Exhibit 10.3

                                 PROMISSORY NOTE


$1,100,000.00
                                                               December 21, 2006

Thermodynetics, Inc.
651 Day Hill Road
Windsor, Connecticut  06095
(Hereinafter referred to as "Borrower")

Wachovia Bank, National Association
5 Research Drive
Shelton, Connecticut  06904
(Hereinafter referred to as "Bank")

Borrower  promises  to pay to the order of Bank,  in lawful  money of the United
States of  America,  at its office  indicated  above or  wherever  else Bank may
specify,  the sum of One  Million,  One  Hundred  Thousand  and  No/100  Dollars
($1,100,000.00)  or such sum as may be  advanced  and  outstanding  from time to
time, with interest on the unpaid principal balance at the rate and on the terms
provided  in  this  Promissory  Note  (including  all  renewals,  extensions  or
modifications hereof, this "Note").

LOAN  AGREEMENT.  This Note is subject to the  provisions  of that  certain Loan
Agreement between Bank and Borrower of even date herewith, as modified from time
to time.

LINE OF CREDIT.  Borrower may borrow, repay and reborrow,  and, upon the request
of Borrower,  Bank shall advance and readvance under this Note from time to time
until the maturity  hereof (each an "Advance" and together the  "Advances"),  so
long as the total principal balance  outstanding under this Note at any one time
does not exceed the principal amount stated on the face of this Note, subject to
the  limitations  described in any loan agreement to which this Note is subject.
Bank's  obligation to make Advances under this Note shall  terminate if Borrower
is in Default. As of the date of each proposed Advance, Borrower shall be deemed
to represent that each  representation  made in the Loan Documents is true as of
such date.  30-DAY PAYOUT.  During the term of the Note,  Borrower agrees to pay
down the  outstanding  balance  to a maximum  of $0.00 for 30  consecutive  days
annually.

If Borrower  subscribes to Bank's cash management services and such services are
applicable  to this line of credit,  the terms of such service shall control the
manner in which funds are  transferred  between the  applicable  demand  deposit
account and the line of credit for credit or debit to the line of credit.

USE OF PROCEEDS.  Borrower  shall use the  proceeds of the loan(s)  evidenced by
this Note for the  commercial  purposes of  Borrower,  as  follows:  for working
capital.

SECURITY.  Borrower  has  granted  Bank a security  interest  in the  collateral
described  in the  Loan  Documents,  including,  but not  limited  to,  real and
personal  property  collateral  described in that certain Open-End  Mortgage and
Security Agreement of even date herewith.

INTEREST  RATE.  Interest shall accrue on the unpaid  principal  balance of this
Note from the date hereof at the Bank's Prime Rate, as that rate may change from
time to time in accordance with changes in the Bank's Prime Rate, to be adjusted
daily ("Interest  Rate").  "Bank's Prime Rate" means that rate announced by Bank
from time to time as its prime  rate and is one of several  interest  rate bases
used by Bank.  Bank lends at rates both above and below Bank's  Prime Rate,  and
Borrower  acknowledges  that Bank's Prime Rate is not represented or intended to
be the lowest or most favorable rate of interest offered by Bank.



<PAGE>

DEFAULT  RATE.  In addition to all other  rights  contained  in this Note,  if a
Default  (as  defined  herein)  occurs and as long as a Default  continues,  all
outstanding  Obligations,  other than Obligations  under any swap agreements (as
defined in 11 U.S.C.  ss. 101, as in effect from time to time) between  Borrower
and Bank or its  affiliates,  shall bear  interest at the Interest  Rate plus 3%
("Default Rate").  The Default Rate shall also apply from acceleration until the
Obligations or any judgment thereon is paid in full.

INTEREST AND FEE(S) COMPUTATION  (ACTUAL/360).  Interest and fees, if any, shall
be computed on the basis of a 360-day year for the actual  number of days in the
applicable  period  ("Actual/360   Computation").   The  Actual/360  Computation
determines the annual  effective  interest yield by taking the stated  (nominal)
rate for a year's  period and then  dividing  said rate by 360 to determine  the
daily  periodic  rate to be  applied  for  each  day in the  applicable  period.
Application of the Actual/360  Computation produces an annualized effective rate
exceeding the nominal rate.

