Hot-water circulation pump

[desA]

I'm trying to locate small hot water circulating pumps, similar to the ones shown below, but with variable speed. The ones shown below are 3-speed, fixed setting. I'd like a decent quality product.



Thanks for your suggestions. Variations on the theme will be most welcome.

[chemi-cool]

The three pumps I use are:

Salmson, Wilo and Pedrollo.

All good and reliable makes.
I cant tell you about prices outside my country but here the are cheap.

[Quality]

Try Grundfoss they are not the cheapest but very reliable

[desA]

Thanks very much Chemi-Cool & Quality.

[sedgy]

normally to pump hot water , it is recomended to use a bronze cast pump, if you use a carbon steel cast pump you will get lots of black gunge in the stytem, hope this helps

[Brian_UK]

normally to pump hot water , it is recommended to use a bronze cast pump, if you use a carbon steel cast pump you will get lots of black gunge in the system, hope this helps

Only if the Hot Water is for domestic use, if it is heating hot water then Bronze is not needed.

[desA]

^ That is a good tip. Thanks very much Brian.

[Brian_UK]

Slightly, or more, .

I got called to a school plantroom where they reported a copper pipe leaking.

The copper tube (1/4") was screwed, via a compression fitting, into a steel reducing bush and the main bronze pipe fitting.

It was the sensing tube for a pressure differential switch across the pump. Glad to say that I was able to valve it shut before I started because...

I put my spanner onto the steel bush and with a quarter turn it fell out of the screwed socket.

The high oxygen content of the heated domestic hot water had speeded up the electrolytic corrosion generated by the mismatch of the fittings.

I had to replace both of the fittings as the steel threads were less than half of their original length.

Also, the inside of the main pipework was 85% blocked with the by-product of the electrolytic action.

So, be warned, always check that the fittings you use match the water service.

[desA]

Excellents points, Brian. Thank you.

[sedgy]

normally to pump hot water , it is recomended to use a bronze cast pump, if you use a carbon steel cast pump you will get lots of black gunge in the stytem, hope this helps

yes thats what I said

[Brian_UK]

^^ OK, me being a pedant I suppose.

[Peter_1]

What do you need to pump, water in a closed or open circuit?

[sedgy]

hi peter , in some large buildings using hight to give pressure , to giveenough hot water to each hot water tap , is not enough, so on each floor one would fit a hot water ring main to give enough hot water to each and every tap= sedgy

[nike123]

I'm trying to locate small hot water circulating pumps, similar to the ones shown below, but with variable speed. The ones shown below are 3-speed, fixed setting. I'd like a decent quality product.


Thanks for your suggestions. Variations on the theme will be most welcome.

Check Grundfoss Alfa 2:

http://www.grundfos.com/web/grfosweb...grundfos+alpha

[desA]

What do you need to pump, water in a closed or open circuit?

Hi Peter,

In my case it would be for hot water in a closed loop.

[desA]

Check Grundfoss Alfa 2:

http://www.grundfos.com/web/grfosweb...grundfos+alpha

Would it be possible to post the Alpha data sheets to a download site, as I cannot access them off WebCAPS, where I am at present.

This would be incredibly helpful.

[nike123]

Here

Why you need variable speed?

[desA]

Thanks so much nike - you are an absolute star.

Variable speed allows a few tricks in terms of overall system efficiency.

[nike123]

DesA, try to use proxy if you cannot access Webcaps from your location.
http://www.proxy4free.com/page1.html

[nike123]

Variable speed allows a few tricks in terms of overall system efficiency.

If you need constant differential pressure, that is easy to achieve with overflow valve.

[Endex]

Hot water circulation pumps used to be bronze but now they are stainless steel

[desA]

Hot water circulation pumps used to be bronze but now they are stainless steel

For chlorinated water?

[desA]

If you need constant differential pressure, that is easy to achieve with overflow valve.

Thanks nike.

Could you perhaps go into more detail on this?

[nike123]

Check this PDF!
And this!

[desA]

Check this PDF!
And this!

Thanks so much, nike. Very nice & simple.

I wonder if the pump thermal input would gradually raise the circulating water temp, over time?