Immersion heater help!

Cardew

Cyclone_Cyd wrote: »

A timer will be cheaper, but not by a huge amount.

WRONG! Using a timer properly will be loads cheaper than just leaving it on.

Care to debate why you are so certain you are right and I am wrong.

Like discuss heat loss from tank? Use BTUs or kWhs - it matters not.

Perhaps give us your definition of 'loads?

mute_posting

Cyclone_Cyd wrote: »

Not so. Simply adding a timer into the flex from the DP switch to the heater constitutes a minor modification to the existing circuit. Therefore it is not notifiable work, unless the tank is actually in the bathroom (inside an airing cupboard with a door is not in the bathroom). Therefore no electrician required.

The phrase "like for like" does not appear anywhere in Approved Document P. If you believe it does, please give us a page reference.

I don't recall saying the words were specifically mentioned in the approved document. I was merely pointing out that your response that that an electrician was not required was far too much a sweeping statement and provided some examples to elaborate on my PoV.

I'm pretty sure if you asked a building control officer (or whoever it is) "can I change the switch on my IH for a different type" they would want it doing by either a part P registered spark, OR require it to be notified through the normal building regs route for homeowners.

MP

Edit

Also, even if the tank is within an airing cupboard within the bathroom (as oposed to outside of the bathroom) AFAIK it is still classed a "special location" as those using the bathroom are likely to be at higher risk if that makes sense? I think that the only way around this would be for the tank to be located within an enclosure/cupboard that required tools to access.

But as you are so knowledgable, perhaps you can provide a link to backup why an electrician / notification ISN'T required?

Cozworth806

Unless it is warm I would go gathering kindling and sticks/logs, if you can access free firewood/fuel then it is worth the savings.

In the summer, it dpends what you want to do but I am of the mind to leave the water in the IH cold and boil a kettle if I want a wash or to wash up. Only an issue if you want a bath.
No idea if it is cheaper, as I have never compared.

As for E7 I would think long and hard about when you are in the house. If you are in during the day then the savings at night will be lost when you use elec in the day, so it may not be that much cheaper overall.

Cyclone_Cyd

http://www.planningportal.gov.uk/england/professionals/en/4000000001253.html

I am a Part P approved Spark. so, if you can show me I'm wrong about not needing a registered Spark, I would be most grateful.

A few years ago, myself and some ex-uni buddies put a meter on an immersion and left it on for 3 months and then fitted a timer and repeated for 3 months. The saving yielded was about 35%. Over a few more shandies we even came up with some maths to support the finding. The details are lost in time now, but the Energy Saving Trust amongst other bodies agrees with the principle (if you care to read the page carefully).

I do know that a standard 120 litre, foam dipped tank loses about 2.5kWhr per day when held at 65C. This is about £110 of leccy in a year at todays prices. So having the tank remain cold for about 8 -10 hours a day (when there will be no heat loss) will save about a third of this loss.

Then there's the safety aspect....

mute_posting

Cyclone_Cyd wrote: »

http://www.planningportal.gov.uk/england/professionals/en/4000000001253.html

I'm aware of where to find the registered document
I am a Part P approved Spark. so, if you can show me I'm wrong about not needing a registered Spark, I would be most grateful.

I know where to find the approved document, I asked (as you appear so knowledgable) If you could quote the part that supports your sweeping statement:

Does an electrician need to do it?

NO.

It could be argued that a timer could come under additional note "n" on page 9

A few years ago, myself and some ex-uni buddies put a meter on an immersion and left it on for 3 months and then fitted a timer and repeated for 3 months. The saving yielded was about 35%. Over a few more shandies we even came up with some maths to support the finding.

And I'm sure that as "uni" folks they would appreciate that that is hardly a scientific way to measure it. Had they done it under controlled conditions (i.e. fill tank with water, turn IH on [and leave on] and then use set ammount of water at set periods over 24 or 48 hours, then repeat but with only having IH on at certain times) I can almost guarantee different results!

The details are lost in time now, but the Energy Saving Trust amongst other bodies agrees with the principle (if you care to read the page carefully).

