Immersion only heats part of the hot water cylinder?

kodak

Hi all,

Bit of advise needed here. The immersion is only heating part of the hot water cylinder. Its around 230 litres i'd say and is factory insulated.
The immersion is on a timer to come in the morning for 1.5 hours (night rate elec).
However this wouldn't even get a bath out of it.
The switch is on bath and thermostat is set to 65oc.
The element is 36 inches long and is rated at 2-3kw.

Is it time to get a new immersion or could the thermostat be wired wrong ? The brown live wire goes into the thermostat from the sink output and the black (bath) goes into an element.
I put it on sink and left it on for an hour and only got a tiny amount of hot water.

Thanks for any input!

Martron

is your immersion tank full of water?

kodak

How would i check that?

demanufactured

Obviously its full if theres water coming out of the hot taps , try setting it to sink and see what happens , i have seen it in houses where the switch was wired wrong and sink meant bath and bath meant sink.

kodak

Yeah i tried the sink switch and it gave less water again!

There is a slight problem in the heating with the pressure release vavle beside the cylinder was leaking so its turned off and doesn't heat the cylinder. (not using heating much yet) But this shouldn't effect the heating of water by the immersion or would it?

Its a sealed system btw.

danjo-xx

The immersion is on a timer to come in the morning for 1.5 hours (night rate elec).
However this wouldn't even get a bath out of it.

I wouldn't expect enuf water for a bath when the switch is only set to sink, maybe your expecting too much hot water from the sink setting.

kodak

Sorry if i'm a little unclear. The immersion is set to bath for the 1.5 hours and would heat only enough water to reach 90mm high of hot water in the bath.

I tried the sink setting to eliminate the wiring mix up.

ballsymchugh

is 1.5 hours long enough??

Martron

demanufactured wrote: »

Obviously its full if theres water coming out of the hot taps , try setting it to sink and see what happens , i have seen it in houses where the switch was wired wrong and sink meant bath and bath meant sink.

well i ment that if it was only half fillin then when the hot water was out of the tank and was refilling with the cold. and would always be a constant flow of water.

was thinking the tank was oonly half filling for some reason

kodak

ballsymchugh wrote: »

is 1.5 hours long enough??

I could leave it on for 3 hours and get the same amount! Something is funny...

RichieO

kodak wrote: »

I could leave it on for 3 hours and get the same amount! Something is funny...

It really sounds like a thermostat problem if the temperature is the same after 3 hours, does it heat more water or the same amount if it's on longer? When there is a dual rating IE 2kw - 3kw the 2 is for sink and 3 for the bath.. At 1.5 hours @ 3Kw it should be plenty hot enough for a bath. Or you could turn it up to 75c this should be too hot, if there is no difference it has to be the stat...

Go here for info... http://diydata.com/problem/immersion/immersion_adjustment.php

Pete67

a 3kW immersion heater will take 4.5 hours to heat a 230 litre cylinder from 15C to 65C.

doubtfir3

I would check for an airlock.

When I moved into my house I would turn on the immersion and then go to fill the bath.. water would come out for a while and then it would slow to almost a trickle.. even with the immersion on bath setting I would have to half fill bath, and then leave immersion on again for another 30-40 mins before filling remainder of bath.

Plumber came while my gf was home and fixed it in a few mins, said the airlock was causing problem.

kodak

RichieO wrote: »

It really sounds like a thermostat problem if the temperature is the same after 3 hours, does it heat more water or the same amount if it's on longer? When there is a dual rating IE 2kw - 3kw the 2 is for sink and 3 for the bath.. At 1.5 hours @ 3Kw it should be plenty hot enough for a bath. Or you could turn it up to 75c this should be too hot, if there is no difference it has to be the stat...

Go here for info... http://diydata.com/problem/immersion/immersion_adjustment.php

I think you could be right. The water is very very hot but not alot of it!
Would this trip out the safety thermostat and stop heating the water?

Can you buy a replacement thermostat and if so where? It would be a lot easier than the whole immersion element.
I checked to see if it needed to be reset but its ok.

