BOILER PUMP QUERY

[Neil Carroll]

Recently I have been getting full CH however hot water runs for a while , then goes warm then fires up again then gets hot for a few minutes and then does the same , ferroli boiler optima 901 , its been suggested that its the heat exchanger , however this morning Ive noticed that the boiler pump is really hot , ive taken off the small metal disc at the front and it is spinning freely. when the boiler fires up it does spin , I can hear it moving , i have a few questions about this .

if the pump isnt working would the central heating / water work at all as the pressure seems to be there?

if the pump is working why would it be getting hot? , it is really hot! , I have read that if its hot its not working but it does seem to be spinning ,

can I remove front of pump be removing the 4 fixings and examine it or would it be a nightmare to re assemble.

id appreciate any help .

Thank you.

Just an additional thing , water board turned water off 2 weeks ago due to new houses being built at top of road , as per normal when it came back on the water from the taps looked like coffee for the first 40 minutes! im sure this is related as no problems beforehand

 

[ianmcd]

Its not the pump, your boilers pump only runs for heating, it doesnt run when HW is demanded, a scaled main heat exchanger isa possible cause if you are in a hard water area and dont have scale prevention fitted, if it is then its new boiler time, but I would be looking at other things first, I would start with changing both temperature sensors, on your boiler always change these as a pair

 

[Neil Carroll]

Thanks , can i just clarify something please? , ive replaced the 2 sensors on the vertical copper pipes that have wires connected to the pcb (no difference) , replaced them both , however I have since seen that there are 2 temperature sensors on the actual heat exchanger , are they the ones you are referring to ? Also in Birmingham which is soft water area.
Thanks for advice.

 

[ianmcd]

Will look the same as this one, if you are in a soft water area it wont be the heat exchanger you will be happy to know as they are over £500

https://www.ebay.co.uk/itm/262990217409?epid=1337943773&hash=item3d3b7040c1:g:4pkAAOSwK6RZHGEe

 

[Neil Carroll]

Yeah, I've done those, thanks,

So as it stands if it's not the heat exchanger, the symptoms are,

Pump is very hot which can't be right

Water is hot then warm,

Heating seems OK

However system does seem to loose pressure when heating not on to the point where pressure is at zero, no obvious leaks.

Would a faulty diverter valve provide a difference in water temperature?, I did consider this however thought it would be a case of a faulty diverter producing totally cold water rather than hot / warm water.

 

[ianmcd]

Pump is very hot which can't be right

Again your pump is not used when running HW forget the pump, IT IS NOT THE PUMP.

Would a faulty diverter valve provide a difference in water temperature?, I did consider this however thought it would be a case of a faulty diverter producing totally cold water rather than hot / warm water.

your boiler does not have a diverter valve, you have a Bi-thermal heat exchanger, sometimes called a twin pass heat exchanger, when the burner cuts out when running HW what is the boiler display showing ?, video it and upload to you tube and put the link on here so I can see what is happening