Water Heating - Timed vs. Continuous

dannygray

Hi there,

I recently moved to a new apartment that uses electricity for hot water and electric panel heaters for heating. Both work off a central timer switch that can be set to switch on/off for a set time (1 time slot per day) or remain on continuously.

So far I have the timer to come on for 2 hours in the morning to heat the water needed for the day. Fortunately so far I haven't had to use the heating so can ignore that for now.

The problem is that by the evening all the hot water in the tank is used up and I have to wait for the next day for the timer to come on unless I manually override it (which naturally racks up extra electricity charges).

The meter isn't Economy 7 as far as I know so heating up water during cheap rate is no advantage.

My question: would it be crazy expensive to leave the timer on all day so it would just heat up a full tank of water and replace what was used during the day vs. just having the timer on for a couple of hours and heating and filling an empty tank?

First time with electric - gas was much more straightforward.

Thanks!

victor2

It will of course cost money to have the water heater on all day. The only way you'll find out how much, is to try it while taking meter readings to establish a typical day with the heater on for just the timed sessions, versus on all day.
Can you adjust the timed slot to fit in with your lifestyle more, or even replace the timer with one capable of multiple sessions in a day? What uses so much water in the evening? If it's timed to give you enough water for a shower in the morning, then what do you need hot water for in the evening that just using an electric kettle can't provide?

tanith

Well just switching it on for an hour in the evening isn't going to cost as much as having it on all day so why can't you just do that with the overide button? I get more than enough hot water from an hour in the morning and evening.. is your tank lagged? or do you just use loads of hot water during the day, ours is on for 2hrs daily and that does 2showers, runs the dishwasher or washing machine plus any other hot water I need during the day and the tank is always hot I never run out..

jalexa

dannygray wrote: »

The problem is that by the evening all the hot water in the tank is used up ....

Do you mean *used up* or no longer really hot? Only a bath should "use up" all the hot water.

My question: would it be crazy expensive to leave the timer on all day so it would just heat up a full tank of water and replace what was used during the day vs. just having the timer on for a couple of hours and heating and filling an empty tank?

The most important factor in answering that question is how well insulated is the hot water cylinder?

Anyway the problem to solve will be control of the panel heaters when heating starts in earnest.

Are you the owner or are you renting?

Cardew

Welcome to the forum.

If you have a conventional Hot water Tank(as opposed to a combi boiler which heats water 'on-demand') it doesn't matter if you heat with gas, oil or electric as the principle is exactly the same.

Are you sure that the timer hasn't provision for two timed slots, or a manual overide? It is also surprising that a tank would lose all hot water during the day - how is it used?

Anyway taking a conventional HW tank,if you leave the water heating on 24/7 the additional cost will be to replace the heat loss from the tank. If you have a modern well lagged tank(usually a foam coat) the losses are actually quite low. They are tested to a British Standard and should lose no more than 2kWh when full with water @65C.

So that heat loss will cost around 20P a day. However that heat is not lost at this time of year as it warms the fabric of the house - think of it as a small radiator.

There is of course nothing to stop you putting the timer to continuous for a couple of hours and then back to timed.

dannygray

Thanks guys.

@victor2, I considered testing it on the meter readings but unfortunately don't have direct access to the meters - it's an apartment building so have to ask the concierge. Might be able to get a breakdown for a 24 hour period online from electricity provider.

@tanith, not sure if the tank is lagged. 90 min-2 hours in the morning only seems to do enough for 2 showers. I'll stick with that and just override in the evening as needed and see how it goes. Cheaper electricity provider will also help

victor2

Unless you've got smart meters, your supplier won't have meter readings except from when they've read the meters for billing purposes, so I wouldn't hold out much hope there.
Decent lagging on your hot water tank is inexpensive and the tank shouldn't be too hard to find - they're big and warm!
Don't know how it would be in an apartment though - you might be able to find out from the concierge if you really can't locate it.

dannygray

Thanks for the replies!

@jalexa, the water starts to flow cold after 2 showers. There is still water coming through but I assumed that the tank was emptied of hot water and now cold water is flowing through that it hasn't had chance to heat.

Indeed figuring out the panel heaters without spending a fortune will be interesting.

I'm renting - would never buy somewhere with this type of heating or if I did would change it ASAP.

@Cardew, thanks for the welcome. Yes it's a conventional HWT. The timer has only 1 slot per day so it's trying to figure out what the best time would be. It does have manual override but I'm wary about just leaving that on for ages and racking up the charges, have to be vigilant I guess.

In answer to your question - the hot water that is there from the morning slot is gone after 2 showers and isn't replaced until next day or override later same day.

Thanks for the info on heat loss - it's a fairly new apartment so should be built to latest regs. Might give it a 24h run and see what that does to the electricity use for that day.

jalexa

dannygray wrote: »

Indeed figuring out the panel heaters without spending a fortune will be interesting.

I'm renting ...

Assuming you are out most of the day, my workaround would be to buy a cheap heater and timer (Lidls have a combined convector/timer at the mo) for the morning heat-up and switch the water heating/panel heating slot to early evening.