Grundfos UP10-16 A PM BU/AC - Sensor Placement

[Baumgrenze]

The installation 'instructions' for the Grundfos UP10-16 A PM BU/AC call for the sensor that 'trains the pump' by checking for hot water demand to be installed on the line flowing from the hot water heater to the hot water delivery line and specifies 8-20 inches from the outlet (20-50 cm.) My water heater is installed with 24" long stainless accordion flex lines. The closest to the outlet I can find pipe onto which to affix the sensor is 26" or 75cm. It does not make sense to me to try to attach the sensor to a flex accordion connector.

http://imgur.com/a/7yIlH

Has anyone installed one of these pumps? Is the 8-20 inches really critical?

Does the whole 'training' concept work in the household of a retiree where the pump is never going to be able to sense a regular routine?

I think the pumps are pretty well built, but the company is very hard to communicate with. Does anyone else have the same experience? The only source that seems to work is a local 'manufacturer's representative.

Thanks,
baumgrenze

 

[CountryBumkin]

I have not used this model - I have a different style. I think the 26 inch distance is fine.

But I think the heat sensor needs to be on the return line (the opposite line from where the pump is mounted), so it can sense that water to the bathroom/kitchen has returned to WH and therefore heated the water sufficiently.
Where does your return line connect to the WH, at the bottom?

 

[Sponsor]

 

[Baumgrenze]

This is a new model with changes. Here are images from the EU Comic Book format installation manual.

http://imgur.com/a/0bbCJ

It appears that there is an 8' (2.5M) pull out tape format cable that is to be run (with support) to a point 8-20 inches from the top of the water heater. There is little supporting documentation as to how this works, but I gather that the sensor responds to demands for hot water (outlet pipe on water heater gets hotter) and a computer chip 'learns' about household hot water use over 1-2 weeks and anticipates needs by turning on the pump in advance. It may be with a second setting of the pump that is identified by a 'thermometer logo' the pump can be set up so that if you turn on hot water the pump starts and then runs (the running time is not described to my knowledge) to get hot water to remote points. I my house this takes 2-3 minutes for the master bath.

The illustration showing the location of the sensor suggests that Grundfos anticipates that you will use the existing cold water lines as recirculation return lines. In my setup I have a dedicated return line. I hope this will work. My 'fail safe' approach is to use an interval timer. I've found several on the web that look promising. I'd go back to an arrangement where I turn on the pump at 5 AM, run it for a set interval, then run it on and off for that interval until bedtime.

Thanks
baumgrenze

 

[Baumgrenze]

See the next post. I somehow posted before I was done.

 

[Baumgrenze]

My apologies. First, thank you for responding, then for my not having answered your question.

The system has the pump in a long "U" shaped diversion. The pump is mounted on the up leg. The flow is up the leg. It is connected to the cold water inlet on the water heater, in my case, on the top, but clearly the water is delivered to the bottom inside.

Here's a link to a picture of the installation. I still have to reinstall the insulation. I also need to ask Grundfos if the pipe where the detector is mounted can be insulated, or if this will interfere with the 'adapting process.' I found one youtube video that says there is a software processor that correlates pressure, temperature, and adjusts flow accordingly.

http://imgur.com/a/uNJ2a

thanks again,
baumgrenze

 

[Ken R]

I am installing this same pump and have similar questions. Did you confirm that placing the sensor on the hot "supply" line is correct? My thinking is like yours - seems like it should be on the dedicated return line. But if the idea is that it "learns" the demand pattern, it does make sense that it is on the supply line. New question: the most logical place for me to place the sensor would be on a copper flexible pipe, do you have any idea if that matters? In other words, the diagram shows it being placed on a standard copper pipe, but I don't have that option.