NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/sci/engr/mech/692

Text File | 1992-12-22 | 1.9 KB | 38 lines

Newsgroups: sci.engr.mech
Path: sparky!uunet!mcsun!sunic!news.lth.se!pollux.lu.se!news
From: [e-mail] (Johan Winberg)
Subject: re: Domestic hot water heaters - oil vs. electric
Message-ID: <[e-mail]>
Sender: [e-mail] (Owner of news files)
Nntp-Posting-Host: jwi.vok.lth.se
Organization: Lund Institute of Technology, Dept of Heat and Power Eng.
References: <[e-mail]>
Date: Tue, 22 Dec 1992 12:05:59 GMT
Lines: 25

In article <[e-mail]> [e-mail] (Doug Bliss) writes:
>I have heard that oil-fired domestic hot water heaters are very ineffecient (
>20-30% efficiency) compared to electric hot water heaters.  Does anyone have
>any information on efficiencies and heat losses expected from these types of
>hot water heaters?

I think your figures are too low! Of course they depend on the system
and how you define efficiency...

It is true that oil (and other) fired heaters are less efficient than
electric heaters, when some kind of total efficiency is defined.
This efficiency loss is caused by the flue losses, heat losses from
the burner itself and stand-still heat losses, i.e. losses which aren't
there on electric water heaters. The heat losses from the storage tank
should be about the same for the different types (50-400 W for a typical
one-family house water heater, i.e. with a volume of 100-300 l). In
Sweden, fired systems are most often built together with the radiator
circuit and I think some figures for total year efficiency is 80-85%
for a non-condensing furnace, >100% for a condensing furnace and 99%
for an electric heater.
_________________________________________________________________
Johan Winberg                  Dept. of Heat & Power Engineering
[e-mail]           Lund Institute of Technology
vox: [phone]              P.O. Box 118
fax: [phone]              S-221 00 LUND, Sweden