Water Separators for domestic oil fired heating

[KenT]

My oil tank collects several litres of water each year, from condensation. Is there a water separator on the market for such applications. Oil flow is very low, maximum flow being 3 litres per hour, but the amount of water is HUGE, so an auto-drain into a 5 litre container would be useful, or at least a one litre capacity in the bowl. The Oil Filter (Part 34081) sold by Toolstation would be brilliant, if only the tiny bowl did not need emptying so often.

I only burn about 100 to 200 litres per year, from a 1200litre tank, hense the large volume breathing in condensation from our Welsh very-wet climate.

I have searched for hours for a suitable separator, without success.

 

[lame plumber]

need a smaller tank kept filled to stop the problem of condensation.

 

[MarkOil]

are you 100% sure it's condensation and not something on-top of your tank letting rain in? is it a plastic or metal tank?

 

[KenT]

are you 100% sure it's condensation and not something on-top of your tank letting rain in? is it a plastic or metal tank?

Well,99% sure. I've had the problem for 10 years now. All three hole covers are firmly in place, and I've searched for cracks in the top of the tank. It's plastic. I think I get the condensation because it is near-empty all the time. Neighbours have had their oil stolen, so I am loath to fill it.

I wonder if an airline water-separator would work. £13.35 on ebay, but it's got a pressure regulator built in, to get in the way, and the bowl is only 150ml capacity, with a manual drain.

 

[Best]

Careful the fill cap isn't letting rain water in!
I suspect a lot of the fill caps that fit more or less flat to the top of tank, are letting water in. Heavy rain & strong winds will get past a lot of those seals.
I have looked inside tanks with a torch that are 20 years old & there's no water at all, except a dot or two directly below the fill cap probably from the odd time cap is off. Yet other tanks with the flush fitting screw lids are full of water! Also a lot of the hinges on the lids are into open holes where rain will def enter.

 

[EPH]

OFTEC sell them. Where are you?

 

[kimbo]

A national tamk installation company told me you don't get condensation with plastic tanks and I must admit I have never seen one that suffers from it. The neoprene washers usually crack. Use a mastic on all the joints to seal them.

 

[KenT]

I am dumbfounded by, and grateful for, all the replies and the effort taken to reply to my question. Many thanks to everyone.

Several interesting points have been made.

A smaller tank may help, but getting deliveries of less than 500 litres is difficult, expensive and almost impossible round here. A £13 water separator seems a cheaper solution than replacing the tank.


I think “best” has pin-pointed the real problem. Following your comments, I went and had a closer look at the filling hole. Sure enough, it is almost flush with the top surface of the tank. I was vaguely aware that it has a rubber seal,but on studying it closely, the seal is between the tank top surface and the flange or housing that the cap screws onto. The cap itself has no rubber seal, and just relies on the plastic to plastic interface to keep driving rain out. The cap is embossed “Cap must be closed tight”, but I had not realised why, and may have often left it slightly loose. I dip the tank about once a week, more often if I am running the boiler daily. The cap and its housing appear to have been designed specifically to encourage driving rain to get into the tank, with smooth curved surfaces and no ridges to interrupt the flow!


Furthermore, I live on a hillside in rains-every-day Wales, (Between Ammanford and Llandeilo – Wear the fox hat, as Prince Philip said to Queeny when she told him she was coming here to open our village hall.) with only open fields behind the tank. The wind fair whistles up the fields, driving the rain almost horizontally. Clearly I need a more protective cap to fit over the existing cap.


The rubber seal is well past its use-by date, so I shall be out for a tube of mastic tomorrow.


I shall probably give it all another try, with just the ToolStation water separator, or buy the £14 airline filter and try that, or buy the OFTEC one. I have searched OFTEC's Service and Commissioning, Installation, and Miscellaneous shops, but cannot find a water separator – any chance of a little more guidance on where to find it.

 

[Best]

I think “best” has pin-pointed the real problem. Following your comments, I went and had a closer look at the filling hole. Sure enough, it is almost flush with the top surface of the tank. I was vaguely aware that it has a rubber seal,but on studying it closely, the seal is between the tank top surface and the flange or housing that the cap screws onto. The cap itself has no rubber seal, and just relies on the plastic to plastic interface to keep driving rain out.

...exactly! A plastic to plastic "seal" which isn't a seal at all!
I have never believed that condensation was the cause of loads of water in certain tanks but others had no water. Watch the flange to tank seal as well as the lid to flange seal & also the air vents can be letting water pass. The tanks with a raised filling point moulded as part of the tank, are a safer bet to keep rain out. Never had much bother with water in them.

 

[basildog]

A national tamk installation company told me you don't get condensation with plastic tanks and I must admit I have never seen one that suffers from it. The neoprene washers usually crack. Use a mastic on all the joints to seal them.

You may not get condensation but my understanding is that heating oil just like diesel or sugar come to that is in fact Hygroscopic ?