Boiler water pump for radiators starting to make an intermittent relatively high pitched vibrating noise

[Rollerball]

When it's happening, (it's intermittent) I can even hear it vibrating in the radiators as well as the pump itself.

The pump is attached to a water pipe that's more than an inch in diameter, presumably it's one that circulates the hot water to the radiators. I see that it goes into the back of the oil fired boiler.

The pump is a Grundfos Selectric UPS 15-50, like this:

Grundfos UPS 15-50 (130) Selectric Domestic Heating Circulator 240V

GRUNDFOS UPS 15-50 (130) CIRCULATOR 240V Central Heating Pump Refurbished and quality checked by experienced engineers and comes with 12 months warranty.

www.heatingandcateringparts.com

I'm guessing that a bearing is wearing out (or maybe dirt inside?) but should I be looking to repair or replace the pump?

Are they relatively easy to teardown and repair?

If I decide to replace the whole pump then is it a job I could do myself ? I two stop taps (no wheel attached to either though) each side of the pump so at least I won't need to drain the system, just attach a wheel/handle or use a wrench.

Anything in particular that I need to be aware of if replacing it? I note that I'll need to connect it up electrically.

It it simply a matter of take old the old and put in the new or do I need to also make sure that I use PTFE tape on the threads, etc?

I also notice that you can buy new or refurbished, not sure what I'd go for.

 

[Johntheo5]

Quite easy to replace your self especially since you have the gate type pump isolation valves.
You could install a second hand pump, or for ~ £100, a new Wilo Yonos Pico 6M pump like I have which is a very quiet pump with excellent settings, any of these high efficiency pumps will save a few bob on energy costs vs a second hand pump, you would get the £50 or so difference in cost back in 3 or 4 years or less.
Can you measure the distance across the flats of one of the two nuts that attach the pump to the pipes and post back before buying anything.
You dont require any PTFE tape on the threads but buy 2 rubber gaskets (not fibre) for installing with the new pump, the Wilo comes with them but should only be a few quid in any case.
How many rads have you got and is it a sealed or open vented system with a feed&expansion (small) tank in the attic?.

 

[Rollerball]

John, many thanks for the detailed reply.

Is there any recommended online shop to buy a Wilo Yonos Pico 6M ?

When you ask about the "the distance across the flats of one of the two nuts that attach the pump to the pipes" do you mean the diameter of the nuts? If so then measuring across the flats I get 55mm.

I think I'll also need a special wrench to undo them?

I assume that the Wilo Yonos Pico 6M be the same length as the Grundfos Selectric UPS 15-50 ?

How about the wiring? Just had a look online and the Grundfos appears to have its own internal plug that the wires are attached to, so I guess I'll need to wire up a similar type of plug in the Wilo? (in other words there's no standard connector?).

There are nine radiators in the property (it's only a bungalow)

Afraid that I have no idea if the system is sealed or open vented (there is though a small water tank in the attic (also a very large one about 20 feet away) but I'm not sure if the small tank is part of the heating system or not - it is though roughly above the boiler so I guess it is?).

 

[Rollerball]

Here's another puzzle - at the time of typing this the boiler has been off for just over an hour, however I just noticed the vibration sound from the radiators once again and on checking the pump it's making the noise and there's the sound of water circulating.

Putting aside the noise for now, should the pump be active even though the boiler is off? Perhaps it's normally like this but I've never noticed because it's not produced the vibration that I only noticed today.

The oil boiler is a Danesmoor 15/19

Edit: Also, on touching the pump it's very hot. Think I'd best turn it off at the wall? That said, the pipes are hot too of course so maybe it's normal, although the heating is off and the radiators are cool.

 

[Johntheo5]

No, the pump certainly shouldn't be running on like that, can you see if your system has a number of 2 port (2 pipe) motorized valves or just one 3 port (3 pipes) motorized valve like the one(s) shown below.

You don't have to take the nuts off the pump, just need the measurement where the spanner fits on, if your piping is 1 ins or say 28mm then the pump will have different diameter ends so need to identify.

 

[Rollerball]

Thanks. It has two motorised valves. I can feel a slight vibration in them but the main vibration (and intermittent noise) is from the pump.

The nut diameter across the flats is 55mm.

The copper pipe diameter is 28mm.

Due to the sound it's making I guess the pump is at fault but could that also cause it to be running on? I assume that it has some internal circuitry which governs how it runs because the wire it's connected to is power only.


BTW, does the replacement Wilo pump need to be the Yonos Pico 6M? I ask because my local plumbing supplies shop is City Plumbing (apparently open tomorrow, bank holiday Monday) and their web site lists the following when I search for the 6M:

https://www.cityplumbing.co.uk/search/?text=Wilo%20Yonos%20Pico%206M

Will any of those do instead? I"m keen to replace it on Monday you see.

