Grant Vortex Condensing Combi 26 - no hot water

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Okay, have another problem with my oil boiler: central heating works fine but no hot water. Boiler fires when CH is engaged, but doesn't fire when hot tap is turned on. I'm thinking it's likely to be the flow switch, but is there a test I can do to confirm this and isolate the problem?
 
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Isolate cold water
Remove flow switch
Use multimeter to check for continuity when you flick the switch
If that's working look at water pressure or any filters and then any Divertor valves etc
 
Thanks for the advice. On what part of the flow switch should I use multimeter? On the switch itself or the two wires that go to the pcb?
 
Test the switch itself at this stage......normally you can hear it click when you turn the tap on.
John :)
 
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If you have a Vortex Pro model with 8 red LED's simply run a tap and see if the "Demand" light is lit, if not probable flow switch fault is the HW pump light flashing? this would indicate a possible primary pump fault ;)
 
No, I don't have any LEDs on the front. Gonna get the wife to help me test flow switch today and report back. She can turn the hot tap on while I listen hear if flow switch clicks.

EDIT: Just did test, switch does not click or make any noise at all when hot tap is engaged. Tested it a few times to make sure. Also, don't think it's a pcb issue as store hot water function still works as normal. Boiler comes on at various times during day & night for 5 minutes at a time to keep stored water hot. so looks like the flow switch.
 
Right, new flow switch fitted and still no hot water/boiler not firing when hot tap is turned.
Removed TMV and checked for scaling, seemed fine.

Removed heat exchanger and checked for scaling, seemed fine too.

Water pump engages when store hot water is engaged, so don't know what else to try!

Any ideas?
 
Check the 2 plug in relays in the boiler control panel it may be that one of the contacts has blown? (difficult to advise when not actually in front of the boiler) ;)
 
I have just revisited my old posts, and have realised that you have Two boilers one oil & one gas, I assume that both are combis and that they are both connected in order to supply your hot water, it could be that the cold feed to you gas boiler needs to be switched off to allow full flow of water throuth the grant in order to make the flow switch - well it is worth a try! ;)
 
I have just revisited my old posts, and have realised that you have Two boilers one oil & one gas, I assume that both are combis and that they are both connected in order to supply your hot water, it could be that the cold feed to you gas boiler needs to be switched off to allow full flow of water throuth the grant in order to make the flow switch - well it is worth a try! ;)

I doubt it. Been using current set-up for 2 years and problem has only recently developed.
 
So that's one of the relays in the pic? Ok, I've ordered one and will update when it arrives. Thanks for the advice, appreciate it.
 

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