appears to be saying he'd
had no problems in a "hard water"  area.

So, appreciate any input.

Cheers,
Milo




Posted by Jim Wilkins on December 26, 2008, 12:30 am
 
On Dec 25, 6:07pm, humphil...@yahoo.com wrote:

My recent thread on fiberglass tanks brought several good suggestions:
http://groups.google.com/group/alt.energy.homepower/browse_thread/thread/bc=
a87aeee238a7f4?hl=en#

The water is heated in kettles on top of the wood stove, or in a solar
heater. I drilled a small hole for a metal dial thermometer in the lid
of a cheap WalMart 5 gallon kettle. For me, 100F to 115F is
comfortable for a shower.

The simplest idea was a solar shower bag for camping. A garden sprayer
gives more pressure in return for modifying or tolerating the spray
head. If you are out in the bush a hoistable bucket might be best but
it may not be easy to install in a finished residential bathroom.

jw

Posted by Neon John on December 26, 2008, 2:01 am
 On Thu, 25 Dec 2008 15:07:30 -0800 (PST), humphill40@yahoo.com wrote:



You've read my other posts about the Paloma so you know how well I like it.  

Freezing is a problem.  We had the one on my mom's hobby house freeze a couple
of times.  Each time they forgot to turn on the anti-freeze kit.  

The pilot does provide some protection from freezing but out of the box it is
so small (adjustable) that the protection is minimal.  If the unit is in
conditioned spaces then either a thermostatic or barometric damper is the
solution.  Even better, if you can sacrifice a tiny bit of electrical power,
is a motor-operated damper, triggered by a thermostat in the flue.

Though I would NOT recommend it, I ran mine for several days when I
re-installed it in the restaurant without a flue.  No CO indicated on a
NightHawk CO monitor in the same room.  Still I'd not take a chance with doing
that in living spaces.  Reason I mentioned this is that the CO output is so
low that there would be no risk using a thermostatic damper that would remain
closed until the flue heated a bit.  Until the flue opened, the exhaust gases
would simply escape into the room.

A tempering tank helps a lot, especially when the incoming water is near
freezing.  I used one that consisted of an old water heater that didn't leak
with the jacket and insulation stripped off.  It absorbed heat from the room


My old building wasn't very air-tight but I can positively tell you that there
was NOT a sensible draft coming into the little room where the unit was
installed.  It continued to work fine even with the high powered restaurant
vent hood operating in the same space.


My HX was corroded through by the grossly excessive chlorine that the city put
in the water in Cleveland.  That same concentration of chlorine ate out the
regulator diaphragm every year.  I kept a stock of diaphragms on hand because
of that problem.  

The unit that I took out because of the corrosion had zero scale buildup
inside.  I sectioned several tubes to be sure.  Other than the pits from the
corrosion, the copper tubes had a dark brown patina of oxide but with no
build-up.

There should be little to no scale even with fairly hard water (ours was
medium) because there is no boiling going on in the tubes and the water
velocity is too high to allow any to precipitate out.

I could probably have stopped the chlorine corrosion with anodic protection
but unfortunately the idea never came and they don't mention it in the book. I
have the unit here in Tellico now but it isn't connected, as propane has been
too expensive the last couple of years.  When I do install it, it will have an
anode in both legs.

I am intensely interested in tankless heaters so I pay attention.  So far I've
found nothing that even comes  close to the Paloma.  I can understand how hard
it is to get propane to a remote site (probably about as hard as getting
broadband here!) but IMO, it's worth it.  To me, a nice hot shower is
something that is almost sacred and I do NOT want anything hosing it up or
making it complicated.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com  <-- best little blog on the net!
Tellico Plains, Occupied TN
Better to pass boldly into that other world in the full glory of some passion
 than fade and wither dismally with age. -Joyce


Posted by humphill40 on December 26, 2008, 9:10 pm
 Hi John. Many thanks for replying, and so quickly!

