Thermostat, And Also A Schematic Symbol Quest., Please

Hello,
Have a home forced hot water heating system.
Regarding the numerous Thermostats that have been available for it, and similar systems over the years, are all of these simple SPST switch closures, without any voltage/current being provided by the Thermostat itself ?
(irrespective of whether there are "fancy electronics" for the display, etc. these days)
I think that this is the case, but wanted to ask here for all you experts to be sure. At one time we had a Honeywell round Mercury switch Thermostat, so this one absolutely had to be nothing more than a contact closure, obviously.
And, let me also ask this, please:
Have a symbol on a schematic I am not too sure what it means. Unfortunately, I do not think there is any way of showing it here, so let me try to describe it.
The symbol for a Resistor is the triangular up down points, several of them up, several pointing downward.
What is a symbol where it only goes from the baseline up, down below the baseline, then up again to the baseline ? (one triangular point up, one triangular point down)
Is it a switch, or a relay contact, perhaps ?
Thanks, Bob
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On Tuesday, September 11, 2018 at 8:48:41 AM UTC-4, Robert11 wrote:

could be a light bulb, need more context
maybe this will help
https://www.apumpstore.com/electricalsymbols.html
mark
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On Tuesday, September 11, 2018 at 8:48:41 AM UTC-4, Robert11 wrote:

Yes. No thermostat provides power, some may use power from the system if available instead of batteries.

I would describe it as a zig/zag, showing an obstacle to the flow of current.

IDK, can't say I've seen that before. The context of where it's used could help. Since you're talking about a thermostat, if it was in a schematic for a furnace where the thermostat would be, I'd say it could be a symbol for the thermostat.

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On 9/11/2018 7:48 AM, Robert Rose wrote: ...

...
As others said, need context, but generally would represent the coil of a magnetic relay or overload breaker or the like...often will be parallel line of the associated contacts with it or in line with the contact depending on the physical layout of the device...
Oh, indeed it's shown on the symbols linked to by the other poster...that's a nice collection, indeed.
--


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Are there home hot water heating systems that are not forced, that is, do not use a pump?
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On 9/11/2018 9:04 PM, catalpa wrote:

http://www.oldhouseweb.com/how-to-advice/gravity-hot-water-heating.shtml
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Thanks for the link. Don't think too many people use gravity hot water these days. Same principle as gravity hot air, but much more complicated.
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