REPAYMENT  TERMS.  This Note  shall be due and  payable in  consecutive  monthly
payments  of  accrued  interest  only,  commencing  on  January  21,  2007,  and
continuing  on the same day of each month  thereafter  until fully paid.  In any
event,  all principal and accrued  interest shall be due and payable on December
21, 2008.

AUTOMATIC DEBIT OF CHECKING ACCOUNT FOR LOAN PAYMENT.  Borrower  authorizes Bank
to debit demand deposit  account number  xxxxxxxx or any other account with Bank
(routing number xxxxxx) designated in writing by Borrower, beginning January 21,
2007 for any  payments  due under this Note.  Borrower  further  certifies  that
Borrower  holds  legitimate  ownership  of this account and  preauthorizes  this
periodic debit as part of its right under said ownership.

APPLICATION OF PAYMENTS. Monies received by Bank from any source for application
toward payment of the Obligations  shall be applied to accrued interest and then
to principal.  If a Default occurs,  monies may be applied to the Obligations in
any manner or order deemed appropriate by Bank.

If any  payment  received  by Bank under this Note or other  Loan  Documents  is
rescinded,  avoided or for any reason  returned  by Bank  because of any adverse
claim or threatened  action,  the returned  payment  shall remain  payable as an
obligation  of all persons  liable  under this Note or other Loan  Documents  as
though such payment had not been made.

DEFINITIONS. LOAN DOCUMENTS. The term "Loan Documents", as used in this Note and
the other Loan Documents, refers to all documents executed in connection with or
related to the loan  evidenced  by this Note and any prior notes which  evidence
all or any portion of the loan evidenced by this Note, and any letters of credit
issued  pursuant  to any loan  agreement  to which  this  Note is  subject,  any
applications  for such  letters of credit and any other  documents  executed  in
connection therewith or related thereto, and may include,  without limitation, a
commitment letter that survives closing, a loan agreement,  this Note,  guaranty
agreements,  security agreements,  security  instruments,  financing statements,
mortgage  instruments,  any  renewals  or  modifications,  whenever  any  of the
foregoing are executed,  but does not include swap  agreements (as defined in 11
U.S.C.  ss.  101,  as in  effect  from  time to  time).  OBLIGATIONS.  The  term
"Obligations",  as used in this Note and the other Loan Documents, refers to any
and  all  indebtedness  and  other   obligations  under  this  Note,  all  other
obligations under any other Loan Document(s), and all obligations under any swap
agreements  (as  defined in 11 U.S.C.  ss.  101, as in effect from time to time)
between Borrower and Bank, or its affiliates,  whenever executed.  CERTAIN OTHER
TERMS.  All terms  that are used but not  otherwise  defined  in any of the Loan
Documents shall have the definitions provided in the Uniform Commercial Code.

LATE CHARGE.  If any payments  are not timely made,  Borrower  shall also pay to
Bank a late  charge  equal to 5% of each  payment  past due for 10 or more days.
This late charge shall not apply to payments due at maturity or by  acceleration
hereof,  unless such late  payment is in an amount not greater  than the highest
periodic payment due hereunder.



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<PAGE>

Acceptance by Bank of any late payment without an accompanying late charge shall
not be deemed a waiver of Bank's right to collect such late charge or to collect
a late charge for any subsequent late payment received.

ATTORNEYS'  FEES AND OTHER  COLLECTION  COSTS.  Borrower shall pay all of Bank's
reasonable  expenses  actually  incurred  to  enforce  or  collect  any  of  the
Obligations including, without limitation, reasonable arbitration,  paralegals',
attorneys'  and  experts'  fees  and  expenses,  whether  incurred  without  the
commencement of a suit, in any trial, arbitration, or administrative proceeding,
or in any appellate or bankruptcy proceeding.

