April 11, 2017

Via EDGAR

Securities and Exchange Commission

Division of Corporation Finance

100 F Street, NE

Washington, DC 20549

Attention:    Ms. Pamela Long, Assistant Director

Ms. Kate McHale, Staff Attorney

Ms. Asia Timmons-Pierce, Staff Attorney

Mr. Dale Welcome, Staff Accountant

Ms. Anne McConnell, Staff Accountant

Re:     Tecogen Inc.

Registration Statement on Form S-4

Originally Filed on December 21, 2016

Amendment No. 3 Filed April 11, 2017

File No. 333-215231

Ladies and Gentlemen:

In accordance with Rule 461 under the Securities Act of 1933, as amended, the undersigned respectfully requests that the effective date for the Registration Statement referred to above be accelerated so that it will be declared effective at 4:00 PM, April 12, 2017 or as soon thereafter as is practicable.

Very truly yours,

Tecogen Inc.

By: /s/ David A. Garrison

David A. Garrison

Chief Financial Officer