 

What parts of the heater did she loose?, and do you remember roughly
what the temps of conditioned and outside spaces were?


Interesting that the flame is adjustable, so maybe I could increase it
for more insurance. Spring thru fall I would probably keep off. Big
news for me here is that thermal dampers exist, but I can't seem to
find a supplier or even a description online, tho apparently they are
included if you buy a gas fireplace. Do you know of a retailer?
especially one who will do small orders? Even a manually operated one
might be okay. I do have the juice for a motor one also. Solar
electric 12v plus outback inverter.
Have you tried this? do you feel confident it would protect a unit in
45 degree conditioned space?


This is pretty cool info also, about the CO test.



Lost you here. This would save propane, but are you saying it would
some how lower freeze risk?


Does this last sentence mean you had a large gas stove using interior
air in the same room? roughly what was the cubic space and was the
door shut?

This is good news. How do you define or judge "medium"?. if not in gpg
then buy scale amount around your hot faucets? Was this your
restaurant model?, i.e, high use over 10 years?

I don't know what is worse risk in the quest for easy heat. Putting in
a direct vent tank heater and then discovering condensation does put
out the pilot or having my paloma freeze and/or suck all the oxygen
up.

Milo

Posted by Neon John on December 27, 2008, 12:15 am
 On Fri, 26 Dec 2008 13:10:14 -0800 (PST), humphill40@yahoo.com wrote:


I'm sure that the whole heater froze but it was the control valve that took
the hit.  The regulator is assembled with what look like truncated conical
washers under each screw heat.  Too tall and sharp angled to be Belleville
washers but they serve the same function.  Apparently they anticipated the
freezing and designed it to freeze gracefully.  Unfortunately, the cones
crushed under the force, allowing a large amount of water to spew out of the
diaphragm chamber and into the area.

The heater was mounted in an unfinished, initially unheated attic.  The roof
joists had insulation between them so it wasn't like the unit was outside.
After the first freeze, I bought and installed the freeze kit.  It still
froze.  After that I installed a small space heater with an external
thermostat that turned the heater on at 35 deg.  NO more freezing.

I lobbied unsuccessfully to move the heater down to the conditioned spaces.
The year before she sold the house, she forgot to plug in the heater and
freeze kit, the unit froze and cracked the control valve.  I think the new
owners installed a small electric tank heater.


Sorry, but I don't.  I've always purchased them at my local HVAC wholesaler.
You might try Johnstone Supply (national chain, with a website).  Most HVAC
wholesalers won't sell to the public but Johnstone will.


I'd definitely go with a motor-operated one and a thermostat, then.  Much more
rapid operation.


I haven't tried it on the Paloma but it's becoming routine to install some
sort of anti-down-draft damper with gas appliances.  Not only does it prevent
cold air from back-drafting but if the appliance is in conditioned spaces, it
prevents conventional draft from carrying away heat.


No, just improve the performance.  Tankless heaters are rated in terms of how
much water they can raise to how many degrees.  Typically the spec is in terms
of GPM for a 100 deg rise.  The 2400 can do 3.5 gpm if memory serves.  If the
water is at freezing, a 100 deg rise is still not all that hot.  OTOH, if the
incoming water is at 70 deg, the result is HOT water.  The adjusting knob can
be set on the front to allow more flow and a resulting lower rise.


there

three 100,000 BTU burners.  Room was about 300 sq ft with 10 ft ceiling.
Internal room with no connection to the outside.  A 1 hp vent fan exhausting
the space over the stoves.



It's not hard enough to leave soap feeling slimy but it's not soft like the
well water is here.  Heater was in use for a bit over 10 years.  Same model as
you're looking at.

It ran a heavy duty cycle, as my wash sink had 60 gallon compartments.   The
wash water got changed about every 30 minutes and the sanitizing bath about
once an hour during mealparts.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com  <-- best little blog on the net!
Tellico Plains, Occupied TN
Alcohol, Tobacco & Firearms should be a convenience store, not a government
agency.


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