USURY. If at any time the effective interest rate under this Note would, but for
this  paragraph,  exceed the maximum  lawful rate,  the effective  interest rate
under this Note shall be the maximum  lawful  rate,  and any amount  received by
Bank in excess of such rate shall be applied to  principal  and then to fees and
expenses, or, if no such amounts are owing, returned to Borrower.

DEFAULT.  If any of the following occurs, a default  ("Default") under this Note
shall  exist:  NONPAYMENT;  NONPERFORMANCE.  The  failure  of timely  payment or
performance  of the  Obligations  or  Default  under this Note or any other Loan
Documents.  FALSE WARRANTY.  A warranty or representation made or deemed made in
the Loan  Documents or furnished  Bank in connection  with the loan evidenced by
this  Note  proves  materially  false,  or if of a  continuing  nature,  becomes
materially  false.  CROSS DEFAULT.  At Bank's option,  any default in payment or
performance of any obligation under any other loans,  contracts or agreements of
Borrower, any Subsidiary or Affiliate of Borrower, any general partner of or the
holder(s)  of the  majority  ownership  interests  of Borrower  with Bank or its
affiliates  ("Affiliate" shall have the meaning as defined in 11 U.S.C. ss. 101,
as in  effect  from  time to time,  except  that the  term  "Borrower"  shall be
substituted for the term "Debtor" therein;  "Subsidiary" shall mean any business
in which  Borrower  holds,  directly or  indirectly,  a  controlling  interest).
CESSATION;  BANKRUPTCY. The death of, appointment of a guardian for, dissolution
of, termination of existence of, loss of good standing status by, appointment of
a receiver for,  assignment for the benefit of creditors of, or  commencement of
any bankruptcy or insolvency proceeding by or against Borrower, its Subsidiaries
or  Affiliates,  if any,  or any  general  partner  of or the  holder(s)  of the
majority  ownership  interests of Borrower,  or any party to the Loan Documents.
MATERIAL CAPITAL STRUCTURE OR BUSINESS ALTERATION. Without prior written consent
of Bank, (i) a material alteration in the kind or type of Borrower's business or
that of  Borrower's  Subsidiaries  or  Affiliates,  if  any;  (ii)  the  sale of
substantially  all of the  business  or assets of  Borrower,  any of  Borrower's
Subsidiaries or Affiliates or any guarantor, or a material portion (10% or more)
of such  business  or assets if such a sale is outside  the  ordinary  course of
business of Borrower,  or any of  Borrower's  Subsidiaries  or Affiliates or any
guarantor,  or more than 50% of the  outstanding  stock or voting power of or in
any such entity in a single  transaction or a series of transactions;  (iii) the
acquisition of  substantially  all of the business or assets or more than 50% of
the  outstanding  stock or voting power of any other entity;  or (iv) should any
Borrower or any of Borrower's  Subsidiaries or Affiliates or any guarantor enter
into any merger or  CONSOLIDATION.  MATERIAL ADVERSE CHANGE.  Bank determines in
good faith, in its sole reasonable discretion, that the prospects for payment or
performance of the Obligations  are materially  impaired or there has occurred a
material  adverse change in the business or prospects of Borrower,  financial or
otherwise.

REMEDIES  UPON  DEFAULT.  If a  Default  occurs  under  this  Note  or any  Loan
Documents,  Bank may at any time thereafter,  take the following  actions:  BANK
LIEN.  Foreclose  its  security  interest  or lien  against  Borrower's  deposit
accounts and investment  property  without  notice.  ACCELERATION  UPON DEFAULT.
Accelerate  the  maturity of this Note and, at Bank's  option,  any or all other
Obligations,  other than Obligations under any swap agreements (as defined in 11
U.S.C.  ss. 101, as in effect from time to time)  between  Borrower and Bank, or
its  affiliates,  which  shall be due in  accordance  with and  governed  by the
provisions  of said swap  agreements;  whereupon  this Note and the  accelerated
Obligations  shall be immediately  due and payable;  provided,  however,  if the
Default is based upon a  bankruptcy  or  insolvency  proceeding  commenced by or
against  Borrower or any  guarantor  or endorser of this Note,  all  Obligations
(other than  Obligations  under any swap  agreement as  referenced  above) shall
automatically  and  immediately  be due and  payable.  CUMULATIVE.  Exercise any
rights and remedies as provided under the Note and other Loan  Documents,  or as
provided by law or equity.



