Baxi Solo 3 40 PF Pump Stays On constantly - PCB or wiring?

[TheCorm]

Hi,

My first post here but I have been reading other posts relating to Baxi Solo pump issues.

I am trying to figure out if I have a faulty PCB or if it's just wired wrong. The pump runs all the time except when I shut off power to the boiler completely.

Here is a photo of how things are wired going into the boiler...



I am slightly confused as to why the neutral and earth for the pump aren't wired into the pump section but instead the other side. Should it also be wired into the switched live.

I thought about moving the neutral and earth across to the pump side but I wasn't sure if that was right or if it would event make any difference.

Thanks,

Jamie

 

[SLIPSHOD & SLAPDASH]

You can see that the pump has been wired in a multi core flex which is also powering other items, maybe a valve or stat. Nothing wrong in connecting it this way.

 

[batty]

First question has it always been wrong or only recently.

 

[TheCorm]

I'm pretty sure it's been like this since we moved in (September this year) as I always could hear a noise when I was going to sleep and was thinking there must be something on even though the heating had not been on and it was only recently I went looking.

There is a valve up in the airing cupboard right next to the pump so am guessing this must be powered off the boiler too? There is a junction box where wires from downstairs go in, I can't actually find a a way to turn the boiler only off and see if the pump then goes off (no obvious switch unless there is one hidden away in the boiler)....i'm guessing when it was put in they didn't think a wall mains switch was necessary!

So when you say there is nothing wrong with it being wired this way I assume that means having the live there means it still should operate on the time delayed switch off and not run continuously?

Thanks,

Jamie

 

[SLIPSHOD & SLAPDASH]

I meant there was nothing wrong in using a multi core cable. There is something wrong that, A) the pump appears to be running 24hrs & B) there is no isolator for the boiler.

I would disconnect the pump at the pump L terminal of the boiler and see if it(pump) still runs, if it does then its picking a feed up from elsewhere, such as a stat or valve. If it does not run , test the L pump terminal on the boiler and see if that is live.

 

[TheCorm]

I meant there was nothing wrong in using a multi core cable. There is something wrong that, A) the pump appears to be running 24hrs & B) there is no isolator for the boiler.I would disconnect the pump at the pump L terminal of the boiler and see if it(pump) still runs, if it does then its picking a feed up from elsewhere, such as a stat or valve. If it does not run , test the L pump terminal on the boiler and see if that is live.

OK will test and let you know, many thanks.

Jamie

 

[TheCorm]

I shut off the power, disconnected the pump and put the power back on, the pump remained.

The heating then came on (not intentional!) and after about 10 seconds the pipes starting clonking, so it didn't like the pump being off, I quickly shut it down.

Power back off, pump reconnected, power back on. I had it set now so the heating wouldn't come on, but the pump was on straight away before the heating even kicked in (there was of course power to the boiler and the programmer was on with the heating on but not active as the thermostat was set to 10c)

I have attached a photo of the pump and valve upstairs, in case this is of any help.

Jamie

 

[kme]

This sounds like a fault on the over-run connection at the boiler. It IS possible to get around this; but I`m a bit uneasy suggesting it on an open forum. If the pump is connected to the correct point at the boiler, then there`s a fault within the boiler............

Hang on.....thought just came at me...........................

We`d need to see the connections in that box shown on the last piccie, AND know which cable is which at the boiler photo.

 

[SLIPSHOD & SLAPDASH]

I cant see that pic due to the forum update, but it sounds to me like the valve is slightly sticking slightly open (normaly due to limescale) this is triggering the boiler to fire up on Heating which also makes the pump run.

 

[hxsarge]

not sure about the solo but ive had trouble with the pump over run on a new baxi duo-tech 2 combi, with the pump running constant, also fans being very temperamental even though the internal wiring checked out ok, when i rang tech help they said they have had a few problems with newer pcbs, swapped it and now its a runner.

pcb faults are a nightmare! ive had allsorts of symptoms occur due to a faulty pcb faults, internal clocks losing time, ho****er constantly calling, you name it.

