Fitting diverter in Vaillant Turbomax 282E
- Thread starter bethrob99
- Start date
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1 hour, replace the pump seals at the same time.
N
namsag
Pump seals can be cleaned and smeared with silicone grease to make water tight. Give the screw that holds mounting plate a sharp hit before trying to undo it otherwise the head may shear then require drilling out. As said first one may take an hour but after that easily done in half hour.
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Personally, I'd change the pump seals every time, they're notorious for leaking. If you have no choice (ie not available at the time) then I'd certainly go along with the clean/greasing method.
As an aside, does anyone know why such seals are so perishable?
garethgas
As an aside, does anyone know why such seals are so perishable?
garethgas
I view that task as one of the more difficult particularly if good underneath and right hand side access is not possible.
Although I always do things very carefully, drying the sealing surfaces and using silicone everywhere, I would always allow about two hours but expect to do it in somewhat over one.
My repairs always include a basic service and performance check so time has to be allowed to cover that.
Tony
Although I always do things very carefully, drying the sealing surfaces and using silicone everywhere, I would always allow about two hours but expect to do it in somewhat over one.
My repairs always include a basic service and performance check so time has to be allowed to cover that.
Tony
Know what you mean, it makes me very cross.
If you stooge around an O ring manufacturer's site you find that the materials we see quoted for plumbing stuff are the cheapest. (Includes the ones in pushfit plumbing of course!)
Yet sometimes you take one out from what must be the most difficult environment in a hot part of a boiler and the O ring's fine cos they used a better grade.
I once cut open a Glow Worm 3 y.o. cast iron heat exchanger with @O@ ring pipeconnections.
The HE had overheated due to debris so I had expected the seals would be in pretty poor condition but they looked and feal just like new!
Which are the nitrile ones?
And what type does the shuttle launch vehicle use now following early failures of the two ring seals?
Tony
The HE had overheated due to debris so I had expected the seals would be in pretty poor condition but they looked and feal just like new!
Which are the nitrile ones?
And what type does the shuttle launch vehicle use now following early failures of the two ring seals?
Tony
Nitrile are failry low on the price/spec list but not at the bottom. Probably one of the better types we do see. RS do a box of nitrile ones which is a few times the price of the cheaper ones, iirc.
The shuttle ones failed at low temperature. I doubt they publish the spec, but noted that their "fix" included using two, and installing a heater!
The shuttle ones failed at low temperature. I doubt they publish the spec, but noted that their "fix" included using two, and installing a heater!
Obviously copied that idea from the Yorkshire TE rad valve then 
O ring failures are tend to be either poor mechanical design ie incorrect clearances/alignment or incorrect material selection for the operating environment.
There is no excuse for poor design but it continues to be a problem on boilers. Take the Vokera Option/Compact for example. Notorious for leaking on the hose connections and the blanking plug on the left hand side on the pump block.
The hoses are strained to the extent that the O ring clearance is unequal around the circumference. Easily solved with a simple design modification. The blanking plugs often leak - again due to unequal clearance and poor design - only a single securing clip.
Many O rings are operated way past their elastic limit - and with time will loose their elastic property - an example would be the Puma thermistor seals - with time they become brittle. The design should only allow the thermistor to compress the O ring a limited amount.
Sometimes the plastic mouldings are of such poor quality with moulding tool flashing lines still present. There is evidence of this on Vokeras.
In terms of material selection manufactures are obviously heading for lowest cost option but it is not always their fault if the seals fail.
Temperature is perhaps the initial selection criteria however the operating environment is equally important. By this I mean compatability with the associated brass/plastic moulding and the system water.
Some plastics can leech plasticisers etc into the O ring and vice versa, having a detrimental effect. A similar problem can occur with metallic castings - oils used during machining can be absorbed into the metal surface gradually effecting the O ring with time.
The system water contains all manner of contaminants. failure to flush and clean adequately can leave a chemical cocktail incompatible with the seals.
Some boilers have suffered greatly and on investigation the problem has been found to be due to a particular mineral oil used by a radiator manufacturer.
Since boiler manufacturers are unable to know the exact environment the O rings will operated under we will continue to see problems.
O rings enable low cost/unskilled manufacturing but for long term reliability they are not the answer. Within the boiler industry the O ring has become one of the most abused and misunderstood seal options.
Talking of leeching plasticisers - a colleaque of mine designed telecom repeaters. They were having problems with the units going out of spec when operated in high temperature environments (middle of Africa). It turned out to be the plasticiser from the Pvc wiring within the unit. The gas emited built up to a sufficient concentration to be absorbed by the very low pF polystrene capacitors. In the end a change of wiring was the only solution. A completely unexpected problem that cost a fortune to resolve.
There is no excuse for poor design but it continues to be a problem on boilers. Take the Vokera Option/Compact for example. Notorious for leaking on the hose connections and the blanking plug on the left hand side on the pump block.
The hoses are strained to the extent that the O ring clearance is unequal around the circumference. Easily solved with a simple design modification. The blanking plugs often leak - again due to unequal clearance and poor design - only a single securing clip.
Many O rings are operated way past their elastic limit - and with time will loose their elastic property - an example would be the Puma thermistor seals - with time they become brittle. The design should only allow the thermistor to compress the O ring a limited amount.
Sometimes the plastic mouldings are of such poor quality with moulding tool flashing lines still present. There is evidence of this on Vokeras.
In terms of material selection manufactures are obviously heading for lowest cost option but it is not always their fault if the seals fail.
Temperature is perhaps the initial selection criteria however the operating environment is equally important. By this I mean compatability with the associated brass/plastic moulding and the system water.
Some plastics can leech plasticisers etc into the O ring and vice versa, having a detrimental effect. A similar problem can occur with metallic castings - oils used during machining can be absorbed into the metal surface gradually effecting the O ring with time.
The system water contains all manner of contaminants. failure to flush and clean adequately can leave a chemical cocktail incompatible with the seals.
Some boilers have suffered greatly and on investigation the problem has been found to be due to a particular mineral oil used by a radiator manufacturer.
Since boiler manufacturers are unable to know the exact environment the O rings will operated under we will continue to see problems.
O rings enable low cost/unskilled manufacturing but for long term reliability they are not the answer. Within the boiler industry the O ring has become one of the most abused and misunderstood seal options.
Talking of leeching plasticisers - a colleaque of mine designed telecom repeaters. They were having problems with the units going out of spec when operated in high temperature environments (middle of Africa). It turned out to be the plasticiser from the Pvc wiring within the unit. The gas emited built up to a sufficient concentration to be absorbed by the very low pF polystrene capacitors. In the end a change of wiring was the only solution. A completely unexpected problem that cost a fortune to resolve.
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