I have a two Baldor Sequence multi-duty 240v 1/4hp pond pumps (around 12 years old). I currently just operate one for economy.

It runs dry when the plastic pot filter gets blocked with pond debris (plant and algae slime). Frequent cleaning of the filter mostly avoids the problem but not always. The pump can run dry for many hours (such as over night or even longer if I'm away) and obviously the pump gets extremely hot and bothered (as do I!).

I understand that most modern pumps are fitted with protect to avoid them running dry but I have been looking in vain for a device that I can retro fit that can detect when the pump has run dry (or hopefully before) and could kill the mains supply. The pump is housed in a weatherproof structure with mains connection and isolating switch.

Please, does anyone know of such a device or how this could be achieved economically, (without buying a new pump)?

"Malcolm Davis" wrote


I have a two Baldor Sequence multi-duty 240v 1/4hp pond pumps (around 12
years old). I currently just operate one for economy.

It runs dry when the plastic pot filter gets blocked with pond debris
(plant and algae slime). Frequent cleaning of the filter mostly avoids
the problem but not always. The pump can run dry for many hours (such as
over night or even longer if I'm away) and obviously the pump gets
extremely hot and bothered (as do I!).

I understand that most modern pumps are fitted with protect to avoid
them running dry but I have been looking in vain for a device that I can
retro fit that can detect when the pump has run dry (or hopefully
before) and could kill the mains supply. The pump is housed in a
weatherproof structure with mains connection and isolating switch.

Please, does anyone know of such a device or how this could be achieved
economically, (without buying a new pump)?

.................................................

Wrong Ng really but anyhow, I can't find a separate "Float Switch" available
so the only way to do it would be to build your own. You could simply use a
ballcock float and an electrical push switch so if the water level falls the
pressure comes off the switch and the power is cut.

--
Regards
Bob Hobden
W.of London. UK

On Sun, 10 Apr 2011 07:55:10 +0000, Malcolm Davis
wrote:


I have a two Baldor Sequence multi-duty 240v 1/4hp pond pumps (around 12
years old). I currently just operate one for economy.

It runs dry when the plastic pot filter gets blocked with pond debris
(plant and algae slime). Frequent cleaning of the filter mostly avoids
the problem but not always. The pump can run dry for many hours (such as
over night or even longer if I'm away) and obviously the pump gets
extremely hot and bothered (as do I!).

I understand that most modern pumps are fitted with protect to avoid
them running dry but I have been looking in vain for a device that I can
retro fit that can detect when the pump has run dry (or hopefully
before) and could kill the mains supply. The pump is housed in a
weatherproof structure with mains connection and isolating switch.

Please, does anyone know of such a device or how this could be achieved
economically, (without buying a new pump)?


A flow switch in the output line.

Samples:
http://www.grainger.com/Grainger/flo...ecatalog/N-cca

You would need a momentary bypass on the switch to start the pump when
it wasn't running.

Malcolm Davis wrote:
I have a two Baldor Sequence multi-duty 240v 1/4hp pond pumps (around 12
years old). I currently just operate one for economy.

It runs dry when the plastic pot filter gets blocked with pond debris
(plant and algae slime). Frequent cleaning of the filter mostly avoids
the problem but not always. The pump can run dry for many hours (such as
over night or even longer if I'm away) and obviously the pump gets
extremely hot and bothered (as do I!).

I understand that most modern pumps are fitted with protect to avoid
them running dry but I have been looking in vain for a device that I can
retro fit that can detect when the pump has run dry (or hopefully
before) and could kill the mains supply. The pump is housed in a
weatherproof structure with mains connection and isolating switch.

Please, does anyone know of such a device or how this could be achieved
economically, (without buying a new pump)?

You could attach a Thermal Switch to the pump to cut out when the pump
gets to an objectionable temperature.
See for instance http://www.thermodisc.com/productdetail.asp?ProductID=2
Bob Williams