Thanks for everyones help, one step closer to a full bath!

Pete67

Normally the thermostat is built into the element assembly and switches both the sink and bath elements. It may be switching the neutral, with two separate live supplies from the sink/bath switch to the corresponding part of the element.

The sink portion of the element only heats the top section of the cylinder no matter how long you leave it switched on. To heat the whole cylinder the bath element must be working. Sorry to say it but from your description it does sound like either there is a fault in the wiring, or the element itself is faulty.

If you are competent and comfortable working with live electrical systems, remove the cover of the element, and check for 230V at the appropriate heater terminals when switching from sink to bath. That will tell you if the wiring and immersion switch is ok. Check also the current draw with a clamp on ammeter if possible, this will tell you if the element is OK. Check the insulation resistance of the element with a megger. The combination of this information should tell you what is going on. If this does not make sense then it is time to get an electrician to take a look.

JamesM

If the element is 36" long, then the heat should be approx 36" down the side of the cylinder - it should be as simple as that. Before you fill the bath, see how far the heat goes down the side of the cylinder - it won't be much lower than 36" from the top. As you fill the bath the you will feel the cylinder getting colder from the bottom up. When the cold reaches the top, the hot water is gone. It should be as simple as that
Jim.

(Edit) If the cylinder is factory insulated as you say, there may be a problem checking the temperature down the side of the cylinder.

slavetothegrind

What ever happened to bottle heaters?

See them much anymore James? Pete?

cast_iron

I agree with Pete67. On initial analysis, I can't see how a faulty thermostat will result in a small amount of hot water. Faulty thermostat = temperature problem. You have a capacity issue.

For a start, 1.5 hours is not half long enough to heat a tank that size.
It does sound like the sink/bath might be mixed up.

Pete's step would be the first things to check.

kodak

Pete67 wrote: »

Sorry to say it but from your description it does sound like either there is a fault in the wiring, or the element itself is faulty.

.

Thanks Pete67,

Yeah i think there is something up with the whole lot, sure the best bet is probably to replace the whole thing.

Now off to find the other thread about replacing one!

Luckily its just a gasket and a new enough tank.

Any recommendations on the lenght of the new one? 36 inchs seems very long or does it matter?

Thanks again everyone

kodak

cast_iron wrote: »

I agree with Pete67. On initial analysis, I can't see how a faulty thermostat will result in a small amount of hot water. Faulty thermostat = temperature problem. You have a capacity issue.

For a start, 1.5 hours is not half long enough to heat a tank that size.
It does sound like the sink/bath might be mixed up.

Pete's step would be the first things to check.

I know 1.5 hours isn't long enough but it should give me more water than i'm getting! i only have on that much as it doesn't make a difference.

The wiring is as follows;

Sink(brown) goes thru thermostat and onto a transfer cable

Bath (black) goes directly to an element

Blue goes to neutral

Earth goes to Earth

TJJP

--- Nonsense post removed - Pete67 has it sorted.

danjo-xx

ballsymchugh wrote: »

is 1.5 hours long enough??

thats plenty for a single bath allright, even an hour would do.

The timer unit could be faulty !!

kodak

danjo-xx wrote: »

thats plenty for a single bath allright, even an hour would do.

The timer unit could be faulty !!

Doubtfull enough as it's only new and still a problem if i put in on constant!

Pete67

I would not go to the trouble of replacing the element until I was certain it was faulty. There could be a simple wiring error. Can you post up a picture of the wiring at the back of the immersion switch and under the cover of the immersion element?

If you do replace the element, you should use the longest element you can fit into the cylinder, the element can only heat water at its level and above.

kodak

Pete67 wrote: »

I would not go to the trouble of replacing the element until I was certain it was faulty. There could be a simple wiring error. Can you post up a picture of the wiring at the back of the immersion switch and under the cover of the immersion element?

If you do replace the element, you should use the longest element you can fit into the cylinder, the element can only heat water at its level and above.

Here the pic's!

It appears bath is wired to the thermostat!

