Gas boiler efficency

aboard_epsilon

After years of running paraffin heaters ..I know exactly how much it takes to keep my house warm WHAT EVER THE WEATHER.


however the stuff is becoming expensive and i need to move on...and the inconvenience and the palava is changing my mind.

My house is a well insulted , cavity wall, double glazing 3 bedroom semi.

my calculations are so .

outside ambient temp of 5 - 10 degrees ........need constant 2kW 24/7
outside ambient temp of 0 -5 degrees...........need constant 2.75 kw 24/7
outside windy temp 5 - 10 degress...............need constant 2.75 kw 24/7
outside ambient temp -5 -0 degrees..........need constant 3kw 24/7

Ive noticed when temp drops below zero degrees it never seems to be windy ..so above figures will do as good guide.

A GOOD PARAFFIN HEATER IS ABOUT 99 PERCENT EFFICIENT ..and they use roughly 0.1 litres per KWh of heat produced

at 64 pence per litre (BULK) that works out at 6.4 pence per KW inc vat..no fixed charge and almost zero servicing costs

bad points smelly........and turns the paintwork yellow qiucker..and would be a bit of a fire risk for some people.

BTW .........to use paraffin, house does need to be kept at one constant temperature 24/7 of about 17.5 -19 degrees to experience zero condensation problems..which i do..take it from me it works like that.

its also nice not to get up in the morning in a cold house ..which is just the way i like it.

bright sparks amongst you would have calculated that to be £30 a week to heat my house in constant outside ambient temps of 0 - 5 degrees...i don't know how that compares with gas

now then..

all gas boilers seem to start off with... the lowest i could find, being 4KW min (all the ones i can find so far that is )..........why is this ..........why cant i have one that starts off at 2 kw min ..and use it constantly at low settings rather than it turning on and off via thermostat..( turning on and off which is probably like you, using full throttle in a car to get from point A to point

Having not had a gas boiler before ..this is confusing to me ..as i see the most efficient way to run anything is constantly on and on the lowest setting possible to give the desired results .never open door for more that a few secs etc.and don't waste anything...........also...a constantly on boiler will last longer because its not going through thermal cycles all the time ..


What am i missing ..why cant someone design the above ..

is there something i don't understand ..

Please someone explain.

is there a boiler out there..that is cheap to buy ..and caters for my needs, in the above explained way.

all the best.markj

penrhyn

Are you planning to install gas central heating or what?

aboard_epsilon

The central heating is already in ..I have a parkray ..so all the pipes and rads are there .

its main fuel is anthracite... way to expensive ..it burns wood or coal as well , but too much work involved with wood ..no storage etc ..
hence i started on paraffin ..10 years ago when it was 15 pence a litre.

I've been looking at the whispergen as well ..but........when will it be available ...doupts hanging over its reliability ..price of spares..the price of the unit itself and if it broke down would you loose all the savings from it...despite the feed in tariff.

all the best.markj

Ben84

I'm sure you'd save money with natural gas on price per kW. I'm paying a 25p daily charge for connection to the pipes, and 2.5p a kW for the gas.

I really like the central heating because it's clean, safe and heats the house well. We have a back boiler which heats all the radiators in the house and has a radiant gas fire on the front. There's a programmer that we use to turn it on first thing in the morning for when we get up and run it for a few hours in the evening when it's cold. Aside from a bit of noise I really don't know it's there. No smoke, smells, fuel to handle or mess to clean up. It doesn't run constantly, but the heat is transferred quite efficiently as within a minute or two of the burner lighting up the radiators are hot. When the gas burner switches off the heat stored in water in the pipes/radiators isn't lost, it will still radiate in to the house, so you shouldn't lose energy by stopping and starting it, and you will not find the heating to feel uneven as this stored heat keeps radiating until the thermostat opens the gas burner again.

The often used car analogy for stopping and starting being less efficient doesn't really apply to much other than cars. When you stop a car you're converting motion in to friction/heat with the breaks, which is in this example not useful, so it is lost. Central heating doesn't suffer any conversion of energy in to non-useful forms when it stops, so nothing is lost. The benefit of the large burner is that when you switch the heating on it heats the house fast because it can deliver a big boost of energy, then maintain the temperature by switching on for a few minutes every now and then to keep the radiators hot. It also means that in very cold weather that the heating is powerful enough to keep the house warm if needed.

The only down side to central heating is that you cannot easily use the radiators individually, it's very much a whole house thing, and the boiler has a big gas burner (about 14 kW system installed in our 4 bedroom house). It's also very comfortable, which is where you might find your savings not so great. Having instant heat at the flip of a switch now has encouraged me to use more gas.

