direct hot tank probs

[PlumbBobBob]

hi all, went to a house today to change the upper of two immersion heaters in a direct hot water cylinder which was about 1500mm or more tall. How long should it take to drain down?
as it was draining i noticed that the tank around the upper immersion was getting hot but the lower one was staying cold, please could someone let me know why this was happening.
i didn't want to remove the immersion and be hit in the face with hot steam or water. there wasn't any makers sticker on the insulation otherwise i could google the tank.

thenk you steve

 

[justlead1]

Hi. Probably stratification. As you drain down via DOC at base of cylinder the water level with in the cylinder drops, The hotter water will remain at the head of that column as it slowly empties. ( its usual to untighten /crack the thread whilst cylinder is full as is gives more support to the walls of the cylinder when the heaters under tension from spanner) Good Luck

 

[PlumbBobBob]

thanks, thought it might be just didn't want to chance it without asking first (first job only been putting leaflets out since last sunday, already this job and two quotes!!)

 

[unguided1]

is it an economy 7 cylinder

 

[PlumbBobBob]

yes i think it is

 

[unguided1]

the bottom immersion is the economy 7 one and only works after midnight to heat the tank, the top one is there so that if you use all the hot water you can then turn it on for a boost
Regards
Mike

 

[PlumbBobBob]

thanks for the info mike, i will report back to the customer their daughter whose place it is didn't get any information left when they moved in.

 

[PlumbBobBob]

went back tuesday to fit new immersion and discovered why old one didn't work, the looped end had been bent out straight which caused the copper to break.
while i was finishing up i was asked to work out a quote to do the whole bathroom, result!!