Haetrea Sadia Megaflow with electric elements not producing enough hot water

[jogey]

Hello all,

I am a very ignorant diyer but am posting here out of desperation as the professionals don't seem to be fixing my problem.

I have a haetre sadia megaflo with 210 litres capacity which came with a new build 2 bedroom flat I bought and moved into 3 years ago. My flat is all electric. No gas. It has two electrical elements on it for heating. The lower one is meant to be used all the time and the upper one is a booster to be used only if you want extra quick worker, but in general not used. There is a timeguard timeswitch attached to the lower element. It was fine until about 6 months ago when it stopped working on the lower element but the upper element continued to function. The thermostat and element were replaced and it started working again. However it only heats up about 70% of the volume of one bath ie a little under the overflow holes of the bath and then it runs cold. It doesn't matter how long you heat it or even if you use both elements at one time it heats up less than one bath full. I have a standard bath 1700 by 700 and Haetre Sadia have told me that the true volume of my boiler is 172 litres and a standardbath (filled to below the overflow holes) is about 60 litres. It should be giving me 2 bathfulls and is only giving me one..

Haetre sadia have told me that the lower one alone should heat the whole tank in three hours 19 minutes and the upper one should heat up

100 litres (the top half) in an hour. Both together should heat the whole tank in 1 hour forty minutes. This morning I heated it up with both elements for four hours and it still ran cold before fully filling up one bath.

As I have recently replaced the element and thermostat on the main lower element (the plumber showed me the old element and it had white scale on it) what could be causing this problem?

I am tearing my hair out! Any advice gratefully received

Jonathan

[Owain]

overnight on cheap rate electricity

hot water during the day

[del: quick worker, but in general not used.]

to run the lower element on cheap rate electricity.

- Check that electricity is actually reaching the immersion elements for the expected length of time using a test lamp or multimeter and taking appropriate care with live terminals.

- There may well be separate MCBs for upper and lower elements - check that neither have tripped.

- There may be fuses in the outlet plates to the heaters if Fused Connection Units have been used instead of flex outlets or DP Switches.

- The overheat cutout may have tripped on the element and need resetting. This is probably a red button under the element terminal cover.

Owain

[Harry Bloomfield]

jogey formulated on Saturday :

Is it possible that the actual temperature set on the thermostat is much lower than it was originally set? A lower temperature would mean less cold is used and much more volume of hot water.

[jogey]

Hi Guys

And thanks for the suggestions. But I don't think that the thermostat cutout could be operating because the water is still heating up half the tank. If the thermo cutout was operating it would switch the heating off and stop it heating up altogether. and I don't think the temperature can be being read too low because the actual hot water is very hot this morning (just using the lower element)

Any other suggestions gratefully received

Jonathan

[Lurch]

On 20 May 2007 00:41:48 -0700, jogey mused:

But you haven't checked it though? If you can't be bothered to just have a look then I'm not sure there's any point anyone offering further suggestions.

If your thermostat on the lower immersion heater is set lower theN before then, because of the temperature differences in the tank, it will give the symptons described.

[Heliotrope Smith]

Sounds to me that the element could have been put in upside down.

Not so daft as as this may sound.

As far as I remember the bottom element is about 500mm long with a 90deg bend in it. The element should be fitted with the bend pointing to the bottom of the cylinder, thus heating the water from the bottom rather about

1/3 the way up. These elements do not screw in like the ordinary immersion types that have a large screw. There is no screw on these and are held in place with a captive nut that needs the use of a special tool. If the problem only started when the element was replaced then this could be worth investigation.

[jogey]

Hi Everyone,

Thanks for your continued input

1) The temperature is not set lower tan orginally. It is set at 4 which is what Haetrae Sadia recommend 2) I had a chat today with Haetre Sadia's technical support helpline and they said they cannot understand how this could happen, because if the lower element is working at all (which it definitely is) it should be heating the whole tank not half. The lower element is working so they themselves do not know how this could happen 3) I told them the idea suggested here that the element may have been replaced upside down and they said this could explain it. They told me to check this by checking if the reset buttons were on the right of the thermostat dail and the temperature settings at the top. I have just done this and they are in the correct position so unfortunately that can't be the right explanation 4) I asked them if limescale in the tank or pipes or whatever could cause this and they said no because limescale could not cause such a large loss of water heating volume 5) Finally they recommended another plumber from their list who is mercifully coming to look at it tomorrow morning. I will ask him what the problem is (if he manages to solve it) and will post here what he says

Jonathan