120V time-delay switch

"off delay timer"
For example:
Don't count on all manufacturers using the terminology in exactly the same way. Best to check the wiring and timing diagrams before purchasing.

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 .

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.

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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.

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

That would work, if I could get one that would work with just a 10-degree rise or so.

Liberate the capillary bulb style mechanical thermostat from an old fridge. Should have about 5-10F hysteresis and might go high enough for you. 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.

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

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

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

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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.

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