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<PAGE>

FINANCIAL AND OTHER INFORMATION. Borrower shall deliver to Bank such information
as Bank may reasonably request from time to time,  including without limitation,
financial   statements  and  information   pertaining  to  Borrower's  financial
condition. Such information shall be true, complete, and accurate.

WAIVERS AND AMENDMENTS. No waivers, amendments or modifications of this Note and
other Loan  Documents  shall be valid unless in writing and signed by an officer
of Bank. No waiver by Bank of any Default shall operate as a waiver of any other
Default or the same  Default on a future  occasion.  Neither the failure nor any
delay on the part of Bank in exercising any right,  power,  or remedy under this
Note and other Loan  Documents  shall operate as a waiver  thereof,  nor shall a
single or  partial  exercise  thereof  preclude  any other or  further  exercise
thereof or the exercise of any other right, power or remedy.

Except to the extent  otherwise  provided by the Loan Documents or prohibited by
law,  each  Borrower  and each  other  person  liable  under  this  Note  waives
presentment,  protest,  notice  of  dishonor,  demand  for  payment,  notice  of
intention to accelerate maturity,  notice of acceleration of maturity, notice of
sale and all other notices of any kind.  Further,  each agrees that Bank may (i)
extend,  modify or renew this Note or make a novation of the loan  evidenced  by
this Note,  and/or (ii) grant releases,  compromises or indulgences with respect
to any  collateral  securing this Note, or with respect to any Borrower or other
person liable under this Note or any other Loan Documents, all without notice to
or consent of each  Borrower and other such person,  and without  affecting  the
liability of each Borrower and other such person; provided, Bank may not extend,
modify or renew this Note or make a novation of the loan  evidenced by this Note
without  the  consent of the  Borrower,  or if there is more than one  Borrower,
without the consent of at least one Borrower;  and further provided, if there is
more than one  Borrower,  Bank may not enter  into a  modification  of this Note
which increases the burdens of a Borrower without the consent of that Borrower.

MISCELLANEOUS  PROVISIONS.  ASSIGNMENT.  This Note and the other Loan  Documents
shall  inure to the  benefit  of and be  binding  upon  the  parties  and  their
respective  heirs,  legal  representatives,   successors  and  assigns.   Bank's
interests in and rights under this Note and the other Loan  Documents are freely
assignable,  in whole or in part, by Bank. In addition,  nothing in this Note or
any of the other Loan  Documents  shall prohibit Bank from pledging or assigning
this Note or any of the other  Loan  Documents  or any  interest  therein to any
Federal  Reserve  Bank.  Borrower  shall not  assign  its  rights  and  interest
hereunder without the prior written consent of Bank, and any attempt by Borrower
to assign without Bank's prior written  consent is null and void. Any assignment
shall not  release  Borrower  from the  Obligations.  APPLICABLE  LAW;  CONFLICT
BETWEEN  DOCUMENTS.  This Note and, unless otherwise  provided in any other Loan
Document,  the other Loan Documents shall be governed by and  interpreted  under
the laws of the state named in Bank's  address on the first page hereof  without
regard to that state's  conflict of laws  principles.  If the terms of this Note
should  conflict with the terms of any loan agreement or any  commitment  letter
that  survives  closing,  the  terms  of this  Note  shall  control.  BORROWER'S
ACCOUNTS.  Except as prohibited by law, Borrower grants Bank a security interest
in all of Borrower's  deposit  accounts and marketable  securities with Bank and
any of its affiliates.  SWAP  AGREEMENTS.  All swap agreements (as defined in 11
U.S.C.  ss. 101, as in effect from time to time), if any,  between  Borrower and
Bank or its  affiliates  are  independent  agreements  governed  by the  written
provisions of said swap agreements,  which will remain in full force and effect,
unaffected by any repayment,  prepayment,  acceleration,  reduction, increase or
change in the terms of this Note, except as otherwise expressly provided in said
written swap  agreements,  and any payoff  statement  from Bank relating to this
Note  shall not  apply to said swap  agreements  except as  otherwise  expressly
provided in such payoff statement. JURISDICTION.  Borrower irrevocably agrees to
non-exclusive  personal jurisdiction in the state identified as the Jurisdiction
above.  SEVERABILITY.  If any  provision  of  this  Note  or of the  other  Loan
Documents  shall be prohibited or invalid under  applicable  law, such provision
shall be ineffective  but only to the extent of such  prohibition or invalidity,
without invalidating the remainder of such provision or the remaining provisions
of this Note or other such document.  NOTICES.  Any notices to Borrower shall be
sufficiently  given,  if in writing and mailed or  delivered  to the  Borrower's
address shown above or such other address as provided hereunder,  with a copy to
Kenneth B. Lerman,  P.C. 651 Day Hill Road,  Windsor,  Connecticut  06095 and to
Bank,  if in  writing  and  mailed  or  delivered  to  Wachovia  Bank,  National
Association,  Mail Code VA7628, P. O. Box 13327,  Roanoke,  VA 24040 or Wachovia
Bank,  National  Association,  Mail  Code  VA7628,  10 South  Jefferson  Street,
Roanoke, VA 24011 or such other address as Bank may specify in writing from time
to