I have read the page carefully and it doesn't give savings - It says savings can be made, but then I never disputed they could be. I (and many many others) have said that the savings are small...

I do know that a standard 120 litre, foam dipped tank loses about 2.5kWhr per day when held at 65C. This is about £110 of leccy in a year at todays prices. So having the tank remain cold for about 8 -10 hours a day (when there will be no heat loss) will save about a third of this loss.

Then there's the safety aspect....

Strange that when you are pushing so hard for OP to go onto E7, you quote the savings based on normal rate electricity! (2.5 * 365 * 0.12)

pinkbubble

Whew, mornin everyone, thanks so much for all your replies
Ok, so E7 - my youngest is 1 and I'm at home all day, the kids get back from school at 3 and go to bed at 6 then get up at 6 and go school at 8.45. I'm trying to think how much elec we use - not much really now, don't watch much telly but I do use the tumble dryer as we don't have many clothes and I often need something washed and dried quickly. Luckily my washing machine heats its own water from the cold pipe. My main usage of lights, kettle ect is between 6am-6pm, and my major things (washer & dryer) are usually afer 8. In the summer I will have the immersion heater on from 5am (maybe til 6? not sure how long it take to heat enough for what I need yet) for my morning shower & washing up, and it will be on from 4pm for the kids bath. In the winter though I won't need the immersion in the evenings cause I need to keep the house warm for the little ones so I will always have hot water, on the other hand I will use more elec as it's dark. Also I might need elec room heaters in the winter in the mornings before I get the fire going, they'll be on timers to come on at 6. Oh, and the bathroom light is on all night too. I don't know what company I'll be with yet but I'll find out when the E7 cheap rates end in the morning, cos if it ends at 8 then I might be better running my washing at night and having my room heaters and immersion on in the mornings before 8?
I'll find that out.
It's early, and my brain hurts from all this thought, I'm off to make a cuppa coffee and sit in front of my lovely sensible gas fire, gonna make the most of it while I can!!!

Cardew

Cyclone_Cyd wrote: »

I do know that a standard 120 litre, foam dipped tank loses about 2.5kWhr per day when held at 65C. This is about £110 of leccy in a year at todays prices. So having the tank remain cold for about 8 -10 hours a day (when there will be no heat loss) will save about a third of this loss.

Well I would agree with the 2.5kWh heat loss* per day.

* heat loss being something of a misnomer as the heat goes into the fabric of the house - which is why most HW tanks are in an airing cupboard.

Your assumption that there will be no heat loss during the day(because the tank will be cold) is not supportable. That would happen only if every bit of hot water was used.

In practice the water will be below 65C but in most normal circumstances well above the ambient room temperature, say 40C-45C on average??

So there will be heat loss during the period the heating is off. The savings will be the difference between heat loss at 65C and heat loss at 45C(or whatever)

I note you use a rather high price of 12p/kWh for your electricity.

Then of course you give figures of savings for 12 months, and even with your questionable assumptions of a cold tank and high priced electricity you calculate savings of around £30 per year - for a tank heated by electricity 12 months each year.

Well the OP will only be using electricity for HW in the summer a few months.

So in practice for the OP(whose the question I was addressing) the difference between leaving the Immersion on 24/7, or buying a timer and getting someone(qualified electrician or not!!) to fit it, will be probably less than £10 a year. I would think £5 p.a. might not be an unreasonable figure.

Care to discuss it further? or do you still maintain I was "INCORRECT"?

Now your £30 a month saving from using Economy 7 electricity - as this is a Money Saving website, I would love to see your calculations.

moonrakerz

Cyclone_Cyd wrote: »

A few years ago, myself and some ex-uni buddies put a meter on an immersion and left it on for 3 months and then fitted a timer and repeated for 3 months. The saving yielded was about 35%. Over a few more shandies we even came up with some maths to support the finding. The details are lost in time now, but the Energy Saving Trust amongst other bodies agrees with the principle (if you care to read the page carefully).

Amazing ! this topic comes up on this thread, and someone just happens to have carried out a test to prove their point of view some years previously. Shame the details have been "lost in time" ! :rolleyes: :rolleyes: