Hot Water ... or rather lack of it!

ForestBluebells

I live in a property that only has electric as there is no gas service the area and i dont have oil heating. currently i have a 70litre megaflow water tank ( I am told this is a good one) and the water pressure is great but i have so little hot water, should this be enough for 1 person? I dont have long showers but some days i only get luke warm water (i heat the water for 30 mins...is this long enough?) other days it is quite warm but not boiling, there doesnt seem to be any correlation to outside temperature to whether the water will be hot or not. Either way it is only enough for a quick shower then i run out. I am not sure if the tank/heater is faulty or it genuinely is too small in which case i need to replace it with a bigger one?

Alex1983

A general rule is 55l per person per day.

Don’t think 30mins will be long enough but I wouldn’t swear by it, try leaving it on for a couple of hours a day for a week and see if it improves.

bris

Its cheaper to leave it on and just keep it at temp than putting it on when you need it.


Think of it like a giant 70 litre kettle, how long will that take to boil? It takes a lot to bring it from scratch to temp but not very much to maintain it there.

nofoollikeold

bris is right. The cylinder you have will take 92 minutes to heat up. Once hot, it will lose about 1.0 KwH of heat per day (so about 15 to 20p). If you keep your hot water at 60 degrees, and assuming your incoming cold is 5 degrees, you would get roughly a ten minute shower at 40 degrees with a ten litre per minute shower head.

ForestBluebells

I can't get the temperature I don't think I just have a basic timer where you press down little keys for 15 min slots when you want it to come on and as I have economy 7 I put it on at around 5am for half an hour. Seems like I've not been hearing it for long enough though so I'll try heating it for longer and see if that helps/ provides me more water as it frustrating if I want to wash my hair knowing it will be freezing cold by the end of my shower.

Heedtheadvice

I cannot agree that leaving the heater on all the time is cheaper. Whilst the tank is hot and not being used the losses to the exterior will be made up by using electricity.

However that loss ought to be very small with your system running on economy seven and will cost very little if heated for the full economy period - and also that cost will be almost insignificant compared to hearing a full tank from cold.

So provided the thermostat is set at a reasonable temperature (60 degrees C) that slight cost is likely to be a small price to pay for convenience.

Some thermostats are not very accurate so worth getting a thermometer to check it and ensure accurate setting (can be had for a couple of pounds). A too high a setting increases losses (and the cost to keep hot) and increases the risk of scalding. Too low a temperature increases the risk of legionella bacteria (keep over 50 degrees or increase to 70 degrees once a month).

For the future, not having gas, if you have the outside space and the capital to invest you should maybe consider an air source heat pump?

Le_Kirk

If you have economy 7, do you have a dual meter and separate circuits, such that, when the economy 7 kicks in at night (mine is 12.45 pm) it powers up a separate circuit which is used to power storage heaters and immersion heaters.

ForestBluebells

i believe that only my storage heaters auto come on at night but any other electicity i use (lights, water etc) will still use the night tariff over night. I think the heaters come on by radio or something like that.

Ok so if i heat my hot water for 3 hours say, if it reaches temperature in an hour it wont actually keep trying to heat the hot water for the full time?

I wasnt aware that my water tank had a thermometer to be honest, i will have a look at it and see if i can see anything, i wouldnt know where to stick the termometer to check temperatures either? Do you mean check the temperature the water comes out the tap?

ForestBluebells

I was actually wondering if it was worth installing an oil based heating system to replace all this, i wasnt sure if it was worth the hassle or not though.

Ectophile

If you've got E7, then you should be putting it on all night. Once it's up to temperature, the thermostat should switch it off anyway. Make sure the thermostat's not set excessively high or it may trip the safety cut-out. 60C is enough to kill legionnaire's disease.

A full tank of hot water should last all day if it's a well insulated tank.

Safety warning - if it's an old system which doesn't have a safety cut-out, and if you have a plastic cold water tank, then don't leave it on all the time. It's very rare, but if the thermostat gets stuck on, then it can boil the water in the tank. The boiling water overflows into the cold tank. Eventually the cold tank gets so hot it collapses, dumping scalding hot water on anyone unfortunate to be enough to be below it.

Le_Kirk

sambo84 wrote: »

i believe that only my storage heaters auto come on at night but any other electicity i use (lights, water etc) will still use the night tariff over night.

It should be easy to check, just look at your hot water storage tank and it should have two immersion heaters in, one for day and one for night. There will likely be a switch so you can switch it/them on/off. It is most unusual to have E7 but not make use of it to heat water overnight.

sambo84 wrote: »

I think the heaters come on by radio or something like that.

Well, now I have heard everything! How do you work that one out?

sambo84 wrote: »

If i heat my hot water for 3 hours say, if it reaches temperature in an hour it wont actually keep trying to heat the hot water for the full time?

I wasnt aware that my water tank had a thermometer to be honest, i will have a look at it and see if i can see anything, i wouldnt know where to stick the termometer to check temperatures either? Do you mean check the temperature the water comes out the tap?

There will be a thermostat (well probably two, one for temperature control and one for overheat) that should prevent it trying to heat water for the whole time. However, if the water cools after temperature is reached and providing E7 is still available it will switch on the immersion heater again.