Grundfos Alpha 2 Setting Advice needed

[Samba123]

Hi there,

Newcomer to these forums and looking for some CH advice.

We had a Grundfos Alpha 2 15/60 fitted earlier this year to replace a standard Grundfos 15/50 pump. This pump ran constantly on Speed 3 but had got very noisy so we replaced with a Greener pump. We run the new pump on Auto Adapt and have been very happy with the pump and has been perfect for what we wanted in that it is much quieter and seems efficient.

Problem we have now is that it's not quite efficient enough to cope with the current cold snap and we need to up the pump speed so the rads warm up quicker and make the house warmer than is currently.

What I'm looking for is some guidance as to what setting would be best for what we need. I understand how to change the setting but am not 100% sure what would be correct for our situation.

Our house is a 4 bed detached - 11 radiators fitted and 8 of those have Thermostatic valves on. The radiators upstairs are getting hot with no problem but downstairs are taking longer to warm up and are cold in comparison.

I've looked at the manual and searched online and can see I have these 7 options:

I, II, III which is for Fixed Speed operation
CP1 or CP2 which are for Lower (CP1) & higher (CP2) constant pressure
PP1 or PP2 Lower which are for (PP1) higher and (PP2) proportion pressure

I assume that setting to a fixed speed operation would be the equivalent to what was set on the old pump, but as I said wanted some advice as to what would be best to change to while the cold continues.

Thanks in advance!

 

[Samba123]

Bump from me - nobody else have one of these pumps or knowledge of them so can offer some advice? I just want some reassurance as to the right setting so I don't cause any damage to the system.

Here are some links to more info anyway.

Table showing what the advice for different modes are:

Alpha 2 settings

• Samba123
• 2 Dec 2010
• 1

Alpha 2 sales brochure:
http://www.grundfos.co.uk/web/homeu...0035d238/$FILE/ALPHA2 Sales Leaflet 0208 .pdf

Alpha 2 Manual:
http://www.prestigepumps.co.uk/data/downloads/Alpha 2 Instructions.pdf

 

[Samba123]

Another Update from me.

I took the plunge and set the Pump over to a Fixed Speed Setting of II.

Seems to be ok - boiler isn't noisy, no real greater noise from pump or rads and the downstairs rads are now much hotter which was the desired result.

Cheers.

 

[ajrobb]

If the lockshield valves are wide open on your smaller radiators, you should balance your system. I don't think it is possible to have radiators perfectly balanced all the time, especially if you have TRVs. (I think pressure drops vary differently with flow for valves and pipes.)

There are various recipes for balancing radiators:

http://www.diydata.com/projects/centralheating/balancing/radiator_balancing.php

With an automatic pump, I suppose all you can hope for is that all the radiator return temperatures are about the same. Personally, I'd start with the smallest radiators. If their return pipe is nearly as hot as their flow pipe, you need to reduce the flow with its lockshield.