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PostPosted: Sun Mar 31, 2019 1:10 pm 
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Having problems with my hot water. Symptoms are like a blocked P2P exchanger, but more severe - and happened more suddenly. (Hot water would run cold after 5 minutes, and F14 would come on - with CH flow pipe getting very hot suddenly.)

Removed diverter motor (but can't actually remove it fully away from the boiler as the pressure sensor is in the way - I really want to find the 'designer' and commit a very serious crime.)

The diverter valve pin in the actual 'hydrobloc' is pushable in and springs back out with no sticking issues, so that seems ok.

With the diverter motor's drive pin facing me, it doesn't come out when hot tap turned on. Boiler does go 'click' and starts up and produces hot system water in response to the hot water flow - so presumably flow switch is fine - but motor drive pin doesn't move. (Also noticed that it's loose and will fall forward when valve turned upside down - is that normal?)

Can I test it by applying a voltage? If so, what voltage and to which of the three terminals, labelled 1, 2 and 3.

Thanks.


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PostPosted: Sun Mar 31, 2019 2:54 pm 
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Progress - of a kind.

The diverter motor CAN be eased out from the boiler by placing it on its side, shoving it on top of the P2P exchanger and sliding it out the LH boiler casing (which can be hinged open when the three front screws are removed.)

The motor has three terminals marked 1, 2 and 3. Thanks to a YouTube vid, I found that these are: 2 = Neutral, 1 = Live to open the valve (it'll whirr and the drive pin will come right out and the motor will self-stop) and 3 = Live to make the motor retract the pin (and again self-stop).

This all worked ok.

Then checked voltages on the motor plug and found that '3' was permanently Live (meaning pin should be retracted, meaning diverter valve is in the default 'CH' position) and this didn't change when the hot water was turned on and the boiler fired up.

Sooooo, there's my issue; why doesn't the motor supply switch round to give a Live Terminal 1 to operate the valve when the hot water is flowing? I'm guessing it ISN'T the Flow Switch since turning on the tap DOES fire up the boiler, and surely it wouldn't do this if the flow switch didn't trip?


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PostPosted: Sun Mar 31, 2019 3:50 pm 
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Scrap just about everything in my post #2... :( I was misinformed about the terminals.

Looks like it's Term 3 wot becomes Live when DHW is called for, not Term 1. So actually my terminals were working ok. That also means that the diverter valve motor activates to drive the pin OUT when CH is called for, and not t'other way around. Ie, the default position - the diverter valve at rest - is for DHW, and not CH as I'd assumed from the info I'd found.

Soooo, the diverter valve is actually working as it should be. That kinda suggests it's another blocked P2P exchanger again, and this despite having a Magna Pro fitted and having run chemicals around the system for ages last year.

Brand new P2P exchanger winging its way to me and should be here by the mid of next week. Total cost? £30.

The instructions suggest a pita to replace this, but actually there might be enough room behind the boiler to push the exchanger backwards, and then slip it out the side. If there isn;t enough room, I am definitely going to track down the designer...


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PostPosted: Tue Apr 16, 2019 8:56 am 
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Out of mere curiosity, can anyone here confirm the operational behaviour of the diverter valve in a CXi, please?

What I found was that when the CH is called for, the motor activates and pushes out its pin to drive the valve to the CH position. For DHW the motor turns again (the same direction - it's a cam) to retract the pin. What I'm curious about is, once that pin moves to whatever position it's needed - in or out, DHW or CH - does it then stay there once that demand has stopped until the next type of demand?

Eg, if the DHW is called for, the motor will be in the retracted positioned. If you shut off the hot tap, I presume the motor stays put. Then, if the hot tap is turned on again it'll be in the 'right' position for this. If the CH is called for, the motor will extend its pin to divert the valve for CH, but what happens when the CH demands has stopped? Does the valve stay in the CH position until a 'new' demand?

Cheers.


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PostPosted: Tue Apr 16, 2019 5:19 pm 
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:dunno: Our Boiler boys seem to have gone AWOL :roll:

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