Grant Vortex 36kw - Needs rebooting daily

21 Apr 2017
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United Kingdom
We've got a 10 year old Grant Vortex (outdoor, 36kw oil fired) has developed a odd problem. If you turn it off and on, it works fine (mostly, the hot water temperature is a bit inconsistent) but if you leave it for a long time it stops working. No CH or DHW. There are no warning lights on, it's all fairly cold inside the boiler housing - however, if I turn it off and on again it works fine. Any ideas? Getting fed up of going outside in my PJ's every morning!

Many thanks!
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It does need topping up from time to time, but the low pressure light isn't on. The programmer seems to be working as I can see the feed from it is live when CH is on. What's odd is once it's fired up again (sometimes takes some coaxing) it works fine. Sometimes if I take the right hand clear relay out, it will fire up fine. I leave it for a bit and put that relay back in and the CH & HW work. It's getting worse as just turning it on and off is not always the cure now. I've ordered a replacement clear relay as I can see some scorch marks but there is a good contact when checked with a DVM. Any ideas? Which PCB gets replaced the most? Bit reluctatant to change it as it's £100+

Also, does anyone have the internal wiring diagram to hand?
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