# Oil or gas condensing boilers for UFH??? Which is cheaper to run??



## diverightin (14 Dec 2011)

I really need some expert advice here please as we're freeeeeezing!!! Our current oil fired central heating system is very expensive - an old firebird boiler outside heating a 2000 sqft house with underfloor heating. We use it very sparingly, only a couple of hours in the morning and again in the evenings, but it's so expensive. Instead of pouring more money into the oil tank we want to upgrade and get a condensing boiler and more efficient controls, but should we stick with oil or go LPG? We've had a few people in to look at our system and see how it can be upgraded, quotes range from over €5,000 (oil) to about €2,900 (gas). While installation costs are a factor (funds seriously low) it'we want to choose a system that will be efficient and cost less to run annually. We have thermostats throughout the house (four zones - it's a split level build).


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## diverightin (14 Dec 2011)

this 'gasSaver' sounds very interesting. if it does what it says on the tin, it would tip me in favour of LPG. Has anyone installed (or even heard of) these??
I can't post the link cause I'm a newbie but google 'Zenex GasSaver':
Basically "Most boilers, even high efficiency SEDBUK "A" rated condensing boilers,  still lose a substantial amount of heat through the flue outlet. The  GasSaver captures this heat and uses it to help generate hot water for  domestic use. The result is a *typical annual saving of 37%* of energy required to deliver hot water."


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## lowCO2design (14 Dec 2011)

have you considered that the boiler may not be your only problem?
I wonder what your 


insulation levels?
and air-tightness is like?
I would lay bets, they are not up to scratch. especially when you have a slow release heating element like under floor. 

along with an unsuitable means of delivering heat to the underfloor, insulation and air-tightness are the main causes of your troubles!

3.  so what year was your house built? 

4.  and what is your current spend on heating?

to answer your question a new boiler will reduce your bills by probably 20%

do you have space near where your boiler is? that you could consider installing a buffer tank (300l approx .5 x 1.8 + room for insulation and pipework) maybe in a utility type space? this would allow you more options than oil/gas, which are always going to be rising in cost.. 

think 'energy hierarchy' firstly:


reduce then need for heating, through maximising the building fabric potential (more insulation and reduced air-leakage (with appropriate ventilation)
use energy more efficiently - renewable source of fuel (timber?), heat generated efficiently (stove, pellet or gasification boiler), and deliver the heat appropriately (if your UFH is not doing it.. maybe its time to go back to rads! or if you get your air-tightness real low, maybe a mix of UFH and MVHR..)
lastly, get your energy requirements from a renewable resource (but we'll start with your heating for now)


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## diverightin (15 Dec 2011)

Hi, thanks for your reply. Our house was build in 2000, the entire house came in two containers from Canada (along with two canadian builders), so the insullation is to their country's specifications (basically, way more than we need for our moderate climate but no harm there), the house is air tight, windows are low e tripple glazed, and we also have a canadian heat recovery ventilator. The problem with heating the house stems from a poorly installed heat link underfloor system. It was a damn expensive system, top of the range at the time, but it was installed poorly by the Irish company and does not run efficiently. Also our old firebird oil boiler is outdooors, about 30 feet from the house and was laid in a inadequately insullated pipe - in the snow, for example, we can see a clear path from the boiler to the house. Makes me weep. This will all be upgraded. The boiler will be upgraded to a condensing boiler and moved against the house or indoors, and the heating controls will be upgraded/balanced etc. 
What I really need to know is, with all things being equal, which fuel is more economical to use - oil or LPG?
An expensive overhaul of our heating system (rads, as you suggested) or switching to geothermal/wood pellet boiler etc is just waaaaaaay out of our budget right now. We've had the various renewable energy people in during the past year or so to give us a quote but €15,000 approx is just not the kind of money we can gather for at least another few years. 
As for our oil usage - last year we used it very, very sparingly from October to April and it cost €1,000. In 2009, it cost us €2,000 (same period, but less sparingly - must have had a bit more money back then!!)
Thanks for your help


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## TripMeUp (15 Dec 2011)

Given last year's weather, €1000 was very good..!! Not too many woudl have grumbled at that I think..

I do note that you say you used it sparingly, so does that mean ye were cold in the house, say for example, during the very cold snap...?


