New boiler rusting baffles

ratplumb

I have a clients oil Grant boiler I fitted last year. It is a Vortex pro 26-46 system.
It is just a small system loop as it is a pool boiler. Heated through a heat exchanger directly behind the boiler.
I went to service today and took about a handful of rust off the baffles. There was even signs of rust on 2 of the chamber door nuts.
Boiler has a 150mm vertical flue about 2.6mtrs located in a pool pump house with all pool filter and chemicals.!.. First thought on the rusty nuts was the pool chemicals in the air. But this does not explain the rusting baffles. Could this be result of a blocked condensate or flue fault.
I then done a combustion test and all spot on .
Any advice and ideas where to check appreciated.

Test and the boiler had been running so allowed to cool down. The pool heat exchanger was showing pool water already at 25deg .
So started the boiler at -
1.40pm and T1 Flow - 28degC T2 Return - 25degC
1.47pm T1 flow - 44.4 deg , T2 return 35.6deg , diff 8deg
1.50pm Flow - 61.5deg , Ret 48.0 , diff 13.5deg
1.55 F - 66.6 d , R - 51.3 d, diff 15.3deg
2.05 F - 70.8 d , R - 55.8 d , diff 15deg
Then roughly levels out , slowly creeps up only 1 deg to 71.7d - 56.2deg over the next 50 min.
So it took roughly 7 min to get up to 40 deg return temp and another 7min to get to return of 50 deg.

Jamie Hall

Flue temperature? OIL fired boilers aren't usually meant to run with condensing flue temperatures.

Mad Dog_2

Relative humidity...dew point....Mad Dog

EBEBRATT-Ed

I guess you in Europe where they have Grant boilers.

I am not familiar with weather this is a condensing boiler or not. If it is not a condensing boiler your return temps are too low. Could be the pool chemicals as well.

ratplumb

Hi. It is a new condensing boiler . Flue temp goes from 65 deg to 78deg when settles after 10min running. (Burner settings at 41kw suggest flue temp at +/-80 -85deg) Also rusting on a steel plate that is holding the expansion vessel just above the burner. Checked yesterday and had probably been running for about 1.5 hrs and was Flow of 68.5 Return of 48.4 . Delt T20.1 deg.

The boiler is not used in winter but has a 5 deg frost stat . Unsure if it was drained by the pool maintenance guy who drains pool pumps in winter, But just up and running when I got there this week. I put in some boiler anti freeze this week. System water content is probably only 26ltrs

I switched it off yesterday and will retest Monday when all cold to compare.

EdTheHeaterMan

The boiler location is my guess. What is the relative humidity of the boiler room. Are the other pool components in the same room, filter and pumping system etc? When filter maintenance is completed is there splashing/spilling/leaking pool water in the boiler area. Are the pool chemicals located in the boiler room?

I have a feeling you already know this.

I only worked on 2 pool heaters in my career, and I installed one oil fired boiler that was designed to be outdoors. The outdoor boiler and the boiler I installed outdoors were both in bad shape after only 5 years of use. But I was able to keep them operating for about 20 years. They were just a bucket of rust by the time I retired.

The other pool heater was for an indoor pool and that one held up a little better but the boiler room was attached to the very humid pool enclosure. That oil fired boiler was in a separate room that the door to the pool could be closed and I installed combustion air openings to the outdoors to get some drier fresh air in there. That boiler lasted longer and did not have as much rust on the boiler metal covers and metal parts.

I think you are stuck with regular maintenance that will require replacing rusted baffles every few years.

ratplumb

Thanks Edward. Yes the previous boiler was pretty rusted up. The pool filter, pump and all the chemicals are right next to the boiler ( 1ft) and would be shock treated every spring and definitely smells of chlorine. The pool house is a wooden 3x4mtr room . This could explain the corrosion on the exposed parts but what about the baffles and combustion chamber, as this is a balanced flue so taking air form outside. ?

I scooped off about 2 handfulls of rust from off the baffles with boiler only running for 4 mths..