System was working fine yesterday with the Alpha pump set on lowest proportional setting. I noticed in the evening the radiators barely warm. So opened up the trvs no difference. Rads warm to the touch but no more. So checked oil boiler over nothing looking amiss. So I switched the pump over to fixed and set to highest. Rads now nice and hot. As it has been set to lowest proportional for ages, years, and rads got hot why the sudden change? Am I missing something obvious here?
- Thread starter Bogart
- Start date
View the thread, titled "Grunfos Alpha pump" which is posted in DIY Plumbing Advice on UK Plumbers Forums.
Miraculous I would say if you were heating all your rads on PP1 on a (any Grundfos) 6M, 45W alpha1 or 2, based on a fairly typical system like mine which requires 3.6M head to give 15.0LPM (0.9m3/hr) then PP1 should flow 8.7LPM (0.52m3/hr) at a 1.2M head, ~ 8W power, PP2, if selected, 11.2LPM (0.67m3/hr) at a 2.0M head & 13W. highest speed3 should flow 17.7LPM (1.06m3/hr) at a 5M head & 45W. (all based on mine)
If the pump (which it might) shows the power in watts, W (newer models also give the flowrate in m3/hr), note and post the readings both in PP1 mode and full speed mode.
Pump is a fair few years old and does not have an info display on front except the 3 settings on each arrangement. I must point out that we rarely have many radiators on anyway, log burners work overtime.
I had planned this morning to switch back to the original setting and see results so will do that.
I had planned this morning to switch back to the original setting and see results so will do that.
Is product 95047568 which is to give its full title is an Alpha2 L 15-60 130. Same power/current as your photo.
On page 12 of the handbook it shows various pump settings for different arrangements ie radiators,
underfloor heating, and shower. Using the prefered setting for normal radiators I have used setting 2 of the proportional setting, as previously used. All seems to be fine at present.
On page 12 of the handbook it shows various pump settings for different arrangements ie radiators,
underfloor heating, and shower. Using the prefered setting for normal radiators I have used setting 2 of the proportional setting, as previously used. All seems to be fine at present.
That model seems to have better PP settings than the settings I see in the Mis for the Alpha2 generally.
PP2 (4.0 on your pump) should flow 13.8LPM @ 3.05M (based on my requirements), you said in post #1 that the pump was on the lowest proportional setting, PP1 (2.5M), it should have given a flowrate of 9.8LPM @ 1.53M, head too low IMO, but any head around 3.0M should be OK as you are now finding.
PP2 (4.0 on your pump) should flow 13.8LPM @ 3.05M (based on my requirements), you said in post #1 that the pump was on the lowest proportional setting, PP1 (2.5M), it should have given a flowrate of 9.8LPM @ 1.53M, head too low IMO, but any head around 3.0M should be OK as you are now finding.
Official Sponsors of Plumbers Talk
Reply to the thread, titled "Grunfos Alpha pump" which is posted in DIY Plumbing Advice on Electricians Forums.
Similar plumbing topics
- Question
