Grundfos Alpha pump suitability

[AlanRob]

Hi,

Could anyone tell me if the above pumps are suitable for a Glowworm 30HXI condensing boiler and if so, anything to watch out for?

 

[Agile]

If the boiler does not contain its own pump then it probably will be suitable BUT ask the manufacturer's tech help first because the type of pump fitted could affect the warranty on the boiler.

Also the pumps own variable head characteristics may conflict with the boiler's modulation.

As far as I know there are no boiler designs which use these new pumps yet. Its not up to the pump maker to decide if its suitable, its Glow-Worm who provide the guaranty on their boiler but only if its correctly fitted!

Tony Glazier

 

[ChrisR]

The instructions say
"A variable duty pump should be set to give a temperature
difference of no greater than 200C between the flow and return,
with the thermostat set at “MAX”, which is about 800C, to give
a flow rate as shown in table 3."

It is not clear whether GW mean manual or automatic variability .

Suggest you call GW. Grundfos are spectacularly incompetent in having no technical information available on/from their website.

 

[AlanRob]

OK, thanks for the help guys. Think I'll stick with the bog standard 15/60 then, put in a auto by-pass valve and not risk voiding a warranty.

Rgds,

Al

 

[chrishutt]

"A variable duty pump should be set to give a temperature
difference of no greater than 200C between the flow and return,
with the thermostat set at “MAX”, which is about 800C

Shouldn't that be 20 C and 80 C ?

 

[ollski]

Can't see why there would be any problem...it only adjusts the pump speed depending on the resistance of the water circuit to maintain a constant which should only be beneficial.

 

[AlanRob]

Can't see why there would be any problem...it only adjusts the pump speed depending on the resistance of the water circuit to maintain a constant which should only be beneficial.

Would an auto by-pass be needed on a y plan with the alpha pump?

 

[Agile]

I would tend to think not BUT I understand the Building Regulations expect a stand alone auto by pass regardless.

If thats correct then its seems to me to be a little bland. As far as I can gather its to require that TRVs are fitted to ALL the rads to avoid the bathroom rad wasting heat when it acts as a bypass.

Tony

 

[Agile]

The instructions say
"A variable duty pump should be set to give a temperature
difference of no greater than 200C between the flow and return,
with the thermostat set at “MAX”, which is about 800C, to give
a flow rate as shown in table 3."

If the manufacturers instructions really say that, then someone should point it out to Glow-Worm. At least setting the stat to 800*C will prevent the copper pipework from melting! Pity about the solder joints though and as for plastic pipework, well that gets pretty soft at 130*C !

Tony