Battery backup for furnace?
Mike Walker
Hi all;
My elderly mother lives alone a farm. She's pretty self-reliant, but when
the power goes out, so does her oil furnace. Wasn't a problem when my
father was alive last winter, he had a tractor-powered generator connected
to the main power panel. I'm trying toi figure a way she can keep her self
warm this winter. Power is rarely out more than 4 hours at a time, but I
worry, living quite a distance away....
Strikes me that all the heating system really needs is some sort of battery
packup system for the thermostat; the actual oil burner doesn't require
electricity, does it? I'm tempted to take the UPS off the server at work
(hell, they'd never miss it...) and wire it into her heating system. (Just
kidding, we don't even HAVE a UPS on our server at work... but that's
another story!). Seriously, would something like that work, do battery
back-up systems for oil burners exist? Thanx . . . Mike
Randy Hubbard
Mike Walker wrote:
FWIW,
You need to check the voltage/current requirements for the furnace and
thermostat. I'm no expert on this but it seems many thermostats use 24V if
memory serves me correctly. If the blower motor, and solenoids use the same 24V
then you could rig up (2) 12V automotive type batteries in series, and use a
trickle charger with automatic shut-off to keep them charged. Make sure you
have a proper DISCONNECT from the home power line that must be activated to
connect the battery back-up system!!!
A typical UPS, unless you get one for a big server, doesn't have a long
operation capacity. It's not unusual to have only 15-30 minutes reserve when
running a typical PC, which has a very low current draw. Two inexpensive
automotive batteries would have enough storage capacity to proving electricity
to the furnace for four hours or more without any difficulty I would guess.
You might spent $150-$200 for the whole deal, which is as cheap as the very
small UPS units.
In a UPS unit you're paying for the convenience of surge protection, output
voltage stability during brownouts, etc. and a very quick switch-over time
which is not necessary for the furnace application. And seeing as though the
UPS's I've seen are all 12V, you'd still need two of these or a transformer,
etc. to make a viable system.
Randy
Jim Mais
Randy Hubbard wrote:
>
> Mike Walker wrote:
>
> > Hi all;
> >
> > My elderly mother lives alone a farm. She's pretty self-reliant, but when
> > the power goes out, so does her oil furnace. Wasn't a problem when my
> > father was alive last winter, he had a tractor-powered generator connected
> > to the main power panel. I'm trying toi figure a way she can keep her self
> > warm this winter. Power is rarely out more than 4 hours at a time, but I
> > worry, living quite a distance away....
> >
> > Strikes me that all the heating system really needs is some sort of battery
> > packup system for the thermostat; the actual oil burner doesn't require
> > electricity, does it?
>
>
> You need to check the voltage/current requirements for the furnace and
> thermostat. I'm no expert on this but it seems many thermostats use 24V if
> memory serves me correctly. If the blower motor, and solenoids use the same 24V
> then you could rig up (2) 12V automotive type batteries in series, and use a
> trickle charger with automatic shut-off to keep them charged.
Although the oil valve (on a pot burner) *may* operate on reduced DC
voltage supply, the blowers and pump motor (on an atomizing burner)
will not as they are ac motors, in general.
If you use a UPS for this type of scheme to supply 120 v ac, keep in
mind that the UPS usually must be connected to the line and energized at
the time of the power failure or it won't produce any output.
I agree with the previous poster that a UPS will not have nough capacity
to run a furnace for any length of time.
Speedy jim
Sam Goldwasser
You CANNOT use 24 VDC to power 24 VAC devices - they will melt down.
A typical oil furnace uses power for the burner (blower, igniter) and probably
circulating pump(s). A generator is probably a better option than batteries
though may not be that realistic for your circumstances.
--- sam : Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Lasers: http://www.geocities.com/CapeCanaveral/Lab/3931/lasersam.htm
Usually latest (ASCII): http://www.pacwest.net/byron13/sammenu.htm
In article <3495403D...@wwnet.net> Randy Hubbard <race...@wwnet.net> writes:
You need to check the voltage/current requirements for the furnace and
thermostat. I'm no expert on this but it seems many thermostats use 24V if
memory serves me correctly. If the blower motor, and solenoids use the same 24V
then you could rig up (2) 12V automotive type batteries in series, and use a
trickle charger with automatic shut-off to keep them charged. Make sure you
have a proper DISCONNECT from the home power line that must be activated to
connect the battery back-up system!!!
A typical UPS, unless you get one for a big server, doesn't have a long
operation capacity. It's not unusual to have only 15-30 minutes reserve when
running a typical PC, which has a very low current draw. Two inexpensive
automotive batteries would have enough storage capacity to proving electricity
to the furnace for four hours or more without any difficulty I would guess.
