Comments on: Euro 2008

By: betty

betty — Thu, 03 Jul 2008 13:38:11 +0000

Liam, I believe on a cost benefit analysis it takes 14 years to recover the cost of installing solar panels , 8 years to recover the cost of wood pellet stoves (complicated by supply of said pellets) and 18-20 years for geothermal systems(plus high running costs). Use less hot water, turn down the thermostat, wear a cardi,etc, or have a solid fuel in the main living area, downside —dusty ,work , ashes, but felxibility of supply—grow your own, Sarah.

By: Liam

Liam — Thu, 03 Jul 2008 13:15:45 +0000

Would Solar panels look after all your hot water needs from April to October?
The remaining months would be covered by your space heating system, your oil boiler, and by using the two you would have constant hot water, yes? Or is this wishful thinking on my part?

By: pete

pete — Thu, 03 Jul 2008 12:56:56 +0000

Thanks Sarah, your thanks makes the 4 years that I spent in UCC getting a physics degree that never earned me a penny all worthwhile

By: betty

betty — Thu, 03 Jul 2008 11:50:38 +0000

RE your oil system—-ours has 2 switches, one for water and one for room heating—-the water option switches on for 1 hour each am , that gives us hot water all day, though not a lot —if there is extra demand we have to boost it -the immersion or more oil. Sadly we have had to turn on the oil for heating a few evenings this year—too lazy to light the solid fuel stove.

By: Andrew Lawlor

Andrew Lawlor — Wed, 02 Jul 2008 21:12:57 +0000

If all else fails, Sarah, youcould up sticks and move to Iceland.

http://www.guardian.co.uk/environment/2008/apr/22/renewableenergy.alternativeenergy

By: Sarah

Sarah — Wed, 02 Jul 2008 19:45:44 +0000

hmmmmmmmm

thank you

you ARE knowledgeable.

By: pete

pete — Wed, 02 Jul 2008 17:02:18 +0000

Ok. There are basically 2 ways people get hot water to come out of their taps:

1. Stored hot water. This is what you have. Water is heated up in tank, in advance of when it is required, and stored until it is required. Of course, while stored it is losing heat to the surrounding environment (even with a very well insulated tank), and that’s what can make it wasteful. The better insulated your tank, and the less time the hot water is stored for, the less waste.

2. Instant hot water. This is how an electric shower works. Cold water from the mains is fed into the shower, and hot water comes out. Instantly. Since the hot water is not stored, no heat is lost to the surrounding environment. BUT heating water up that fast requires huge amounts of electricity, as much as running 4 tumble dryers at the same time! “Combi” gas boilers do the same thing, by using lots of gas instead of electricity.

In terms of choosing between using the oil boiler and the immersion to heat your water, as you can see from my earlier comment, oil is much cheaper in terms of raw energy (measured in kilo-watt-hours). But you have to consider how efficiently that energy gets converted into hot water.

The immersion is literally inside the tank, in contact with the water, so all of the heat from it ends up as hot water.

The oil boiler loses lots of heat through it’s chimney when it burns the oil, and more heat is lost heating up the boiler and the pipes, and keeping them hot (they will constantly lose heat to the environment). You probably lose 30% of the energy from your oil in this way (unless you have a modern “condensing” boiler and lots of insulation).

But even if you have to buy 50% more kilo-watt-hours worth of oil than electricity, to compensate for the loses, the oil still works out a bit cheaper.

By: Sarah

Sarah — Wed, 02 Jul 2008 15:28:38 +0000

Nerdiness forgiven btw.

By: Sarah

Sarah — Wed, 02 Jul 2008 15:28:18 +0000

I don’t get it. If you don’t have a hot water tank, then where does the water get heated?
In winter, our system is simple. We have oil fired central heating and when the radiators are hot the oil heats the water. We can switch of the oil and the hot water stays hot for hours and hours afterwards. Its not using energy to keep it warm, just to get it warm.
With the immersion we just flick it on 20 mins before we need the water (and to the “sink” option which will do two quick showers or the children’s bath. )
I don’t think that’s wasteful.
I was just wondering that if we turn on the oil, turn off the radiators, and let the water heat that way, which is more expensive? The oil or the ESB?
We did look into the solar panel thing when we built the house. What we discovered was that you had to install the whole solar thing and then the conventional heating systems too. So you need two systems – not one replacing the other. (as you point out) So the capital costs were high. We thought too high. As was the geothermal system and the wood pellet thingy.
People in Europe must heat their water some way. And there has to be some repository between a well and a tap where the water is heated.

By: pete

pete — Wed, 02 Jul 2008 09:09:17 +0000

I hadn’t heard of Gordons idea before, but it makes lots of sense. Use solar panels to keep the hot water tank warm, then boost the temperature to “hot” using an instant gas or electric heater when it’s required. Very simple and efficient.

While electric showers do use shocking amounts of electricity (no pun intended), there’s no point in taking it out. It costs nothing to leave it installed, it’s a great standby if your other water heating systems (oil/immersion) break, and it can be very handy if someone needs a shower NOW and there’s no hot water in the tank.
For a single person, it’s probably cheaper to use an electric shower than incurr the losses of storing a tank-full of hot water, but for a family a ( well-insulated) tank makes much more sense.

On a pedantic technical note, if you have more than one electric shower the ESB installs a line than can supply a higher current, not a higher voltage. Yes, I know, I’m a nerd.