boat in question and how often the compressor cycles. Please note I am not
talking about the air handler fan, but the actual

to the fact an 1100 watt oil filled Delonghi heater was sufficient to heat
an 1200 square foot mobile.

Exactly, Arild.  Just as in your example, the fact that the water heater
temperature stabilizes at 57 degrees in the Ketch in moderate winter
overnight temperatures ( 20s at night, hi 30s to low 40s during the day)
supports the concept that heat gain balances heat loss within the
environmental operating range of the system.  I make no claims about the
thermal losses of the boats involved.  I simply state - again - that there
is a set of different boats in Baltimore in the the Mid-Atlantic Region for
which this system works just fine.  So, we're left only with five years of
those empirical facts.

Since my truthfulness, skills in observation, skills in description, or all
three, have been questioned, here's what I'll do.  Henry had the original
question.  Because he lives in the Baltimore area, what I'll do for him, and
for him alone, is this: if he'd like to see these installations, I'll make
the contacts necessary to have him see them.  That way, he get's to make up
his own mind, based on his situation and his first hand assessment.  Henry,
if interested, please contact me off-list!

Jim Healy aboard Sanctuary,
currently at Charlotte Harbor, Punta Gorda, FL
AGLCA # 3767
MTOA # 3436

Jim,
I appreciate your postings and information.
Our boat is a 47' trawler, 16' beam with raised pilothouse/watch cabin.
We have two 16kw and a 12kw A/C unit.  I have been advised I will need
something in the 40-44kw of heat. The A/C units run off a 1200 gallon pump.
When I looked at Home Depot, they had a 6 gallon and a 20 gallon water
heater.  The 20 gallon unit draws 17 amps.
With that said, I am leaning towards a hydronic system.  We met with an
installer today and looked at several of the fan blowers, exhaust system,
etc.
What been trying to keep the boat warm with 2 1500w oil heaters, 2
1500w element heaters which is keeping the boat in the 50-60s.  We received
an electric bill from the marine for the month of November of $1,252.00.

 Thank you for your help,
         Henry

-----Original Message-----
From: trawlers-and-trawlering-bounces@lists.samurai.com
[mailto:trawlers-and-trawlering-bounces@lists.samurai.com] On Behalf Of Jim
Healy
Sent: Sunday, December 14, 2008 4:02 PM
To: trawlers-and-trawlering@lists.samurai.com
Subject: Re: T&T: Hurricane, Webasto or Espar

boat in question and how often the compressor cycles. Please note I am not
talking about the air handler fan, but the actual

to the fact an 1100 watt oil filled Delonghi heater was sufficient to heat
an 1200 square foot mobile.

Exactly, Arild.  Just as in your example, the fact that the water heater
temperature stabilizes at 57 degrees in the Ketch in moderate winter
overnight temperatures ( 20s at night, hi 30s to low 40s during the day)
supports the concept that heat gain balances heat loss within the
environmental operating range of the system.  I make no claims about the
thermal losses of the boats involved.  I simply state - again - that there
is a set of different boats in Baltimore in the the Mid-Atlantic Region for
which this system works just fine.  So, we're left only with five years of
those empirical facts.

Since my truthfulness, skills in observation, skills in description, or all
three, have been questioned, here's what I'll do.  Henry had the original
question.  Because he lives in the Baltimore area, what I'll do for him, and
for him alone, is this: if he'd like to see these installations, I'll make
the contacts necessary to have him see them.  That way, he get's to make up
his own mind, based on his situation and his first hand assessment.  Henry,
if interested, please contact me off-list!

Jim Healy aboard Sanctuary,
currently at Charlotte Harbor, Punta Gorda, FL
AGLCA # 3767
MTOA # 3436

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Whoa folks,
in my response to Jim, I did not mean to question or impugn any of Jim's
following concerns:

Please let me make the following points:

1. I am sure that Jim is truthful, and further more offered his
   observations with every intent to help the readers.
2. I have no doubt that he saw a system plumbed/constructed as he
   stated, and I don't doubt that it was keeping the boats he saw it in
   sufficiently warm and not freezing up the tank.
3. I believe that he has described it very well, and I fully understand
   what they are doing.  It is just that I believe there is a much more
   cost effective way to solve the problem the live aboard boat owners set
   out to solve.  Hence the following, also meant to be constructive.

Here are the only points that I would make:

1. The tank system can not help but be less efficient than direct
   resistive heating, --- because --- it is in fact a system that solely
   relies on resistive heating.  Namely the resistive heater in the tank.
   That is where all the heat can and does come from, period.  The rest of
   the system is just if anything a slight efficiency reducer.

