Cold morning start up problem

[Robert Tyrrell]

I'm just curious on this one as I think that I have the answer already but I'd like to be certain.
A customer of mine with an old Trianco Eurostar 125 (External) has had a fault develop in that the boiler won't start first thing in the morning. It always goes to lockout, but when he restarts it, it will run without any problem at all.
I went over a couple of weeks ago and diagnosed a pump problem as the pressure was flicking up and down all the time the boiler was running but haven't been able to get back to replace the pump (I usually keep them on the van but I'd just replaced one prior to getting to his place so needed to re-stock). Whilst I was there I did notice that there were a lot of small air bubbles in the tiger loop and, although I know its an air separation unit, it did concern me as I haven't noticed them before when I've been over to service it.
Sooooo ..... my query is - as its still working, after the initial lock out and restart, and running ok every day, could it be anything else that I might have overlooked?
I was going to post a video of the pump pressure gauge but I keep getting an error message so the explanation will have to do 🙂

 

[SimonG]

Over aired.

 

[Best]

+1 for probably over aired.
Or nozzle could be partly blocked creating over aired mix.
If the bubbles very noticeable in Tigerloop, maybe air is being drawn in. Check the oil hoses or just replace them when you replace the oil pump.
You could clean the boiler shell first and then use analyser before you work on burner to confirm if it is high air mix, with low CO2. Although I usually just get stuck in and fit the usual new nozzle and oil pump or whatever else that I know is faulty.

 

[Chalked]

Could be a small leak in the oil line, allowing air to be drawn in when the boiler is off for a few hours.

 

[DaveyHep]

Check your filters. I had this when I had slime in the oil line.

 

[Robert Tyrrell]

Thanks guys, got to the site and noted that there were builders working away so just to be safe, I went over every joint and made sure it was good and tight.
Changed the nozzle and the pump pressure shot right up, off the scale, and it wouldn't adjust so it was replaced and the combustion settings checked - smoke 0; CO2 11% pump pressure at 115psi air at 5.
Seems to be working now, and just a few small air bubbles in the tigerloop 🙂

 

[SimonG]

Glad you got sorted.

I would have it a bit lower than 11 on the co just because of the age of the unit.

 

[Robert Tyrrell]

Glad you got sorted.

I would have it a bit lower than 11 on the co just because of the age of the unit.

Yep - I would normally but I just couldn't get it to go lower in the time I had. Needed to make a 35 minute journey afterwards, collect the better half, and take her for a medical appointment.

 

[SimonG]

Was it a conventional flue?

 

[Robert Tyrrell]

External unit with balanced flue

 

[Gazzt]

Check motor capacitor

 

[Robert Tyrrell]

Check motor capacitor

Thanks - I've been back to this again yesterday and the settings have completely changed.
Now I cannot get the CO2 below 11.7% and I've had to drop the pressure from 125psi to 100psi. Doesn't matter what I do to the pump, or the air settings, it seems to have no effect at all.
Every time it starts up it stutters momentarily then fires with a big Whoomph.
I had the analyser gong from 12.3 to 11.7 and back again. It even went as high as 13 on one occasion.
If I can't sort it soon, I'll be fitting a new burner for him 🙂

 

[Gazzt]

What type of burner is on it, did you run it with the snorkel off to see what the co2 is at

 

[Gazzt]

It could be recycling flue gases. If it shudders on ingnition with abit of a boom it could be over aired . Sounds like a head scratcher.

 

[SimonG]

Take a baffle out.

 

[Best]

Some ideas, -
Disconnect any air snorkel.
or
Replace nozzle, as even a brand new nozzle could be faulty or get damaged
or
Check if air shutter is actually moving
Check air route including fan and to blast tube is all clear and no dead mouse, etc.
Consider possibility burner motor might be running slow, although unlikely.
Keep oil pressure to what it should be, - really best it is at the higher setting

 

[Gazzt]

I had a mouse break down. Autopsy report said "electrodes working well"

 

[Best]

View attachment 32106 I had a mouse break down. Autopsy report said "electrodes working well"

Sterling job!
Surprised a mouse could get into that Sterling burner.
The B11 burners are always a problem and just a large mouse trap

 

[Robert Tyrrell]

What type of burner is on it, did you run it with the snorkel off to see what the co2 is at

It's branded as Trianco but it looks very much like an RDB1 and there's no snorkel on it at all.

 

[Robert Tyrrell]

Some ideas, -
Disconnect any air snorkel.
or
Replace nozzle, as even a brand new nozzle could be faulty or get damaged
or
Check if air shutter is actually moving
Check air route including fan and to blast tube is all clear and no dead mouse, etc.
Consider possibility burner motor might be running slow, although unlikely.
Keep oil pressure to what it should be, - really best it is at the higher setting

New nozzle at service around 6 weeks ago. Changed it again when I changed the pump. Nothing in the airways, Motor appears to be running well, and the air shutter look as though it's moving but I didn't take it apart to check so that might be the problem

 

[Robert Tyrrell]

Take a baffle out.

I know there is an obvious reason for you to say this but why take a baffle out? I they're all clean then surely it can't be to do with that?

 

[Best]

I find a lot of the Riello RDB burners have the plastic air adjustment door seized or/and the adjustment bolt thread slipping. I remove the top air cover and take a look at it while adjusting air. Lots of them I have to manually push them with a screwdriver while using Allen key on air screw.
I would think highly likely to be the problem.