Why are you so obsessed with it being the PCB ? more likely to be a problem external from the boiler as everyone keeps telling you
Baxi Solo 3 Pump Continuously Running (Tried 2 Replacement PCB's)
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S
spacedmonkeys
Because I had the same problem 3 times over the last 10 years or so and it has always been the pcb.
Anyway thanks for the help but what you are telling me is beyond my skills, I’ve no idea about zones or anything, there’s just the boiler, pump, actuator and a thermostat on the tank. Can’t see anything else.
Anyway thanks for the help but what you are telling me is beyond my skills, I’ve no idea about zones or anything, there’s just the boiler, pump, actuator and a thermostat on the tank. Can’t see anything else.
post some pics of what you have, as in what you are calling an actuator, (your boiler doesnt have one) I suspect you mean a 3 port valve, basically when your boiler senses that the demand for heat has stopped then the burner will switch off but the boiler will keep the pump running to cool the boiler, if the pump cant move this heat it will keep running , a photo of your set up will help us give you the advice that you need
S
spacedmonkeys
Ok so pics .. boiler in kitchen feeds to airing cupboard. This potterton panel is on airing cupboard floor, this has cables to pump etc. Pump is red/black. Actuator sits above pump.
The pump is definitely the thing being kept on... can feel it vibrating the actuator. Adjusting the level on left of the pump seems to increase or decrease the power.
The pump is definitely the thing being kept on... can feel it vibrating the actuator. Adjusting the level on left of the pump seems to increase or decrease the power.
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its not an actuator, it is a mid position or three way valve the plastic bit on the top of it is the actuator
you do not need a By-Pass with your set up
H
Hot&Cold
For your current fault the pcb is the prime suspect but thats assuming the system has been installed correctly 
.
When was it last serviced
.When was it last serviced
This is a very well known and probably the most common fault with the Solo 2 & 3 boiler PCB's, and can be tested quite easily. With the system running and room thermostat calling for heat, check that the 'Boiler on' light shown below is lit. [Other lights may /may not be lit also, but for this test, that doesn't matter]
Now turn 'off' the heating and hot water. The 'Boiler On' light (and any others if lit) should go 'off' this shows that the external controls / motorised valve are no longer calling for heat. Now the boiler PCB should run the pump for a while, maybe up to 8 minutes, and as long as the 'Boiler On' light has remained 'off' for the duration, the pump should stop after this time.
If the 'Boiler On' light remains lit there is a problem elsewhere.
As it has worked OK previously, it would seem to be wired OK, but the wiring is easy to check too. The pump should be wired directly to the boiler PCB terminals provided for it. So that the boiler has exclusive control of the pump without any external influences.
Now turn 'off' the heating and hot water. The 'Boiler On' light (and any others if lit) should go 'off' this shows that the external controls / motorised valve are no longer calling for heat. Now the boiler PCB should run the pump for a while, maybe up to 8 minutes, and as long as the 'Boiler On' light has remained 'off' for the duration, the pump should stop after this time.
If the 'Boiler On' light remains lit there is a problem elsewhere.
As it has worked OK previously, it would seem to be wired OK, but the wiring is easy to check too. The pump should be wired directly to the boiler PCB terminals provided for it. So that the boiler has exclusive control of the pump without any external influences.
S
spacedmonkeys
Yes exactly what happens. All lights go off. Pump usually runs for 5 minutes or so but last few months has continued to run.
Wiring is as per the diagram. However there is no pump neutral or pump earth, just a pump live.
Boiler and heating system in general had a good deal of investigative work done on it back in October 2016 when kitchen fitter had unwittingly gone through live cable leading up to airing cupboard. Symptons of that were no heating and no hot water. Gas engineer and electricians both did loads of tests and never mentioned anything about bad/strange wiring or bad/strange plumbing.
Had a gas engineer come out to check for gas leaks a few months ago (thought I could smell gas when opening the meter) and his comment when seeing the boiler was "how many times have you had to change the pcb on that?" hence my "obsession" with the pcb.
Going to take a chance and order a brand new pcb and if that still doesn't fix it get an engineer in to investigate these valves, zones and bypasses that people have mentioned.
The pump will pick up the earth and neutral from somewhere else then. That's not unusual, as long as the 'live' is connected properly, because that's what controls the operation of the pump and switches it on / off. It is possible that it has been wired up incorrectly, in that there may be another 'live' connected to the pump from somewhere else, but if it used to work OK, and the pump wiring hasn't been changed that wouldn't be a concern.
Also, if the 'Boiler On' light is going out, you can forget about the problem being caused by any external controls such as the cylinder thermostat or motorised valve. If they were causing it, the 'Boiler On' light would still be lit. Once the 'Boiler On' light is extinguished, the timed overrun of the pump is controlled by the PCB.
As has been said, the Solo 3 does need a 'by-pass' to give the water somewhere to circulate whist the pump is running on when the heating and hot water have switched off. This can be achieved via the 3 port motorised valve, (provided that not all of your radiators have TRV's fitted) because at least one of its ports will be open at any time and allowing water to flow through it. If there was a problem with the by-pass, you would know because the red 'Overheat' light would be coming 'on' and the boiler wouldn't operate until it was manually reset.
Also, if the 'Boiler On' light is going out, you can forget about the problem being caused by any external controls such as the cylinder thermostat or motorised valve. If they were causing it, the 'Boiler On' light would still be lit. Once the 'Boiler On' light is extinguished, the timed overrun of the pump is controlled by the PCB.
As has been said, the Solo 3 does need a 'by-pass' to give the water somewhere to circulate whist the pump is running on when the heating and hot water have switched off. This can be achieved via the 3 port motorised valve, (provided that not all of your radiators have TRV's fitted) because at least one of its ports will be open at any time and allowing water to flow through it. If there was a problem with the by-pass, you would know because the red 'Overheat' light would be coming 'on' and the boiler wouldn't operate until it was manually reset.
Just as an afterthought, and in light of your comments about it happening frequently and so quickly, I was wondering if there maybe a problem with the pump, in that it is drawing too much current through the PCB and thus damaging it. I'm not sure of the design parameters to know how to check it....but was just thinking...
Having said that, I know of at least 2 second hand PCB's that were sold 'as working' having the aforesaid fault when reinstalled.
Having said that, I know of at least 2 second hand PCB's that were sold 'as working' having the aforesaid fault when reinstalled.
S
spacedmonkeys
I will feed back once the new pcb has been fitted, I’m guessing I just got unlucky this time and bought 2x dodgy pcb’s. Got away with it the time before for a few years at least!
afraid that the attending first call operative from your supplier to investigate your smell of gas , is not qualified to work on your boiler and is likely to know as much about boilers as I know about quantum physics.By all means go and get another PCB you are determined to waste more money .
really Ian? i was a first call OP the other year with 36 years of breakdown experience with all my tickets for appliances know many guys who are first call ops that are still fully qualified (paid by themselves) and as the baxi solo2/3 was out before the BG /transco split many of the older guys would be used to these boilers in the past .
I done my area`s part of the national recall on the 3 `s when they first came out .
But yes i totally agree all outside possible causes should be eliminated first.
Boiler its self is not staying on just pump so that rules out motorised valve microswitch fault
I done my area`s part of the national recall on the 3 `s when they first came out .
But yes i totally agree all outside possible causes should be eliminated first.
Boiler its self is not staying on just pump so that rules out motorised valve microswitch fault
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