Help with grundfos re-circulating pump.

[andy789]

Hi everyone
We inherited a heating system in our house with a grundfos UPM3 AUTO L which is connected to the hot water cylinder to push hot water around the house.

But I have no clue if it's set correctly or how it works. The valve to it had been turned off by the previous owners. Hot water takes ages to get to the end of the long run.

With the circulator operating obviously it comes through quicker.

I've read the grundfos pump info but all it tells me is that there certain curves. What curve should it be set to, what do they mean?

What I'd like to know is what should it be set to and is it a false economy? What I'm wondering is if it circulated the hot water from the tank around the house - surely it will eventually cool the whole tank down and I'll be spending more money heating the water to keep it circulating warm.

My family complain that it takes about 3-4 minutes to get hot water from the tank when the circulator is off but obviously we're pouring gallons of cooled water from the pipes down the drain.

What's everyone's thoughts and advice please because I don't know if I'd be better off leaving the circulator on but therefore constantly heating it costing a fortune in gas. Help!

Thanks
Andy

 

[ianmcd]

Sorry but you are confused about what your grundfos UPM3 AUTO L does, it does not circulate the HW from the Cylinder around the house, it circulates the hot water from your boiler to the indirect coil in the cylinder and heats up the water in the cylinder, it has nothing to do with the water that comes out of your HW taps, there are circulators that can do this but that is not the system that you have

 

[andy789]

Thanks for the reply Ian.
Obviously I have an odd /bad set up then.
It definitely takes water from the hot water cylinder and sends to the taps, see photo.

 

[polesapart]

You could wire it through a timeswitch set to come on when when hot water is likely to be required.


(iain I had to google it, but it does seem that the upm3 is multipurpose, including secondary circulation)

 

[andy789]

Thanks poles.
I was thinking that might be an option.

 

[picasso]

 

[DP]

It definitely takes water from the hot water cylinder and sends to the taps, see photo.

Not when you have unvented cylinder.
If the pump has a connection going to the cylinder, it does not mean it is the HOT WATER that is being pumped.
Follow the pipe off the top of the cylinder and see if the pump is connected to it or onto a connection high up on the cylinder.

If the pump has been fitted to aforementioned connections, then pump is the wrong type ( iron body not suitable), should be bronze for secondary circulation. Secondary circulation is there for instant hot water at all taps rather than increased pressure which you will already have with unvented hot water cylinder. If pressure is the issue instead of long wait to get hot water when tap run, look at the mains supply

 

[andy789]

thanks DP.
Well now i'm really confused about what's been put in this set up.
It does connect to the side of the cylinder 2/3 of the way up (see pic) and the eipe then goes off around the house. Hot water does come through quicker when the valve to it is opened up and its running.

We don't have a problem with water pressure - that's good. It does take ages for hot water to get to the end of the run though except when this (re)circulator is running - but again that is my issue. Can it be controlled or if it's running will it just ultimately mean i have to be constantly heating the hot water cylinder? what is the best setting to have it on? I've attached a screenshot of the grundfos spec sheet.

Thanks for all your input .

 

[picasso]

Ignore DP as he does not seem to understand the type of circulator you have, as said before put the hot water circulator on a timer and pir sensors also look at pipe stats to control the pump and that will save you money also insulate as much pipework as you can get to.

 

[DP]

Ignore DP as he does not seem to understand the type of circulator you have, as said before put the hot water circulator on a timer and pir sensors also look at pipe stats to control the pump and that will save you money also insulate as much pipework as you can get to.

Pray tell what secondary circulation is (which I am implying that pump is for) ?
Also that pump for what it does, seems to have iron base instead of bronze unless it is plastic.

You might want to read what is written instead of jumping in feet first. Give me some education as to what I am missing.

 

[picasso]

Polesapart has already posted that the pump is suitable for dhw secondary circulation.

 

[DP]

Polesapart has already posted that the pump is suitable for dhw secondary circulation.

Education indeed. Did not know a pump with iron base could be used for secondary circulation. Always thought it had to be bronze pump

 

[JohnD]

there are stainless steel versions now.

the bronze one was (is?) very expensive (painted dull yellow)

 

[oldbutnotdead]

Not sure if that pump of yours is one of the clever ones that learns your hot water use...if the hot weather comes back (or you keep the heating off) you might try reading the gas meter weekly & running a week with recirc on and a week with recirc off. And then decide if the benefit of rapid hot water is worth whatever the cost per day turns out to be....

 

[andy789]

Thanks oldbutnotdead
I think this is a dumb one as it keeps running regardless and the water eventually gets cold.
Can't justify running the boiler constantly to get instant hot water a once or twice a day at the far end of the house.

thanks again
Andy