Furnace blower re-wire? [RE-wrenches]

[Travis Creswell, Ozark Solar]

Hey Geoff,

I'm not sure I've got enough information to answer your question, sorry for
my ignorance.  But that's rarely stopped from talking before...

Looks like he has a heat pump with back up heat strips in addition to the
water to air heat exchanger installed in the plenum fed by the outdoor wood
boiler.

You are trying to back up the fan motor and the electronics with the battery
back up system, correct?  And you're trying to keep the heat strips and the
heat pump off of the battery back up system, correct?

The boiler installer/supplier has probably already installed some sort of
relay assembly installed to prevent the heat pump (and heat strips) from
kicking on until the boiler can no longer satisfy the heat load.  I fiddled
with a few of these and that's how they are set up.

One approach would be to power the above mentioned relay assembly, the fan
motor and whatever transformers, etc. by the back up system.  You'll need to
make sure that this whole thing works when parts of the heat pump don't have
power and that might be a real treat as that some of bundle of wires you
mentioned probably leads to lock outs and safeties installed to prevent just
that from happening.  It could be terrible simple or just the opposite.

To be politely honest this isn't a good application for a battery back up
system.  When he really needs heat he's not going to have it.  Have you
though about suggesting a battery-less grid tie system with a back up
generator to get him through the power outages?  Total price wouldn't be all
that different. 

Best,

Travis Creswell
Ozark Energy Services

-----Original Message-----
From: Geoff Greenfield [mailto:Geoff at Third-Sun.Com] 
Sent: Friday, February 03, 2006 11:59 AM
To: RE-wrenches at topica.com
Subject: Furnace blower re-wire? [RE-wrenches]

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Just got back from a site visit and need some help...

The customer has a heat pump with backup coils.  He also has an outdoor wood
furnace with fan coils retrofitted.  The compressor is fed with a double 30,
and the blower unit has 2 double 60 circuits feeding 2 double 60 breakers on
the unit.  It is a Lenox Elite CB 30U - 41/461P.  The fan motor is 240 V 1/3
HP and is listed as being 350 watts draw...

My goal is to put the fan circuits (and control circuits?) on a backed up
sub panel. The way things are set up, if there is a battery back up
situation while he is out of town and the water furnace ain't hot, we don't
want the resistance strips to drain the batts!

I opened up the unit (which has a sliding cover allowing a third double
breaker) and found that there were heating elements on both breakers, the
fan motor, relays and a spaghetti of wires on one side.

SO - my game plan is to install a third breaker in the unit (double 15 or
20?) served by our backup panel and move all the non heating element wiring
to that.  Customer knows he may be affecting warranty etc...

SO - am I nuts? am I right on?  am I in between?  Any advice or heads ups
(or better yet an "I've done that before and it worked like a charm") would
be greatly appreciated!

For a brighter energy future,

Geoff Greenfield
NABCEP Certified Energy Practitioner

THIRD SUN SOLAR & WIND POWER Ltd.
340 West State Street
Athens, OH 45701

www.third-sun.com
(740) 597-3111