2. No doubt the system causes the heat pump to run for a shorter period
   of time than it would with cold seawater.  The 1500 watts of the tank
   heater is apparently more than enough to heat the boats.  However, why
   run the heat pump at all?  That is the key question.  One poster implied
   that it is due to the greater heat per kilowatt that heat pumps give
   relative to resistive heating.  That is only true when the heat pump has
   access to nearly infinite amounts of water with useful heat.  I
   explained this in my original posting, that heat pumps transport and
   concentrate available heat, but do not create heat.  When you are in a
   closed system, the ONLY significant heat there is available to the heat
   pump is that which is put into the water from the resistive element.
   Otherwise, you would have found a way to amplify heat and solved our
   national energy crisis.

3. I do believe that it does not freeze the tank, for one very simple
   reason.  That is that all heat pumps vary efficiency as the water they
   are extracting heat from approaches the setting of the system evaporator
   temperature.  When they are equal, there is zero efficiency, so the
   system will pull the tank water down to some temperature where an
   equilibrium is reached.  As the water falls in temperature, the heat
   pump efficiency progressively reduces its ability to extract BTUs from
   the water, till it reaches a point that it is capable of extracting
   exactly the same amount of heat from the water as is being put into the
   water.  This will vary from system to system, but the 47 deg. F
   mentioned sounds very right to me for a typical system. For this reason
   (constant addition of heat), the system will never freeze.  The perfect
   example of the potential for inefficiency of heat pumps is the whole
   driver behind the folks that devised the tank system.  They no doubt
   found that in the winter the heat pump was eating its normal around 12
   amps (or so) at 120 volts (1440 watts) and providing virtually no (or
   very little) heat.  Here there efficiency was negative.  On the other
   hand in early fall, when the water was say 55 deg. F, during the cold
   night they could get a lot more heat from the heat pump amperage drawn
   than a resistive element would have given them at the same amperage.
   These are the boundary conditions.

4. Remember that heat pumps do not create heat, they only transport
   it.  Now think about it:  (a) the only heat available for the boat is
   from the resistive heater in the tank. (b) delivering it from the tank
   to the A/C blower requires that the compressor and the pump be running
   to transport the heat from the tank to the forced air (via the heat
   exchanger). (c) all the time this compressor and pump are running, they
   are eating about 1500 watts (1.5 kW) and contributing very little heat
   for those watts -- all they are really doing is just transporting the
   heat that the resistive element already made.

5. If you are going to use resistive heat anyway, rather than put it in
   the tank, just install proper heat strips in the A/C unit.  When heat is
   called for, it is nearly immediately available (strip heats up very
   fast), and only the fan is running in the A/C unit thereby dropping the
   additional current demand down to only likely about 2 to 3 amps for the
   fan, since the compressor and the pump are not needed.

6. I do not know of any instance where there has ever been a fire from
   the properly engineered heater strips internal to a commercial marine
   A/C system, so I doubt that there is much of a safety argument against them.

Now, I know what would happen if this logic is brought to the users of
the system.  It would be instantly dismissed.  They are convinced that
they are getting a benefit, and would give the "well, I don't know about
all that stuff - but I just know the system works".  The last thing they
want to hear, and therefor will not believe, is that "yes it works but
not as well as it could and costs more than it should, with more
complication than necessary including compressor wear and tear, and
circulating pump wear and tear".  No doubt they went direct from a heat
pump system that in winter would not heat their boat to comfort levels
-- to a hodge-podge of various ceramic heaters, etc. that were a real
aggravation -- to this tank system, which seemed to them like Valhalla.
I will be willing to bet that not one of them ever tried the heater
strips heating in the A/C system.

Ken Bloomfield
Tellico Lady
50' Marine Trader

Ken,

I was not referring to you, I assure you. In this discussion, I've had a
number of unfortunate off-list exchanges from one individual who has
challenged my truthfulness, intelligence and "pigheadedness" for not simply
admitting I invented the whole thing because it plainly cannot work.  He's a
very bright guy with a very poor sense of interpersonal relationships and
effective approach to getting to a mutual understanding.  Perhaps email is
just not his media.