You might spent $150-$200 for the whole deal, which is as cheap as the very
small UPS units.
In a UPS unit you're paying for the convenience of surge protection, output
voltage stability during brownouts, etc. and a very quick switch-over time
which is not necessary for the furnace application. And seeing as though the
UPS's I've seen are all 12V, you'd still need two of these or a transformer,
etc. to make a viable system.
Randy
> Hi all;
>
> My elderly mother lives alone a farm. She's pretty self-reliant, but when
> the power goes out, so does her oil furnace. Wasn't a problem when my
> father was alive last winter, he had a tractor-powered generator connected
> to the main power panel. I'm trying toi figure a way she can keep her self
> warm this winter. Power is rarely out more than 4 hours at a time, but I
> worry, living quite a distance away....
>
> Strikes me that all the heating system really needs is some sort of battery
> packup system for the thermostat; the actual oil burner doesn't require
Jim Sokoloff
mwa...@astral.magic.ca (Mike Walker) writes:
> Hi all; My elderly mother lives alone a farm. She's pretty
> self-reliant, but when the power goes out, so does her oil
> furnace. Wasn't a problem when my father was alive last winter, he
> had a tractor-powered generator connected to the main power
> panel. I'm trying toi figure a way she can keep her self warm this
> winter. Power is rarely out more than 4 hours at a time, but I
> worry, living quite a distance away....
For four hours, you could rely on a propane stove or wood fire for
survival. Problem is what happens when power's out for 48 hours?
> Strikes me that all the heating system really needs is some sort of
> battery packup system for the thermostat; the actual oil burner
> doesn't require electricity, does it?
It sure does. There's an electrode across which a spark jumps to
ignite the atomized oil. Now that you've got oil burning, you need to
move that heat around. This is typically done by a fan (forced hot
air) or by pumps (forced hot water). Both of these need power. It's
possible to have a passive system that relies on convection, but those
tend to be rare as well as not as comfortable as a forced system.
> I'm tempted to take the UPS off the server at work
> (hell, they'd never miss it...) and wire it into her heating system.
Anything short of an enormous UPS probably won't cut it. Best solution
sounds like a generator and an optional nice neighbor if your mother
can't start the generator and cut it over herself.
---Jim
Randy Hubbard
Sam Goldwasser wrote:
> > Hi all;
> >
> > My elderly mother lives alone a farm. She's pretty self-reliant, but when
> > the power goes out, so does her oil furnace. Wasn't a problem when my
> > father was alive last winter, he had a tractor-powered generator connected
> > to the main power panel. I'm trying toi figure a way she can keep her self
> > warm this winter. Power is rarely out more than 4 hours at a time, but I
> > worry, living quite a distance away....
> >
> > Strikes me that all the heating system really needs is some sort of battery
> > packup system for the thermostat; the actual oil burner doesn't require
> > electricity, does it? I'm tempted to take the UPS off the server at work
> > (hell, they'd never miss it...) and wire it into her heating system. (Just
> > kidding, we don't even HAVE a UPS on our server at work... but that's
> > another story!). Seriously, would something like that work, do battery
> > back-up systems for oil burners exist? Thanx . . . Mike
Yup, agreed 100%. I failed to mention an inverter/converter as required depending upon
the power requirements of the furnace. Thanks for catching my over-sight.
Randy
Jeff Benjamin
> Although the oil valve (on a pot burner) *may* operate on reduced DC
> voltage supply, the blowers and pump motor (on an atomizing burner)
> will not as they are ac motors, in general.
Okay then, how about a gas-fired steam boiler with no blowers, pumps,
or other AC motors? Can I just hook up 24V DC (2 12V batteries in
series) to the wires that come out of the AC transformer, or is it
more complicated than that?
--
Jeff Benjamin benji(at)fc.hp.com
Hewlett Packard Co. Fort Collins, Colorado
(Direct reply won't work: use address in .sig)
"Think! It ain't illegal yet." -George Clinton
Jim Mais
Jeff Benjamin wrote:
>
> > Although the oil valve (on a pot burner) *may* operate on reduced DC
> > voltage supply, the blowers and pump motor (on an atomizing burner)
> > will not as they are ac motors, in general.
>
> Okay then, how about a gas-fired steam boiler with no blowers, pumps,
> or other AC motors? Can I just hook up 24V DC (2 12V batteries in
> series) to the wires that come out of the AC transformer, or is it
> more complicated than that?
In *general* the answer is yes; you can substitute dc in place of the
24v transformer.
And by connecting as you suggest, you retain whatever safety devices
(pressure, overtemp) were in the circuit.
One caveat: DON'T try this scheme with electronic ignition or induced
draft blowers. But it will work fine with old-style boilers with
standing pilot.