To give some idea of possible household consumption, during the coldest three months of this winter in our four bedroom house, not terribly well insulated, 1970s windows, back boiler from 1980 (about 60% efficient), we used the heating as much as we wanted and the gas bill averaged £25 a week. That also includes hot water and cooking.

Owain_Moneysaver

aboard_epsilon wrote: »

all gas boilers seem to start off with... the lowest i could find, being 4KW min (all the ones i can find so far that is )..........why is this ..........why cant i have one that starts off at 2 kw min ..and use it constantly at low settings rather than it turning on and off via thermostat..( turning on and off which is probably like you, using full throttle in a car to get from point A to point

Having not had a gas boiler before ..this is confusing to me ..as i see the most efficient way to run anything is constantly on and on the lowest setting possible to give the desired results .

Not so with condensing gas boilers - they are most efficient at peak load and once the load drops below a certain point they stop operating in condensing mode and get markedly less efficient.

aboard_epsilon

Well i have not a clue how the condensing boilers work ..or have i looked into it yet .

Ive only the facts about my paraffin heaters ..

and the facts Ive learnt along the way ..say that a continuous input of 2-3 kws 24/7 is all that is needed to keep my house cosy ..

Been on to Worcester tech department today .they reckon their latest boilers are good for 15 to 20 years ..can this be so?

So given those stats above in my first post can anyone recommend a system.........what range of boiler do i need .

I was looking at a Worcester 12RI boiler .....because of its low kw setting range..but Owain has just chucked that idea down the plug hole now, with saying that they work completely different than the way i originally imagined.

the truth is i don't know what i want ..

You see i also have a massive workshop ....i wouldn't mind heating that place as well....because as it is now ..i don't like going in there because its too cold ..

so Ive got the dilemma ....do i go with just heating the house ..with smallest most efficient unit available ..or do i think about my workshop.

All the best.markj

Cardew

aboard_epsilon wrote: »

Been on to Worcester tech department today .they reckon their latest boilers are good for 15 to 20 years ..can this be so?

Thats why they guarantee all their products for a whole - errr 2 years.

The truth is that all modern condensing boilers are stuffed full of electronics; and I suspect these electronic boards are a common item used by most manufacturers set up for a specific boiler.

These boards go faulty - or give a fault indication and a plumber has little option but to change the boards at a cost of £hundreds.

Even if you have a BG maintenance contract costing £200 pa or so they are reluctant to 'insure' if more than a few years old; and I believe that the very expensive items like heat exchanger are simply not covered after the manufacturer's guarantee has expired.

So in the name of progress we cannot get old fashioned non-condensing boilers that were good for 30 years and are compelled to have condensing boilers that have the reliability of a 1960's Skoda.

That's progress.

aboard_epsilon

Cardew wrote: »

Thats why they guarantee all their products for a whole - errr 2 years.

The truth is that all modern condensing boilers are stuffed full of electronics; and I suspect these electronic boards are a common item used by most manufacturers set up for a specific boiler.

These boards go faulty - or give a fault indication and a plumber has little option but to change the boards at a cost of £hundreds.

Even if you have a BG maintenance contract costing £200 pa or so they are reluctant to 'insure' if more than a few years old; and I believe that the very expensive items like heat exchanger are simply not covered after the manufacturer's guarantee has expired.

So in the name of progress we cannot get old fashioned non-condensing boilers that were good for 30 years and are compelled to have condensing boilers that have the reliability of a 1960's Skoda.

That's progress.

Well i cant afford to take knocks like that .Ive posted this in another forum...and I'm getting similar reports of unreliability issues ...and from worcester....maybe i should take another look at an efficient wood burner and have a storage shed built ..
what are the tariffs on wood burners ..are there any .

i know from expermentation ..that

to heat my house, a woodburner, only has to burn from 6pm untill 12am

and the heat is retained in the house untill fire-up the next day ....

consumption is £40 one wagon load of wood every 2.5 weeks on the coldest days .

EDIT 19 MARCH

wood burners ...30 percent grant available.

there is a catch...has to be installed by one of the "approved installers" which usually means that youre going to be paying 30 percent more for it anyway.

I cant win at this game, no matter how hard I try.


All the best.markj

Ben84

aboard_epsilon wrote: »

and the facts Ive learnt along the way ..say that a continuous input of 2-3 kws 24/7 is all that is needed to keep my house cosy ..

If you have a suitable chimney in the house, this output is within the range of a typical radiant gas fire with the white bricks. Radiant fires are also very efficient, 80% or more should be expected. Mine runs at 1.5 or 3 kW, and some do offer more settings.