Ideas for Stirling Engine for heating pump

A house with an open fire. It has a back-boiler. The boiler has a small pump and this drives three radiators in other parts of the house. (*).
Out of interest, I was wondering about doing without the electricity to drive the pump, and instead running the pump from the energy in the fire. So, to me, the obvious trick is a heat engine to run the pump.
The question is; any clues/pointers as to where to start on a design or self-build ? The stuff I've turned up so far is either industrial scale, or lab/bench demonstration of principle engines. I think I need something inbetween.
(* there is also a conventional LPG gas central heating system, with usual electrical pumps, motor valves, electronic timer, thermostat, hot water cylinder, etc, but that's entirely separate. I have given thought to using the fire to top-up the hot water cylinder, rather than using LPG, but that again, is a different project, along with the solar thermal gain ideas, etc..).
- Nigel
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Nigel Cliffe wrote:

At a demo here:
http://oldenginehouse.users.btopenworld.com/Forncett.htm
I saw a small IC engine (brigg and stratton or similar) converted to stirling-ness.
BugBear
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More obvious still would be gravity feed. This requires thoughtful layout of pipes but no pump at all.
Is that possible ? Are the rads above the fire ?
-adrian
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Adrian Godwin wrote:

Done this way "in the old days"
Took very careful layout, and large bore pipes.
BugBear
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Adrian Godwin wrote:

Not easy, or at least not easy with my understanding of gravity feeds. If it were possible, I'd use it as its simpler.
The fire and rads are about the same heights. Horizontal runs are >4m and >8m. The hot water cylinder (on the gas fired system at present) is over 10m away horizontally, and on the same floor. I'd rather not have to rip out lots of pipes.
- Nigel
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Good idea, but as far as I am aware ( please correct me if wrong ) all "stirling" etc engines are not self-starting, which would make it a real difficulty in integrating this sort of thing- I agree with other previous posts, that the thermo-syphon route would be the best, but awkward to arrange.

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all
real
previous
to
design or

lab/bench
inbetween.
IIRC the Norwegians are using a Sterling engine in an ultra quiet submarine, and I very much doubt that the Captain hand cranks it to get going !
AWEM
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news:5u-

Self starting Sterling engines are also being used in domestic micro CHP boilers such as this one: http://www.whispergen.com /
Greg
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Just had a look at that. I am not that well up on hot-air engines, but the configuration of this thing seems dashed clever to me. Four double acting cylinders, phased at 90 degrees, arranged around a nutating doodah, each with a hot end and a cold end, cold end of one connected through a regenerator to hot end of next, so there is no separation of power and displacer cylinders. I could almost want to make one.
--
Charles Lamont

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Here's an even cleverer one, it only has two moving parts that oscillate, is completely sealed and maintenance free, and appears to lock to the grid by it's very nature: http://www.microgen.com/how_it_works.asp
Greg
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Mark G wrote:

The demo engines you tend to see around are usually not self-starting. But there is nothing, in principle, which prevents a twin cylinder engine being self-starting.

Awkward, radiators about same height as the fire, fair size horizontal runs, and standard bore pipework already in place. Fire also about same height as hot water cylinder (and 8 to 10m of horizontal pipe away), so thermo-syphon might be hard work for that use.

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pump
using
I did not think Stirling engines where self starting. Having to have a starter would complicate things..
Regards Jonathan
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Jonathan Barnes wrote:

See other thread where I deal with this misunderstanding; It depends on the detail of the specific engine design, but an expansion cycle engine can be self starting (eg. high pressure steam, low pressure steam, stirling, etc). Self starting is often achieved by having multiple cylinders running out of phase. Compression-expansion engines (eg. petrol, diesel, etc), require starters to get over the initial compression phase.
- Nigel (been away, so late reply).
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and also sunmachine this link about... ( in French ) http://cogeneration.discutforum.com/votre-1er-forum-f1/micro-cogeneration-a-moteur-stirling-alpha-t2.htm#5
best regards
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SWINGREGORY
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Greg Wrote:

:D
and also sunmachine :) this link about... ( in French ) http://cogeneration.discutforum.com/votre-1er-forum-f1/micro-cogeneration-a-moteur-stirling-alpha-t2.htm#5
best regards Grgory
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SWINGREGORY
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