Electric property, only top element working not bottom (water tank) - is there any issue with that?

me1000uk

Hi there,
I'm moving into a new place, and have been sorting out a few things (as per a couple of other threads). 
One thing that seems the case during the refurb is the hot water is barely warm so there's an issue with the bottom element. 

I know I read somewhere that water needs to be heated to 60 deg for safety but is that just initially or all the time? Can I just depend on a boost for an hour or two a day using the top element, or does the whole tank need to be hot. Any other things I could check? maybe the thermostat isn't up or something if it has a thermostat. I assume it's a plumber job rather than electrician? Just worried about water safety really and functionality if top elements are designed for less usage.

Small Notes -
1) Gas isn't an option. It is an all electric property with an 'economy 7' style insulated water tank with a bottom and top switch, and a boost button in the kitchen.
 2) I know what you're thinking in that the daytime boost will be expensive, but I'm on something called THTC in Scotland, which essentially means my electricity has an expensive rate (all the non-heating electrics are for that meter), and a heating rate which is 24/7 for heaters and shower/water with a dedicated meter (bottom immersion and storage heaters have a radio controlled aspect that controls the times they come on and are also on the heating rate/meter). Econ 7 has already been analysed by me and it won't help me. The cost of daytime immersion heater is identical to overnight use for me. For those used to Economy 7, this is something completely different and I myself had never heard of it until recently. The discussion of switching to Economy 7 for various reasons isn't related to my query in this thread but if you have questions on this tariff you're welcome to contact me as I've been obsessing over this a while

Thanks for your help.

Jeepers_Creepers

Hmm, never thought of the Legionnaires issue due to the bottom element not working, but it's a fair point - the lower half of that tank will never get to 60oC+ (the hot water will largely remain floating on top of the cold).

You'll also struggle to run a bath, if that's an issue for you. You may even find that a good shower is pushing it.

The top element is usually just for a quick heat - if you come home to a cold tank and need some hand and washing-up water pdq.

You certainly need a plumber for the water side of the job, and you'd kind of hope they'd also be competent enough to tackle the wiring too, but most plumbers simply won't so many will know - and work regularly with - a sparky. I'd ask for recommendations on your local Facebook page, and see how the respondents would tackle this. I think you should be able to get a pretty close estimate figure for such a job too.

southcoastrgi

Plumbers job you wouldn't get a sparks in for that 

me1000uk

Thanks for the responses. I will see whether plumbers can sort it out if necessary.
 Is there anything conclusive on safety or durability? Like can the top element in no way heat the whole tank eventually, even if you keep it boosted for 2 or 3 hours?

Usage will only be for washing up or washing hands. Showers are electric which is what we use. Soaking in a tub isn't part of our routine so no baths needed.

Jeepers_Creepers

The top element won't heat the whole tank - I can't see any way it will. However, the water in the tank will always be replenished, and the top part - which you use - will/should always reach 60-odd oC before it comes out to you, so you should be safe...

However, it doesn't sound ideal. Imagine coming back from a few days break; any build-up of bugs in the tank will only have their tops singed.  

nofoollikeold

1. Modern immersion heaters have two thermostats:
1a. The ordinary one, which shuts off once the water reaches the set temperature.  It then turns itself on again when the water cools.
1b. An "overheat" thermostat.  This shuts off when the water reaches a high temperature (around 85 degrees), but does not turn itself on again when the water cools.  The user has to manually press a button, sometimes using a thin rod, to reset it.
2. It is possible that your lower thermostat has, and has triggered, its overheat thermostat.  If so, and it hasn't been reset, then the immersion will not function.
3. Unless you are confident and know how to isolate electrical supplies and work safely, you MUST ignore the following:
3a. Turn both immersion heaters off.  This is best done by shutting off the supply fully at the consumer unit(s) - so only during daylight.
3b. Remove the cover of the lower one, and see if it has an overheat thermostat.
3c. If it has, press the reset button in.  This may be a surface button, or it may require a thin rod, preferably plastic, inserted through a small hole.
3d. If you feel a "click" then the overheat thermostat had tripped, and you have now reset it.
3e. Put the cover back on.
3f. Turn the power back on.
4. There are ways of testing the immersion element and the thermostat, but these really require a multi-meter and the expertise to use it.

