120V time-delay switch

I may have asked this before.
My office is heated by one of those oil-filled electric radiators, but
the only spot I have for it is tucked into a corner.
It works a lot better at keeping things warm if I set a fan in front of
it to circulate air. But that leaves me with a choice of either having
the fan on all the time, or switching the fan on at the same time as the
heater.
I've got the thing running off of a thermostat for a baseboard heater*,
so I can turn the fan on and off with the heater. But what I'd like to
do is have the fan on a delay, so that it keeps running for a couple of
minutes after the power to the heater turns off, and, preferably, takes a
couple of minutes to switch on.
Is there a small, easy to apply gizmo that can be used for this? I know
they make thermal switches for exactly this sort of task in furnaces, but
the ones I know of work off of the low-voltage supply to the furnace
controller. Since I don't have that, I'd really like one that works off
of the 120V going to the heater.
I could Google for it, but I suspect that I'd get the search terms wrong
and waste a bunch of time -- so if all you give me is the _right_ Google
terms, that should get me going.
*
Yes, I know -- I'm essentially cobbling together a one-room furnace.
Reply to
Tim Wescott
Loading thread data ...
"off delay timer"
For example:
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Don't count on all manufacturers using the terminology in exactly the same way. Best to check the wiring and timing diagrams before purchasing.
Reply to
Ned Simmons
Rather than a timer, a line voltage close-on-rise thermostat attached to the heater would give you on and off delays that match the heater's temperature. jsw .
Reply to
Jim Wilkins
You can get thermal switches in any voltage rating. The ones on the furnace in my place all switch 110. The only thing the low voltage does is control the gas burner. blower and over limit are both 110 switched.
Reply to
Steve W.
[ ... ]
Such things exist. Thermal delay relays -- sealed heater around a bi-metallic bar which bends at it heats, and touches another contact after the delay time -- and stays in contact for a while after it is shut off. If the fan you are running is something like a Rotron muffin fan (7W or 14W) these could likely handle it directly. If the fan is bigger, you will want a relay to handle the higher current.
Skip over most of the ones below until you get to the last one, which looks like your best choice. These are from the first page (of three) of hits with a search string of:
thermal delay relay
I've found one on eBay which runs from 115 (AC or DC) to the heater, has a normally-open contact, and has a delay of '3' (based on the part number -- maybe seconds maybe minutes. I think that the slowest hat I have ever seen was down around 15 seconds, to the '3' likely means minutes. They have a click here for a PDF of the spec sheet, which does not work for me. But the auction number is:
131144329108
And here is another -- 30 seconds, I believe.
161250981254
The first fits into an old 7-pin miniature tube socket, the second into an Octal tube socket.
Another auction has a number of 27 V ones -- not very useful for you.
O.K. I found a two second one, so I guess that the first one is really three seconds.
Next -- 120 V 25 seconds:
270631940484
Here is a 60 second 115 V one -- but they are really proud of it: $90.00
141217653573
Even more proud -- and in Australia, but 120 V 62 seconds delay:
291107234059
115V 60 seconds:
400223290908
***** THIS ONE *****
115V 90 seconds -- $14.95
380235353379
Good Luck, DoN.
Reply to
DoN. Nichols
Look for "CLIXON" thermal switch. They come in all kinds of temperature and electrical ratings. I have a bunch salvaged from electronic gear over the years. I am sure you can figure a way to clamp one to the heater and wire up the rest of the circuit.
Paul
Reply to
Paul Drahn
That would work, if I could get one that would work with just a 10-degree rise or so.
Reply to
Tim Wescott
Liberate the capillary bulb style mechanical thermostat from an old fridge. Should have about 5-10F hysteresis and might go high enough for you.
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sells them for about $25 for the 0-90C version that we use in production at work. I know others sell them, that's just one place I know.
----- Regards, Carl Ijames
That would work, if I could get one that would work with just a 10-degree rise or so.
Reply to
Carl Ijames
I suspect that a thermostat set as high as 50C / 120F would extract almost all of the available heat. You could let it warm to 120F, shut it off and turn on the fan, and see how warm the breeze feels for how long. A KillAWatt would tell you how much energy it holds at 120F. jsw
Reply to
Jim Wilkins
Probably need a relay between the Clixon and the heater. If in a living space, a solid-state relay will not make distracting clunks.
Joe Gwinn
Reply to
Joe Gwinn
Joe Gwinn fired this volley in news:280320141923265625% snipped-for-privacy@comcast.net:
Jeesh! Joe, he's not controlling the heater with it. He's controlling a little (maybe 100W, probably less) fan.
Exactly why would he need a relay for a 0-1A load? A Clixon that small isn't going to make "clunks". Little 'snaps', yeah; clunks, no. So? It's an audible indicator that the switch is working.
Lloyd
Reply to
Lloyd E. Sponenburgh
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[ ... ]
If he were switching the load of the "oil-filled radiator", yes. It has its own thermostat, however. (And mine had two switches in a single housing, which died. I replaced it with a heavier switch wired to switch both sides on or off at once.
But *he* is switching a fan -- and perhaps something as small as a Rotron Muffin fan -- 7 or 14 Watts, so not much to switch.
Enjoy, DoN.
Reply to
DoN. Nichols
I did think he was switching the radiator heater.
The clunk would be from a mechanical relay, not the clixon.
But the fan is probably a fairly inductive load, able to draw a nice spark when opening the circuit. Clixons are not that big, so a RC snubber is required, at the very least.
Joe Gwinn
Reply to
Joe Gwinn

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