Small water tank in loft

[Gadbury]

Greetings all.

I am a new house owner confused about the water system in our home. Any advice would be greatly appreciated.

We have two cold water tanks in our loft. One large 50 gallon, another small 5 gallon. The small tank is full up to just below the mid-point of the overflow outlet (inside the tank) and the ballcock has sunk an inch below the water level. The valve is allowing supply of water as it will fill the small tank if I press the ballcock down further.

My concern is that the small tank overflow to outside was seen dripping some weeks ago. This has now stopped. The pipe at the bottom of the small tank goes to the bottom of a hot water cylinder, the upper pipe (hanging above small tank overflow) goes to the upper-middle part of the hot water tank.

What is this small tank used for and what would be the expected behaviour? I assume it should fill up just below the overflow with a new ballcock fitted (although I don't know what would cause the tank to drain). We don't have known issues with water supply or heating in our home, I am just concerned about the water level in the small tank and would like to learn about its purpose.

Many thanks.

James

 

[Dotty]

The small tank is the feed and expansion tank for your heating system and is fairly vital.

It sounds as though your ball valve is letting by. Unless you feel confident in servicing the valve yourself I should call a pro in to look at it. In fact it might be an idea to get your boiler serviced at the same time to give yourself peace of mind.

Make sure you mention your f&e tank problem, it's not ordinarily part of the service and we get grumpy when surprised by stuff like that.

The lack of tea and biccies makes us a wee bit tetchy too......

 

[Chalked]

Hi
Could be the ball valve letting by. Or could just be natural expansion of the heating water. Check the level when the heating is not on and cold.

 

[Best]

When you say the tank if filled up to "the mid point" of the overflow, I assume you mean the water level is just below the overflow fitting?
The water level in those expansion & feed tanks is only supposed to be about 4" deep (normally about at the line in the tank where it begins to get wider). A lot of plumbers have the tanks too full, so it might have been partially due to a plumber, or perhaps the Ballvalve is faulty.
The heating tanks are only for topping up water to the system and to allow expansion when heating is going, but not as a storage tank

 

[joni os]

OP states pipe from small tank goes to bottom of DHW cylinder. Please check and confirm. It would normally be pipe from large tank to bottom of cylinder. Upper pipe, "hanging above", to ,"upper middle of cylinder", also questionable. If this DHW cylinder as in an airing cupboard surrounded by clothes, suggest removal of clothes and reappraisal of pipework.

 

[rpm]

............. are you saying the ball of the ballcock is 1 inch under water?

 

[heliotrope]

Would appear the OP has gravity hot water set up with pumped heating.

Cold feed into bottom of primary coil and open vent from top was quite usual.

 

[joni os]

Would appear the OP has gravity hot water set up with pumped heating.

Cold feed into bottom of primary coil and open vent from top was quite usual.

Tees into: Yes. "Goes to". ? Perhaps OP could clarify.

 

[Gadbury]

Thank you everyone for your responses. I will make a diagram today and reply later.

To clarify a couple of things.

The small tank is near full - the water level is just covering the overflow fitment.
The ballcock is completely submerged but not sat at bottom of tank (approx 1 inch between top of ball and water level).
The small tank's feed does tee in to the bottom of the hot water tank.

Thanks again and will respond later.

James

 

[rpm]

A simple line drawing should do James.

 

[rpm]

A simple line drawing should do James.

To add photo`s click on the 3rd icon from the right on the little task bar just above where you type a response.

 

[Gadbury]

Hopefully this diagram is clear.



Should the small tank be near empty or near full? The water heating is done by a gas burner which is part of an old warm air unit.

Thanks again for your time.

James

 

[snowhead]

Small tank should be half full, or half empty and well below the overflow level.

 

[joni os]

Would expect small tank to be almost empty with system cold and no more than 2/3 full with water hot. Reduce water level in tank,(Bale out into bucket) so only 1/3rd full, ball cock should still stop water entering tank. If ball cock doesn't seal replace ball cock.
Line 5 in your diagram is hot water take off from cylinder I would expect 5 and not 6 to extend above large tank with 6 coming off bottom of tank and being tank fed cold feed to shower.

 

[Gadbury]

Thank you all for your responses.

Would expect small tank to be almost empty with system cold and no more than 2/3 full with water hot. Reduce water level in tank,(Bale out into bucket) so only 1/3rd full, ball cock should still stop water entering tank. If ball cock doesn't seal replace ball cock.
Line 5 in your diagram is hot water take off from cylinder I would expect 5 and not 6 to extend above large tank with 6 coming off bottom of tank and being tank fed cold feed to shower.

My apologies - I have indeed got 5 and 6 muddled. I rechecked. Top of hot water tank does tee off to top of large water tank. Bottom of large water tank feeds the upstairs bathroom, I presume.

I shall reduce the level of water in the small water tank, check operation of ball cock and see how that goes. Will report nack. Thanks again.

James