Central Heating problems - pump runs constantly, boiler buzzes

[JohnnieDerby]

Hi everyone,

I have a few central heating issues at the moment.

Firstly the red Grunfos pump which is in the airing cupboard runs constantly. I used to turn the heating on when required and turn on the pump while the heating was on. When the heating was off I used to flick the 3 speed switch on the pump so it was between positions 3 and 2 so not running.

However last night the pump got really noisy and failed so today I bought a new Grunfos UPS2 which replaces my old UPS unit. However this has a digital three speed switch so you can't turn it off manually and it is running constantly now.

I also fitted a new Drayton Mid Position Actuator about 2 years ago.

Also my boiler often makes a buzzing sound, sometimes not too noisy and sometimes very noisy like a hornet in a cage. I think this might be down to failed smoothing capacitors?

I would like to get all the issues sorted but money is very tight and I just spent £110 today on the Grunfos pump.

1. Do I need a new circuit board in the boiler and will that fix the buzzing AND the pump running constantly?

2. Could I get the board repaired locally at an electronics specialist I know?

3. Should I get a specialist to sort it all out or am I safe to swap the circuit board myself?

The boiler is a "Gloworm Ultimate" which has been fitted since the house was new so coming up to 20 years old now.

Thank you in advance for any advice.

 

[Terry lambert]

On the front of the boiler there should be an over heat stat, has that popped out ?

 

[JohnnieDerby]

Thanks for the reply.

I took the lower cover off the boiler and on the left is a metal box with a black rotary knob for temperature and also what I presume is the over heat stat - looks like a red plastic button that can pop out. If that's the correct part then NO it wasn't out.

 

[jackthom]

Is the pump wired directly into the boiler control panel and what controls do you normally use to turn the heating ON or OFF eg Room Thermostat, Timer, Main boiler switch etc?

 

[ollski]

The pump should be wired back to the board and run on for around 3-4 minutes after the demand is removed on switch live.

 

[JohnnieDerby]

The pump runs 24/7 regardless of what the boiler is doing. That's why I used to switch the pump on/off manually by moving the switch to between positions 2 & 3. The old pump was noisy so you knew instantly when it was running and it is in the airing cupboard in my bedroom and it woke me up a few months ago when it started running constantly. The new pump is very quiet but it is still running 24/7 and I cannot turn it off as the three speed switch is now digital.

I leave the heating turned on on the boiler control panel all the time but use the thermostat in the hall to switch the heating on and off. The boiler is downstairs and in the airing cupboard upstairs I have the pump. There is a white plastic junction box with three wires going into it - one from the pump, one from the Drayton Mid Position Actuator and the third from the Drayton unit fitted to the copper water tank. I think there is a fourth wire which you cannot see under this box which travels through the walls of the house presumably to the boiler control panel.

Under the boiler I have a Tempus Seven digital control panel and in the hall a Drayton thermostat.

That's about as much as I know.

I could get my local electronics specialist to replace the capacitors on the boiler circuit board but I don't know if I should remove this myself or not. I don't want to accidentally endanger the family. Also I might stop the buzzing but will it stop the pump running constantly?

I would appreciate some advice on whether to repair the PCB, replace it or bite the bullet and fork out for a plumber to sort me out which I can't really afford right now.

Thank you all again.

 

[JohnnieDerby]

Quick update - the boiler just started "buzzing" as it does randomly. I took the bottom panel/cover off and it sounds like it is coming from the metal box on the lower left which has the "Boiler Thermostat Control Knob" and the "Overheat Cutoff Button" on the front of it. I was able to stop it buzzing by turning the control knob down to nothing - the boiler would also stop running at this point. Turning it back up fired the boiler up and the buzzing would start again. This went on for 2-3 mins and now it is silent again.

 

[muggles]

Could be the PCB but could equally be the gas valve at fault causing a buzzing noise - they sometimes buzz if the solenoids are failing.

As for the pump running constantly, you'll need to find where it's wired to and be handy with a multimeter to diagnose that one