Spillage (RGI)
 
This is the technically interesting topic for me in all this. I am curious to know why the alteration to 32.689.33 has forced a significant shift in the spillage test protocol. RGI are asked to bear with me. I want this page also to be accessible to the understanding of lay visitors as well, as far as that is possible. Another sketch with an exaggerated caricature is posted below. The gaps indicated between component parts are exaggerated for illustration purposes. For all practical purposes there are no gaps.
 
The letter A denotes the gap of only 40mm (1.5") behind the appliance. The spigot shown black is screwed to the now familiar draught diverter by the RGI. The spigot slides into the letterbox sized slot in the closure plate, as shown. The spigot is a good fit with negligible gap and needs to be. The arrow at B points to that negligible gap. See photograph below.

The draught diverter almost touches the closure plate. Only the dome head screws securing the spigot to the draught diverter, prevent the draught diverter touching the closure plate.

The new MI states in step 5(4) that the outer case should be refitted. Step 6 is the new spillage test, which cannot be carried out with the outer case fitted. I can see no reason why the outer case could not be removed to enable the spillage test to be performed. But that is not for me to determine. RGI have to do things by the numbers. I could not advise that if I was an instructor. The MI must dictate all processional steps.

Assuming that is corrected in the MI, there is another problem which depends on the installation design. If a typical decorative fire surround is included (as in my case), that could prevent a smoke match tube being inserted into either side. A combustible surround may be as close as 75mm (3") to the appliance. A shelf over the appliance may be as close as 150mm (6"). The RGI will struggle to see behind the appliance. Bear in mind the appliance is on full heat for at least five minutes. Glasses, if worn, get steamed up. See pop-up image.
 
The smoke match used for the spillage test fits into the end of a steel tube, has to be lit then inserted precisely (and quickly) under the draught diverter at C on the sketch. An indent in the tube indicates to the touch (you may not see it) that the tube is correctly located. In every case I have ever known, evidence of spillage is sought at the point where where the smoke match is introduced.

Very odd, step 6(5) includes the comment "if an appreciable amount of smoke escapes from above the flue spigot or from the sides ...".

I have a problem with this:

  1. Even if it could happen (it cannot possibly happen), the top and sides of the spigot are totally concealed by the tight fitting draught diverter which is much bigger on all sides (see photograph below).

  2. The gap around the spigot is negligible by deliberate design. Certainly less than 1mm. B on the sketch. As all RGI know very well, regulations are ultra strict about the admission of air into the flue passage, which must be strictly controlled. Hence the rear of the fire area has to be fully sealed and in my case, redundant holes (the legacy of a BBU) involved (Technical Bulletin 009 refers). The only air admitted is via the purpose-made slot at the base of the closure plate provided by the manufacturer. Even the hole around a gas pipe which may pass through the closure plate has to be fully sealed. It is self-evident that allowing any air to be pulled into the flue around the outside of the spigot, would not be acceptable. I therefore reject any premise that suggests 'spillage' should be looked for emerging from around the outside of the spigot.

  3. The smoke match generates a low volume of visible smoke and even if the smoke climbed above the level of the spigot and was then pushed back, it would simply fill up into the void behind the appliance. The total volume of smoke claimed for a smoke match, only two cubic metres. Useful smoke I would suggest even less. They burn about 14 seconds, usefully even less (video below).

  4. If the outer casing was on you could not see anything at the back anyway. The casing is designed to prevent that by definition for cosmetic reasons. The punter would not like that. There are discreet narrow slots (10mm) on each side of the casing to admit air. Those are low down against the marble (fireplace).

  5. If spillage was occuring, the smoke from the smoke match could not enter the flue by definition in order to reach the top of the spigot where indicated by the arrow and B above. Spillage, if there is any, would (could) only occur at C. That has been true since time immemorial.

  6. I would not want to be the one to try to peek behind the appliance, into that narrow 40mm gap, with the appliance on full flame and the outer casing off. Roll mouse over image to see the difficulty (tap on a smart phone).
 
 
A view behind 32.689.33 (MKII) showing the back of the appliance, the draught diverter and the spigot. As for seeing smoke emerging from above the flue spigot or sides, any RGI can see that is not possible. Form your own opinion on this page (smoke match video opens in new window).

NB: On open flue boilers and warm air units I have traditionally and confidently used smoke pellets rather than smoke matches under draught diverters. That said they have much larger draught diverters. As the video suggests, there is no chance of a smoke match delivering enough smoke to be seen above the spigot under any conditions whatsoever. If you waste time looking for smoke above the spigot, you may miss spillage at C, where the smoke match is introduced.

All considered, I am led to the conclusion that the obvious difficulties of accessing either side of the appliance visually in some installations, may be what has led to the suggestion of looking for spillage around the spigot. I would need to see confirmed evidence from an approved Notified Body on this subject before I could considered using any of these products in the future.
 
 
Return to Home Page
 
Previous page Next Page