Oil boiler questions...

MickLimk

Moved into a new house about 18 months or so ago and finally got around to installing a proper heating controller (Horstman H37XL) last week. The motorised valves were already there but never wired so thankfully it was primarily a wiring job to get separate upstairs, downstairs & hot water control.

Anyway, when I completed this job, I decided to have a look at the boiler itself. It's a Grant Euroflame 50/90 kitchen/utility boiler with a Riello RDB 1 burner. It's in the utility room but there's always been a fairly strong smell from it. Never had an internal boiler before so didn't know if this was normal so seeing as the covers were all off I figured I'd have a look.

First thing I noticed was a blackening around where the balanced flue connected to the top of the boiler. Stripped the flue and found that the gasket that goes between the flue & the boiler was broken and had a gap of about 10mm or so that was allowing exhaust fumes escape. Went to refit the flue and discovered that the hole through the wall wasn't drilled straight which meant the flange on the flue wouldn't sit flat. Enlarged the hole to allow the flue run horizontal and reassembled. Fired up the boiler and the smell wasn't as strong but still very noticeable...

Next step was to take out the burner. As soon as I did that, I found a few more problems. The flange that the burner was bolted on to was cracked and broken at the top. It also looked like there was never a proper gasket fitted either, just a ring of high temp sealant between the flange and the boiler. Had a look at the burner itself then and noticed that the the o-ring that seals where the burner meets the inside of the gasket was broken in half and worthless - yet another source of fumes...

So, got a new gasket and flange and ordered the seal kit for the o-ring. Fitted the gasket and flange and noticed that the new flange is considerably thicker than the old one, especially where the other one had broken (at the top where the mounting bolt is). As a result of the difference in thickness, the front cover of the boiler won't fit when the is cover on the burner... I also noticed that the feet of the burner are not touching the floor of the boiler so the entire weight of the burner it pulling on the top bolt of the flange (where the previous one cracked).

Apologies for the rambling - finally to my questions!
1. Are all my problems related to incredibly poor work by the installer or a combination of poor workmanship and design faults with the boiler? Is there a history of these flanges cracking and breaking? Should I find out who originally installed this boiler and complain?
2. Do I need to support the feet of the burner to take the weight off the flange bolt or is it normal for the burner to be off the ground?
3. Is there any problem with leaving the cover off the burner once the front of the boiler is left on? Any problem with the insulation of the front panel pressing up against the burner?
4. When I had the burner out, I had a look at the inside of the boiler. There is no soot but funny spotting on the inside. Is this normal?
5. Given the problems I've outlined, should I get someone in to give the burner a service and check the nozzle, pressures, CO2, exhaust temperatures etc. as outlined in installer manual? If you think it necessary, can anyone recommend someone around the Cappamore area of Limerick who will do all this properly? I certainly don't want to get the original installer out!

Thanks in advance,
Mick

JamesM

Not sure where to start.
The photos first. The flange is the normal type for the RDB burner, although I have seen a slightly different one on a recent burner - it seems to have 2 hooks of brackets at the top - probably for a different model or something like that.
The gasket is not the original. The proper gasket is slightly smaller than the flange and sits into a groove around the edge of the flange. The flange is helt to the boiler by the 2 side bolts. The burner is held on to the flange by the top bolt only - that is normal.
The photo of the inside shows normal combustion deposit.
There are 2 types of smell. One is vapourised oil - if there is any small oil leak near the burner, when the boiler heats up it will vapourise and the smell will be very strong and sharp. The other is combustion - if the adjustments are not exactly correct, the exhaust gasses will have quite a strong smell. Either too much air, or too little air can cause this - too little air can also cause black marks at the exhaust vent.
Going by the photo of the inside of the boiler, the combustion is pretty OK.
Look for leaks around the oil pump. There is a plug right beside where the flexible oil line connects to the pump. This was often loose on new burners and not spotted by the installer, causing a slight drip.
The flange usually only cracked if it got too much heat from back pressure, if there was a combustion problem with the boiler.
You can also get a smell sometimes if the exhaust vent is in a side passage or an exposed area, and the wind is blowing from a certain direction or swirling around.
Jim.

MickLimk

Thanks Jim,

The gasket in the photo was the one from where the balanced flue attached to the top of the boiler and not where the burner attached to the boiler. There was actually no gasket at all there, just the remains of some high temp sealant on the back of the old flange. When I replaced the flange I put in a new gasket like the one you mentioned. I also replaced the gasket between the flue and boiler with one similar to the one in the photo.

Replacing these parts has almost eliminated the smell and it could well be that it's just in my mind at this stage. Will leave it burn for a couple of hours and ask an independent opinion on the smell then. Must make sure the bins are outside the door at the time!

Glad to hear that the deposits on the inside are normal. The last thing I want is to find that having the burner adjusted incorrectly is causing the internals of the boiler to oxidise and break down faster than would be expected.

I don't think that there should be any problem with back pressure given that the flue run is short and vented directly to the outside. On the other hand, it does vent to an external corner that appears to be a wind trap. This may explain future smells that seem to be wind dependent...

Will be happy enough to draw a line under this one once the new o-ring is in place and just keep a better eye on it in the future. If I knew the name of the installer, I'd name and shame him here...

Next project I'm considering in my heating efficiency quest is retrofitting TRVs on all the rads. Is this a worthwhile exercise?