Help needed - UFH not working. Grundfos UPS2 25-40/60 potential replacement, Valliant system

[acideraser]

Hi All,

This forum helped me a lot in the past and I am hoping that I can get help and advice this time .

I just noticed that UFH is not working and when checked the pump it appears it has no light on. It has been working fine for 8 years.
There is supply current and boiler control unit (Valliant VRC470) is showing pump status as ON, but there is no light, and pump is clearly not operating. All pipes coming in and out are cold when touching.

I am wondering if it is possible to replace the pump DIY and what would be the best way to do it without flooding the house?

Pump is located inside the base cabinet so access is not ideal but possible.

This is Grundfos UPS2 25-40/60 130.
Should I order exactly the same model or there are better/newer and possibly more reliable options which would fit?

Any help would be very much appreciated as it is quite cold outside.

 

[cross thread]

Need to test for 240 v at the underfloor pump before going further

 

[acideraser]

 

[acideraser]

Need to test for 240 v at the underfloor pump before going further

Thank you Cross Thread, I added more photos. Indeed there is no current at the pump at all, the simple tester doesn't light up. There is also no current on the rightmost connector in the wiring box. I tested after boiler fired up to activate UFH.

 

[acideraser]

Not sure what is wrong, but this morning pump and UFH worked, everything was fine, but in the evening not working again and no current.

It also appears that motorised Honeywell valve for UFH and pump are not activated while VRC shows that pump is on UFH working.

Any idea what could be the issue ?

 

[SpecialK]

Not sure what is wrong, but this morning pump and UFH worked, everything was fine, but in the evening not working again and no current.

It also appears that motorised Honeywell valve for UFH and pump are not activated while VRC shows that pump is on UFH working.

Any idea what could be the issue ?

Manually activate the UFH zone valve and see if the pump comes on?

 

[acideraser]

Manually activate the UFH zone valve and see if the pump comes on?

Thanks very much for the response. Tried that and could feel hot water coming through to UFH to the system.
Changed heating curve setting on control display which was for some reason set incorrectly to 1.30. and is started working.

 

[acideraser]

Manually activate the UFH zone valve and see if the pump comes on?

This morning however UFH did not start again, so I manually opened valve and pump came on.
Does this mean valve is faulty and need replacement or something more complicated?

 

[SpecialK]

This morning however UFH did not start again, so I manually opened valve and pump came on.
Does this mean valve is faulty and need replacement or something more complicated?

Its possible or something is not telling the valve to come on. You have ruled out the pump at least. Ideally you need a mulitmeter to fault find otherwise its just guesswork. Could be a dodgy relay in the control box?
You could remove the head from the valve and make sure its nice and free?

 

[acideraser]

Its possible or something is not telling the valve to come on. You have ruled out the pump at least. Ideally you need a mulitmeter to fault find otherwise its just guesswork. Could be a dodgy relay in the control box?
You could remove the head from the valve and make sure its nice and free?

Thanks you SpecialK.

I've got a multimeter, can test, where it is connected to the relay in the control box.
Will watch it for a while, at least I seem to be able to switch UFH on when it gets cold.

Will be back for further advice soon!

 

[DP]

Thank you Cross Thread, I added more photos. Indeed there is no current at the pump at all, the simple tester doesn't light up. There is also no current on the rightmost connector in the wiring box. I tested after boiler fired up to activate UFH.

To be precise, you only get current if there is voltage or power.
Voltage is missing hence pump is not running.
Use a multimeter to check for voltage,

Warning. Be careful what you touch in the box on picture 2
SMPS. High DC voltage and capacitor that will bite long after supply disconnected

 

[Johntheo5]

This morning however UFH did not start again, so I manually opened valve and pump came on.
Does this mean valve is faulty and need replacement or something more complicated?

Surprised to hear that opening a zone valve manually has closed the end switch contacts, its not supposed to, and certainly doesn't on my Honeywell ones, opening zone valves manually is for draining/filling systems but most of us would probably be happy enough if the do close the end contacts.

 

[oldbutnotdead]

Surprised to hear that opening a zone valve manually has closed the end switch contacts, its not supposed to, and certainly doesn't on my Honeywell ones, opening zone valves manually is for draining/filling systems but most of us would probably be happy enough if the do close the end contacts.

From memory on Honeywell valves if you push the manual lever all the way open it will close the microswitch but it opens when the lever goes back to the latch position.

 

[Rodders53]

Sounds like the UFH zone valve motor drive mechanism (or the valve itself, possibly) is sticky and although powered (call for UFH made) cannot move the valve open (and therefore never operates the end microswitch in the head - the 'call for heat to pump and boiler').

Manual operation of lever then allows the motor / valve to be opened/held open and microswitch made = it works.

Multimeter will confirm that voltages are present / absent as expected (or not).

It may be possible to clean up re-grease the head? It may need a new motor? It may be the valve itself it stiff? Those investigations can happen once the multimeter measurement/checks are completed to confirm the valve is being told to open correctly.
Edit: it may even be a dodgy motor terminal (some are crimped push on spades) that gets 'fixed' by such manual intervention. Until the next time?

I can confirm Honeywell (and Drayton/BG) valves will operate the call microswitch when manually operated all the way across to 'open' fast enough, but only briefly as the motor then backs off via the springs to reopen the switch. (I have literally just confirmed this on my CH system in the garage for Honeywell.)

 

[DP]

microswitch made = it works.

As said earlier, on latch, auxillary switch does not operate. That is the case with all valves. There might be an odd one that rule does not apply to

A temporary solution would be latch open the UF heating valve and let another zone fire the boiler and boiler pump