The only thing I would change is the voltage. 12 volts will be more
than adequate for most gas valves (you might want to try 6 volts,
first).
Speedy jim
Douglas Rudoff
A couple of years ago I read a short article in _Popular Science_
about a company that was coming out with a furnace that had a
thermoelectric generator to charge a battery while the burner was
one. Normally it would run on house power, but if it went out it would
rely on the battery and the electricty-generated heat to power the
igniter and blower. I don't recall anything else about it, but it
would have been about four years ago.
I also recall reading about a water heater that had a photoelectric
cell that was tuned towards the light frequencies in a gas flame and
use it to charge a battery used for an igniter. Again, another product
I haven't heard about since.
--
Doug Rudoff
dou...@speakeasy.org
jbveale@remove
What about a small power generator? They are inexpensive, put out several kW
and the newer ones are quiet and apparently easy to start. You should get it
properly wired in though if you are going to use it to supply household power.
Sam Goldwasser
Either of these would be suitable for some igniters but not for powering
the oil burner or circulating pump :-).
--- sam : Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Lasers: http://www.geocities.com/CapeCanaveral/Lab/3931/lasersam.htm
Usually latest (ASCII): http://www.pacwest.net/byron13/sammenu.htm
Bill Hale
Jeff Benjamin (be...@see.sig.for.address) wrote:
: > Although the oil valve (on a pot burner) *may* operate on reduced DC
: > voltage supply, the blowers and pump motor (on an atomizing burner)
: > will not as they are ac motors, in general.
: Okay then, how about a gas-fired steam boiler with no blowers, pumps,
: or other AC motors? Can I just hook up 24V DC (2 12V batteries in
: series) to the wires that come out of the AC transformer, or is it
: more complicated than that?
Isn't there a pump to circulate water from the boiler? I suppose
some systems use thermosyphon operation, but most don't.
You may NOT use 24vdc. The impedance of the valves/relays etc
is the vector sum of their inductive reactance and dc resistance.
At DC, there is no reactance, so they would melt as one poster
pointed out. You might be able to use some lower DC voltage...
would have to be figured out on a case/case basis.
Bill Hale ha...@fc.hp.com
: --
Jeff Benjamin
> : Okay then, how about a gas-fired steam boiler with no blowers, pumps,
> : or other AC motors? Can I just hook up 24V DC (2 12V batteries in
> : series) to the wires that come out of the AC transformer, or is it
> : more complicated than that?
>
> Isn't there a pump to circulate water from the boiler? I suppose
> some systems use thermosyphon operation, but most don't.
No, it's a steam system, not hot water. The steam moves via low
pressure (2-3 psi) built up in the boiler. Condensation returns
via gravity.
> You may NOT use 24vdc. The impedance of the valves/relays etc
> is the vector sum of their inductive reactance and dc resistance.
> At DC, there is no reactance, so they would melt as one poster
> pointed out. You might be able to use some lower DC voltage...
> would have to be figured out on a case/case basis.
--
Bill Burdick
>> Isn't there a pump to circulate water from the boiler? I suppose
>> some systems use thermosyphon operation, but most don't.
>No, it's a steam system, not hot water. The steam moves via low
>pressure (2-3 psi) built up in the boiler. Condensation returns
>via gravity.
I believe "millivolt" gas controls are still available. They have a
standing pilot light which heats a thermopile; the pile generates a
tiny electric current which is enough to operate the main gas valve.
You need a special millivolt thermostat also. Using these components,
you can run the heating system with no AC or battery power at all.
They've been used for gas floor and wall heaters in remote cabins,
etc., where there is no electricity, for many years. A gas fitter
should be able to convert your boiler for a few hundred dollars, and
you'll never have to worry about power failures or batteries.
--
"What contemptible scoundrel has stolen the cork to my lunch?"
(W C Fields)
Bill Burdick
Email address in header is false. Delete spam block to reply.
Peter Bucy
>Hi all;
>
>My elderly mother lives alone a farm. She's pretty self-reliant, but when
>the power goes out, so does her oil furnace. Wasn't a problem when my
>father was alive last winter, he had a tractor-powered generator connected
>to the main power panel. I'm trying toi figure a way she can keep her self
>warm this winter. Power is rarely out more than 4 hours at a time, but I
>worry, living quite a distance away....
>
>Strikes me that all the heating system really needs is some sort of battery
>packup system for the thermostat; the actual oil burner doesn't require
>electricity, does it? I'm tempted to take the UPS off the server at work
>(hell, they'd never miss it...) and wire it into her heating system. (Just
>kidding, we don't even HAVE a UPS on our server at work... but that's
>another story!). Seriously, would something like that work, do battery
>back-up systems for oil burners exist? Thanx . . . Mike
Mike, you could get a couple of large, deep-discharge, batteries and
run them through a device that converts 12v or 24v dc to 110v ac and
keep them on a trickle charger until needed.
