Oil Heatslave 12/14 hot water issues

alsun · 6 Sep 2010

I have an Oil Heatslave 12/14 which is not giving hot water. The central heating appears to be fine however. The burner will fire up if the boiler is switched on from cold and will continue to work if there is demand but appears to switch off when it reaches full temperature and then will not re-light when the temp drops or there is demand. The Lock out light does not light up.

Can any of you knowledgeable people point me in the right direction?

Thanks

Burnerman · 6 Sep 2010

The fault here is the 3 port motorised valve that sits just above the water pump in the boiler casing.....it needs a new drive motor that sits in the top, under an aluminium can.
Access is reasonably good with the boiler top off.
If memory serves, its a Honeywell V4044 diverter valve, which is hideously expensive to buy complete.
John

alsun · 6 Sep 2010

Thanks

Any suggestions where I can buy a replacement?

Burnerman · 6 Sep 2010

You can get the motors at Plumbcenter for about £20 - but take the top off the valve first so you can see how it fits. Make a note of any numbers, too.
John

alsun · 6 Sep 2010

Thanks again John

I'll have a look now and drop down there tomorrow.

Burnerman · 6 Sep 2010

Be lucky!
When you have the top off, check that the brass automatic air vent (AAV) isn't leaking....they usually do!
John

mikeyd · 6 Sep 2010

When I scrapped my heatslave 12/14 I removed PCB, burner assembly and 3 port valve in-case the replacement used the same parts, but the replacement was a greenstar condensing boiler which looks totally different inside so I probably have no use for them.

It's not worth sending a second hand valve if you can get new for £20 but make a note of my user name and if in future you need a PCB or burner parts (including fan motor, oil pump, control unit) PM me, I'll only want postage costs.

There is a lever on the 3 port valve which can be locked open. I don't know how safe it is to do so (someone please advise if not) but you could perhaps lock the lever over and then you will get hot water until you get the replacement part.

outinthestix · 6 Sep 2010

Doesn't the mv rest in the hot water position ? if so you should get hw but not heating if the motor has failed. It may have jammed open though. Another possibility would be the flow switch.
When the op talks of demand is he referring to hw, ch or both ?

mikeyd · 6 Sep 2010

Good point outinthestix. Just had a look at my old valve and it has a label saying when filling the system the lever must be locked open. But is that the HW heatslave circuit or the CH system?

OP: if you take the top panel of the boiler you should see the diverter valve and it's lever. Does it move when the boiler switches from HW to CH? With the boiler off If you move it by hand does the spring return it?

alsun · 6 Sep 2010

so...

The arm on the valve does move when switching from HW to CH, if I move the arm by hand it will raise and spring back to its centre position, although it does not push down through its full range of movement as it does when the boiler switches from HW to CH. Earlier I meant the boiler does not fire on HW demand, CH seems to be working as normal.

Is this the valve motor or likely another fault?

outinthestix · 6 Sep 2010

Likely another fault. Check the flow switch is getting power and test for voltage going through it when a hot tap is open.

alsun · 6 Sep 2010

Will do thanks

alsun · 6 Sep 2010

flow switch (measured on the output of the control board) shows 230V when hot tap is closed and 0V when tap is open.

Is this correct?

mikeyd · 6 Sep 2010

I have more of an electronics background than plumbing or boiler repair

If you measured volts across the two pins on the main PCB and the switch is closed (water flowing) then it would read 0 volts. No water flowing then switch open and it could read 230V.

Hopefully Burnerman or another boiler guru will pick up on this thread and advise you further.

Any other info would help. Tell us step by step what happens from a cold start.

Burnerman · 7 Sep 2010

Hey if I've jumped in here too heavily with my big feet and sent you down the wrong path I sincerly apologise, but your symptoms were exactly the same as mine when my own 12/14 packed in.....

My own boiler flow switch gives an audible click when a hot tap is opened so i tend to ignore that......operating the manual lever on the 3 port valve gave me hot water too.
I have looked at these PCB's before - thankfully enough they are quite simple, and any faulty (burnt) tracks are easily visible.
John

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Oil Heatslave 12/14 hot water issues

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