Immersion Heater - Water Not That Hot - Some Advice Please

Andrew_P

Hi All,

Just after some advise as we moved into our new flat a couple of weeks ago, however we have been having problems with only getting luke warm hot water despite the immersion being on for a couple of hours.

We had called an electrician out to check over our electrics as they hadnt been checked in around 8 years, and he also changed the thermostat for us and turned temperature up to 80 degrees I think he said. He checked the other heater at the bottom of the tank (I think this is if we want enough water to do say washing up etc as it only heats the bottom half of the tank) and pushed the reset switch as this had popped out apparently).

The heater has now been on 2 hours as turned it on at about 5.45 and yet water is only luke warm still and i am stumped as to what the problem is. The tank is getting really hot so dont think its the heating element that's the issue.

The other thing we needed to get was an insulation jacket as it does not have one at the moment however don't want to get one put on it yet if the tank needs to be drained if a new heating element is needed for example. Its an old copper tank with some dents in it as well so does not look like it has been looked after by the previous owners, and could even be the existing tank that was put it when the flats were build in 1990.

So far since moving in we have just spent out to have jobs done!. I dont think I am going to have much choice other than to call a plumber out to take a look .

Anyone got any ideas on what could be wrong? Any help or suggestions would be greatly appreciated.

Thanks

Andrew

Ectophile

If it's got no insulation on it at all, then the tank's going to be losing heat at a huge rate. That could be why the tank feels hot but the water doesn't. That said, I don't think it's possible for the tank to be hotter than the water inside it.

Also bear in mind that hot water rises. So an element at the bottom of the tank will be heating the whole tank, as all the water it heats will rise to the top, pushing the cold water down to the bottom. An element at the top will only heat the top of the tank. If the system is plumbed correctly, hot water should be drawn off from the top of the tank, to be replaced by cold water going in at the bottom.

A well lagged tank will stay hot all day if the water isn't used. The modern ones are supplied covered with thick foam. For added heat holding, stick some foam lagging on the pipes going in and out of the tank.

Andrew_P

Ectophile wrote: »

If it's got no insulation on it at all, then the tank's going to be losing heat at a huge rate. That could be why the tank feels hot but the water doesn't. That said, I don't think it's possible for the tank to be hotter than the water inside it.

Also bear in mind that hot water rises. So an element at the bottom of the tank will be heating the whole tank, as all the water it heats will rise to the top, pushing the cold water down to the bottom. An element at the top will only heat the top of the tank. If the system is plumbed correctly, hot water should be drawn off from the top of the tank, to be replaced by cold water going in at the bottom.

A well lagged tank will stay hot all day if the water isn't used. The modern ones are supplied covered with thick foam. For added heat holding, stick some foam lagging on the pipes going in and out of the tank.

Thank you for your advice Ectophile

I am not sure whether the element is at the top or the bottom, is there an easy way to tell?

What would you say the best thing is for me to do next? Shall I try and get a jacket and see whether that makes any difference? The modern tanks look really good, but I am guessing for someone to remove the current tank and replace it with a new one could be talking around £500? Would you just replace it and be done with it? Just dont want to keep have issues with it if its because its old and packing up.

Thanks once again

Andrew

wealdroam

Andrew_P wrote: »

I am not sure whether the element is at the top or the bottom, is there an easy way to tell?

Are you saying you can't tell which element is doing the heating? If so, that's easy.

If the lower part of the tank is hot, then it is the lower element doing the heating.

If only the top part of the tank is hot, maybe just above the higher element, then the top heater is on.

Remember that immersion heaters in the top of the tank may well go down the tank some way.

googler

Andrew_P wrote: »

The tank is getting really hot so dont think its the heating element that's the issue.

So are you saying the tank is getting really hot, but you're only getting luke warm water from your hot taps?

How many hot taps do you have? Do you have all mixer taps?

When you run any hot or mixer tap, can you feel the pipes that lead to the taps? Are they really hot?

konark

and he also changed the thermostat for us and turned temperature up to 80 degrees

That's verry hot!

I think this is if we want enough water to do say washing up etc as it only heats the bottom half of the tank)

Good luck with that!

You've got 2 immersion heaters, one at the top for enough to wash-up etc and one at the bottom which is used with the top one for baths, showers etc. From what you've said it seems the top one is broken and the bottom one is struggling to heat all the water up alone. I may be wrong!

Ruski

Two elements is an economy7 setup - top element is only for 'topping up' if you run out of hot water and will only heat about 1/3 of the cylinder.

Overnight the bottom element should heat the whole cylinder at E7 rates.

If this is not happening then check that your timer is working correctly/set to the right mode.

HTH

Russ

Le_Kirk

It is easy to tell. Look at the tank, is there one round plastic thing sticking out the top of the tank or are there two round plastic things sticking out the side of the tank, one near the top and one near the bottom? Do you have two switches? It is normal, especially for economy 7, to have one immersion heater mounted in the top of the tank which contains two elements, one short and one long. The short one is used for top-up and the long one is used for heating up the whole tankful. Economy 7 uses the long element and is switched on by the economy 7 system. This cannot be varied by the user as it is set at your meter. Look to see what you have and report back

Andrew_P

Le_Kirk wrote: »

It is easy to tell. Look at the tank, is there one round plastic thing sticking out the top of the tank or are there two round plastic things sticking out the side of the tank, one near the top and one near the bottom? Do you have two switches? It is normal, especially for economy 7, to have one immersion heater mounted in the top of the tank which contains two elements, one short and one long. The short one is used for top-up and the long one is used for heating up the whole tankful. Economy 7 uses the long element and is switched on by the economy 7 system. This cannot be varied by the user as it is set at your meter. Look to see what you have and report back

Thank you for help Le_Kirk

We have 2 switches and there are 2 round plastic things one near the top and one near the bottom. We actually have Economy 10 with our energy supplier which is E.ON.

Le_Kirk

You then need to determine if your Economy 10 is working, that your lower immersion is switched and find out from your supplier what time it switches.

J_B

Andrew_P wrote: »

We have 2 switches and there are 2 round plastic things one near the top and one near the bottom. We actually have Economy 10 with our energy supplier which is E.ON.

OK - my take on it ...

The bottom one should be on during all of the economy10 period giving you a full tank of water heated at the cheap rate (*)

The top one is to give a boost to heat just a smaller amount of water if you run out.

Remember that a) heat rises and b) the tank empties from the top, not bottom

*= it's then up to you to keep the 'cheap' hot water warm by insulating the tank.