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## diverightin (15 Dec 2011)

€1,000 was the lowest spend so far (10 years in the house), the average is €1,700. And yes it did mean that at times a portion of the house was colder than we would have liked. Last year, we had a nestor martin stove inserted into our open fire, which is situated in a large open plan space - basically our sitting room, kitchen and dining room, on split levels, with a high vaulted ceiling to the apex (it's at least a third of the overall floor space in the house). That stove heated this huge space very effectively, it was so warm by evening we'd have to open up the doors to the hallway. That saved our bacon last year on the many occasions we couldn't afford to drop €200/300 into the oil tank! And it's the only room in the house that has any heat right now. It's not good enough, we have to fix our heating issues and get our home warm again.
I've been doing a lot of calculations today, and here's what I've figured out:

[FONT=Verdana, Helvetica, Arial]Oil cost 0.85 cent (average) per litre (this price varies. It was 1 euro in April this year but has dropped since)

LPG gas cost 0.68 cent per litre (this is Calor’s price for customers converting from oil, it has not increased in 2.25 years, and is fixed at this price for the next 15 months)

There is up to 20% more heat in oil.

So to calculate the cost of the energy units you get per litre of fuel, you convert it to kilowatt hours.

Oil: 0.85 divided by 10.09 (kWh/litre). That’s 0.084. Multiply by 100 (to get the cent value) and it costs 8.4 cent per kWh.

Gas: 0.68 divided by 7.12 (this value is lower than oil because there’s less heat in gas). That’s .095, so it costs 9.5 cent per kWh

So if all things are equal – boilers running at equal efficiency etc - it would cost 1.1 cent more per kWh to use gas to heat the house.

However:

I'm told that gas condensing boilers are least 10% more efficient than the oil condenser boilers (which need a high temp for condensing to take palce) – so there’s an energy saving to be made there.

Also, carbon tax this March will put an addition 1.2 cent on a litre of oil, but only 0.4 cent on a litre of gas. This trend is bound to continue as oil will attract the higher tax as it's coinsidered 'dirtier' - correct me if I'm wrong on this 

I'm told that, in the past, those who sold home heating oil and installed oil heating systems were correct in stating that you get more heat from oil, ergo it’s cheaper to use. But these days, the new technology in gas condensing boilers has hugely increase efficiency, and oil is getting more expensive as a ‘dirty’ fuel attracting carbon taxes. This apparently has more than levelled the playing field.[/FONT] Of course, this info is coming from a Calor gas man.

It would be great to hear the opinion of someone in the oil heating business.......


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## micheller (15 Dec 2011)

Condensing gas boiler is pretty good, we're using
- Condensing boiler
- Thermostat on Boiler, and UFH system
- Thermostats in the main zones
- Timer

If you are in NE and need a recommendation I can let you know who did ours and very happy with their work.


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## diverightin (15 Dec 2011)

Micheller, that would be the exact set up we'd be looking at installing.  How large is your house and how much is it costing you to heat  annually? Thanks for letting me pick your brains!! ;-)


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## Baile (18 Feb 2012)

Hi, 

I'm building a new house and am looking for advice on oil condenser boilers. The house is approx 4,000sqft and we want to have ufh. We've looked at geothermal but it will cost 30k to install which is too much. The other option is ufh with an oil condenser boiler. 

Does anyone have advice on these, which boilers are best and how are the running costs. We have good insulation and good windows and are going to air seal the house too so heat loss should be minimal. 

Any help/advice would be really appreciated.


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## burmo (19 Feb 2012)

Comparison costs for different kinds of fuel:

[broken link removed]


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## Shane007 (19 Feb 2012)

I haven't seen this chart before but it is bang on. Well done Burmo. Natural gas is indeed the cheapest form energy overall. LPG is one of the most expensive. What seems to be cheap is not as considerations must also be taken into account for tank rental, etc. Oil delivered cost 8.46cent/kwh compared with 12.54cent/kwh for LPG. That is 50% more!

Gas condensing boilers are not more efficient than oil condensing boilers, in fact they are pretty much equal, in oil not a little more efficient, however, the grat advantage of a gas boiler over an oil boiler is that they can modulate. This makes their usage more efficient in that they can turn down their output when demand is lowered, i.e. when only one zone is demanding heat.

In the pipeline, there will be a Riello retrofit modulating oil burner released to suit condensing boilers. About a couple of years away. This will have a fantastic affect on the industry as it will really highlight the importance of zoning.

UFH is notorious for using kerosene on poorly controlled systems and espcially if the oil boiler is 30ft away from the house. I would very much either bring ther boiler to the house or replace the underground pipework with zero loss pipework. This is expensive pipe but it only loses 1C over 50m. You are heating a second house in the ground! You could indeed change to LPG but unless you address the other issues then you make be reverting back to replacement again.

I know many people on LPG that in a typically sized house are paying €150 per month standing order plus get €1,100 at the end of the year as they have been under-paying. 

My advice is do some more homework and have your UFH controls looked at.


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