Hot water tank/heatexchanger

[Knevil]

Hi, new to forum and seeking help. Got an indirect system with a hot wtertank or heatexchanger in cupboerd upstairs. Problem is tank has started making a god awful roaring noise as if its goin to take off. This goes on for a few seconds then noise stops and blows back into expansion tank in the loft . Was told it was Honeywell t/stat on side of tank faulty. Changed that but no difference. Now been told could be 3/way valve or t/stat on boiler . Is water overheating or could it be airlock. if airlock how do i cure it ? Need help as on the verge of redundancy so cant afford anymore big bills coming in . Any help much appreciated

 

[stevetheplumber]

Hi, new to forum and seeking help. Got an indirect system with a hot wtertank or heatexchanger in cupboerd upstairs. Problem is tank has started making a god awful roaring noise as if its goin to take off. This goes on for a few seconds then noise stops and blows back into expansion tank in the loft . Was told it was Honeywell t/stat on side of tank faulty. Changed that but no difference. Now been told could be 3/way valve or t/stat on boiler . Is water overheating or could it be airlock. if airlock how do i cure it ? Need help as on the verge of redundancy so cant afford anymore big bills coming in . Any help much appreciated

is the water boiling hot at the tap when this happens ?if yes probably boiler stat
make sure the immersiond not switched on as well or it could be the stat on that
almodt certainly an overheat problem airlock would have different symptoms

 

[tackleburger]

He said he has changed the stat. Stats are easy to test so why chage it if it's not faulty?? If it happens when your heating is on you have a two or 3 port valve passing. With the heating on feel the flow and returns into the cylinder the return should be cold and the flow may be warm near the cylinder. If that is the case the 3 port valve is ok and you boiler stat is faulty try turning it down. To keep it under control only put your water on with your heating this will lessen the flow through your cylinder or only put the water on for a very short period 15 mins at a time should be enough. Also ensure an immersion heater hasn't been left on. Get the stat swapped by a resitered gas fitter.