Hot water from overflow.

Would really like some idea of this problem before calling in engineer.
I have fairly new oil fired central heating system installed (4yrs). Now hot water is coming out of the overflow,not dripping pouring.Can stop this by turning hot water tap for a while,but it soon comes back. Can anyone please give me some idea how to proceed. Thank you.

Roguemale, I'm no expert but, even if I was, you'd need to provide more detail. Is this a combi boiler or open vented system? What make/model? Which overflow?

You cannot expect people to help you without helping them.

Over to someone else.

Is the feed and expansion tank higher than the cold water storage (f&e=little tank )

If so could be the coil within the hot water cylinder is holed.

does you hot water look clean?

does the ballvalve in the bigger tank run all the time?

I cant think of another explaination as the water in the cws tank should not be hot??

I have a similiar / same problem, I have an open vented hot water system heated by a heat exchanger from the boiler. The heat exchanging system is venting into it's feed + expansion tank when hot water is swiched on at the timer (which I think it is supposed to?). The water is not being drawn away quickly enough (it is being drawn away as I can feel the other pipe moving) though and because of this it is going out through the overflow pipe. Any idea what could cause this?

PS.
The bottom of my f&e tank is level with the bottom of the cold water tank - they both sit on the same piece of wood. Hot water looks clean. Ball valve is dripping but only slightly - fixing this separately.

Scotty - I think you're confused about the purpose of the vent pipe ending above your Feed & Expansion tank. It's not supposed to run or even drip. It's there in case awful things happen and the water in your boiler / rads / HW cylinder needs somewhere to go quickly (often along with a lot of steam) when (for example) the boiler goes wrong and actually boils. If water is dripping (or, especially, running) out of the vent back into the F&E tank, chances are you have a pipework fault or design problem. The most frequent fault is a blockage in the pipes just above the pump, where the cold feed from the F&E links in to the rest of the system. Combination of the pump set to too high a speed and bad plumbing design can also cause a drip. Either way, it needs to be fixed because you're introducing aerated water into the system (from the F&E) which will corrode the rads and boiler, and possibly filling your loft with steam (also a bad idea)

Roguemale47 - From your description likeliest cause is a split coil. If so, the water level in your cold water storage tank will be HIGHER than the level in your F&E and the ball valve in the cold tank will be running continuously. Only solution: get a new cylinder.

Scotty, not sure if yours was pouring or not. Constant pouring is probably a breach of the heating coil in the tank. Since I moved into my (new) house I have always had steam and drips going into the expansion tank (and ultimately coming out of the overflow pipe) with the pump on speed 1. Turning the pump to speeds 2 or 3 would cause it to pour into the expansion tank, so could only run the system on the lowest pump speed. If you have this, check how high above the tank the expansion pipe goes before bending back down into the tank. Mine was only a few inches above the tank before bending back down into the tank, therefore, even with the rest of the system being ok, the normal warming and subsequent expansion or water in this pipe was pushing it so close to the top of the pipe, steam was coming out or condensing in the top of the bend and then dripping into the tank. My fix to this was to increase the height of the expansion pipe above the tank before it bends over and goes into the tank. As the water then expands and rises into the pipe its own gravitational weight soon overcomes it and it settles to a good level in the pipe; no steam, no drips, because it is not near enough to the top bend in the pipe. I raised mine up to about 2 feet above the top of the expansion tank. I now get no problems at all on speeds 1 and 2 of pump and only regular dripping on speed 3. Maybe I should have taken it 3 feet up and cured it completely, but I can live with this result.