Elderly Parkray

[mikethepipe]

Hope someone here can help.
I have been asked to sort out the poor performance of an elderley Parkray (G model I believe).It is in a rented property,the landlord assures me it was working fine last winter,but now heats only the hot water-the rads getting only tepid after a long period.

I replaced the pump which was knocking badly,checked cold feed not blocked and lit a good fire.

it took a long while for the primary flow to get hot-say 25 mins after the fire was established,then,when the pump was turned on,all the heat in the flow pipes disappeared-as you would expect,but did not recover,-ie the back boiler was not keeping up with system demand.I stayed for an hour or so,but no improvement.

I initially thought the boiler was scaled up but I have read about the throat plate/baffle position being important-any help would be appreciated-I am struggling to find info on this type of fire- my experience is around oil and gas set ups.
thankyou.

 

[OwainDIYer]

Parkray G's can chuck out a surprising amount of heat. The HW cylinder is unlikely to be a quick recovery one and should be gravity circulation, so the rads are a significantly greater load on the system and will show up a scaled heat exchanger or any airlock etc on the rad pipes.

If the HW is working then it's unlikely to be the throat/bafffle plate, but with no CH load and the fire going full tilt the back of the firebox should be approaching red-hot.

 

[mikethepipe]

Thanks-going to do another test run on monday- crossed fingers it is not a scaled-up boiler-replacement is not an easy,or cheap option!