Central Heating problems

Mr_Tilly

southcoastrgi wrote: »

of course both sides of the mid pos valve are hot because you have put it in man which opens up both sides, turn your cylinder stat back down to 60d this controls your hot water temp coming out of the taps it has nothing to do with your rad temp

it could be a faulty mid pos valve or pump but most likely the system is full of sludge & needs cleaning out, which can be a right pain in the backside on microbore even for a plumber with a powerflush machine

Hi Southcoast - Forgot to say I did move the selector back to Auto from manual (sorry). The cylinder stat was turned to minimum (20c) to theoretically cool the hot tap water pipe IF the valve was working. However, as the tap water side was still scorching hours later, I assume a valve fault. I had the system power flushed two years ago... But I guess it could need redoing. Thx.

southcoastrgi

if it was powerflushed & a magnet filter fitted providing it was done correctly then it shouldn't need doing again, if the h/w side of the valve (port is still getting hot then yes it is prob faulty, now whether this is just the actuator (head) that needs replacing or the whole valve is difficult to say from this side of the keyboard

Mr_Tilly

southcoastrgi wrote: »

if it was powerflushed & a magnet filter fitted providing it was done correctly then it shouldn't need doing again, if the h/w side of the valve (port is still getting hot then yes it is prob faulty, now whether this is just the actuator (head) that needs replacing or the whole valve is difficult to say from this side of the keyboard

Agreed. I'll assume it was done correctly. The selector on the head has no resistance behind it so this is also making me feel like the actuator (motor or gearing) has gone.

southcoastrgi

if it's a honeywell valve (silver box) it will only have resistance if it's on h/w only, if you are calling for heat & h/w or heat only then the lever will move freely with no resistance

Mr_Tilly

southcoastrgi wrote: »

if it's a honeywell valve (silver box) it will only have resistance if it's on h/w only, if you are calling for heat & h/w or heat only then the lever will move freely with no resistance

Thanks, it's a Danfoss (white box) but I assume the same holds true.
From what I've described, are there any other tests that I can perform?

Mr_Tilly

I've caved in and called a plumber for Monday. £130 plus vat to change the whole unit.

Mr_Tilly

Just to finish this story off... The 3 port valve was replaced today and there's plenty of heat in most of the rads. Just need to work on a couple but basically problem solved. Thanks to all for assisting and advice.