Grundfos Superselectric UPS 15-60 pump - what setting?

[BritishBeef]

Hello there!
I'm just a house owner looking for some advice from some of you plumbers!

I recently noticed that it sounded like the heating was on 24/7 even when the central heating was switched off. The noise was coming from our airing cupboard where our hot water heater is situated (Heatrae Sadia MegaFlow). I found out what the problem was in that the noise was coming from our central heating pump (Grundfos Superselectric UPS 15-60). It would seem that the 3 selector switch on the side of the pump had been knocked onto '3' the highest setting. I understand (with the help of Google) that the settings are for efficiency reasons. If I switch it to 1, the pump is practically silent and 2 is louder then 3 the loudest (obviously). As I was unaware of the pump noise before, then I can safely assume that '3' was not the setting that the pump was set to when installed. Now my question is, what setting should it be on? 1,2 or 3? or how can I work it out?

Thanks for any help, it's really appreciated.

I have attached some images for reference:

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• BritishBeef
• 21 Apr 2008
• 1

Untitled

• BritishBeef
• 21 Apr 2008
• 1

 

[D_Hailsham]

I understand (with the help of Google) that the settings are for efficiency reasons. If I switch it to 1, the pump is practically silent and 2 is louder then 3 the loudest (obviously). As I was unaware of the pump noise before, then I can safely assume that '3' was not the setting that the pump was set to when installed. Now my question is, what setting should it be on? 1,2 or 3? or how can I work it out?

The setting is only indirectly related to efficiency. The main purpose of having three speeds is so the flow rate of the water circulating through the boiler, and radiators can be set to give the designed temperature drop between flow and return pipes. This will depend on which boiler you have.

 

[BritishBeef]

Thanks for the reply.
The boiler I have is an Ideal Classic FF350 if that helps?

 

[puzzlebobble]

Hi,
I'm not a heating engineer or plumber- in-fact I'm on here trying to figure out (in my lunch break) roughly what rebalancing will be needed now I've put some TRV's in. However, I've got the same pump and had the same question a while ago.

i found the answer by reading the boiler installation manual; it required a certain flow per minute; then looking at the grundfos instructions it was clear that it needed to be on III to deliver that flow (it was on II). At a previous place I lived I think the boiler installation manual mentioned a temperature drop between the incoming water and leaving water (something like 11 degrees but it's probably different between boilers). So my suggestion would be to find yourself the boiler installation instructions and see what it says.

 

[D_Hailsham]

Thanks for the reply.
The boiler I have is an Ideal Classic FF350 if that helps?

This boiler works best when the difference between flow and return temperatures is about 11°C; i.e 75°C flow and 64°C return. The exact difference is not important. The difference is inversely proportional to the flow of the water. At a low pump speed (1), the flow will be slow and the temperature differential high . At a high pump speed (3) the flow will be faster and the differential lower. If the speed is too low, the water may start overheating and you will hear kettling. This is because the heat is being generated by the burner faster than the water can take the heat away.

 

[BritishBeef]

Thanks for the helpful replies.
One last thing. It seems that the pump is on all the time. Surely the pump should only come on when the central heating calls for it ie. when the rads need heating?

 

[D_Hailsham]

It seems that the pump is on all the time. Surely the pump should only come on when the central heating calls for it ie. when the rads need heating?

You are right; something must be wrong with the wiring.

If you let me know how many motorized valves you have, I can post a wiring diagram.