Smart Pump Setting with gravity fed system

[Kingfisher1]

Central Heating Pump - G Pump Force HE-RS25/6PWM-130

Hi,

I would be grateful if someone could explain whether our CH system can cope with the AUTO (adaptive mode) setting on this the new pump or which mode it is best set at (recently had our old 3-speed pump replaced with the above smart pump). New pump has been installed and left running in the factory setting - constant speed 3.

System set-up: Old flooring-standing open flued gas Potterton Kingfisher 150 boiler (a beast but reliable). Gravity-fed system with tank & expansion tank in loft, twin coil cylinder in airing cupboard, fixed bypass valve, CH pump on return, 3 motored valves (up/down rads, water), all rads have TRVs fitted apart from 2 in rooms with thermostats, all copper piping.

Modes on pump: Auto (adaptive mode), PP1/2/3 (proportional pressure curve, speed 1/2/3), CP1/2/3 (constant pressure), CS1/2/3 (constant speed), PWM (external control of motor speed).

Question: Although old pump had failed, one of reasons we were advised to have this new smart pump was the energy saving…..but it has just been left installed at highest setting. Can our system design cope with using any of the other settings - auto being the most energy efficient I presume? Not sure what PWM mode is as I cannot see anything else has been added to the system to control motor speed of pump (sensor etc). If not just wondered what the point was installing this type of pump rather than like-for-like accepting that internal mechanics of pump design have improved. Cannot find a simple explanation of which ch system is best suited to which setting….

Thanks folks

 

[Last Plumber]

Did the installer of the pump not check that the system was balanced and that there were no issues? Why was it left on MAX?


PWM is pulse wave modulation. It is used to regulate/control speed on things such as motors. A lot of modern pumps and fans use it but you won't have that capability on your system.

 

[Kingfisher1]

Thanks for reply - now understand PWM not applicable. If you mean did plumber balance rads etc then no he didn’t and I have no idea why it was left on Max other than guessing that it is because it is the factory setting (I would get him back but busy guy and pretty tricky to get hold of). Are you able to help with answering question of Auto mode or other modes? Thanks again

 

[John.g]

How many rads?, all circ pumps come set to CS 3 (actually CC, constant curve), CC2 should, in most cases, be quite sufficient. Have you a link to that model?.

Found the link so will have a look.

Auto Adapt, forget it IMO, I've never seen it working on a Grundfos.
CS3 is far too high IMO at 6.4M except you have a awful lot of rads.
CS2 should do most systems.
But because you have TRVs, would suggest PP3 and just maybe PP2 (once the number of rads are known)

 

[Kingfisher1]

How many rads?, all circ pumps come set to CS 3 (actually CC, constant curve), CC2 should, in most cases, be quite sufficient. Have you a link to that model?.

Found the link so will have a look.

Auto Adapt, forget it IMO, I've never seen it working on a Grundfos.
CS3 is far too high IMO at 6.4M except you have a awful lot of rads.
CS2 should do most systems.
But because you have TRVs, would suggest PP3 and just maybe PP2 (once the number of rads are known)

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View attachment 86612

Brilliant thanks John - very helpful. We have 8 rads downstairs and 8 upstairs.

 

[John.g]

Try constant pressure CP2 at 3.6M, or PP3.

 

[Kingfisher1]

Try constant pressure CP2 at 3.6M, or PP3.

Thanks John - understand the proportional pressure idea with trvs, so will give that a go tonight.

 

[Kingfisher1]

Everything working fine on PP mode - thanks for the advice John.