Ravenheat combi HE85 T not firing sometimes for DHW

5 Oct 2004
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United Kingdom
Hi all

I am not getting much joy with my 2 year old Ravenheat HE85T combi boiler. Ravenheat say its similar to CSI85T.

I've recently had the issue of DHW cutting out randomly in shower and changed the CH thermistor (dry clip on type) which solved the issue.

Then there was a leak from the diverter valve. Was suggested that the system could be dirty, so the system was thoroughly mains flushed, fixed magnaclean, replaced diverter valve, added inhibitor and there is no leak now..

Another issue that now I've been seeing is that sometimes when the BOILER is COLD (and NOT ALREADY ON for CH), and we open the DHW tap in kitchen sink, the boiler does not seem to do anything. No fan, no pump, no noise etc as if there is no demand for CH or DHW.
This is remedied by:
1. If I close the tap and open it again the boiler starts working as usual in an attempt or two.
2. If I switch the boiler ON/ OFF through the instrument panel, it starts working as usual.

The CH comes ON when demanded without a beat (touchwood).

Previously I thought it could be due to diverter valve but a few days after replacing the diverter valve, it again failed to do anything today when the DHW was called for..

One thing to note is that we did not see this issue of DHW not coming with the CH ON. But then the boiler with fan and pump are already ON for CH, so we get instant hot water..

I am thinking it could become a bigger issue come summers as CH would be OFF, so the only demand from a COLD boiler would be DHW.

Any ideas?

Thanks in advance..
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Sounds like the leak you had from the diverter has knacked up the microswitch head.
If you haven't changed this with the DV then you need to.
Check that the pin is coming out of the DV head when you turn a tap on and operating the switches correctly.
Thanks for your reply guys...

You are right, I've just replaced the valve and connected old microswitches to new DV.

I will check if the pin is coming out tonight.

Any idea about the part number/ price of new microswitch?

Also this issue happens once in a few days, so might have to wait till I see pin not coming out...

Also, would a delay in changing microswitch cause any harm to DV or any other part in boiler?
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No, won't harm the boiler, just your patience.

When you check the pin, check it moves properly and fully depresses the microswitch. If it's doing that, then definately faulty microswitch.
Thanks Chris, I will check and update the forum..

Part number from Ravenheat is 5012052. They always supply a new DV with a microswitch. However, my vendor from net did not..

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