Hot water tank not keeping heat

ForestBluebells

I have an electric only property and my water is heated by immersion off peak. I have a megaflo water tank which is apparently very good and I believe it’s already insulated by design? I may be wrong. 

I was on economy 7 heating my hot water for 45 minutes about 5.30 am about 1 hour before I had my shower and I could still have a shower later in the day if I’d gone for a run just fine. 

I’m now on cheap electric between 12.30-4.30am so heating my water 3.15-4am for the same amount of time but it’s not very hot anymore when I want to use it. I’m using the hot tap only and it’s only mildly warm. 

I’m assuming this is just my tank loosing the heat in those extra hours but not sure if you can install a blanket on a megaflo system?

I heated my tank for 15 minutes in peak hours the other day as I wanted a shower and it was too cold and that did heat the water well. 

I have a very small water tank if that matters 

any ideas on how I can fix this?

NSG666

It's unlikely to be an insulation problem more likely a problem with an immersion element if it has two or it's not being left switched on long enough to get hot. Can you post details of the model of Megaflo and/or a photo of it?

Ebe_Scrooge

Puzzling.  To your first question - yes, you can always add more insulation to a tank if you want to, there's nothing wrong with doing that.  But, as you say, most modern tanks come with insulation pre-installed, as it were, and it's usually good enough - a tankful of hot water will usually stay pretty much hot enough all day if it's not used.

I'm tempted to suggest that the actual heating element may be faulty - but you say that if you give it a boost when you need it, it heats up just fine.  So that would tend to rule out that option.

To state the bleedin' obvious - are you sure you've got your timer set correctly - is the element actually switched on between 3:15 - 4:00?

Obviously, heat can be lost from the pipework as well as the tank itself.  But if nothing else has changed, and 3/4 of an hour's heating used to give you what you needed, it's a bit of a puzzle.  There's nothing else using the water, is there - you haven't got a hot-fill washing machine that comes on after the tank's been heated?  Unlikely, but I'm just trying to think of what could cause it.

I guess you could add a jacket to the tank, and just see if that helps.  They don't cost much money, and it certainly won't do any harm, so there's little to lose by giving it a go.  I assume the "built-in" tank insulation is all intact and not damaged?

ForestBluebells

This is the tank, it’s very small but it’s a 1 bedroom property and just me in there

ForestBluebells

Nothing else uses the hot water and the only difference is I’m heating it for the same amount of time but about 2 hours earlier in the morning 

ForestBluebells

The time it’s set to is correct so I’m not sure why it doesn’t seem to work when it was fine all day heated at 5/6am ish

ComicGeek

Is it just now when it's cold that the water isn't hot enough? There's a big difference in water supply temperature between summer and winter, can be about 15 degrees difference.

So in the summer your stored water after 45 mins heating could be 15 degrees hotter than after the same amount of heating in the winter. 

The initial answer is to be extend your heating period. That unit has a heat up time of 92 minutes from cold, so I don't think you're running it for long enough.

ForestBluebells

ComicGeek said:

Is it just now when it's cold that the water isn't hot enough? There's a big difference in water supply temperature between summer and winter, can be about 15 degrees difference.

So in the summer your stored water after 45 mins heating could be 15 degrees hotter than after the same amount of heating in the winter. 

The initial answer is to be extend your heating period. That unit has a heat up time of 92 minutes from cold, so I don't think you're running it for long enough.

Yes it might be due to the colder weather. I’ll try heating it for longer and see. Just frustrating as 45 minutes was fine heated 2 hours later in the morning but my overnight energy is cheaper now at 5p so I can probably heat it for longer and it still cost me less

koalakoala

Exactly as comicgeek says

ForestBluebells

Thank you everyone. I’ll try increasing it in15 min increments and see what is required. 

ComicGeek

The immersion will turn off automatically when the storage temperature is achieved, so I would personally set it to run for 1.5-2 hrs, and just leave it to sort itself out - you won't lose much heat from the cylinder during the day, so good to make sure it's fully heated during the cheaper elec period.