pump favours HW only

[mariaduffy]

Hi - I have a pump which seems to work for HW only! I say this because I have (please don't laugh) recorded the sound of it using a mic and analysed the sound wave using a sound studio software.

The waveform of the pump when HW only is called is a regular sine-type wave indicating a 'pulse' or pump if you will (the hertz of the thing ??). The waveform of the pump on CH only is pretty much flatline.

I know this is an unorthodox way to test a pump but it begs the question - is it possible for the pump to work ok for HW only? If the CH water circuit is blcked would that not also affect the capcity to generate hot water, or are they on two separate water pipe circuits?

 

[gavinda]

tells us more about the system type and boiler.

not such a mad idea either... bg has a similar tool.

 

[seco services]

is this to do with your smart- valve ?

is all your rads getting hot when heating on ?
is your pump actually running when heating on ?

you said you have changed the actuators over and no difference on the heating one maybe be the heating valve is cruded up
you can strip these valves down if you have a pair of circlip pliers.

 

[mariaduffy]

Open vented - Hnoeywell wiring base, smartfit actuators (2), wilo gold 50 pump, room stat/controller, 5 rads - one rad warms only and this only upstairs - HW warming. System drained and refilled this week (inhibitor will be added tomorrow IF can be circulated otherwise unwilling to proceed). System is venting okay and not pumping over.

A lot of black water came when the system was drained and I cleaned out the rusty water from the F&E. The cold feed is clear.

Is the rad upstairs only heating by convection do you think. I have traced the path of hot water from the boiler thorugh the CH valve but it doesn't seem to 'want' to go to the any rad flow pipes unless a singlr TRV is open. Only one rad will heat - open more tRVs and everythings cold.

 

[D_Hailsham]

Honeywell wiring base, smartfit actuators (2)

Does the wiring base say Smartfit? If yes, are there any error codes?

If the wiring base does not say Smartfit, why are you using Smartfit actuators?

 

[mariaduffy]

Yes the base unit says 'Honeywell Smartfit' .

On further investiagtion we are not getting either HW or CH (the supposed hot water we got was probably transferred heat from CH pipes when the boiler was on for long periods)

It looks like a dead pump after all then - I can't still figure out why the waveforms were different from the same pump, same speed when called for CH and HW. Perhaps it has to do with the different sources of each being echoed back to the pump screw where the recorded waveforms were taken. Anyone any thoughts on that?

 

[seco services]

never go to them lengths to check a pump.

 

[mariaduffy]

@ seco - I know, I just wondered..

I was wondering (again ) if you could tell me if I open a pump via the allen keys with the gate valves shut either side would I be able to see if the impeller was connected to the shaft still or would it be best to remove it completely (assuming the gates worked brialliantly) to investigate?

Is there any booby traps with ch pumps that I should be ready for - like springs or washers that fall out when the pump is dismantled?

 

[seco services]

as you say undo the allen screws and pull it out just place a rag under pump.

 

[mariaduffy]

Thanks seco - I'll do that tomorrow

 

[mariaduffy]

I couldn't wait til tomorrow - I opened the pump (head??) after isolating the pump electrically and water(ically). Unfortunately one or both of the gate valves are passing so I'hh have to get those replaced. The installer had installed the pump upside down and the control switch box got wet . I have spent a half hour hair-drying (med, low heat) the electrics and I intend to leave the pump off for 24 hours.

The pump impeller seems firmly attached to somthiing inside the head which I'll have to assume is the shaft because I cant seem to be able to see any more of the pump anatomy (WILO GOLD 50).

Would it be possible to disconnect the pump - when the valves are replaced and off - and wire the pumps flex to a mains plug to see the pump in action in the yard for a few seconds? Could a pal feed in some water to see if the pump pumps?

 

[seco services]

you can do. the pump can spin but don't mean its 100% when its in the system.

 

[gash2024]

whats the best way to test if your pumps working as it should?

 

[mariaduffy]

you can do. the pump can spin but don't mean its 100% when its in the system.

Yes Seco I think I understand what you mean. There are a lot of variables that can impinge on performance that will be absent when a pump is tested outside the system ...mmmm

I am tempted to buy an exact replica of the pump and replace the head from the new - if it works then the some part of the old head may have been to blame, if it doesn't then I will have to persue another avenue but I at least have a new pump for the eventuality of the pump dying for real. Do you think this is a sensible way to proceed?

 

[Agile]

Have you done the most basic test on a pump of seeing if the shaft is turning after removing the silver screw?

If the head is off the the bucket test op opening each valve in turn would be useful.

Its very possible the leaking valve is not opening either. Test that to the bucket.

Tony