hi htg engineer need help again ? Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[bazza]

hi mate sorry 4 late reply bin busy this week working late now ive got my mums boiler up and running wen in hot water mode everything is fine but wen she puts the ch on the bar pressure goes up to 3bar and wen she turns the hot tap on the water runs hot and cold (only does this wen on ch and hw) and the main burner keeps coming on then going off ..with pressure rising i .thought the expansion vesssel but wud that cause the hot water to do that or cud it be the heat exchanger or a build up of scale n sludge and is there a way to test 2 find out which one is at fault thanx 4 all the help bazza ps the circuit board was £165 gutted ah ah by the way this problem was happening b4 the boiler broke down my mum sed but only just told me she is 75 tho ah ah

[htg engineer]

What happens to the pressure ?
does it stay at 3 bar
does it discharge via PRV
does it return back to 1 - 1.5 bar ?

Could be a fault with plate heat-ex, could be corroded the water may be mixing with the heating side causing the pressure to rise, or the plate heat-ex could be partially blocked, HW sensor ok ?

diverter ok ? does the heating flow get hot when the hot water is being used

[bazza]

hi mate very strange boiler the pressure seems to be ok now worked fine last nite staying at 2bar wi heating on but wen i run the hot tap it still runs hot and cold but at least thats the only fault now any ideas thanx bazza

[htg engineer]

Hot water sensor or maybe plate heat-ex is scaled up, causing the boiler to think it is at correct temperature.

[bazza]

cheers mate thanx alot youv bin brilliant appreciated very much bazza