 

[Johntheo5]

Are you saying that the pump runs from a independent power source?, if so, this isnt correct, it should start with the boiler/burner and when the boiler cuts out then it might run on for say 3 minutes or so and then stop??. It should be wired into a wiring centre with a lot of terminals.
If you fire up the boiler does the vibration go away??.

Re Pump selection, the third one on the right, in your link, the 25/1-6 at £113.28 is the one BUT I would bring the old pump with me as I'm not, but almost are, 100% sure that the threaded ends are the same, I measure 51mm across the nut flats on mine and 47/48MM across the pump threaded ends, its more than likely that your old pump is the same but safer to remove the old pump, it should be 130mm between the flanges.

When/if you do remove the pump cable from the wiring centre, ensure you note which terminals its connected to.

You can buy two nuts and cut off the old ones (see attachment) and slip on the new nuts without draining down the system and dont really need a special spanner, just ensure you have the new nuts before doing any cutting.

Also note the old pump setting, it will probably be on setting 2 or 3 and very important to note the direction the pump is pumping in, yhere is a arrow on the (all) pump casing.

 

[Rollerball]

Sorry, yes, the pump wiring goes into a central wiring 'box' on the wall, so when I turn off the power to that it all goes off, including the pump.

Out of interest, is it possible that one of the two valves on the pipes is causing this issue?

Also, what would cause the pump to run on like it does, and could that be related to the intermittent noise it's making? I assume it has an internal control PCB of some description?

Thanks for the other info too.

 

[Johntheo5]

Yes, quite possibly one of the mot.valve end switches staying on and giving a run signal to the boiler/pump but if so then the boiler will also fire up occasionally as the boiler stat opens/closes, you can sometimes fairly easily check by (with mot.valves deenergised) pulling on the manual lever, there should be a fairly stiff resistance while pulling it across, if failed, this lever can sometimes feel floppy. The surest way of checking is to remove the orange wires from both mot.valves in the nearest wiring centre and see if the pump stops, if it stops when first one is removed then its that valve has failed, if it stops when the second one is removed then its that valve. Of course it could be the boiler PCB, you occasionally see that mentioned, also some weather compensated systems have the completely daft requirement of keepng the circ pump running continuously, believe it or not.

 

[Rollerball]

Thanks for that info, I'll have a look into those suggestions this morning.

You mention the boiler PCB, do you mean the control box? (in this case the TF830.3) which also has the lockout button? Or is there another PCB in a Danesmoor 15/19?

So I left the boiler, water pump, etc powered off overnight (I had turned off the switch at the wall) and when switching on at the wall the boiler fired up straight away even though the control panel wasn't set to switch it on. (therefore no lights on the panel). Is that normal?

I've never left it switched off at the wall before, hence my puzzlement.

 

[Johntheo5]

Yes, the control box but very unlikely IMO to be the problem.
It looks very like a mot.valve problem. When you power up the (switch on wall) system it also puts permanent power to the mot.valves (grey wire), when there is a call for heat/HW the appropriate mot.valve opens and when fully open its end (micro) switch closes and supplies power via the orange wire to fire the boiler/circ pump, remove the orange wires in turn and you will soon see the (if) problem.

Re your circ pump, is that installed vertically and in which direction is it pumping in?, up or down, or is it installed horizontally?.

 

[Rollerball]

Very interesting, if it's one of the valves and not the pump then what do you think was causing the intermittent high-ish pitched vibration sound I heard yesterday? It seemed to be coming from the pump (I didn't initially check the valves when the sound was occurring, so might it have been coming from one of the valves and vibrating in the pipes, making it sound like it was coming from the pump?). Unless I have a pump AND a valve problem .......

The circ pump is mounted vertically and it's pumping water from the boiler.

So to easily test the valves I turn off the power and carefully pull on each lever?

 

[Johntheo5]

Doubt if the valve would be the noise problem but if the pump is pumping against closed valves (dead heading) then it might cause the (pump) noise, does the noise persist if the heating is on "normally"?.

 

[Rollerball]

I've not heard the high-ish pitched vibration noise when the boiler has fired up, is that what you mean? I do though hear a slight trickling/movement of water when the boiler is quiet, indicating that water is being moved through the pipes.

Also, if one or both valves were closed wouldn't that mean the radiators and hot water wouldn't be functional? Yet the radiators and hot water are hot when expected.

 

[Johntheo5]

Carry out those two tests I suggested, 1. with power off on the wall, pull on both levers and check for resistance when pulling across.
2. with power on at the wall but programmer off check that pump restarts, if so, remove orange wire(s) to prove which one is faulty.