Boiler not staying on

[Craigi1990]

Hi,

I am looking for for some help if possible to avoid me buying the wrong parts if required.

My boiler is not staying fired up for either HW or CH. It will initially fire up for maybe 30 seconds-1 minute when I press the thermostat but will then shut off.

It is an open vented system. With a three port valve. The three port valve actuator is connected but has not been working for some time, I have manually had to turn the valve by hand. The heating was making some awful banging noises when the heating came on for a couple of weeks before this new problem happened. Once the heating was on for a few minutes the noises stopped.

The pump is not kicking in, when I disconnect the plug and reconnect it, it seems to try but then stops. It is a Grundfos Alfa 2L. I have bled this via the bleed screw and also taken it off to check for blockages. All appeared fine.

I have bled all radiators, I have one currently off the wall as I was replacing it a few weeks back. (This is when the knocking when the heating came on started).

The F&E tanks looks fine, no blockage to the feed.

Any thoughts on what else needs to be tried? Air lock somewhere?

I have no bleed valves on radiators to drain it down fully.

 

[ShaunCorbs]

Need to sort the original issue out first eg 3 port as your not supposed to use it manually

 

[Craigi1990]

Thank you,

I will do this regardless this week. Something I have been putting off. Could this actually be causing the issue? As it has been working for quite some time with nothing else changing.

 

[ShaunCorbs]

Needs that sorting first yes before any fault finding of the new issue / maybe nothing

 

[Deleted member 120897]

Your circulating pump comes on with the boiler on the switched live (call for heating/hot water/both)

 

[Craigi1990]

Replacement actuator will be here tomorrow. Hopefully that will sort it. Thanks for the responses.

 

[Craigi1990]

So this has now been replaced. As I though it hasn't fixed the problem, but it's good to know it will be working for when the problem is fixed.

Any other ideas as to what could be causing the heating to not stay fired up or anything else I can try?

I can hear some gurgling in the boiler and a bit of whistling, I have vented it (greenstar ri) but this also made no difference.

 

[ShaunCorbs]

Pump running now ?

 

[SJB060685]

Sounds like air in the boiler but as Shaun is getting at you need to confirm if the pump is OK, could be a couple problems.

 

[Craigi1990]

Pump running now ?

Hi,

No exactly the same thing. Couple of spurts like it is trying then the lights go off and it just shows the power light. According to manual, this is low voltage or a blockage. Voltage at 240 when I've tested it. Took the pump apart yesterday, no debris, moves freely ect.

I read somewhere about wiring it to a plug to test it?

 

[SJB060685]

What pump is it? Does it have a small capacitor?

 

[Craigi1990]

What pump is it? Does it have a small capacitor?

I just attached a photo to my previous post. It's a Grunfos Alpha 2L 15-60

 

[SJB060685]

I'm not sure if this pump has a run capacitor to be honest. Data states 230 volt supply with a permanent magnet motor but that's all.
Causes of just power light on are 1. Supply voltage failure ie too low or 2. Blockage somewhere.
You say the impeller spins freely and there are no impurities or blocks at the pump but that doesn't me there's not a blockage down stream.

 

[Craigi1990]

I've managed to record some of the noise it is making in the boiler. Excuse my poor camera work I was trying to get closer for the sound to be heard. It is quite a bit louder in person.

 

[Ben-gee]

Check along with a magnet on any pipework you can access - there may be a blockage, most likely at elbows and tees.

 

[SJB060685]

It's hard to make out frow the video but it sounds like there's very little/no flow through the boiler, although I could be wrong. If there is a blockage somewhere this can cause the water in the boiler to heat very rapidly and as the pump is not circulating it away the boiler will shut off on temperature, and then cycle on and off again every little while.
I'm not gas certified but it would be advisable for an accredited engineer to rule out a systems control fault. If there is power to the boiler and pump at all times of a demand from a stat then one could rule that out.
The fact you have recently drained down is probably not a coincidence and I wouldn't be surprised if some dirt/impurities have lodged somewhere, again I could be wrong.

