Immersion Problem

kao123

Hi all,
I am hoping some on here might be able to advice on this problem.
I recently had my immersion tank swapped out due to a plumber making a mess of replacing the thermostat and kinking the tank, so much for it being a 20 minute job!!
Anyway I now have a newer slimmer insulated tank with a new thermostat installed, the thermostat is rated for the tank as well.
This is controlled by a timer which has a boost as well and now the problem is that the water is not heating properly.
I have had the timer and the thermostat both checked by an electrician and they are wired correctly and getting the right amount of power.
If I turn the immersion on for an hour or 3 hours I get the same amount of hot water which isn't very much ( compared to before all this happened).
If I turn the temperature up on the thermostat I get pretty much the same result.

So before I go spending more money I thought I'd ask here to see if anyone can think of anything else to check?

Thanks in advance.

DoneDL

Change the thermostat as it might be misreading. I am assuming that the immersion is the right length.

kao123

DoneDL wrote: »

Change the thermostat as it might be misreading. I am assuming that the immersion is the right length.

Hi DoneDL, the plumber claims he put in a 36 inch in order to fix the problem but obviously it hasn't fixed the problem.

Thanks.

DoneDL

Ok if you turn the stat up or down can you feel a click when the stat recognises the temperature. They are usually quite robust and tend to fail rather than misread but it`s worth replacing as worst scenario you have a spare stat. As has said on other posts there is a lot of power feeding a immersion so make sure the power is off.

kao123

There is actually a click when I change it above 50 degrees, there is a wee spark as well as a click!
I was hoping not to have to change the thermostat as this is what kicked all this off in the first place.

thanks.

DoneDL

There shouldn`t be a spark, what`s the thermostat set at as it should be set at 65 C and you will not need to change the immersion just the thermostat.

kao123

I did think the spark shouldn't be happening alright, but I have tried the thermostat at 55 and 65 degrees but the lack of hot water still rears it's head.

The spark is just under the little dial (blue plastic) to change the temperature.

I should have mentioned before that it's a 117 litre tank (long and thin) and the thermostat is 36 inches so it should heat loads of water if it is working right.

I suppose changing the thermostat is my next port of call.

DoneDL

kao123, the thermostat is a removable part of the immersion.

meercat

any chance of a picture of the connections around the thermostat
you will get a small spark when the thermostat switches on and off
this is normal

meercat

is there any chance water is coming out of the cylinder and thus not allowing the water to heat up fully(turn off the hot water stopcock and turn immersion on for 3 hours or so,then turn stopcock on and check water temperature)

kao123

meercat wrote: »

any chance of a picture of the connections around the thermostat
you will get a small spark when the thermostat switches on and off
this is normal

Here is a picture of the Thermostat (it's white not blue the old one was blue)

And I don't think there is any water leaking from the cylinder, how would I know if this is happening? do you mean a leak somewhere or taps dripping?

thanks

Pete67

Looks like a dual element immersion heater - is there a bath/sink switch close by and is it set to bath? Also possible that the switch/timer is wired incorrectly and/or the bath element (the longer one that goes close to the bottom of the cylinder) is open circuited. The sink element will only heat a small portion of water near the top of the cylinder. The thermostat should be set at 60-65C to prevent bacterial growth in the stored hot water (Legionella). 50C is too low.

From the pic, looks like the black wire is the 'bath' element - you should get 230V at that terminal when the timer is on (assuming bath/sink switch is at bath) if so, and the cylinder is not heating, then you need to check for current draw with a clamp meter to see what is happening. If no amps, then either a faulty thermostat, neutral fault, or burnt out element. Usual warning, only poke around mains electrical terminals if you know exactly what you are doing.

Anyway, from your description it sounds like only the 'sink' element is working, you just need to figure out why. Hope this helps.

meercat

Pete67 wrote: »

Looks like a dual element immersion heater - is there a bath/sink switch close by and is it set to bath? Also possible that the switch/timer is wired incorrectly and/or the bath element (the longer one that goes close to the bottom of the cylinder) is open circuited. The sink element will only heat a small portion of water near the top of the cylinder. The thermostat should be set at 60-65C to prevent bacterial growth in the stored hot water (Legionella). 50C is too low.

