Stove Cost Calcs

GTE

Hi all,

I want to seriously delve into the costs involved with the heating stoves, and the ones which hook up to central heating.

The overall cost is one thing, but I am trying to work out the maths of it all in terms of cost savings.

For example, I worked out how long it would take for the savings in fuel to cover the cost of a basic bog standard stove. I looked up average efficiency of open fires and basic stoves and worked out how much the stove would save us each year.

What I am wondering now, are the stoves with central heating hooked into it.

So, if we take the amount of fuel to heat the sitting room as X; would a stove which needs to heat a house with ~11 rads use more or less than X?

If a bog standard stove used Y amount of fuel to heat the room, would a stove with central heating still only need Y for reasonable house heating, or would the people in the sitting room notice a colder room from using Y fuel as the rest of the house takes what it needs?

With these points answered (and perhaps others which users here think are useful), I can then figure out how long it would take to pay off the investment in saved fuel costs.

I am thinking no gas bill, aside from what is needed to cook. A lower electric bill for heating the water tank, if the stove can meaningfully contribute to the heating of that.

Would it even be the case that gas plus electric would just be cheaper than solid fuel, in the first place?

I am looking forward to working it out; whether the higher ups in the family agree to the work is another thing!

Thanks!

MicktheMan

You are over complicating the task at hand.

If I understand your post, you are trying to work out what the payback period would be of installing a stove and using it to heat the house instead of an already installed gas central heating system.

It boils down to the efficiency of each appliance and the unit cost per kWhr for each fuel type.

As an example:

Stove efficiency 70%; unit cost of wood 10 cent/kWhr; unit cost of coal 6 cent/kWhr

Gas boiler efficiency 85%; unit cost of natural gas 7.5 cent/kWhr

So for each kWhr of heat required it would cost:
Wood: 14.3 cent
Coal: 8.6 cent
Natural gas: 8.8 cent

So, depending on the heat demand of the house you can work out the math (if you know the BER figure then you can guesstimate your heat demand).

Note: I have intentionally excluded the distribution losses and pump costs as these would be similar.

You then also need to factor in the "cost" associated with having to manually feed the stove with fuel, cleaning out the stove, fuel storage, control-ability and automation.

GTE

Thanks for the reply.

It is difficult for me to translate your post into what I was trying to figure out. How open to error would the cent to kWhr be with respect to local fuel costs and appliance efficiency?

My premise is that the open fire uses X amount of fuel to heat the sitting room every Winter. What I need to know is whether the stove which is integrated into the central heating will use more or less fuel per Winter when heating the house, in like-for-like comparisons of the real world.

At the moment, the open fire is used as the older family like having the fire and a bit of extra heat compared to the central heating, so the cost of maintaining it is nil, from their point of view.

With the sitting room used so much and the fire used so regularly in the Winter, a stove which would could heat the house but use less fuel than the open fire does now would benefit the rest of the house as it would kill the need for the gas heating in the evening/night times, which is just a two to three hours. If the stove with central heating would return that kind of cent to kWhr figure, then I think the savings of Open Fire Fuel Savings + Lessened Use of Gas Savings would combine to offset the cost of installation, each year.

Tis what I think anyway. I need to find some bills!

The BER of another house in the estate is C3.

Thanks

GTE

These figures have not been checked by me, but according to the higher ups, they spend around 861 euro per year of fuel for the open fire.

By my maths, 680ish is being wasted due to the open fire being approx 20% efficient.
The same fuel being consumed by a stove (no central heating) would result in around 170 wastage, at 80%, but that fuel should last for much longer. 4 times longer? I am not sure if I am right there.

whizbang

Also factor in the amount of heat lost to an open chimney, when the fire is not in use.
A stove should seal off this airflow, so will reduce heat lost.

Regarding fuel for the stove, you may be able to obtain wood at a lower price, so that's more confusion for you.

I suspect the benefit of a boiler stove Vs a non-boiler model is down to usage and preferences. If you only want heat for a few hours in the evening, then a boiler stove is prob not the way to go, certainly in payback terms.

antoinolachtnai

Unless you are getting the fuel for free, you are probably not going to get any saving. Even if it is 'free', you still have to transport it, store it and dry it. There is all the trouble of manually handling the wood and the ashes. Gas or oil is pretty cheap at the moment by contrast and there is no manual handling involved.

If you want to invest to save money, I would try to get your heating system set up so that the hot water can be heated using gas throughout the year. Insulating the house is also going to give a much faster return.