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<PAGE>

time.  Notices to Bank must  include the mail code.  In the event that  Borrower
changes  Borrower's  address at any time prior to the date the  Obligations  are
paid in full,  Borrower agrees to promptly give written notice of said change of
address by registered or certified mail, return receipt  requested,  all charges
prepaid.  PLURAL;  CAPTIONS.  All  references in the Loan Documents to Borrower,
guarantor,  person,  document or other nouns of reference mean both the singular
and  plural  form,  as the case may be,  and the term  "person"  shall  mean any
individual,  person or entity.  The captions contained in the Loan Documents are
inserted for convenience only and shall not affect the meaning or interpretation
of the Loan Documents.  ADVANCES.  Bank may, in its sole discretion,  make other
advances which shall be deemed to be advances  under this Note,  even though the
stated  principal  amount  of this  Note may be  exceeded  as a result  thereof.
POSTING OF PAYMENTS.  All payments  received  during normal  banking hours after
2:00 p.m.  local time at the office of Bank first  shown  above  shall be deemed
received at the opening of the next banking day. JOINT AND SEVERAL  OBLIGATIONS.
If there is more than one  Borrower,  each is jointly  and  severally  obligated
together with all other parties  obligated for the Obligations.  FEES AND TAXES.
Borrower  shall  promptly pay all  documentary,  intangible  recordation  and/or
similar taxes on this  transaction  whether  assessed at closing or arising from
time to time.  LIMITATION ON LIABILITY;  WAIVER OF PUNITIVE DAMAGES. EACH OF THE
PARTIES  HERETO,  INCLUDING  BANK  BY  ACCEPTANCE  HEREOF,  AGREES  THAT  IN ANY
JUDICIAL,  MEDIATION  OR  ARBITRATION  PROCEEDING  OR ANY  CLAIM OR  CONTROVERSY
BETWEEN OR AMONG THEM THAT MAY ARISE OUT OF OR BE IN ANY WAY CONNECTED WITH THIS
AGREEMENT,  THE LOAN  DOCUMENTS OR ANY OTHER  AGREEMENT  OR DOCUMENT  BETWEEN OR
AMONG THEM OR THE OBLIGATIONS  EVIDENCED  HEREBY OR RELATED HERETO,  IN NO EVENT
SHALL ANY PARTY HAVE A REMEDY OF, OR BE LIABLE TO THE OTHER FOR,  (1)  INDIRECT,
SPECIAL OR CONSEQUENTIAL  DAMAGES OR (2) PUNITIVE OR EXEMPLARY DAMAGES.  EACH OF
THE PARTIES HEREBY  EXPRESSLY WAIVES ANY RIGHT OR CLAIM TO PUNITIVE OR EXEMPLARY
DAMAGES  THEY MAY HAVE OR WHICH MAY ARISE IN THE FUTURE IN  CONNECTION  WITH ANY
SUCH  PROCEEDING,  CLAIM  OR  CONTROVERSY,  WHETHER  THE  SAME  IS  RESOLVED  BY
ARBITRATION,  MEDIATION,  JUDICIALLY OR OTHERWISE.  PATRIOT ACT NOTICE.  To help
fight the funding of  terrorism  and money  laundering  activities,  Federal law
requires all financial  institutions to obtain,  verify,  and record information
that identifies each person who opens an account.  For purposes of this section,
account shall be understood to include loan accounts. FINAL AGREEMENT. This Note
and the other Loan Documents  represent the final agreement  between the parties
and may not be contradicted by evidence of prior,  contemporaneous or subsequent
oral agreements of the parties.  There are no unwritten oral agreements  between
the parties.

