How to use unvented hot water systems effectively?

frnd4u81

Dear Energy experts.
I live in a rented flat (2002 built) which has unvented hot water systems. Santon Premier Plus model PP150CE.
150 litres in capacity.
My energy bills (and units consumed) are over the roof. I am looking for tips on using this hot water systems efficiently.
I can't change or repair this system as a tenant (and not keen to spend money).
I read the manual which simply explains installation procedure and nothing on energy efficiency or using it effectively.
We have been running it overnight and now planning to run only for 4 hours per day.

Any practical tips will be gratefully accepted.
Thank you

Gerry1

Assuming you have a gas boiler, switch off both the immersion heaters and programme the hot water controls appropriately. Use price comparison websites and see whether the cheapest offering is dual fuel or separate suppliers, and perhaps with some cashback as well if you're really lucky.

matelodave

There's nothing particularly special about a non-vented system over a vented in terms of usage however with either system there are a couple of things to bear in mind whether they are heated by gas or leccy.

You shouldn't need to keep them boiling hot all day, just try heating them for an hour or so in the mornings before you get up and see how long the hot water lasts. Used sensibly you should be able to mange right through to bed time.

If you are using an immersion heater on E7 then the tank should heat overnight using off-peak electricity. However if you run out of hot water and use the boost heating function then you'll be using peak rates so makes sure it's shut off and don't use it during the day (any time between around 7am and midnight) because it will cost you a lot of money.

Dont waste hot water by letting it run down the sink, use a bowl or put the plug in. Save your washing up and do it in one go rather than lots of little washes

Dont rinse stuff (including your hands) in hot water - every time you run off a gallon or so of cold to rinse your hands or wash a cup in warm water leaves a gallon or so of expensive hot water sitting in the pipework to get cold.

Take shorter showers (five minutes max), shallower baths and fewer of them. Fit a flow restricter or eco shower head on your shower to reduce the amount of water you use. Showers can use a vast amount of water especially if its got a good flow and you stand there for ages.

Dont forget that there's lots of other stuff using your electricty so look at other things as well and see how you can reduce their consumption. Heating, lighting, cooking, washing, computers etc. TBH hot water isn't really everso expensive compared with everything else, it's probably the heating thats ramping up your bills. What sort of heating have you got and how do you use it

Last but not least, ensure that you are on the best tariff available for your circumstance

frnd4u81

Thank you @Matelodave and @Gerry1.
These are practical tips. In particular, I will only switch on for an hour each day and see how it goes. I will also follow other tips. Unfortunately it is all electric and no gas.
Regarding tariff: I am kind of stuck as the flat has two MPANs and unlisted. You might see from my other thread.

matelodave

frnd4u81 wrote: »

Thank you @Matelodave and @Gerry1.
These are practical tips. In particular, I will only switch on for an hour each day and see how it goes. I will also follow other tips. Unfortunately it is all electric and no gas.
Regarding tariff: I am kind of stuck as the flat has two MPANs and unlisted. You might see from my other thread.

TBH it really doesn't make a lot of difference if it's on all night on an E7 or even a complex or restricted meter supply because it should only heat up during the off peak period and then the thermostat takes over. A decent cylinder doesn't lose much heat during the day so try to use it wisely so ensure that you dont use it all up otherwise you'll have to heat it with peak rate leccy.

It's using the immersion during the peak period that will cost you. The same with your heating. Storage heaters should only come on during off peak times.

It's the use of electricity during peak times that's costing you the most so you need to evaluate what you use and when - try not to use supplementary heating during the day or the evening.

There's no easy way, you need to be reading and recording all your meter readings on a regular basis (possibly daily for a couple of weeks) to try and establish what it using it and when so you can avoid using energy when it's most expensive.

There are a lot of threads on the subject of multiple meters, complex and restricted tariffs and they all have the same theme - they are getting very expensive nowadays. Energy companies dont want to take them on and those who do have them want to get rid of them. Their time has now passed and they aren't economically viable anymore

Unfortunately the household wiring was set up for these systems and it's not just a case of a meter change to get rid of them, some wiring may have to be changed and you ideally want to get rid of one of the meters to avoid pay two standing charges.

Gerry1

As you're all electric it will cost an arm and a leg. One wonders why the place has a tank designed for a boiler if there isn't one !

Make sure the overnight supply to the lower immersion heater is switched by the meter and leave the 'anytime' upper immersion heater permanently switched off except in emergencies.

What's your space heating system? That's probably where most of the money goes.

matelodave

Gerry1 wrote: »

As you're all electric it will cost an arm and a leg. One wonders why the place has a tank designed for a boiler if there isn't one !

Make sure the overnight supply to the lower immersion heater is switched by the meter and leave the 'anytime' upper immersion heater permanently switched off except in emergencies.

What's your space heating system? That's probably where most of the money goes.

It's probably not specifically designed for a boiler, it's ftted with two immersion heaters - the bottom for off peak heating and an upper one for peak boost.

Gerry1

matelodave wrote: »

It's probably not specifically designed for a boiler, it's ftted with two immersion heaters - the bottom for off peak heating and an upper one for peak boost.

It has a big fat coil at the bottom ! What's that for?

matelodave

Probably because it's easier to make them all the same rather than just having a special for electric only.

It also makes it a bit easier for retrofitting a boiler, solar thermal or other hot water fed heating.

Who knows why some of this stuff gets fitted into houses or why they have weird and wonderful systems - many of which may be legacy system which may not have any relevance nowadays

My hot water tank has two coils, one for the the primary source (mine is connected to my heatpump) and a second for a secondary form of heating, like solar thermal or an additional boiler

Cardew

Personally I think there is too much emphasis on the heat loss from the tank, and thus the need to only have it on for 1 hour a day etc.


I have a 180 litre unvented tank. The BSI standard gives it a heat loss of 54 watts when it is filled with water at 65C - so it will lose 1.3kWh in a 24 hour period, so that is a worse case scenario.



I don't keep the temperature at 65C and am not worried about ensuring that it is heated just long enough for the house needs. Consumption varies, sometimes lengthy deep baths are taken, sometimes a quick dip and sometimes showers(one of which is an electric shower)


Given the worse case for heat loss is 1.3kWh/24 hours, I suspect my heat loss is under 1kWh/24 hours. I wonder just how low I could reduce that heat loss by being 'anal' and risking the bath water running cold - as it did when I were a lad.


It is also pertinent to point out that any heat loss isn't wasted for much of the year as it heats the fabric of the building - which is why tanks are often put in an airing cupboard.


I am not making a criticism of those who want to heat water for xx minutes a day, but just get savings in perspective.

Talldave

In addition, if the thermostat is working correctly, even if the timer is set for 4 hours, if the water's up to temperature in 40 minutes, the immersion switches off. The only downside to the longer period is if thermostat has a small hysteresis and keeps cycling on/off.