Hot water pump

[David Sims]

Does anyone know why there is a water pump (labelled) in my system ?.

It is on permanently (just wired into a plug)

[Owain]

when openining a tap? - usually used in hospitals and the like to avoid cool spots where legionella can breed.

Owain

[Ron Lowe]

Looks like a shower pump ( or similar ) to provide high-pressure hot water to some outlet ( perhaps some high pressure only mixer taps, or a shower mixer, where the cold HP feed comes off the mains. )

Even though it's plugged directly in, there might be a flow switch so it only kicks in when there's flow in that leg.

Can you hear /feel the pump run? Go round turning things on till you hear the pump start.

If it really does run 24/7, then it may be secondary circulation, but I don't see the return coming back to the cold feed via a check-valve and swept tee.

[David Sims]

Thanks for the replies

Have now had a further look:

wired into a junction box (where the mains cable to the pump goes) is a connection from a Honeywell L641A1005 stat attached 2/3 the way up the cylinder set just under 50 degrees C

Switching the pump off

the pipe leading to the pump from the cylinder gets hot

turn pump back on pipe cools

The pump body itself is very warm

[Andy Hall]

Photo of pump?

Make/Model?

Can you trace where the pipe on the other side of the pump goes?

Is there another pipe connected to the cylinder that gets cooler when the pump is off and hot when the pump is on?

[David Sims]

Pump is a Grundfoss Type UM 20-07 N 150 PC

I am unable to trace the pipe ATM I need someone to help (will do tonight)

The only other pipes connected to the cylinder are the boiler connections - none change

[David Sims]

Couple more things:

If I manually turn the stat connected to the pump to just under 70 c the pump stops

There is another stat on the cylinder lower down connected to the Y plan valve

[David Sims]

[Lurch]

On 27 Mar 2007 02:22:09 -0700, "David Sims" mused:

Try using Imageshack, free and easy. ;)

[David Sims]

Sorry try this:

ttp://ph.uncle-dave.co.uk/upload/images/hw.jpg

[Lurch]

On 27 Mar 2007 04:10:56 -0700, "David Sims" mused:

guess is secondary hot water circulation pump but someting should get hot as there would be a return.