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Ask The Trades › DIY Forum › Plumbing Questions › Hot water stops when cold tank drains

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Hot water stops when cold tank drains (Read 3991 times)

Had99

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Hot water stops when cold tank drains
Oct 14^th, 2011, 8:15am

Hi there,

we have a low pressure hot water cylinder where the cold water tank directly from the mains sits above the hot water cylinder. Recently I turned off the mains pressure and drained the cold water tank in order to cap off an old leaking tap in the roof cavity. Since then the hot water runs out whenever the cold water tank empties, this didn't happen prior to this, and since there should still be plenty of hot water in the actual cylinder I'm not sure why its happening. Is there a way to fix this problem?

thanks

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Natedog Full Member Offline Ask The Trades Posts: 347 Total Thanks: 9 For This Post: 0 Swindon United Kingdom	Re: Hot water stops when cold tank drains Reply #1 - Oct 14^th, 2011, 8:26am I'm presuming you mean water stops doing out of the tap, and not that you then get cold.water from the hot tap? This would be normal surely? It's the cold water in the tank that pushes the hot water out of the cylinder. Are you sure you've got the valve you turned off to drain the tank fully open?
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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Hot water stops when cold tank drains Reply #2 - Oct 14^th, 2011, 10:12am As above, not turned the valve on fully or you have a blockage in the ballvalve.
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CWatters Super Member Offline "Daddy fick it" says James Posts: 5150 Total Thanks: 58 For This Post: 0 Gender:	Re: Hot water stops when cold tank drains Reply #3 - Oct 14^th, 2011, 3:41pm Perhaps some sort of air lock in the cylinder so it's not full?
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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Hot water stops when cold tank drains Reply #4 - Oct 14^th, 2011, 4:19pm No CW
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CWatters Super Member Offline "Daddy fick it" says James Posts: 5150 Total Thanks: 58 For This Post: 0 Gender:	Re: Hot water stops when cold tank drains Reply #5 - Oct 15^th, 2011, 9:45am Quote: Since then the hot water runs out whenever the cold water tank empties, this didn't happen prior to this Clarification required... What didn't happen before? a)The hot water didn't run out when the cold tank emptied or b) The cold tank didn't empty before
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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Hot water stops when cold tank drains Reply #6 - Oct 15^th, 2011, 11:40am Typical blocked ballvalve or not turned on fully CW
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