SIMPLE electrical job. Cost via electrician? chg direct-wire to plug & socket

Page 5 of 6  
On 2/6/2012 1:54 PM, David Combs wrote:

There is no description of why the draft inducer was installed or whether the boiler can be safely run without it.
I have a condensing boiler that has a draft inducer. Some of the features: - pre-burn purge run to make sure there are not combustible gasses in the boiler - a pressure switch confirms that the draft inducer is running; also confirms that the pressure switch has not failed - post-burn purge run to clear the boiler and flues
RBM commented that you might need a "post purge" run if you do not run the draft inducer continuously.
--
bud--

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
...

OK -- long, long ago *I* was a "ham" (but got bored because all that the people talked about was their equipment. But of course if I had *designed* and built my own transmitter, I wouldn't be bored, but fascinated!)
So I know what a DPDT switch is OK.
But what's a "center-off" one?
Or, at bare minimum, a "break before make"? (Well, that one seems self-evident. Question: aren't ALL dbl-throw switches break before make? I guess not. Please elaborate.)
Thanks!
David
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 6 Feb 2012 19:31:48 +0000 (UTC), snipped-for-privacy@panix.com (David Combs) wrote:

All NORMAL DPDT switches are break before make - some specialty switches are make before break. A DPDT "reversing duty" switch HAS to be break before make
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
...

Thanks!
Which leads to two further questions:
(1) What's an *example* (and thinking behind) some switching being make before break?
(2) (Begging the question), what then is a "reversing duty" switch?
(Lotsa vocab here!)
David
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 11 Feb 2012 19:35:03 +0000 (UTC), snipped-for-privacy@panix.com (David Combs) wrote:

The heater control swith on many cars in make before break so the heater does not shut off between speeds, causing arcing. Hi-Low would be double throw. Most are "multi-throw". Other similar applications - but like I said, generally "specialty" switched.

A switch that is used to reverse a motor - like a drill reverser, or the up/down switch on an electric garden tractor 3 point hitch, or the suck-blow switch on a ceiling fan, They are generally a DPDT switch with a jumper on them. MOST are "center off" but some use a separate switch for on-off and simply handle direction

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Seems interesting, but not really clear to me.
What two places does the jumper connect, and what effect does it have.
FYI I drew this crude picture of a dpdt switch:
Crude drawing of DPDT switch: Where would the jumpers be? With what effect? (What to google for wikipedia or other article?)
L(eft) R(ight) C(enter)
[]---------[] [] []---------[] []
I say, there are LOTS of ideas comong out of this suprisingly long and detailed thread, that I should be thinking about.
Knowing what to google for, or having direct urls, to places that tutorially explain some of this would nice to see, both for me and some others on the thread.
Thanks,
David
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2/14/2012 12:39 AM, David Combs wrote:

Using your diagram: A B C D E F
A connects to F, D connects to C.
A-D wires to one side, B-E wires to the other side.
The switch just reverses the connections (the same as a 4-way switch, which can also be used).
On an AC motor you connect A-D to the start winding and B-E to the motor connections for the start winding. It only reverses when the motor starts.
For a DC motor you connect A-D to the field winding and BE to what the field winding connects to. Reverses while the motor is running.
Center-off would not be a good idea in these applications.
--
bud--

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Particularly with a shunt wound DC motor - open field = immediate overspeed and extreme current draw! Make before break would let the majic smoke out in a hurry too.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

... ...
THANKS, YOU TWO!
PS: If anyone feels like supplying a bit of context for these two answers, feel free to explain what a "shunt would DC motor -- open ..." is, and what's it's used for.
Savid
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2/21/2012 1:34 AM, David Combs wrote:

"Open" is not used. It is a failure mode.
A DC motor has an armature (that rotates) and a field (on some motors the field a permanent magnet). The rotation is produced by interaction of the magnetic fields of the armature and field.
A series motor has the field connected in series with the armature. Shunt motors have the field wired in parallel with the armature (both are connected across the supply).
You can think of the armature as a resistance in series with a generator, which is the generator action of the armature rotating in the magnetic field of the field.
Just looking at a shunt motor, when you start the motor there is just the resistance (of the wire) and the armature current is high. As the armature rotates faster the 'generator' action opposes the supply voltage and the current decreases. At some speed the armature current would drop to zero. The speed stabilizes at a current large enough to supply the torque the mechanical load requires. If you lower the field current, the field magnetic strength is lowered, and the armature 'generates' less voltage. The armature has to spin faster to 'generate' more voltage. Field weakening is used for speed control.
If you open the field connection the 'generator' action produces very little voltage and the armature has to spin really fast, and will have a high current. Low torque may limit the speed, but the high current remains. The control circuit for a shunt wound motor may disconnect the motor if there is no field current.
A center-off switch in the off position will disconnect the field coil.
A single phase AC motor with a center-off switch on the start winding will run OK, but in the off position it will not start. It will draw high current when turned on.
--
bud--




Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

A very, very, VERY late THANK YOU!
David
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 14 Feb 2012 06:39:29 +0000 (UTC), snipped-for-privacy@panix.com (David Combs) wrote:

Look at http://www.1728.org/project2.htm , the bottom of the page. It shows the uses of DPDT switches and, in particular, the reversing switch.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

THANK YOU!
David
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 6 Feb 2012 19:31:48 +0000 (UTC), snipped-for-privacy@panix.com (David Combs) wrote:

The switch has a stable third state/position, in the center, where the commons aren't connected to either of the sides.

No. There are cases where you don't want an interruption between switching from one to the other. Obviously, a switch with a "center off" is also break-before-make.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 02 Feb 2012 17:16:11 -0600, snipped-for-privacy@myplace.com wrote:

Won't run the exhaust fan or any pumps etc.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 02 Feb 2012 17:16:11 -0600, snipped-for-privacy@myplace.com wrote:

By "thermostat", do you mean thermostatically controlled valve?
That, and the thermostat, are in the same circuit and would be powered by the transformer which is powered by the AC.
And the ignitor also. It's not enough to turn on the gas, you have to light it too.

My first month in my 4-year old house, the AC failed, because the furnace transformer failed. I went to a heating supply house and since the transformer was part of the furnace control panel, his reflex was to sell me a new control panel, for 400 dollars (in 1983)
I whined and he sold me a 24 volt transformer for maybe 30 dollars**,. AFAIK all that is necessary is that it be 24 volts and big enough, to power the furnace controls and the AC controls. Since the AC compressor is on a separate cirucit, and the furnace air circulation fan are on separate cirucits from the 24 volt control circuit, the transformer doesn't have to be that big. Are you sure it has to be made for the furnace? In my case it was a generic 24 volt transformer, and I probably could have gotten it for less than the 20 or 30 dollars I paid at Radio Shack if they had one big enough, that is, not a wall wart, not universal, and enough amps.
**I'm still using the same transformer 28 years later. It was too big to fit where the original transformer was, so I mounted it on a shelf/panel inside the furnace, though it could be mounted outside the furnace too.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2/3/2012 5:01 AM, micky wrote:

This is not a furnace, or furnace/AC, it's a steam boiler, and a crude one at that. The 24 volt gas valve is controlled by the wall thermostat. There is a pressure switch or switches that limit the steam. That's it, no ignitor, it's standing pilot, but he does have a draft inducer fan that needs line voltage.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Looks like I need some education here:
What's a "furnace" vs a "steam boiler"?
The thing we have is this big boiler, I guess, with a pipe going (out of the top, I think) *up*, to the floors above.
Provides zero heat (via hot water or steam or whatever) to the same floor (basement) it is sited in.
Now, what's a "furnace", and how does it differ?
Finally, what's a "furnace/AC". I suppose that's one of those horrible! "heat only via hot air" things that uses the same air-conduits for hot or cold air.
("horrible", because there's no heat via *radiation* -- just via conduction from nauseatingly-hot air surrounding your (clothed, ie insulated from the hot air) body, WHILE at the same time your body has net OUTWARD radiation to the windows and, in old houses, walls. OK for Florida, *maybe*, but a real loser for anywhere it gets cold.)
David
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2/6/2012 3:32 PM, David Combs wrote:

A boiler heats water, a furnace heats air. You have a basic steam boiler with a 24 volt gas valve. The draft inducer you have, was not installed properly, probably because it was done by a plumber. The typical draft inducer setup is that the fan gets a constant feed of 120 volts, and in your situation it gets a 24 volt control circuit that intercepts the power from going to the gas valve until the inducer is running, then it allows the 24 volts to continue to the gas valve. The unit may or may not have a post purge, which would allow the fan to continue to run for a few seconds after the burner stops, to evacuate the flue pipe. All of this can be wired to a generator transfer device. I doubt any local electricians are going to just install an outlet and plug for you
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 6 Feb 2012 20:32:13 +0000 (UTC), snipped-for-privacy@panix.com (David Combs) wrote:

Forced air heat is VERY common in the cold (normally) Canadian climate.
Radiant floor and ceiling heat works too - but hot air is "the norm" - and it WORKS.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.