Pressure fault diagnosis and consequences for repair

[Agile]

Then half an hour holding back water with my finger as some twart decided to turn a stop cock on "to see what happened" (where's @gas112 when you need him?).

Not sure that he is up to holding back water with a finger!

 

[gas112]

I could have left the finger there whilst me and dan got on with something else

 

[Dan Robinson]

I'd cut pipes back ready for the building to be lifted onto a lorry. So the incoming main was sitting there open ended.

Could have done with a bung

 

[bernardgreen]

The pressure gauge wire had also been partial snapped which they thought would have effected the accuracy of the gauge itself. Maybe this was why I was seeing pressure in the system holding at 0.5 for 11months but allowed the system to keep firing up?

Could the pressure sensor to the PCB be detecting the correct pressure ( assuming it is an ON-OFF switch and not an analogue signal to the PCB ) while the pressure gauge is not giving the correct reading of pressure.

So I was at least partly correct,

 

[Dan Robinson]

But mainly wrong.

 

[petit_pablo]

Thanks for the update.
I will assume you'll be cancelling the aforementioned contract with major energy supplier now!

 

[gas112]

Makes you laugh dont it Petite sort of basic fault you have already diagnosed from description without looking at it , bit of wire wool silicone grease and halfhour and its fixed , turns into a flood and condemned boiler

 

[bernardgreen]

But mainly wrong.

As were several "trained" engineers if the reports the OP has provided are accurate.

Perhaps their training included too much about earning commission for sales of new boilers.

Please reduce my ignorance. ( ignorance as in lack of knowledge )

It appears that there is a pressure gauge for the boiler's owner to read to enable him or her to set the pressure in the central heating system to about 1.5 bar Which suggests that a pressure of about 1.5 bar ( or some other arbitory value ) is necessary for correct operation of the boiler.

It also appears that the only pressure sensor in the water circuit is a differential pressure sensor to detect there is central heating water flowing through the boiler.

So even with zero overall pressure in the central heating system provided there is flow through the boiler the boiler will fire.

Or is this pressure sensor a double diaphram / bellows sensor that requires both differential pressure due to flow and pressure in the water ?

So if this boiler can fire with zero pressure in the water what advantage is there in pressurising the water ?

 

[petit_pablo]

Makes you laugh dont it Petite sort of basic fault you have already diagnosed from description without looking at it , bit of wire wool silicone grease and halfhour and its fixed , turns into a flood and condemned boiler

Yep, as combi boilers go its pretty simple to fault find on these.
That said i see enough misdiagnosed ones where i work too

 

[Agile]

I went to one of that model that was leaking yesterday.

Instead of condemning it, I assessed the leaks from two joints, dried out the time clock which had shorted enough current when wet to blow the PCB fuse and put it back to work until I can get new seals for the leaking joints.

Just as I was putting it back together the Iraqi tenant told me that the hot water tap needed to be turned on full to get the boiler to fire up. Luckily, I had the appropriate part with me so fixed that.

The Landlord is a friendly English guy who does simple car repairs and servicing and I am sure does a good job at a reasonable cost. It was nice to be able to do a repair at a reasonable cost for him without ripping him off. Even better to be able to get the boiler working again on my visit.

Tony

 

[DP]

I went to one of that model that was leaking yesterday.

Instead of condemning it, I assessed the leaks from two joints, dried out the time clock which had shorted enough current when wet to blow the PCB fuse and put it back to work until I can get new seals for the leaking joints.

Just as I was putting it back together the Iraqi tenant told me that the hot water tap needed to be turned on full to get the boiler to fire up. Luckily, I had the appropriate part with me so fixed that.

The Landlord is a friendly English guy who does simple car repairs and servicing and I am sure does a good job at a reasonable cost. It was nice to be able to do a repair at a reasonable cost for him without ripping him off. Even better to be able to get the boiler working again on my visit.

Tony

Tony, did you have all the necessary parts with you having travelled on the big red bus