Grundfos pump making unusual sound/boiler not coming on

[Stephen JW]

What was the old pump like eg in the outlets of the pump any blockage or was it clean and around 15mm dia ?

What was the old pump like eg in the outlets of the pump any blockage or was it clean and around 15mm dia ?

What is the boiler power and is it a modulating boiler?

How many rads?.

IF the UPS3 is working properly then CCII is more powerful than CC3 was on your old 5M selectric.
The UPS3 on CCII will maintain +5M up to a demand of 1.1 m3/hr, 18.3LPM.
Also, there should be little or no delay in pump startup after changing settings.
Is the system clean as very dirty systems can build up magnetite on these pump rotors which can slow them down or stop them, the pump head can be removed for cleaning.

Hi John. Thanks for all the information you have provided. This is a steep learning curve for me as I am a complete layman and unfamiliar with the terminology and power ratings etc. But this is what I do know:

Boiler is Potterton Netaheat 50e which Google tells me is max. 14.65kw output

We have 10 radiators in all, smallest 72cm, largest 180cm

4 radiators + heated towel rail upstairs

3 long + 2 short radiators downstairs

The engineer drained, refilled and added inhibitor and fitted new valves with the new pump and 3-port valve.

When we put the pump back into CCIII after everything switched off on CCII last night the pump was ‘throbbing’ and making a ‘thrum-thrum-thrum’ sound as it was running. We left it for a few minutes to see if it would return to normal. It didn’t so we turned it off. This morning there was a lot of gurgling and ‘ticking’ but it is now running on CCIII as before. All radiators are hot. The resonating noise is back.

Many thanks again.

Stephen

 

[John.g]

Looks definitely like a pump problem there IMO, there were a few "dud" UPS3s sold, I would inform your engineer as a new pump should be supplied without question, under warranty, except that your system was/is filthy.
You can yourself just ensure that the pump isol valves are fully open and just recheck that the pump is orientated correctly, ie, if on the boiler flow side, pumping away from the boiler and if on the boiler return, pumping into it.

 

[Stephen JW]

Looks definitely like a pump problem there IMO, there were a few "dud" UPS3s sold, I would inform your engineer as a new pump should be supplied without question, under warranty, except that your system was/is filthy.
You can yourself just ensure that the pump isol valves are fully open and just recheck that the pump is orientated correctly, ie, if on the boiler flow side, pumping away from the boiler and if on the boiler return, pumping into it.

Thanks John. Sadly I don't know how to check these things. The pump itself is physically mounted upside down, presumably as if it were the 'correct' way up the mains cable and its mounting would prevent the airing cupboard door from closing. I have attached a few photos. A couple of further things to mention that may or may not be relevant.

1. Our system has no wall-mounted thermostat. We have old Servowarm thermostatic radiator valves on each rad.
2. We usually run the boiler on setting 3-4 on the control dial (range 1-5/max).

Thanks again!

 

[John.g]

There is an arrow on the pump body, see if its pointing up or down, then follow the pipe (up or down) and see where its attached to the diverter valve and we can soon figure it out.

The pump valves, just turn each one clockwise until shut then anticlockwise until fully open, it should take ~ 3 to 5 full turns each way to fully close/open them.

 

[John.g]

Didn't notice attachments before.......if the arrow on the pump body is pointing downwards then the pump is installed correctly.

 

[Stephen JW]

Didn't notice attachments before.......if the arrow on the pump body is pointing downwards then the pump is installed correctly.

Thanks John. Valves seem to be fully open. Can't see an arrow on the pump body. Where should I be looking?
Does the setting on our boiler that I mentioned have any bearing (3-4 on range 1-5/max) on things?. Likewise the thermostatic radiator valves?

 

[John.g]

Settings on boiler and TRVs are fine.

The pump arrow is on the pump body directly behind o the plug socket and is pointing upwards, probably downwards in your installation (on right hand side).


Can you also get a close up photo of the arrowed area in attachment.

And also around the pipework runs from the mid position valve to the cylinder coil flow and return etc.

 

[Stephen JW]

Settings on boiler and TRVs are fine.

The pump arrow is on the pump body directly behind o the plug socket and is pointing upwards, probably downwards in your installation (on right hand side).


Can you also get a close up photo of the arrowed area in attachment.

And also around the pipework runs from the mid position valve to the cylinder coil flow and return etc.

View attachment 65156

Arrow on pump was quite difficult to access and take snap of but have attached the best I could get. It is pointing down.

Also attached close up arrowed.

Many thanks

 

[John.g]

So pump is correct, the arrowed item is a mini ball valve by pass which is partially opened, can't see any reason why CCII shouldn't give perfectly acceptable flow rates compared to CCIII, it should give ~ 90%. so still points to pump problems IMO.
Its a bit surprising that your engineer didn't try out any other modes as most would settle traditionally for CCII even if they knew nothing about the other modes.

Also point out to him that the UPS3 CCII is more powerful than the Selectric CCIII.

Did your engineer make any other changes apart from the new pump & mid position valve?.

So, Stephen, If it were my installation, I would contact him and inform him of results, can't offer any other words of wisdom I'm afraid.

 

[Stephen JW]

So pump is correct, the arrowed item is a mini ball valve by pass which is partially opened, can't see any reason why CCII shouldn't give perfectly acceptable flow rates compared to CCIII, it should give ~ 90%. so still points to pump problems IMO.
Its a bit surprising that your engineer didn't try out any other modes as most would settle traditionally for CCII even if they knew nothing about the other modes.

Also point out to him that the UPS3 CCII is more powerful than the Selectric CCIII.

Did your engineer make any other changes apart from the new pump & mid position valve?.

So, Stephen, If it were my installation, I would contact him and inform him of results, can't offer any other words of wisdom I'm afraid.

Hi John. Firstly thank you so much for all your words of wisdom. You really have gone above and beyond to help and it is very much appreciated. It makes a huge difference to us to be able to call the engineer back knowing what it is reasonable to expect from the UPS3 in general and particularly, as you say, that UPS3 CCII is more powerful than our old pump - which supplied the system perfectly well for many years.

We are not aware of any other changes he made apart from fitting the Grundfos pump (and new pump valves), Drayton mid position valve and rewiring the (previously incorrectly wired) existing Drayton controller. He also drained and refilled the system.

Can I just ask couple more things before signing off?

The engineer initially quoted for a Honeywell mid position valve but actually supplied a Drayton. We didn't query this as the controller is a Drayton. Is this likely to have any bearing on the issue?

I only noticed after our last exchange of messages that, after I tried different pump settings and returned it to CCIII, one radiator that had previously been hot was lukewarm and one had not come on at all (both downstairs). I turned the boiler controller to 5 and both radiators came on. Any implications there?

And finally a (probably) really stupid question... should the circulating pump be constantly running when only hot water is selected on the controller?

Once again, many thanks for all your help John, you have been brilliant!