 

[Craigi1990]

It's hard to make out frow the video but it sounds like there's very little/no flow through the boiler, although I could be wrong. If there is a blockage somewhere this can cause the water in the boiler to heat very rapidly and as the pump is not circulating it away the boiler will shut off on temperature, and then cycle on and off again every little while.
I'm not gas certified but it would be advisable for an accredited engineer to rule out a systems control fault. If there is power to the boiler and pump at all times of a demand from a stat then one could rule that out.
The fact you have recently drained down is probably not a coincidence and I wouldn't be surprised if some dirt/impurities have lodged somewhere, again I could be wrong.

Thank you.

It almost sounds like the boiler has turned into a kettle, gets to the point of steaming in less than a minute, confirmed with steam from the bleed valve.

I have one of these things at the top. Could that help me out? I belive it is some sort of filter?

 

[SJB060685]

Thank you.

It almost sounds like the boiler has turned into a kettle, gets to the point of steaming in less than a minute, confirmed with steam from the bleed valve.

I have one of these things at the top. Could that help me out? I belive it is some sort of filter?View attachment 62961

If the boiler is kettling then stop trying to fire the boiler and have a reputable engineer attend.
The unit in the picture is a filter mounted on the return to the boiler, the idea is it catches any magnetite that's been produced due to corrosion in the system. They should be serviced annually along with the boiler. Kettling can also be caused due to a build up of scale in the heat exchanger if you live in a hard water area.
Either way it sounds like you have a blockage, or several blockages preventing the flow of water from leaving the boiler quick enough.

 

[John.g]

Maybe circulate cold water for a hour or so without boiler attempting to fire.
Ensure boiler switched off/shut down, supply pump with independent power and on speed 3, put diverter valve manually to mid position and keep venting everywhere, if energy monitor available note pump power. (don't think its displayed?)

If you eventually think you have circulation, fire up the boiler with pump still on independent power.

 

[SJB060685]

Maybe circulate cold water for a hour or so without boiler attempting to fire.
Ensure boiler switched off/shut down, supply pump with independent power and on speed 3, put diverter valve manually to mid position and keep venting everywhere, if energy monitor available note pump power. (don't think its displayed?)

Hi John. The energy display was something I was going to mention but it's really not advisable to keep trying to turn the boiler over. However if the boiler can be isolated then running this diagnostic test will show whether or not there is a blockage. I suspect like you are getting at the display in power usage will show close to/if not maximum head no flow.

 

[ShaunCorbs]

Pump isn’t on you should either have lines on the left eg III II I or 4 bar graph so pump looks dead or no power need to confirm there’s 240v going to the pump

Also there’s no head on the 3 port by the looks danfoss make

 

[Craigi1990]

Pump isn’t on you should either have lines on the left eg III II I or 4 bar graph so pump looks dead or no power need to confirm there’s 240v going to the pump

Also there’s no head on the 3 port by the looks danfoss make

Pump has 240v going to it. And the middle light is on. I'll attach a video of what it is doing. It sort of seems to try and go a few times and then the bars and graph lights go out.

I've just put the wiring to a three pin plug in the hope of running it all cold and it's doing the same thing.

Head is on three port now as you had advised, that picture was from the other day

Edit... Just realised there is a whirling noise in the background this is unrelated. The noise happens three time sounds like water moving.

 

[Craigi1990]

Maybe circulate cold water for a hour or so without boiler attempting to fire.
Ensure boiler switched off/shut down, supply pump with independent power and on speed 3, put diverter valve manually to mid position and keep venting everywhere, if energy monitor available note pump power. (don't think its displayed?)

If you eventually think you have circulation, fire up the boiler with pump still on independent power.

I've just tried this, it is doing the same thing. I've attached a video, hard to get the sound, in the above post.

 

[king of pipes]

You need a gas engineer to attend there are to many ifs buts and maybes on this post we are only guessing with the information given, when the boiler fails the sequence of flashing lights on the boiler will denote the fault and help diagnose the problem. Kop

 

[John.g]

I've just tried this, it is doing the same thing. I've attached a video, hard to get the sound, in the above post.

Diverter valve: Port A to CH, Port B to HW. Is yours incorrect?. Also check arrow on pump body is pointing upwards. Are you getting water out of the two manual bottle vents.
What is the red valve to the right of the pump??