Noisy Grundfos Pump

[midas]

My GRUNDFOS SUPER SELECTRIC CENTRAL HEATING PUMP 15-60 has recently started making a humming noise.
It's currently set to 2.
If I turn it down to 1 the noise goes, at 3 it's even noisier.

What's causing the humming sound and how to cure it?
What speed should my pump be set at anyway?

Thanks in advance.

 

[easyas123Viessmann]

The pump speed is related to the resistance of your heating system and the output of your boiler. On average most pumps are correctly set at setting 2. you may have some obstruction in your system causing a bit of pump strain. measure the difference in temperature between the flow and return on the boiler. This should be approx 11 deg c for an old boiler and between 15 and 20 for a condensing boiler. If the temperature difference is to high it indicates a circulation problem. Could be debris in the pump impeller, scaled primary heat exchanger or sludge in the system. Could be your pumps knackered.

 

[midas]

Thanks for your reply.

It's not often I get a lie-in but we're snowed in so no boys footy club this morning.
Our bedroom is directly above the boiler (18 year old oil fired Camray Quartet) and the pump is is our bedroom airing cupboard so basically if anything gets noisier I'll hear it.

I don't run the heating at night, it's comes on around 6:30 so it's starts from cold and I've noticed that lately the whole system,has become much noisier.

The boiler sounds very whiny for a while.

It seems to take about 1 to 1 1/2 hours for the whole thing to quieten down to an acceptable level.

So I wonder whether there's a general problem with the system rather than just the pump?

I also noticed the tone of the humming noise from the pump does vary, as if as you suggested there may be periods of resistance due to crap in the system?

The pump was changed about 5 years ago I think.

In terms of solutions what's the best procedure?

I'm a reasonably confident DIYer so are there any cheap simple options I can try first e.g. adding anything in to the system to quieten it down?

Thanks

 

[joe-90]

Sounds like you need to clean it out big time.

 

[midas]

Which entails what?

 

[joe-90]

You can hire a power flush machine or take your rads out into the garden or even just add a chemical cleaner and follow the instructions on the back of the pack.

 

[ianmcd]

regardless of whether you need a powerflush or a chemical flush it would still be a good idea to fit a system filter so why not put one in first anyway, say a magna clean and run it for a few weeks and clean it regularily and that will give you an idea how much contamination is in the system water, it cant do any harm and you would be well advised to have one anyway even after a power flush if required so not going to cost you anything extra

 

[Agile]

You really need to take a sample of the system water and see what colour that is.

That will then indicate what is the best way to solve the problem.

Tony

 

[midas]

OK thanks

Shall I do that from the lowest rad in the house?

What colours indicate what problems?

 

[midas]

regardless of whether you need a powerflush or a chemical flush it would still be a good idea to fit a system filter so why not put one in first anyway, say a magna clean and run it for a few weeks and clean it regularily and that will give you an idea how much contamination is in the system water, it cant do any harm and you would be well advised to have one anyway even after a power flush if required so not going to cost you anything extra

OK sounds good.
I guess then this filter alone even with regular cleaning wouldn't clean out my system?

 

[ianmcd]

regardless of whether you need a powerflush or a chemical flush it would still be a good idea to fit a system filter so why not put one in first anyway, say a magna clean and run it for a few weeks and clean it regularily and that will give you an idea how much contamination is in the system water, it cant do any harm and you would be well advised to have one anyway even after a power flush if required so not going to cost you anything extra

OK sounds good.
I guess then this filter alone even with regular cleaning wouldn't clean out my system?

not completely but will catch the majority of water based contamination wont loosed any sediment that is lying at the bottom of radiators etc

 

[midas]

I'm planning on doing a flush using Sentinel X400.
What's the correct procedure?
I've read it can be left in for 4 weeks if need be.
Is there any benefit to completely draining the system first then refilling and adding the Sentinel or should I just drain off enough to add it?
Some say I should run the pump at full speed?
Advice welcome.

Thanks

 

[easyas123Viessmann]

I use Kamco hyper flush. Drain the system until the header tank in empty and a further ten litres. Add two litres of hyper flush to the tank. Refill the system. This cleaner is more powerful and can only be left for two weeks max. Fit a Spirotrap rather than a Magnaclean, it's far better. After one or two weeks open the drain points and leave the tank filling. Run like this until the water runs clear. Turn of the feed to.the tank and open the radiator vents on the top floor. When these rads are drained open the powerpoint rad vents. Now do up all the vents and refill the system. Turn off the gas and run the system for about an hour. Repeat until all water is clear. Add the appropriate dose of system safe. This is a very slow and boring method. If you can afford it get the system power flushed.

 

[midas]

Can I ask why you think Spirotrap is better tha Magnaclean?
Also are there any potential downsides to fitting one of these filter systems?
Sorry but what are powerpoint rad vents?
I'm on oil rather than gas but basically you mean turn up the thermostat to kick in the pump but without the boiler on?
Thanks

 

[midas]

Actually if you listen to the pump itself it's not noisy but you do hear what sounds like constant debris rushing through it.
Downstairs however you can hear vibration / loud humming whenever the pump is running and as I mentioned before the tone of the humming changes, so I'm assuming it's linked to the pump?
Is there anything else worth checking?


Thanks