cold storage tank getting warm

[WOLDEN]

i,ve fitted 2 cylinders under a coffin tank in a loft , open vent pipe cold , 2 x 2 ports working correctly , but getting warm water back in the tank . feels like its going back up the cold feed pipe , hot feeds are joined up then go on monsoon neg pump ,

 

[Puddle]

How have you run the vents ?

 

[so-solar]

where is your pump on the system?

 

[Aqua Mechanica]

Where is the CWSC positioned, if that heats up and falls through the ceiling, you'll kill someone. I would recommend turning off the hot water asap.

 

[so-solar]

Good shout aqua mechanica

 

[migoplumber]

pumps incorrectly positioned, vented incorrectly ? either way dont leave the hot water on when your not on site testing - just in case.

 

[justlead1]

Hi. How warm? It if normal for the expansion of water in a cylinder to be expelled via the cold feed. If the cold water storage cistern is small and the gallon or so of hot water from the two cylinder generated when heated is mixed with the cold, the temp would rise. Hence How warm. I take it the pump is down stream of the vent pipe?

 

[WOLDEN]

both cylinders have there own vents , with a air break . water is warm ,not hot , both hot feeds are joined up by the essex flanges then go to pump . i fitted non returns after pump . as insturtions say not before .
50 gallon cwsc.

 

[so-solar]

where abouts have you positioned the pump? and just a quick check, you said you have fitted non returns! are they the right way round? not sure if this could cause it to back feed but just a thought!

 

[justlead1]

Hi, Water will expand back up the cold feed as already said, and the pump arrangement sounds good. Check that any mixer taps/showers that may be connected to the pumped hot distribution pipe are not backing up into the cistern, if the cold is feed from the same CWSC.

 

[WOLDEN]

non returns wrong way ,, na . everything flows great .. do you think 1 cylinder can nick all the heat from the other , causing cylinder to over heat , just a thought

 

[justlead1]

Hi. No i do not think so as i am amusing that both have thermostats fitted. But if essex flange are fitted to both giving two draw off via the pump it does not reason that the flow will be of the same volume on both. I seem to remember a twin cylinder situation where the cold feed from storage feed the first cylinder the hot draw off was vented and then became the cold feed to the second cylinder, then as you describe your system. This system used all the available hot water before drawing cold.

 

[WOLDEN]

both have stat,s . both 2 ports shut off when i turn them off , but not sat and waited to see if the heat do,s it . both stats set at same temp .. could one heat quicker , the other pushing more heat though to the other ,

 

[Jimbob]

Iv had the exact same problem on a job.

When I arrived at it, it has a massive CWSC, and 2 feeds had been brought back down which fed 2 small cylinders, not much head, maybe 1 metre. the hot feeds from the cylinders were then linked and when off in distributing pipework.

even tho both points were level, it seemed to be pusing hotwater back up one of the cold feeds, never both. So I linked both cold feeds together as low as i could and then it seemed to stop.

It was weird because usually cold feeds are freezing, and it doesnt usually expanded so much it warms the feed.

 

[WOLDEN]

thanks , i give a go , should i increase the down pipe feed , as i,m joining both