From the pic, looks like the black wire is the 'bath' element - you should get 230V at that terminal when the timer is on (assuming bath/sink switch is at bath) if so, and the cylinder is not heating, then you need to check for current draw with a clamp meter to see what is happening. If no amps, then either a faulty thermostat, neutral fault, or burnt out element. Usual warning, only poke around mains electrical terminals if you know exactly what you are doing.

Anyway, from your description it sounds like only the 'sink' element is working, you just need to figure out why. Hope this helps.

Have you pressed that reset button
Looks far out to me
Use point from pencil
Listen for a click
Agree with pete about incorrect wiring then
Remove immersion switch and check it is wired right
Blue Neutral
Black sink
Brown bath

Make sure to turn power off

On the water point
Yes a leak somewhere else or dripping taps wipe prevent water staying in the tank long enough to heat up
Check tank in attic to see if there is a continuous flow of water into the tank
If there is then possibly water is flowing through your cylinder and not allowing immersion to heat the water

kao123

meercat wrote: »

Have you pressed that reset button
Looks far out to me
Use point from pencil
Listen for a click
Agree with pete about incorrect wiring then
Remove immersion switch and check it is wired right
Blue Neutral
Black sink
Brown bath

Make sure to turn power off

On the water point
Yes a leak somewhere else or dripping taps wipe prevent water staying in the tank long enough to heat up
Check tank in attic to see if there is a continuous flow of water into the tank
If there is then possibly water is flowing through your cylinder and not allowing immersion to heat the water

Thanks for the reply, the reset switch does not seem to want to press no matter how I try so I am thinking that the thermostat itself might be faulty, (I'll try again tonight) I checked the wiring going back to the timer and yes it is correctly wired.
Sink is going to sink and bath to bath, I have had it checked by an electrician and he verified that the wiring is correct, he checked the power to the thermostat and confirmed that it is all correct.

Despite him checking it all and confirming that it's all correct the problem still persists.

There is an overflow into the water tank in the attic and it doesn't seem to be flowing so I don't think I have a leak there but I will double check tonight as at this stage I'll check anything.

I left the immersion on last night (on Bath) for 3 hours and the water temp still did not get very hot.

@Pete67 the thermostat is normally at 65 it was only at 50 in the photo as I was changing it to double check the click when it's adjusted.

Thanks

Pete67

Just out of curiosity, what happens when the bath/sink switch is left in the 'sink' position?

kao123

Pete67 wrote: »

Just out of curiosity, what happens when the bath/sink switch is left in the 'sink' position?

If it's left on sink then the hot water level is pretty much the same as when it's switched to bath, and that's the problem ...

meercat

any chance of a pic of the connections inside the immersion switch

is the immersion cable continuous or have you joined to the existing cable
(there is a new color code now so joining like with like colors is not right)

check the reset button again
if it has popped out then it should push back in (use pen point)

again
turn power off for safety

kao123

OK then, I might have found the problem, after all your advice and pointers I knocked off the power to the Immersion and took it apart and when I removed the actual thermostat and it's actually only 11 inches 12 including the plastic bit so - thanks to DoneDL for posting the pictures of them.

I've attached a photo of it, so now it looks like I'm going to have to call the guy who said he put in a 36 inch immersion into the tank to come and fit a bigger thermostat, as I assume an 18" thermostat should be fitted to a 36" immersion rather than this 11" one.

I suppose the question remains did he actually put in a 36" Immersion heater at all :mad: ?

Jedstaff

check there is not a circulating pump off another heat source running.like on a back boiler/oil boiler.A long shot but could be on and cooling the domestic water .

kao123

Jedstaff wrote: »

check there is not a circulating pump off another heat source running.like on a back boiler/oil boiler.A long shot but could be on and cooling the domestic water .

As far as I know there is no other heat source in the house, no back boiler, only the Gas boiler for the heating and this will also heat the water but we haven't used it yet this year cause the weather has been so good :rolleyes:

Nothing else here was changed only the tank, immersion heater and the thermostat, i am starting to think that the plumber did not put in a new immersion heater he simply used the old one from the smaller tank hence my lack of hot water problem.

