Hot water cylinder heating issue

[Biscuitman]

Hi I've an issue with a newly fitted gravity fed hot water cylinder. I have just in the process of having a shower pump fitted. In advance of this a new larger cylinder (125L?) was installed. The electric immersion now only heats enough water to fill about 6 inches of bath water where the previous smaller cylinder would fill the bath heated only by the immersion.

The builder's plumber is stating this is because new heating elements are shorter and will never heat an entire tank, and to get a tank of water I will need to have the boiler switched on (difficult at moment as it is sitting on garage floor awaiting re-install). This sounds totally wrong to me, can you tell me whether he is right and if not what the problem might be?

 

[buff]

is the thermostat at the right temperature or it needs turning up
is there two thermostats in the cylinder,bottom,top if so are both on ?
bob

 

[PlumbBobBob]

you can still get longer immersion elements toolstation item no. 40149 for instance 27"

steve

 

[Biscuitman]

What is the right temperature? The thermostat's set at about 55 degrees and is situated about 8 inches from the bottom of the tank (there is only one I can see)

Cylinder is marked:
1050mm x 450mm - capacity 140L, max length immersion heater 850mm (equates to ~33inches)

 

[Plumbstar Tom]

Do you know what sixze immersion is in there now?

As its not too difficult to swap to the 27" one and you should be fine from there

 

[PlumbBobBob]

cylinder stat should be set to 60 degrees

steve

 

[Biscuitman]

Well speaking to the plumber he states that the immersion heater is a 27" one. Looking online the longest I can realistically see is 30" (can't see any 33" ones).

Will wind up the thermostat. If this doesn't work is it worth getting the extra 3"? (cue many sniggers)

 

[PlumbBobBob]

if i was you i would ask the plumber to prove that a 27" immersion was installed by removing it and showing you

steve

 

[Biscuitman]

Many thanks for all your suggestions. I have checked the heater and it is a 27" one. However having now ramped up the thermostat to @63 degrees C it seems to be circulating properly and the tank is heating well.

I suppose I should have done this earlier but just wanted to show my appreciation for the suggestions

 

[Plamber]

hi, some new imersion heaters come with 2 stats. has the plumber tried replacing the stat? could just be a faulty one.

 

[traineedrip]

I dont get this? Wouldnt a smaller heater just take longer? Or is this due to the stat being turned down too low?

The thermostat mentioned is the immersion stat not the boiler stat strapped to the tank?

 

[Plamber]

no, on the immersion heater itself there is a thermostat.

 

[Bernie2]

Interesting post. Hot water rises, so a longer immersion would heat more water.

 

[Toddyplumb]

It does not matter a jot how long the heater is in this case . It is 8" from the bottom of the cylinder so is probably hoizontal. 3kw is 3kw whether its from 12" or 27"

 

[tackleburger]

It was probably just because it was refilled from cold. The initial fill will take a long time to get to temperature once you have it up to 60 deg you are just toppoing up the heat from a much higher starting point as even the tank water will get up a few degrees once it has sat for a while. On a cylinder that size the immersion is a back up. If it was a direct cylinder (no Boiler) you would normally spec it with two heaters side entry top and bottom with the bottom one on overnight at cheap rate only.

 

[traineedrip]

no, on the immersion heater itself there is a thermostat.

My question was aimed at the OP , Ive had it before where a customer is adjusting the boiler stst thinking it adjusts the immersion temp.

 

[Biscuitman]

For info the immersion heater is a standard 27" heater with a cylinder mounted thermostat. It is a top mounted vertically mounted heater. This was left on for many hours but only heated the top 20 odd litres.

I cannot explain why it didn't work properly when the thermostat was set at 55 degrees C as the thermostat and heater are in fact the same as were fitted to the older smaller cylinder (which heated fine).

 

[traineedrip]

some confusion here... Theres should actually be two thermostats. The one 8" off the bottom is a plastic box strapped to the side of the tank. that tells the boiler when to stop heating the water.

Under the metal cap of the immersion heater there is another thermostat which controls it. LIVE EXPOSED WIRES are under this cap so make sure you isolate before touching, better still get your plumber to do it .
I cant see it solving the problem though. The only thing i can think of is someones changed the immersion thermostat to a shorter length? If the water that came out was hot enough turning it up wont help