Conducting paste

[Hugo Nebula]

Quick question; is conducting paste for a boiler thermistor the same as that used for computer processors? Or at least could I use the stuff for PCs in a boiler?

[The Natural Philosopher]

Cobducting paste is paste that conducts.

Silicone grease, possibly loaded with a conductive powder. Why not?

[Dave Liquorice]

Conducts what, heat or electricity?

My first reading of the OP rang the electricity bell and too many variables bell. But I see it could be thermal in which case the white goopy thermal grease as used for processor to heatsink interfaces is probably OK, though a boiler may well get significantly hotter.

[Set Square]

It's probably very similar stuff. My only concern would be temperature stability - since boilers get somewhat hotter (maybe not all that much?) than computer processors. Clearly, you don't want something which runs out when it gets hot!

[The Natural Philosopher]

I am not even sure that is true: semiconductors operate well over 100C, and its unlikely that a boiler water temp sensor is going to go much over 100C.

Or is it some other sensor in the combustion area?

[Malc]

I don't see why not.

[Dave Liquorice]

Mil spec ceramic packaged probably but your run of the mill plastic packaged stuff generally maxes out at around 80C.

Quick google and unverified:

that only AMD Athlon and Duron have max working temps in the 90C range, most other vary from 60C to 85C.

That really depends on the position of the sensor and the constuction of the boiler. Even without being in the combustion area the surface of the heat exchanger may well get >100C.

[G&M]

If you mean the white runny paste - no. It begins to break down at about 90 deg C. If you mean the green sticky stuff (silver loaded epoxy) this is good to over 180 deg C

[raden]

In message , G&M writes

Silver loaded epoxy - great idea

Are you going to drill the bugger out when it fails ?

Use normal heatsink compound, a couple of quid a tube from the usual electronic suppliers

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[G&M]

You scrape it off. The silver particles mean it isn't as strongly bonded as a normal epoxy. Used in most very high temperature electronic systems - military and so on.

It will fail at this temperature.

[Pete C]

Hi,

Superglue is fairly heatproof, something similar is used for shuttle tiles.

cheers, Pete.

[Andy Hall]

So are you saying (in the light of what happened with those) that this is a good solution?

.andy

To email, substitute .nospam with .gl

[Dave Plowman (News)]

Quick glance at the Maplin cat shows their heat conducting compound as you'd use on a heatsink good to 200C

[MBQ]

This used to be true of military grade parts. It is still true of a lot of discrete devices and less complex ICs, but not the multi-million transistor devices you find on a PC motherboard. Most of these are limited to a junction temperature of around 85 deg C. That (and obviously the sheer power they comsume) is why they need such a big heatsink with a fan on it.

Semiconductor firms all but stopped producing military temp range parts a few years ago as it was just too expensive. A lot of military systems these days are made from bog standard commercial components with clever packaging and cooling techniques (still very expensive!). With the explosion of electronic content in cars, there are more complex extended temperature range devices becoming available again.

MBQ

[G&M]

And getting lower. With smaller device geometries (90nm, 65nm and 40 nm coming) the leakage at high temperatures becomes so high it isn't worth using the device as it consumes more power for the same function than an older part.

[Pete C]

Is your boiler capable of being launched into orbit, conducting experiments or launching satellites, and returning to earth in a high temperature re-entry? Knowing you I wouldn't be suprised ;^)

cheers, Pete.

[Andy Hall]

Definitely, but that's another story :-)

.andy

To email, substitute .nospam with .gl

[:::Jerry::::]

It would be after being installed by 'IMM', well at least being launched into orbit !.. :~)

[:::Jerry::::]

Err, but doesn't the said tiles (when present...) stop the heat being transferred to the structure ?....

[Owain]

":::Jerry::::" wrote | "Pete C" wrote | > Is your boiler capable of being launched into orbit, | > conducting experiments or launching satellites, and | > returning to earth in a high temperature re-entry? | > Knowing you I wouldn't be suprised ;^) | It would be after being installed by 'IMM', well at | least being launched into orbit !.. :~)

This is where having two combi boilers comes in handy. With two boilers with the flues as steering thrusters you can modulate the boilers individually, thus achieving directionality. With a two-channel microcontroller you can synchronise the boiler operations to have the pair elegantly tangoing their way around the planets.

A solution most eminent in its winfulness.

Owain