Prior to this discussion, I, personally, was not aware of the heat strips to
which you and Arild refer.  I'm as sure as I can be that the folks I've
referenced are also not aware of them.  The designer of the supplemental
system is a retired Coastie who now makes his "post retirement" living as an
HVAC technician, so I would ass/u/me he is aware of them, but I can't be
sure until I see him.  I don't know whether or not they could be retrofit
into older a/c units, and that may be why he didn't use/recommend them.  My
system, for instance, is an older (1988) MarinaAir, which has the old style
rotary control panel with expansion tube for temperature control.  In my OEM
installation, I am not able to run the fan separately from the
pump/compressor, so getting heat from a heat strip in the air plenum would
involve some invention to avoid running the pump/compressor.  I do not know
if the same constraint applied to my references at the time their
supplemental systems were installed.  I do know a company called Climate
Controls in Maryland makes a digital replacement for the old style
controllers, which I bought at the Annapolis Boat Show, have onboard, and
plan to install on my system after the first of the year.  That will enable
me to run the fan alone, and with a relay, would allow the use of the heat
strips.  When we lived in Indiana, we had a heat pump for the house.  It had
a 25KW electric furnace atop the air handler to supplement the heat pump
when winter temperatures where below 33 degrees and the heat pump's
efficiency fell off, so the concept is clearly viable and well established.
It also had a 400A service entrance, a tiche more than my boat's 2x30A shore
power.

The reason for installing the supplemental system I've described in the
first place was to get the advantages of air and heat distribution
throughout the boat.  In every case I'm aware of, preceding attempts to heat
these boats had involved oil filled and ceramic cube type heaters.  They
result in hot and cold spots, and distributing the heat through out the boat
was a kludge not suitable for life as a liveaboard.  Using the heat pump's
fan distributed the heat better, but the poor efficiency of water at 40
degrees and below meant the compressor ran continuously, which is both
expensive and very hard on the compressor.  So, the supplemental system made
the compressor more efficient. distributed the heat and reduced it's duty
cycle significantly.

I agree with all of the points you've raised in your note.  However, w/r/t
your closing paragraph, I do think my compatriots will all be interested
in the introduction of heat strips into the equation.  I will be with them
after the holidays.  We stop there on our way back to Florida, and you may
rest assured, Ken, I will mention it to them!!!

I appreciate your interest and your welcoming, encouraging approach.  Makes
me much more willing to engage.

Jim Healy aboard Sanctuary,
currently at Charlotte Harbor, Punta Gorda, FL
AGLCA # 3767
MTOA # 3436

-----Original Message-----
From: Ken Bloomfield [mailto:khtb@bellsouth.net]
Sent: Monday, December 15, 2008 12:57 PM
To: Jim Healy
Cc: trawlers-and-trawlering@lists.samurai.com
Subject: Re: Re: T&T: Hurricane, Webasto or Espar

Whoa folks,
in my response to Jim, I did not mean to question or impugn any of Jim's
following concerns:

Please let me make the following points:

1. I am sure that Jim is truthful, and further more offered his
   observations with every intent to help the readers.
2. I have no doubt that he saw a system plumbed/constructed as he stated,
   and I don't doubt that it was keeping the boats he saw it in sufficiently
   warm and not freezing up the tank.
3. I believe that he has described it very well, and I fully understand
   what they are doing.  It is just that I believe there is a much more cost
   effective way to solve the problem the live aboard boat owners set out to
   solve.  Hence the following, also meant to be constructive.

Here are the only points that I would make:

1. The tank system can not help but be less efficient than direct resistive
   heating, --- because --- it is in fact a system that solely relies on
   resistive heating.  Namely the resistive heater in the tank.
   That is where all the heat can and does come from, period.  The rest of the
   system is just if anything a slight efficiency reducer.

2. No doubt the system causes the heat pump to run for a shorter period of
   time than it would with cold seawater.  The 1500 watts of the tank heater is
   apparently more than enough to heat the boats.  However, why run the heat
   pump at all?  That is the key question.  One poster implied that it is due
   to the greater heat per kilowatt that heat pumps give relative to resistive
   heating.  That is only true when the heat pump has access to nearly infinite
   amounts of water with useful heat.  I explained this in my original posting,
   that heat pumps transport and concentrate available heat, but do not create
   heat.  When you are in a closed system, the ONLY significant heat there is
   available to the heat pump is that which is put into the water from the
   resistive element.
   Otherwise, you would have found a way to amplify heat and solved our
   national energy crisis.