Do you think I need a bigger thermostat and or immersion heater for the cylinder ?
My knowledge is limited in these things but I am assuming an 11" thermostat is only going to heat the water in the top 1/3 of the tank, I might have to get another plumber to take out the Immersion heater to check how big it actually is and possibly replace it... more money !

Thanks

Pete67

The actual length of the thermostat is not that important, the water in the cylinder heats up fairly uniformly due to convection currents.

The lenght of the immersion heater is important, as it cannot heat water below the bottom of the longest (bath) element. Therefore the element should go to within a couple of inches of the bottom of the tank.

kao123

Pete67 wrote: »

The actual length of the thermostat is not that important, the water in the cylinder heats up fairly uniformly due to convection currents.

The lenght of the immersion heater is important, as it cannot heat water below the bottom of the longest (bath) element. Therefore the element should go to within a couple of inches of the bottom of the tank.

Thanks for that but I suppose the only way to verify this is to take it out and look ? which is not something I am comfortable doing, I know my DIY limits.

DoneDL

As you have already removed the thermostat find something slim enough to go into the slot, that lenght will tell you what length the immersion is. Then replace the shorter thermostat with one that suits the immersion.

kao123

DoneDL wrote: »

As you have already removed the thermostat find something slim enough to go into the slot, that lenght will tell you what length the immersion is. Then replace the shorter thermostat with one that suits the immersion.

Yeah I did that with a piece of curtain wire when I had the thermostat out and its the same length as the thermostat.... Am running out of ideas at this stage.

meercat

kao123 wrote: »

DoneDL wrote: »

As you have already removed the thermostat find something slim enough to go into the slot, that lenght will tell you what length the immersion is. Then replace the shorter thermostat with one that suits the immersion.

Yeah I did that with a piece of curtain wire when I had the thermostat out and its the same length as the thermostat.... Am running out of ideas at this stage.

is the immersion cable continuous or have you joined to the existing cable
(there is a new color code now so joining like with like colors is not right)

kao123

meercat wrote: »

is the immersion cable continuous or have you joined to the existing cable
(there is a new color code now so joining like with like colors is not right)

The cable was joined by the plumber, and then the electrician I had double checked it so that is all in order, the plumber who did all this in the first place finally called me back and is coming to swap out the Immersion Heater.
He said that the immersion will never heat the tank fully anyway which I find hard to believe as before all this happened the old tank would heat fully providing more than enough hot water for a bath.

Hopefully a new Immersion Heater will put an end to all this.

Thanks

meercat

at a guess
its not wired properly
what are the colored wires connected into the switch
a pic would be great
the switch connections should be
blue neutral
black sink
brown bath
assuming he joined the cables like with like

kao123

I have taken some pctures as best I can.
The dirty white cable is to the switch and the cleaner one is to the immersion heater.

I cannot for the life of me get the cover off the timer switch, I don't want to break it.

bear in mind that these wires were done by the plumber and verified by the electrician.... I just took the ball of tape off it !

kao123

OK got the cover off the timer and it's still intact ... phew! and the connections are as follows ...

Timer Brown wire (no.5 Off peak Load) -- Black Immersion connection -- Bath on the Immersion.
Timer Black wire (no.4 Boost Load) -- Brown Immersion connection -- Sink on the Immersion.

So it would appear that everything is correctly connected even though if I was to do like with like for the colours then in this case it would be wrong I think ??

Pete67

Bad practice to join a cable like that really, most new elements come with enough cable to be connected directly to the switch. If not, a new length of 4 x 2.5mm sq should be used.

Make sure the new element is long enough, they are available in a variety of lengths to suit all the standard cylinder sizes. For example HeatMerchants have 11, 24, 27 and 36 inch immersion elements.

Can you stick up a pic of the timer front panel, and wiring, and also the wiring of the on/off - sink/bath switch if there is one?

meercat

the key to this problem may be the connections in the switch itself(not the timer)
i would love to see the connections there
if the switch has the older type color code then these connections are wrong
i cant be sure without seeing though

if this is the case then the cables should be joined as so

(the original cable colors) connected { the new cable colors}
( blue ) connected { black}
( black ) connected { brown}
( brown ) connected { blue}

i also wouldnt be too happy with a connector block covered in insulation tape
you need a fire proof joint box