Water tank, will water stay hit?

Drmieow · 20 January 2019 at 8:56PM

I have recently moved in to a new house with Night Storage heaters (no gas in the property). What I want to know is if I heat water by putting the immersion switch on at 6am until 7am (When the cheapest rate runs) will it stay hot until evening? I have a little boy and we do a bath before bed. I have been popping the immersion on before bath and it's costing me a fortune using the higher/very expensive rate I don't have a timer switch on the tank so I can't set it to heat up but could pop it on when I wake up at 6am

Cardew · 20 January 2019 at 9:21PM

Welcome to the forum.

It is normal practice to heat a water tank on cheap rate.

If the tank is well insulated - a hard foam jacket is best - the tank will lose very little heat during the day and, provided you haven't been using lots of hot water during the day, the water will be piping hot in the evening.

Robin9 · 20 January 2019 at 10:05PM

You may well find that the immersion heater - like the night stores - come on automatically at 0030 and off at 0730. The hot water tank will only take a couple of hours to heat up and if well insulated will give you hot water throughout the day. There is usually no need to use the boost.

Drmieow · 20 January 2019 at 11:29PM

Thank you both PPs. I switch off both switches on the tank pretty much all day as I am out at work and also, when it was left on overnight, it made a knocking sound in the early hours (in need of a flush I'm sure!)
Tomorrow I will try heating for 1 hour between 6am and 7am (while it's still cheap rate) and see how I go tomorrow evening.
I'm sure I will need to get a timer installed and then, if I also get it flushed, it can come on overnight for more than 1 hour if necessary, maybe 2hrs as @Robin9 suggests.
I will update the post, incase it helps others!

Curly1400 · 21 January 2019 at 12:32AM

A flush on the type of system you have there won't stop the banging. The banging will be the stats turned up too high or failing. A timer would be useful to have fitted, it's easy to alter the temp on the stats however be careful if you do because it's 230v.

fisherjim · 21 January 2019 at 10:11AM

Drmieow wrote: »

Thank you both PPs. I switch off both switches on the tank pretty much all day as I am out at work and also, when it was left on overnight, it made a knocking sound in the early hours (in need of a flush I'm sure!)
Tomorrow I will try heating for 1 hour between 6am and 7am (while it's still cheap rate) and see how I go tomorrow evening.
I'm sure I will need to get a timer installed and then, if I also get it flushed, it can come on overnight for more than 1 hour if necessary, maybe 2hrs as @Robin9 suggests.
I will update the post, incase it helps others!

You don't "flush" immersion tanks, you are getting confused with central heating.

It sounds like your thermostat(s) is faulty and it's overheating that's probably why you were getting high bills.

You really need to get this checked out properly instead of stabbing in the wind.

Cardew · 21 January 2019 at 10:25AM

It really isn't critical to get the exact timing in the morning, when the tank gets up to full heat the thermostat will switch off the immersion heater.

Also in the winter what heat is lost from the tank(very little) warms the fabric of the house, so is not wasted.

The bottom immersion heater is the one you need to heat during the cheap rate period. The top immersion heater should be off all the time and only used if you run out of hot water during the day and need enough to, say, do washing up.

It is also easy to increase/decrease the water temperature by adjusting the thermostat - but naturally be carefull of scalding, particularly with an infant.

G_M · 22 January 2019 at 11:04PM

A modern hot water cylinder will have a foam insulation layer fitted eg here.

An older one should probably have a set of 4 or 5 insulation 'jackets' (like this).

Even if you have a modern one it is worth adding a jacket - they cost £10 and will last a lifetime.

My cylinder keeps the water hot all day - in fact it's still warm enough for a shower the following day so I only turn it on for an hour or 2 every 2 days!

If it is overheating, check the thermostat - usually on the top and can be adjusted with a screw-driver. See relevant utube video for how.

Or get it checked by an electrician. Adding a proper time control is also sensible, or just learning how to use the existing one!

Have you bought this house or are you renting? If bought, it's worth getting it all set up safe and efficient. If renting, ask your landlord to get it checked.

Drmieow · 23 January 2019 at 7:27AM

Thank you all. I have an electrician coming round to set up a timer and look at the thermostat/overheating.
I wasn't considering doing any of this myself, but wanted to see peoples advice in How long the water may be expected to stay hot.
I have tried putting it on from 6am-7am in the morning (cheap rate) and if I'm out all day there is enough hot water by evening for a bath.
I think if I am in during the day I may need to put the immersion on for 2 hours in the morning to provide enough hot water for other things during the day. Having a timer will help with this as there is not one at the moment.

G_M · 23 January 2019 at 6:36PM

INSULATE.

Then insulate a bit more...........

silverwhistle · 24 January 2019 at 11:49PM

Yep, what he said. I've a foam insulated tank and then added another jacket on top, but then I'm a tight lass heating by spare solar PV.

In my case it was worth turning up the thermostat as it means I get hotter water when they're enough spare power. No danger of Legionnaire's disease either!

Water tank, will water stay hit?

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