Oil Flex Hose Problem

[MrDuck]

I have replaced my Camray boiler/Riello burner flex hoses regularly without difficulty but this year have run into a problem with the 1/4 inch BSP connections into the burner oil pump using newly purchased hoses.

Basically the design of this year's manufacture of 'Bio Green' flex hose is such that I can only get one turn of the right angle male nipple into the oil pump female thread before the joint 'bottoms'. To my mind this is quite unacceptable and I have ended up refitting the old 'Bio Green' hoses which had at least two threads of engagement. Earlier designs of hose I recall having four plus threads of engagement (much more sensible), and the basic nipple itself (of whatever period) has about eight threads available.

I am going to raise this with manufacturer soon but would welcome the comments of others first. Is my experience a unique one? Has the basic design been changed for a reason? How should I proceed?

 

[dcawkwell]

Sounds like the thread of your pump are wrong.
It should turn in several turns before bottoming.

 

[MrDuck]

I spoke to the supplier this morning who immediately accepted that they got a large batch of hoses wrong earlier this year and that others had had same problem. Design change wrongly made to pump end fitting.

Replacement pair to be posted today. Not pleased, but at least it's an outcome.

 

[Danoil]

Had the same problem a few times this year, spoke to EOGB in April and they said they would sort it. Guess a few got missed?

 

[MrDuck]

EOGB have replaced my hoses but I still think the thread engagement (1 1/2 turns) into my Riello G5X burner is too small for safety. Am I sourcing the wrong sort of hose or is this a common experience? I thought 1/4" F was a standard for a pump port but it now seems not, as different hose manufactuers seem to have made their own interpretations of critical dimensions!

 

[Danoil]

If your pump is on a one pipe system you can take out the 15mm nut from the return port and put the flexi in this instead. Just a thought to check if it is the flexi or the threads on the inlet port that's at fault. If it works it is possible to run the burner like this as well.

 

[oilboffin]

Keep calm and look at the problem 1turn may be enough after all it's on the suction side so not presuised and if it was on a 2 pipe system then the return pressure isn't too great so seal it well and keep an eye on it and go back to the maker and report your findings to them and see what they say

 

[oilhead]

Take a look at the nipple on the end of the elbow. This will probably be a lot deeper on your new hoses. Also, there may be a difference between where the thread starts on the nut compared to your old hoses. As long as the nut holds the nipple tightly into the seat in the pump port, there is no problem. It is the nipple on the seat that seals, not the thread in the port. as a parallel thread, it would be difficult to seal with only 1 turn, but the thread only needs to hold the nipple in place.

 

[oilhead]

Take a look at the nipple on the end of the elbow. This will probably be a lot deeper on your new hoses. Also, there may be a difference between where the thread starts on the nut compared to your old hoses. As long as the nut holds the nipple tightly into the seat in the pump port, there is no problem. It is the nipple on the seat that seals, not the thread in the port. as a parallel thread, it would be difficult to seal with only 1 turn, but the thread only needs to hold the nipple in place.

 

[MrDuck]

Thanks for the further suggestions. Oilhead, you are right to suggest that the nipple is deeper on the new hoses and that the thread start is further back. Combined with the almost flat end to the nipple rather than a dome shape this reduces the thread engagement to no more than one turn.

As a way forward I have:

1. Temporarily reinstalled the old hoses after carefully inspecting them.

2. Made contact with Riello who have been most helpful with technical details of the required hose fitting.

3. Ordered a pair (it's a two pipe system with a Tigerloop) of genuine Riello hoses to the part number specified by Riello. I intend to examine these very carefully and document all the differences between these and the 'aftermarket' hoses.

4. Made contact again with my supplier who fully understands the issue but notes that there seem to be variations in the dimension of pump ports between different manufacturers so what fits badly in my Riello burner is fine with another make.

Always round it seems that '1/4"F Mectron' is a pretty sloppy 'standard'!

 

[MrDuck]

I have now procured a pair of genuine Riello biofuel flex hoses (Riello Part no. 20022601) which Riello have advised are correct for my G5X burner.

I attach a photo I have just taken of the Riello 'Mectron' fitting versus another manufacturers equivalent.

View media item 51525
You will note that there are significant differences, which put together are the reason that the other manufacturer's fitting only has minimal thread engagement with the Riello burner port. Specifically:

- The rounding of the bullet end is more pronounced on the Riello part, allowing greater seating into the port, which has a tapered seat.

- The length of the bullet end is much less on the Riello component, which gives the nipple greater 'bite' into the thread of the port.

- The thread on the nipple starts much sooner on the Riello component (and also has greater length).

I am no great enthusiast of the metal braided type of hose but in this instance I clearly cannot use the non-Riello hoses I have purchased as they do not give what I regard as a secure connection.

I can only presume others are finding the same issue, which seems quite a serious one to me!

 

[MrDuck]

Good news! The third party manufacturer has agreed that a design improvement is desirable and this is now underway. I am also encouraging OFTEC to establish a standard for the Mectron connector as they appear to be very widely used and there really is no reason why significant variation should be present between different examples.

My thanks to everyone for their support.