Is my Hot Water Cylinder Coil holed?

Redhotferrari · 17 Feb 2008

Hi Guys,

Following recent posts I have been trying to find out the cause of why my F&E tank constantly fills up and overflows.

Having a new boiler installed, wont bore you with the details but a manufacturers fault meant it cant be comissioned untul Monday!

So for this reason I have been heating the water via the immersion which we never do! Initially thought the tank filling up was a problem with the boiler/pump/divertor valve.......however, obviously none of these have been on or working for the last few days, and the F&E is still filling up quite quickly.

The only thing I can think is that if the coil is split this could be causing the problem, what do you think?

Although the boiler is not working the system is filled up including the rads.

Dont think the water is boiler and venting out due to this.

Would really appreciate some thoughts on this as its starting to drive me bloody mad

doitall · 17 Feb 2008

IS the storage tank higher than the header tank then

Redhotferrari · 17 Feb 2008

Yep the level of the CW storage is higher than the F&E. The CW is basically full, with the inlet valve shutting off when full.

I drained the F&E to have about 100mm of water in and set the ball valve to this, but as I say it keeps filling up

doitall · 17 Feb 2008

IS the ballvalve running all the time in the storage tank.

Turn the cold feed to the cylinder off and open the taps, does the header tank empty

Redhotferrari · 17 Feb 2008

Not sure , will have a look tomorrow, bit late to go up in the loft again.

Think the ballvalve is very slowly running, but cant be sure, would this indicate a problem with the coil?

When you say the cold feed, do you mean the tap in the airing cupboard that stops the feed to the cylinder? Do you mean the header tank for the cylinder? How will this empty if the feed to the cylinder is turned off?

doitall · 17 Feb 2008

I just knew you would ask that

Yes turn the cold feed from the storage tank to the cylinder off, maybe a red handle thats round. post a pic if your not sure.

Then open the hot taps and leave them open for an hour, if the water goes down in the header tank then the cylinder has gone.

May pay you to tie the valve up in the header tank, otherwise it will refill

Redhotferrari · 18 Feb 2008

Ok......Cold water store isolated to the HWC, I have isolation valves before the F&E in the loft, so have turned this off, this also turns off the water to the cold water tank which I assume is not a problem?

All hot taps in house are fully open and the hour clock is ticking, will report back later.

Many thanks for your advice on this doitall.

Redhotferrari · 18 Feb 2008

Doitall, test done, not really any drop in the F&E tank when I left it for over an hour!

The hot tap in the kitchen continued to dribble, but I think this is more that the gate valve is no FULLY turning off! Had a similar problem when I changed some taps a couple of years ago.

Any more ideas about why this could be happening?

The only other thing I can think of that I have not mentioned is that I have a venturi type mixer shower which has been in for about 3 years, sometimes when its used and turned off it continues to dribble quite a lot for a few minutes. Is it possible there is a problem with the valve and the cold is forcing its way back through the hot! Just a thought or am I starting to clutch for straws that are not there!!!!

After draining out the F&E yesterday afternoon, the tank has filled back up to the overflow in less than 24hrs.

Any more thoughts you have are greatly appreciated.

Cheers

doitall · 18 Feb 2008

You haven't turned any valves off on the header feed have you

Has the water level dropped or not that you would notice.

Redhotferrari · 18 Feb 2008

Confused now! You said to tie up the ball cock to stop it refilling, I have a tap in the loft that turns off the feed to the F&E and the cold water storage tank for the HWC, so I turned this off as thought it easier.

The only other thing I turned off was the gate valve to the HCW.

Water level did not seem to drop at all, it did slightly but as the level was so high I think it was what was going out of the overflow.

If you think it would help I could try it tomorrow and drain the tank so that its well below the overflow and mark the level of the water on the tank

Redhotferrari · 18 Feb 2008

By 'feed' I mean the tap stops the water going to the ball valves on both tanks, not the feed from the bottom of the tank to top up the system

doitall · 18 Feb 2008

No thats ok, I was worried you turned the one at the bottom off.

Ok, another test

Turn everything back on, and bail the header tank right out. ballvalve off

When the water re-fills is it warm/hot

Redhotferrari · 18 Feb 2008

Will prob have to pick this up again tomorrow as have to go out, Assume you want me to sit up in the loft and wait for some water to come through somewhere?

Sounds like fun

doitall · 18 Feb 2008

No just chuck an greenhouse thermometer in the tank and see how hot it gets

Softus · 19 Feb 2008

doitall said:
Turn the cold feed to the cylinder off and open the taps, does the header tank empty

With the greatest of respect, this is a funny way to go about testing for a faulty coil.

In practise, with no water feeding either CSS or F&E, the F&E level might keep on rising for a while, e.g. if the cylinder cold feed gate valve doesn't entirely shut off.

Also, the F&E level would fall only if the coil hole/split allows water to pass out of it as well as into it. And sometimes they don't.

The usual test is to shut off the supply to the CSS (if necessary, tie up the float valve arm) and run the contents out through a cold tap. If the F&E level stops rising after this single change, then it has to be the coil.

You could achieve the same thing with a clean bung in the CSS outlet that goes to the cylinder, and then open a hot tap.

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Is my Hot Water Cylinder Coil holed?

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