me1000uk

nofoollikeold said:

1. Modern immersion heaters have two thermostats:
1a. The ordinary one, which shuts off once the water reaches the set temperature.  It then turns itself on again when the water cools.
1b. An "overheat" thermostat.  This shuts off when the water reaches a high temperature (around 85 degrees), but does not turn itself on again when the water cools.  The user has to manually press a button, sometimes using a thin rod, to reset it.
2. It is possible that your lower thermostat has, and has triggered, its overheat thermostat.  If so, and it hasn't been reset, then the immersion will not function.
3. Unless you are confident and know how to isolate electrical supplies and work safely, you MUST ignore the following:
3a. Turn both immersion heaters off.  This is best done by shutting off the supply fully at the consumer unit(s) - so only during daylight.
3b. Remove the cover of the lower one, and see if it has an overheat thermostat.
3c. If it has, press the reset button in.  This may be a surface button, or it may require a thin rod, preferably plastic, inserted through a small hole.
3d. If you feel a "click" then the overheat thermostat had tripped, and you have now reset it.
3e. Put the cover back on.
3f. Turn the power back on.
4. There are ways of testing the immersion element and the thermostat, but these really require a multi-meter and the expertise to use it.

Thanks for this, it is very helpful. I certainly wouldn't do it myself but I would check that these things are done based on your comments when I get the plumber.
I'm not sure what you'll make of the following but perhaps it'll mean something.

1) Before I had the builders in, the cover was missing on the bottom immersion, which the plumbers replaced (I am not sure if they reset anything or simply just replaced the cover). I am waiting on the report of what they did during the bathroom refurb but the missing cover may tie in with what you were referring to.
2) The other strange thing was as I have a heating circuit with cheap rates, one part is 24 hr like top immersion/showers/panel heaters, and the other part is the radio controlled over-night for the storage heaters and bottom immersion. For some reason the bottom immersion was swapped from the off-peak timings to the 24 hour one. My assumption was the previous tenant didn't want to heat his tank every day so just did it from time to time (was one person and shower electric so may not have wanted to spend extra on daily water tank heating), but I'm not sure if there's another reason related to this fault. The electricians switched it back to the off-peak but since then the water has only been slightly warm.

Thank you for the advice.

Mutton_Geoff

If you're on economy 7 (dual rate) tariff, it is likely the bottom element is connected only to that supply via it's timer/breaker. Are you sure it's not been turned off so your only option at the moment is the top element "boost" via the switch onto "normal" electricity (at 4x the price). If you turn it on, you'll still have to wait overnight or whenever the rate changes for it to heat up.

me1000uk

Mutton_Geoff said:

If you're on economy 7 (dual rate) tariff, it is likely the bottom element is connected only to that supply via it's timer/breaker. Are you sure it's not been turned off so your only option at the moment is the top element "boost" via the switch onto "normal" electricity (at 4x the price). If you turn it on, you'll still have to wait overnight or whenever the rate changes for it to heat up.

Hi there. Thanks for your response however I am not on economy 7 as explained in my first post (there are some parallels). It's not a particularly common system outside of northern Scotland.

Mutton_Geoff

Is the gizmo that switches on the supply to the bottom element working? Does that cable go live at the correct time of day?

I missed the econ 7 bit as I speed read your post after you said "It is an all electric property with an 'economy 7' style insulated water tank with a bottom and top switch, and a boost button in the kitchen" and your explanation of the Scottish system lost me.

coffeehound

Hi, is the hot water tank an 'un-vented' cylinder do you know?