3. I do believe that it does not freeze the tank, for one very simple
   reason.  That is that all heat pumps vary efficiency as the water they are
   extracting heat from approaches the setting of the system evaporator
   temperature.  When they are equal, there is zero efficiency, so the system
   will pull the tank water down to some temperature where an equilibrium is
   reached.  As the water falls in temperature, the heat pump efficiency
   progressively reduces its ability to extract BTUs from the water, till it
   reaches a point that it is capable of extracting exactly the same amount of
   heat from the water as is being put into the water.  This will vary from
   system to system, but the 47 deg. F mentioned sounds very right to me for a
   typical system. For this reason (constant addition of heat), the system will
   never freeze.  The perfect example of the potential for inefficiency of heat
   pumps is the whole driver behind the folks that devised the tank system.
   They no doubt found that in the winter the heat pump was eating its normal
   around 12 amps (or so) at 120 volts (1440 watts) and providing virtually no
   (or very little) heat.  Here there efficiency was negative.  On the other
   hand in early fall, when the water was say 55 deg. F, during the cold night
   they could get a lot more heat from the heat pump amperage drawn than a
   resistive element would have given them at the same amperage.
   These are the boundary conditions.

4. Remember that heat pumps do not create heat, they only transport it.
   Now think about it:  (a) the only heat available for the boat is from the
   resistive heater in the tank. (b) delivering it from the tank to the A/C
   blower requires that the compressor and the pump be running to transport the
   heat from the tank to the forced air (via the heat exchanger). (c) all the
   time this compressor and pump are running, they are eating about 1500 watts
   (1.5 kW) and contributing very little heat for those watts -- all they are
   really doing is just transporting the heat that the resistive element
   already made.

5. If you are going to use resistive heat anyway, rather than put it in the
   tank, just install proper heat strips in the A/C unit.  When heat is called
   for, it is nearly immediately available (strip heats up very fast), and only
   the fan is running in the A/C unit thereby dropping the additional current
   demand down to only likely about 2 to 3 amps for the fan, since the
   compressor and the pump are not needed.

6. I do not know of any instance where there has ever been a fire from the
   properly engineered heater strips internal to a commercial marine A/C
   system, so I doubt that there is much of a safety argument against them.

Now, I know what would happen if this logic is brought to the users of the
system.  It would be instantly dismissed.  They are convinced that they are
getting a benefit, and would give the "well, I don't know about all that
stuff - but I just know the system works".  The last thing they want to
hear, and therefor will not believe, is that "yes it works but not as well
as it could and costs more than it should, with more complication than
necessary including compressor wear and tear, and circulating pump wear and
tear".  No doubt they went direct from a heat pump system that in winter
would not heat their boat to comfort levels
-- to a hodge-podge of various ceramic heaters, etc. that were a real
aggravation -- to this tank system, which seemed to them like Valhalla.
I will be willing to bet that not one of them ever tried the heater strips
heating in the A/C system.

Ken Bloomfield
Tellico Lady
50' Marine Trader

I don't know whether or not they could be retrofit

I bought at the Annapolis Boat Show, have onboard, and

of the heat strips.

REPLY
Any system can be retro fitted. It all depends on how much design effort
you are able and willing to invest in the project.

If you have to work from scratch, look into ceramic heaters since these
genrally provide better fire safety than resistive heater coils with
glowing wires. The Ceramic stack has air passing through it and a hi limit
klixon thermo disc type safety. (this is essential if you use wooden
panels for air ducting. If air flow is restricted by plugged filter or a
defective fan or control circuit, the disk goes open circuit  preventing
the ceramic stack from getting power. If you can't find them elsewhere or
want to do it low cost(DIY)  cannibalize an old microwave or two. All the
ones I have disassembled had several thermo disc devices inside.  I
scrounged a water cooler that had a failure and fixed it with a thermo
disc from a microwave.  The Water cooler has now been working in my
kitchen for the past year. The same micro wave also gave me a programmable
timer with keyboard for some shop projects.

Even if you do not buy the fancy HVAC controller you can install a by-pass
switch for just the fan portion of your air handler. The fan runs most of
the time and he thermo stat cycles the heater element.

Jim wrote:

involved oil filled and ceramic cube type heaters. They result in hot
and cold spots, and distributing the heat through out the boat was a
kludge not suitable for life as a liveaboard. Using the heat pump's fan
distributed the heat better,

REPLY
Sounds more like insufficient air flow and too small fans than any other
reasons.
BTW  - electric furnaces for homes work exactly the same way. Resistive
heater coils are inserted into the air duct plenum and a large enough fan
assembly blow the air through the duct work.

regards
Arild