Oil combi problem...

[Graham3232]

Hi all,

I have a Worcester greenstar heatslave 18/25 oil combi boiler that’s three years old, serviced last year. First problem is that recently I have noticed the radiators are sometimes getting very hot, way too hot to touch and hotter than usual, thermostats all ok and I can’t see any reason for this.

Secondly I had a mixer shower installed recently. This runs fine with the boilers small hot water store, but once this runs out after a few minutes and water is heated directly off the mains it goes luke warm. I measured it at 35 degrees at the shower and other hot taps. I turned the inlet valve on the boiler down to almost shut to restrict the water flow, but it made no difference. I know a combi will struggle with cold mains at this time of year but this is a high flow rate boiler of 18 litres per minute, any ideas what might be wrong?

It was a complete new system 3 years ago, properly flushed and sentinel inhibitor added, never lost any pressure!

Graham.

 

[oilman]

Hi all,

I have a Worcester greenstar heatslave 18/25 oil combi boiler .....

My sincere condolences.

First problem is that recently I have noticed the radiators are sometimes getting very hot, way too hot to touch and hotter than usual, thermostats all ok .......

One of them isn't, and it's probably the control stat on the boiler.

Secondly I had a mixer shower installed recently. This runs fine with the boilers small hot water store, but once this runs out after a few minutes and water is heated directly off the mains it goes luke warm. I measured it at 35 degrees at the shower and other hot taps. I turned the inlet valve on the boiler down to almost shut to restrict the water flow, but it made no difference. I know a combi will struggle with cold mains at this time of year but this is a high flow rate boiler of 18 litres per minute, any ideas what might be wrong?

Heat exchanger scaling?

 

[cider]

Two problems at once

Id say your diverter may be sticking hence rads excessively hot because water passing to rads but your hw stat is waiting to be satisfied and then when you run hw the water valve is still passing to rads instead of hw.

 

[Kingfisher3]

try turning your heating off. Let it get cold. Turn on the hot tap and see if the heating pipes get hot. If it does you have a sticky diverter valve :