Try ebay for a decent condition pcb just to try it before you buy one new.

hope this helps a bit!

andy

---------- Post Auto-Merged at 23:07 ---------- Previous post was made at 23:06 ----------

that should have been hot-water, may have put my self in hot-water with that one, haha

 

[TheCorm]

This sounds like a fault on the over-run connection at the boiler. It IS possible to get around this; but I`m a bit uneasy suggesting it on an open forum. If the pump is connected to the correct point at the boiler, then there`s a fault within the boiler............Hang on.....thought just came at me...........................

We`d need to see the connections in that box shown on the last piccie, AND know which cable is which at the boiler photo.

I've updated my post so the picture of the pump and valve is now working, i'm not really sure which cable goes where, two go through the ceiling, I can have another look and see if I can tell which is which, will probably have to pull the whole boiler apart as the wires disappear behind, was avoiding doing that as i'm happy on the electrics side of things but am trying to stay away from the fiddling with the other bits of the boiler!

Perhaps the photo I have taken of the valve and pump doesn't show you what you need? If so, let me know and i'll take a better one, you can see the junction box in it where the wires converge, I haven't looked in there.

SLIPSHOD & SLAPDASH - The boilers operation seems normal otherwise, it comes on correctly when the therostat is triggered....do you still think it could be an issue with the valve?

hxsarge - Yeah I Am thinking it might need to be a replacement PCB, hopefully the help I am getting here will confirm if that's likely or not.

 

[kme]

Need to see the connections in the JB mate, TBH.........

As for "other bits of the boiler"........apart from the gas valve - EVERYTHING is electrical mate

 

[SLIPSHOD & SLAPDASH]

Ahh, the dreaded 3 port valve, i personally hate them as by design they are held mid-position all summer to keep the heating off & you cant test the circuitry due to the electronic components in them. Possibly not a sticking valve, thats more common on the 2 ports.

 

[batty]

They do seem to be more problematic than two port valves.

 

[TheCorm]

Hi Chaps.

Some further info. The valve is a "V4073A Motorised Mid Position Valve" I have tried loving the lever about from Auto to Manual and Open but this doesn't seem to make any difference to the pump running, not sure if that means anything or not.

Here is a photo of the junction box open:



And here I have annotated it to show the connections that I know what they are....



Of the wires that go off under the floor I am wondering if one goes to the Central Thermostat and the other goes to the thermostat on the hot water tank?

I know it's difficult to see exactly where the wires go but if anybody has any ideas that would be great

Thanks,

Jamie

 

[SLIPSHOD & SLAPDASH]

Hi Chaps.Some further info. The valve is a "V4073A Motorised Mid Position Valve" I have tried loving the lever about from Auto to Manual and Open but this doesn't seem to make any difference to the pump running, not sure if that means anything or not.

Jamie

OOhhhhh :^O

 

[TheCorm]

Whoops.... definitely not the recommended way to move levers...

 

[TheCorm]

Is there any possibility it could be the programmer that is faulty?

 

[batty]

A programmer is a switch that switches on heating/hot water at set times this is very unlikely to be what is causing pump to run on.

 

[ProDave]

My money is on a stuck microswitch in the 3 port valve.

I'll bet it's been wired so that the pump L from the boiler activates the 3 port valve, and the microswitch in the valve then turns the pump on.

As you manually move the override lever on the 3 port valve (with power turned off) listen VERY carefully. Can you hear a little click inside the actuator body? If not then almost certainly the microswitch has failed. They can be replaced but it's a very fiddly job so buying a new actuator body might be the best solution.

I don't know that particular boiler, but I've found combination boilers that use a 3 port valve inside the boiler, and the same thing, a stuck microswitch leaves the pump running all the time.