But for the money, I would be more inclined to have the furnace
rewired so that all of the power connection to the furnace used an
extension-type cord that could either plug into an outlet near the
furnace or into a small Honda generator when the power went off.
This solution would be more reliable and less likely to cause other
electrical problems with the furnace. Use Stabil (tm) in the gas that
is in the generator and in the gas that you store for the generator.
Run the generator ever month to make sure that it will work and
remember that it must not be used in a confined space. CO gas is a
killer.
The generator could be quite small and the Honda units are very easy
to start and maintain.
If you only need power for the thermostat then you could get by with
a battery backup. But you would still need a way to switch between the
backup unit and the regular power supply.
My parents had the same problem several years ago. Their power went
out for three days. All of the gas appliances worked except for the
furnace (forced air). They escaped to their motorhome until the power
was back on.
Keith
If you really want to go with a battery system then you need to get an
inverter that changer dc to ac and introduces 60 cycles to operate
appliences. You could also get a auto backup generator that runs on LP
gas. There are also millivolt gas furnaces that work on convection, have
no blower and need nothing but LP gas. The inverter system with batteries
and set up will run total from $3-400.00 on up depending on how fancy you
get. The generator is $3000,00 for auto or gasoline with manual change
over @ $ 1500.00. The wall furnace 60,000 BTUS will be around 1400.00
installed plus the LP service. Keith on the Shore
Mike Walker
Hi all;
In December I wrote, under the heading "Battery Backup for Furnce:
> My elderly mother lives alone a farm. She's pretty self-reliant, but when
> the power goes out, so does her oil furnace. Wasn't a problem when my
> father was alive last winter, he had a tractor-powered generator connected
> to the main power panel. I'm trying to figure a way she can keep her self
> warm this winter. Power is rarely out more than 4 hours at a time, but I
> worry, living quite a distance away....
>
> Strikes me that all the heating system really needs is some sort of battery
> packup system for the thermostat; the actual oil burner doesn't require
> electricity, does it? I'm tempted to take the UPS off the server at work
> (hell, they'd never miss it...) and wire it into her heating system. (Just
> kidding, we don't even HAVE a UPS on our server at work... but that's
> another story!). Seriously, would something like that work, do battery
> back-up systems for oil burners exist? Thanx . . . Mike
I received a number of helpful replies which pointed out that the problem
wasn't nearly as simple as my first glance suggested. After some thought,
when I visited over the holidays I helped my mother re-set up the two
wood-burning supplemental stoves that had been little used since my
father's death. Mom liked having real fires again, and proved adept at
lighting them as long as there was ample small wood that she could handle
brought into the house. The woodpile on the porch was increased, and a
neighbor who drops by every few days agreed to bring wood into the house
regularly. A low-tech but pretty good solution, I thought. I returned the
300 miles to my home on January 2nd and promptly got quite ill, ending up
in a hospital bed for 8 days.
My mother lives near Cornwall, Ontario, and as many of you will realize,
several days later the ice-storm of the century struck there. In my
original post, I noted that power was rarely out for more than 4 hours; she
lost power and phone on Jan. 5 and as of this writting (Jan. 17) power is
still out; the local hydro utility has no estimate of when they will be
albe to re-establish rural power in that area.
Mom came through like a trooper. With the help of the neighbor who brought
in wood and a local social service agency that delivered some food, she
weathered the storm with class. Many of her friends and neighbors in the
community also dropped by to check that she was OK and bring warm meals,
etc. She refused to be moved to a shelter when the authorities finally got
through to her. Once her phone line got restored, she joked at one point
that she thought many of her neighbors dropped by because with the wood
stoves she had the warmest house in the township.
My brother drove in from Vermont a few days ago with a generator he
scrounged somewhere. After lots of fussin' and finaglin' he and my son
managed to get the furnace and a few appliances going. They plan to run it
about 8 hours a day, it's on an outside porch so Mom needs help turning it
on and gassing up, but neighbors are helping out. The weather has now
turned quite cold there, so that's a big relief. I just hope the
jerry-rigged generator doesn't give out.
It was really pretty awful lying helpless in hospital worrying about my
mother alone on the farm with no power. The outcome shows to me the power
of a caring, rural community where people know their neighbors and feel
responsibility to help each other. But it also says something about our
virtual community here, and I want to offer a very big thanx to the many
folx here who helped me think out a simple wood-stove solution, which coped
with a crisis beyond my wildest nighmares. The internet is a really cool
place. . . . Mike