WAIVER OF JURY  TRIAL.  TO THE  EXTENT  PERMITTED  BY  APPLICABLE  LAW,  EACH OF
BORROWER  BY  EXECUTION  HEREOF  AND  BANK  BY  ACCEPTANCE  HEREOF,   KNOWINGLY,
VOLUNTARILY AND INTENTIONALLY  WAIVES ANY RIGHT EACH MAY HAVE TO A TRIAL BY JURY
IN RESPECT OF ANY LITIGATION BASED ON, OR ARISING OUT OF, UNDER OR IN CONNECTION
WITH THIS NOTE, THE LOAN DOCUMENTS OR ANY AGREEMENT  CONTEMPLATED TO BE EXECUTED
IN  CONNECTION  WITH THIS NOTE,  OR ANY COURSE OF  CONDUCT,  COURSE OF  DEALING,
STATEMENTS  (WHETHER  VERBAL OR  WRITTEN)  OR ACTIONS OF ANY PARTY WITH  RESPECT
HERETO.  THIS  PROVISION IS A MATERIAL  INDUCEMENT  TO BANK TO ACCEPT THIS NOTE.
EACH OF THE PARTIES AGREES THAT THE TERMS HEREOF SHALL SUPERSEDE AND REPLACE ANY
PRIOR AGREEMENT RELATED TO ARBITRATION OF DISPUTES BETWEEN THE PARTIES CONTAINED
IN ANY LOAN DOCUMENT OR ANY OTHER DOCUMENT OR AGREEMENT  HERETOFORE  EXECUTED IN
CONNECTION  WITH,  RELATED  TO OR  BEING  REPLACED,  SUPPLEMENTED,  EXTENDED  OR
MODIFIED BY, THIS NOTE.

CONNECTICUT  PREJUDGMENT  REMEDY  WAIVER.  EACH BORROWER  ACKNOWLEDGES  THAT THE
TRANSACTIONS  REPRESENTED  BY THIS NOTE ARE COMMERCIAL  TRANSACTIONS  AND HEREBY
VOLUNTARILY  AND  KNOWINGLY  WAIVES  ANY  RIGHTS  TO NOTICE  OF AND  HEARING  ON
PREJUDGMENT  REMEDIES UNDER CHAPTER 903A OF THE CONNECTICUT  GENERAL STATUTES OR
OTHER  STATUTES  AFFECTING  PREJUDGMENT  REMEDIES,  AND  AUTHORIZES  THE  BANK'S
ATTORNEY TO ISSUE A WRIT FOR A PREJUDGMENT REMEDY WITHOUT COURT ORDER,  PROVIDED
THE COMPLAINT SHALL SET FORTH A COPY OF THIS WAIVER.



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<PAGE>

IN WITNESS  WHEREOF,  Borrower,  on the day and year first  above  written,  has
caused this Note to be duly executed under seal.

                                    Thermodynetics, Inc.


                                    By: /s/ JOHN F. FERRARO           (SEAL)
                                        -----------------------------
                                            John F. Ferraro, Chairman


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