Pete67

OK, the wiring at the switch looks fine, but the immersion wiring does not look correct to me. Try the following:

Remove the brown wire from the thermostat and replace with the blue wire.
Move the black wire to the N2 terminal
Move the brown wire to the N1 terminal

Make sure the power is off first at the switch and at the Consumer unit.

The way it is currently wired only one element can operate, the one connected to the N2 terminal. That would be the sink element. As the sink terminal at the switch is connected to the black wire this is where the black should go.

You will end up with the thermostat in the neutral and switching both elements. The two lives will go one each to the other end of the elements. The other option is to rewire the switch so that the sink/bath switch is in the neutral, bring two neutrals to the N1 and N2 terminals, and the live straight to the thermostat. Hope that makes sense.


Pete.

cast_iron

kodak wrote: »

i only have on that much as it doesn't make a difference.

Which makes perfect sense. You can put it on for 24 hours solid, and the sink element will still only heat the same amount of water. And 1.5 hours would be plenty to heat a sink section of a tank, but not near enough for bath (effectively the entire tank).

Pete says it right again. It appears the N1 and N2 are actually the sink and bath supply terminals, leaving the P1 as the common through the stat.
It's the only logical conclusion without a wiring diagram for the element.

Oh, and who the hell has a bath first thing in the morning?:pac:

kodak

Pete67 wrote: »

OK, the wiring at the switch looks fine, but the immersion wiring does not look correct to me. Try the following:

Remove the brown wire from the thermostat and replace with the blue wire.
Move the black wire to the N2 terminal
Move the brown wire to the N1 terminal

Make sure the power is off first at the switch and at the Consumer unit.

The way it is currently wired only one element can operate, the one connected to the N2 terminal. That would be the sink element. As the sink terminal at the switch is connected to the black wire this is where the black should go.

You will end up with the thermostat in the neutral and switching both elements. The two lives will go one each to the other end of the elements. The other option is to rewire the switch so that the sink/bath switch is in the neutral, bring two neutrals to the N1 and N2 terminals, and the live straight to the thermostat. Hope that makes sense.


Pete.

Thanks Pete, It makes perfect sense alright!

I have changed that and i only suspose N1 and N2 can be mixed up now but if i flick the bath/sink switch it should tell me so.

Will let every one now!

Thanks again

kodak

A quick update,

The immersion was on for its 1.5 hours this morning (6.30-8am)

Some hot water was used

Then i changed the wiring as Pete67 said

Pressed boost for an hour at 3pm

Full bath at 4pm!

The water was hot but not boiling (didn't mix any cold with it) but i guess that is due to whole tank heating now.

I will increase the timer in the moring as it's the night meter rate and boost it on and off during the day for a v short period

Thanks everyone for their help, it is really appreciated!

Now where's that person who wired it!!!

Pete67

Glad to hear it worked out. You can set the timer to give you 4 hours water heating on the cheaper night rate (say 3 to 7 am) , you will only use what is needed as once the cylinder is hot the thermostat switches it off anyway. The cylinder is well lagged an will hold its heat throughout the day. This would be cheaper than using boost during the day when the electricity costs twice as much.

Meant to say make sure all connections are tight, no loose strands of wire sticking out and watch out for broken strands not connected to the terminals. 3kW immmersion draws a fair current and any high resistance cable terminations will get very hot.

kodak

Pete67 wrote: »

Glad to hear it worked out. You can set the timer to give you 4 hours water heating on the cheaper night rate (say 3 to 7 am) , you will only use what is needed as once the cylinder is hot the thermostat switches it off anyway. The cylinder is well lagged an will hold its heat throughout the day. This would be cheaper than using boost during the day when the electricity costs twice as much.

Meant to say make sure all connections are tight, no loose strands of wire sticking out and watch out for broken strands not connected to the terminals. 3kW immmersion draws a fair current and any high resistance cable terminations will get very hot.

Yeah i'll have to see experiment with the timer as 4 hours a day would be €60 for the 2 months. It will probably be the best as there isn't much heat loss from the tank and i've insulated as much of the hot water pipe work as i can!!

Made sure all wires were in good condition and tight.