Central Heating Problem!!

[MrGrumpy]

Hi, hope someone can help solve this problem with my central heating. I have a small sealed system, only 4 rads. a Baxi solo boiler with separate pump and pressure vessel with Honeywell controls and V4044C diverter valve.
The problem is when I turn on the heating the boiler starts up fine but the hot water dosent seem to pump past the diverter valve and the pump starts to vibrate noisily. However if I turn off the system at the controls and then turn it back on again it usually then works fine and the rads heat up nice and hot! At first I thought it could be a problem with the diverter valve but I've just replaced this and there's no change, also the pump is only a few months old. Does anyone have any ideas on what could be the problem?? Any help would be very much appreciated, Thanks.

 

[diamondgas]

Hi MrGrumpy

Do you know if the pump actually starts spinning on the initial start up? It sounds like you might have a problem with a pump overrun stat? Not 100% sure of the solo has one ?

 

[MrGrumpy]

Hi diamondgas, yes the pump starts as soon as the heating is switched on.

 

[BLOD]

could be air in system stopping circulation ?

 

[SimonJohns]

What's the system pressure and have you vented


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[SimonG]

Is it in a garage and linked to a frost stat?

 

[MrGrumpy]

Hi simonjohns, the system pressure's around 1bar when cold and 1.3bar when running. sorry not sure what you mean by vented?

 

[MrGrumpy]

No not in the garage SimonG, its in my bathroom.

 

[SimonJohns]

Hi simonjohns, the system pressure's around 1bar when cold and 1.3bar when running. sorry not sure what you mean by vented?

Is the system bled of air

I'm going to assume this is a new problem

Have you checked for any non return or check valves on the pipework for the cylinder. I've had these in pipework sometimes just seal up and now re open

Check all valves leading up to cylinder. I tend to fully close then reopen And turn back 1/2 turn




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[diamondgas]

MR Grumpy.

Is the noise still there when you put the heating on? As simonjohns is saying, it could be something restricting the flow through the hot water cylinder circuit!

 

[MrGrumpy]

the noise seems to be the flow pipe from the boiler vibrating, the pipes either side of the diverter are cold but if i turn the cylinder thermostat down to zero then up and down a few times water will then flow to cylinder or rads!

 

[stevetheplumber]

did you change the whole 3 way valve or just the head ?

 

[MrGrumpy]

i've changed the head and the rubber ball part but not the actual pipe fitting.

 

[bill577]

change the cylinder stat.

 

[GasmanxxxR1]

is there a balancing gate valve on the cylinder pipework, check this is open

 

[bill577]

you should have flow through either the ch or hw as you cant shut both off at the same time, I would recheck the rubber ball you have fitted as it sounds like your shutting off the ab port.

 

[MrGrumpy]

no, theres no gate valve. what i dont understand is why i can get the heating working by twiddling the cylinder stat or turning the heating on or off at the programmer but the next day i have the same prob getting it to work again!!? Also, i can hear the diverter moving so it cant be that can it?